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- Herausgeber: John Wiley & Sons
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Discover the future of medicine in this extensively updated edition of the pioneering textbook, reflecting the rapid progress in the field
Molecular medicine is a rapidly growing field, and the molecular basis of diseases can be used to develop therapeutic approaches in numerous other medical subfields. Research into molecular medicine has been used as the basis for gene therapy, precision medicine, and more. Molecular Medicine provides a fundamental overview of this cutting-edge, interdisciplinary field, incorporating modules from basic immunology to virology to new approaches. Now fully updated to reflect the exponential progress in biomedical research, it promises to put students on the leading edge of a revolution in the life sciences.
Readers of the second edition of Molecular Medicine will also find:
- Detailed discussion of cutting-edge topics including cancer stem cells, mRNA vaccines, organs-on-a-chip, and more
- Professional artwork throughout
- Chapter summaries, exercises, and study questions for each chapter
Molecular Medicine is ideal for graduate students in life sciences and medicine, as well as the lecturers and libraries that support them.
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Seitenzahl: 1303
Veröffentlichungsjahr: 2025
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
Acknowledgments
About the Companion Website
Chapter 1: Introduction
1.1 The Basics of Molecular Medicine
1.2 The Human Cell
1.3 DNA Replication and Gene Expression
1.4 Biological Communication
1.5 The Immune System
References
Further Reading
Acknowledgments
Exercises
Study Questions
Chapter 2: Methods in Molecular Medicine
2.1 DNA Microarrays
2.2 Quantitative Polymerase Chain Reaction
2.3 Next-generation Sequencing
2.4 Proteomics
2.5 Animal Models in Biomedical Research
2.6 Alternatives to Animal Testing
2.7 Additional Methods
References
Further Reading
Exercises
Study Questions
Chapter 3: Genetic Disorders
3.1 Single-gene Disorders
3.2 Polygenic Disorders
References
Further Reading
Exercises
Study Questions
Chapter 4: Molecular Oncology
4.1 Basics of Oncology
4.2 Selected Cancer Diseases
4.3 Oncolytic Virus Therapy
4.4 Cancer Stem Cells
4.5 Cancer Immunotherapy
References
Further Reading
Acknowledgments
Exercises
Study Questions
Chapter 5: Molecular Virology
5.1 The Basics of Virology
5.2 Vaccination
5.3 Detection of Viruses
5.4 Antiviral Therapy
5.5 Prions
References
Further Reading
Exercises
Study Questions
Chapter 6: Bacteria and Eukaryotic Pathogens
6.1 Bacteria
6.2 Eukaryotic Pathogens
References
Further Reading
Exercises
Study Questions
Chapter 7: Genomics
7.1 Whole Genome Sequencing
7.2 The Human Genome
7.3 Sequencing of Ancient DNA
7.4 Follow-up Initiatives of the Human Genome Project
References
Further Reading
Exercises
Study Questions
Chapter 8: Genetic Testing
8.1 Types of Genetic Tests
8.2 Chromosome Abnormalities
8.3 Molecular Diagnosis
References
Further Reading
Exercises
Study Questions
Chapter 9: Pharmacogenetics/Pharmacogenomics
9.1 Uptake and Transport of Drugs
9.2 Drug Metabolism
9.3 Drug Targeting
9.4 Drug Toxicity and Hypersensitivity
9.5 Drug Development and Individual Pharmacotherapy
References
Further Reading
Exercises
Study Questions
Chapter 10: Recombinant Protein Drugs
10.1 Production of Recombinant Proteins
10.2 Classes of Recombinant Drugs
References
Further Reading
Exercises
Study Questions
Chapter 11: Gene Therapy
11.1 Types of Gene Therapy
11.2 Methods of Gene Transfer
11.3 Tissue Specificity of Gene Transfer and Gene Expression
11.4 Applications of Gene Therapy
11.5 Genome Editing with CRISPR/Cas
11.6 Future Prospects
References
Further Reading
Exercises
Study Questions
Chapter 12: Stem Cells
12.1 Embryonic Stem Cells
12.2 Adult Stem Cells
12.3 Induced Pluripotent Stem Cells
12.4 Transdifferentiation and Direct Reprogramming
12.5 Differentiation of Stem Cells
12.6 Medical Applications of Stem Cells
References
Further Reading
Exercises
Study Questions
Chapter 13: Oligonucleotide-based Strategies
13.1 Antisense Oligonucleotides (ASOs) and Ribozymes
13.2 RNA Interference
13.3 MicroRNAs
13.4 Aptamers, Decoy Oligonucleotides, and Immunostimulatory Oligonucleotides
References
Further Reading
Exercises
Study Questions
Chapter 14: Ethics in Molecular Medicine
14.1 The Basis of Bioethics
14.2 Fields of Application
Further Reading
Exercises
Study Questions
Abbreviations
Glossary
Index
End User License Agreement
List of Illustrations
Chapter 1
Figure 1.1 Small molecular drugs and biologics. (a) The chemical structures of ...
Figure 1.2 Stages of drug development. The preclinical stages comprise the iden...
Figure 1.3 Diagram of a typical eukaryotic cell. Membrane-bound organelles incl...
Figure 1.4 Cell nucleus and chromatin organization. (a) The nucleus is surround...
Figure 1.5 The mitochondrion. The mitochondrion is bounded by two membranes. Th...
Figure 1.6 Endoplasmic reticulum (ER) and Golgi apparatus. The ER and the Golgi...
Figure 1.7 The cell cycle. The eukaryotic cell cycle is divided into three main...
Figure 1.8 Extrinsic and intrinsic pathways of apoptosis. Programmed cell death...
Figure 1.9 The central dogma of molecular biology. DNA is copied in a process k...
Figure 1.10 Replication fork. Two DNA polymerase enzymes synthesize the new DNA ...
Figure 1.11 Telomerase. Telomerase is a cellular reverse transcriptase that exte...
Figure 1.12 Types of mutations. Substances such as nitrous acid can induce point...
Figure 1.13 Model of transcription. The DNA is shown in blue and the growing RNA...
Figure 1.14 Posttranscriptional processing of pre-mRNA. The products of transcri...
Figure 1.15 The splicing reaction. In the first step, U1-snRNP binds to the 5′ s...
Figure 1.16 Alternative splicing. (a) Exon skipping. Exon skipping is the most c...
Figure 1.17 Cloverleaf structure of a tRNA. Blue circles show nonmodified RNA nu...
Figure 1.18 DNA methylation and histone modification are the main mechanisms of ...
Figure 1.19 Subcellular localization of transcription, RNA processing, and trans...
Figure 1.20 Protein biosynthesis by ribosomes. Ribosomes elongate polypeptides i...
Figure 1.21 Protein degradation by the proteasome. (a) Attachment of ubiquitin t...
Figure 1.22 Structure of a chemical synapse. At the synapse, the presynaptic neu...
Figure 1.23 Classification of hormones. (a) Hormones can be grouped into endocri...
Figure 1.24 G protein-coupled receptors and the adenylate cyclase (AC) signaling...
Figure 1.25 Formation and hydrolysis of cyclic AMP (cAMP). Adenylate cyclase con...
Figure 1.26 Hematopoiesis. Multipotent hematopoietic stem cells differentiate in...
Figure 1.27 Cells of the immune system. The cells of the innate immune system in...
Figure 1.28 Phagocytosis. Bacteria are recognized by special pattern recognition...
Figure 1.29 Complement system. (a) The complement system can be activated by the...
Figure 1.30 Interaction between T cells and APCs. T cell receptors (TCRs) and CD...
Figure 1.31 The function of T helper cells (T
h
cells). T
h
cells are activated by...
Figure 1.32 B cell activation. Activation of a B cell includes recognition of th...
Figure 1.33 Structure of immunoglobulin G (IgG). An antibody is made up of two i...
Chapter 2
Figure 2.1 Basic principle of DNA array technology. A large number of DNA seque...
Figure 2.2 Methods of genotyping by DNA arrays. (a) Direct hybridization. A flu...
Figure 2.3 Principle of two-color microarrays. Two-color microarrays can be use...
Figure 2.4 Scatterplot of a DNA microarray experiment. The relative expression ...
Figure 2.5 Heat map of a DNA array analysis. Relative expression is shown for 7...
Figure 2.6 The polymerase chain reaction (PCR). (a) A typical PCR cycle consist...
Figure 2.7 Reverse-transcription PCR (RT-PCR). RT-PCR experiments start with th...
Figure 2.8 Typical fluorescence signal of a qPCR run. The fluorescence intensit...
Figure 2.9 Principle of double-stranded DNA-binding dyes as reporters. The dye ...
Figure 2.10 Melting curve analysis of real-time PCR experiments. (a) Melting cur...
Figure 2.11 Fluorescent reporter probes. (a) 5′ Exonuclease assay (TaqMan assay)...
Figure 2.12 DNA sequencing by the chain-terminator method. (a) Dideoxynucleotide...
Figure 2.13 Pyrosequencing. (a) Reaction scheme of pyrosequencing. The four nucl...
Figure 2.14 Emulsion PCR (EmPCR). The fragmented genomic DNA is ligated to adapt...
Figure 2.15 Principle of Illumina sequencing. (a) Example of a reversible termin...
Figure 2.16 (a) Basic principle of SOLiD sequencing. Primers are added to the ta...
Figure 2.17 Single-molecule real-time (SMRT) DNA sequencing. The reaction is car...
Figure 2.18 Principle of nanopore sequencing. A voltage is applied across a memb...
Figure 2.19 Methods used for exome capture. (a) Solid-phase hybridization. For s...
Figure 2.20 Caterpillar and imago of the swallowtail. The caterpillar and the im...
Figure 2.21 Separation of differentially expressed proteins by two-dimensional (...
Figure 2.22 Matrix-assisted laser desorption/ionization–time-of-flight (MALDI–TO...
Figure 2.23 Methods for isotopic labeling of proteins. For metabolic labeling, c...
Figure 2.24 Workflow of shotgun proteomics. In the first step, cells are extract...
Figure 2.25 Generation of transgenic mouse models. (a) Generation of transgenic ...
Figure 2.26 Methods for conditional gene inactivation. (a) Cre/lox system. Cre r...
Figure 2.27 Three-dimensional human skin model EpiDerm.
Figure 2.28 Schematic representation of the most commonly used bioprinting techn...
Figure 2.29 Human-on-a-chip. The envisioned human-on-a-chip device consists of t...
Figure 2.30 Fluorescence microscopy. (a) Setup of an epifluorescence microscope....
Figure 2.31 Fluorescence-activated cell sorting (FACS). The cell suspension flow...
Figure 2.32 Principle of surface plasmon resonance (SPR) experiments. (a) The Kr...
Chapter 3
Figure 3.1 Pedigree depicting Mendelian inheritance. Affected individuals are i...
Figure 3.2 Molecular defects in Prader–Willi syndrome (PWS) and Angelman syndro...
Figure 3.3 Receptor-mediated endocytosis of low-density lipoproteins (LDL). The...
Figure 3.4 Gross pathology of polycystic kidneys.
Figure 3.5 DNA triplet repeats in Huntington’s disease (HD). The genetic basis ...
Figure 3.6 Functional deficiency of the mutant CFTR channel. The normal CFTR ch...
Figure 3.7 Tay–Sachs disease. (a) The disorder is caused by a deficiency in hex...
Figure 3.8 Phenylketonuria (PKU) and the metabolism of phenylalanine. Phenylala...
Figure 3.9 Model of the nucleotide excision repair (NER) mechanism. A lesion in...
Figure 3.10 Recombination events in red and green photoreceptor genes. Opsin gen...
Figure 3.11 The muscular dystrophies. Dystrophin connects the intracellular acti...
Figure 3.12 A typical pedigree of an inherited mitochondrial disease. Mutations ...
Figure 3.13 Diseases associated with defects in the respiratory chain. Disorders...
Figure 3.14 Diabetes mellitus as a complex disease. Interactions between multipl...
Chapter 4
Figure 4.1 Hallmarks of cancer. Cancers typically have acquired a common set of...
Figure 4.2 Major anti-HER therapies. Upon ligand binding, HER2 receptors are ac...
Figure 4.3 Interferon binding to cellular receptors leading to STAT signaling. ...
Figure 4.4 Vogelstein colorectal carcinogenesis model. The sequential accumulat...
Figure 4.5 APC mutation and the β-catenin pathway. Mutations in the
APC
gene re...
Figure 4.6 The epidermal growth factor receptor pathway: EGFR activates the RAS...
Figure 4.7 Androgen receptor signaling. Testosterone circulates in the blood bo...
Figure 4.8 Pathway of steroidogenesis.
Figure 4.9 Mechanisms of castration resistance. During the progression of castr...
Figure 4.10 Karyotypes of patients with chronic myelogenous leukemia (CML). (a) ...
Figure 4.11 Fluorescence
in situ
hybridization (FISH) for a normal and chronic m...
Figure 4.12 Oncolytic viruses. The viruses can infect normal and tumor cells but...
Figure 4.13 The clonal evolution and cancer stem-cell (CSC) models. (a) Accordin...
Figure 4.14 CAR-T cell therapy. A chimeric antigen receptor (CAR) consists of an...
Figure 4.15 Immune checkpoint proteins. (a)The binding of a T cell to an antigen...
Chapter 5
Figure 5.1 Basic structure of a virus. The genome of the virus is shielded by a...
Figure 5.2 Shapes of viruses. Viruses vary in size as well as shape.
Figure 5.3 General steps of a viral life cycle. Viruses enter the host cell and...
Figure 5.4 Time course of HIV infection. The time course shows the viral load (...
Figure 5.5 Structure and genome of HIV-1. (a) Genomic RNA is surrounded by a co...
Figure 5.6 The HIV life cycle. After attachment and entry into the cell, the vi...
Figure 5.7 SARS-CoV-2 organization and life cycle. SARS-CoV-2 enters the cell t...
Figure 5.8 Structure of the hepatitis B virus. The genome of HBV is comprised o...
Figure 5.9 The structure of the influenza A virus. The influenza A virus has a ...
Figure 5.10 Antigenic shift. The antigenic shift represents a major change in a ...
Figure 5.11 Edward Jenner performed his first vaccination on James Phipps, a boy...
Figure 5.12 Types of vaccines. Vaccines can be grouped into live vaccines (atten...
Figure 5.13 Polio vaccines. (a) The attenuated live (Sabin) vaccine is given ora...
Figure 5.14 HPV vaccine. Sexually transmitted HPV can lead to malignant transfor...
Figure 5.15 mRNA vaccine. Left part: first-generation mRNA vaccines do not repli...
Figure 5.16 Electron micrograph of poliovirus 1 particles.
Figure 5.17 Enzyme-linked immunosorbent assay (ELISA). (a) The antigen or sandwi...
Figure 5.18 Rapid antigen test. The rapid antigen test detects the presence or a...
Figure 5.19 Chemical structure of some important antiviral substances. The pepti...
Figure 5.20 Mode of action of Aciclovir. Aciclovir (acycloguanosine) is administ...
Figure 5.21 Inhibition of HIV. Antiviral drugs intervene at various points of th...
Figure 5.22 Enfuvirtide. The viral glycoproteins gp120 and gp41 interact with th...
Figure 5.23 Neuraminidase inhibitors. (a) Mode of action of neuraminidase inhibi...
Figure 5.24 Prion protein conformations. (a) The cellular conformation of the pr...
Chapter 6
Figure 6.1 Major classes of pathogens. Viruses are the smallest pathogens conta...
Figure 6.2 Gram-positive and Gram-negative bacteria. (a) Gram-positive bacteria...
Figure 6.3 Typical shapes of bacteria. Bacteria have a spheroidal (coccus), rod...
Figure 6.4 The plague doctor. The copper engraving shows Doctor Schnabel, a pla...
Figure 6.5 Endotoxins and exotoxins. Endotoxins are part of the bacteria and ar...
Figure 6.6 Lipopolysaccharides. Lipopolysaccharides (LPS) are found in the oute...
Figure 6.7 Penicillin G and ampicillin. Penicillin G and ampicillin differ only...
Figure 6.8 Cellular targets of antibiotics. The major targets of antibiotics ar...
Figure 6.9 Examples of antibiotics. (a) β-Lactam antibiotics are characterized ...
Figure 6.10 Antibiotics bind to the prokaryotic ribosome. Structural elucidation...
Figure 6.11 Mechanisms of resistance against antibiotics. (a) Initially, antibio...
Figure 6.12 The Plasmodium life cycle.
P. falciparum
, the most dangerous malaria...
Chapter 7
Figure 7.1 Cloning of a DNA fragment into a plasmid. A standard plasmid encodes...
Figure 7.2 Chromosome walking and shotgun sequencing. (a) For chromosome walkin...
Figure 7.3 Assembly of large genomes by the clone contig and the whole genome s...
Figure 7.4 Composition of the human genome. Approximately half of the human gen...
Figure 7.5 Potential drug targets for small-molecular-weight drugs. Only human ...
Figure 7.6 Family tree of the genus Homo. Modern humans (
Homo sapiens
), Neander...
Figure 7.7 Svante Pääbo with a model of a Neanderthal skull.
Figure 7.8 Inheritance of haplotype blocks. The schematic representation depict...
Figure 7.9 Analysis of the functional elements in the human genome by the ENCOD...
Figure 7.10 Computer models for personalized medicine. Reference datasets and in...
Chapter 8
Figure 8.1 Sampling of cells for prenatal diagnosis. (a) Chorionic villus sampl...
Figure 8.2 Structural chromosome abnormalities. Alterations of chromosomal stru...
Figure 8.3 Trisomy 21 diagnostic methods. (a) Karyogram of a Trisomy 21 female....
Figure 8.4 FISH analysis for the
dystrophin
gene. (a) In a normal control, the ...
Figure 8.5 Fluorescence karyotyping of normal and cancer cells. (a) Spectral ka...
Figure 8.6 Array comparative genomic hybridization (aCGH). Whole genomic DNA fr...
Figure 8.7 PCR-based genetic testing. (a) Amplification refractory mutation sys...
Figure 8.8 Multiplex ligation-dependent probe amplification (MLPA). MLPA is car...
Figure 8.9 DNA microarray-based risk assessment. RNA isolated from a surgical t...
Figure 8.10 Sequencing of PCR fragments. Either the segment that carries a poten...
Chapter 9
Figure 9.1 Dose curves of drug response. (a) All drugs have dose-dependent ther...
Figure 9.2 P-glycoprotein. PGP homodimer pumps xenobiotics, including many drug...
Figure 9.3 Adjustment of drug dose according to genotype. For debrisoquine, the...
Figure 9.4 Conversion of codeine to morphine. CYP2D6 catalyzes the demethylatio...
Figure 9.5 Metabolism of tamoxifen. Tamoxifen is an inactive prodrug. Two CYP p...
Figure 9.6 Inactivation of 6-mercaptopurine. The cytostatic drug 6-mercaptopuri...
Figure 9.7 Metabolization of paracetamol. The three hepatic CYP proteins CYP2E1...
Figure 9.8 Variations in the drug target. The drug (red triangle) binds to its ...
Figure 9.9 Analysis of Her2 expression levels. Only those breast cancers overex...
Figure 9.10 The EGFR signaling cascade. The binding of the epidermal growth fact...
Figure 9.11 Simplified mechanism of action and metabolization of warfarin. Warfa...
Chapter 10
Figure 10.1 Plasmid for gene expression in
Escherichia coli
. At a minimum, stand...
Figure 10.2 PEGylation of proteins and peptides. (a) Chemical structure of polye...
Figure 10.3 Advantages and disadvantages of host organisms for the recombinant e...
Figure 10.4 Bioreactor. Microorganisms are usually cultivated in a sterile, clos...
Figure 10.5 Inclusion bodies. (a) Electron micrograph of inclusion bodies in
Esc
...
Figure 10.6 Pronuclear microinjection. The genetic material is directly injected...
Figure 10.7 Cloning by somatic cell nuclear transfer (SCNT). The nucleus of a so...
Figure 10.8 Types of mAb therapeutics. Therapeutic mAbs are typically immunoglob...
Figure 10.9 Generation of monoclonal antibodies. The injection of antigen X into...
Figure 10.10 Design of improved mAbs. The first mAbs were of murine origin and in...
Figure 10.11 Basic principles of phage display. (a) Antibody genes for the variab...
Figure 10.12 Nanobody. Nanobodies are derived from camelid antibodies that consis...
Figure 10.13 Biosynthesis of insulin. The first step in insulin biosynthesis is t...
Figure 10.14 Activity profile of insulin and various analogs.
Figure 10.15 Immunodetection of EPO. Concentrated proteins from the urine are sep...
Figure 10.16 Structure of etanercept. The fusion protein consists of the extracel...
Figure 10.17 Simplified representation of the blood coagulation pathway. The coag...
Figure 10.18 Tissue-type plasminogen activator (tPA). (a) Simplified illustration...
Figure 10.19 Image of the common vampire bat
D. rotundus
.
Chapter 11
Figure 11.1 Principles of gene therapy. Due to a defective gene, a protein may n...
Figure 11.2
Ex vivo
and
in vivo
gene therapy. In
ex vivo
gene therapy, cells are...
Figure 11.3 Gene therapy vectors used in clinical studies.
Figure 11.4 Composition and production of viral vectors. For gene transfer, the ...
Figure 11.5 Use of retroviral vectors for gene therapy. The retroviral genes are...
Figure 11.6
Ex vivo
gene therapy with retroviral vectors. Hematopoietic stem cel...
Figure 11.7 Development of adenoviral vectors. In first-generation adenoviral ve...
Figure 11.8 Self-complementary adeno-associated virus (AAV) vectors. Single-stra...
Figure 11.9 Tissue tropism of AAV vectors derived from distinct capsids. AAV vec...
Figure 11.10 Application of plasmid DNA. The DNA is either injected via a syringe...
Figure 11.11 Production of minicircle DNA vectors. Initially, the parental plasmi...
Figure 11.12 Sleeping Beauty transposon system. The expression cassette of the th...
Figure 11.13 Muscle growth in mice. Shown is a comparison of wild-type mice with ...
Figure 11.14 Specificity of gene transfer. The specificity of the expression of a...
Figure 11.15 Clinical targets of gene therapy. More than two-thirds of the gene t...
Figure 11.16 Gene types transferred in gene therapy clinical trials. “Deficiency”...
Figure 11.17 Function of the tumor suppressor p53. Under normal conditions, p53 i...
Figure 11.18 Bystander effect. If there were no intercellular connections, the pr...
Figure 11.19 Targeted genome editing with RNA-guided Cas9. Cas9 is a DNA endonucl...
Chapter 12
Figure 12.1 Cell potency. Fertilization of an egg by a sperm cell generates the ...
Figure 12.2 Isolation and properties of embryonic stem cells (ESCs). ESCs are ty...
Figure 12.3 Human embryonic stem cell (hESC). The image shows a colony of hESC, ...
Figure 12.4 Therapeutic cloning. Therapeutic cloning aims to generate autologous...
Figure 12.5 Asymmetric and symmetric modes of stem cell division. (a) Asymmetric...
Figure 12.6 Generation of induced pluripotent stem cells (iPSCs). The initial st...
Figure 12.7 Direct reprogramming of fibroblasts into cardiomyocytes. Overexpress...
Figure 12.8 Directed differentiation of therapeutically relevant lineages from p...
Figure 12.9 Directed differentiation of pluripotent stem cells. The chart shows ...
Figure 12.10 Bioengineered tooth. The images compare natural and bioengineered to...
Figure 12.11 Production of stem cell burgers. The production of stem cell burgers...
Figure 12.12 Medical usage of induced pluripotent stem cells (iPSCs). In the exam...
Figure 12.13 Potential uses of cells differentiated from pluripotent stem cells.
Chapter 13
Figure 13.1 Localization of aptamers and anti-messenger RNAs (mRNA) oligonucleot...
Figure 13.2 Anti-messenger RNAs (mRNA) strategies. Posttranscriptional silencing...
Figure 13.3 Antisense oligonucleotides (ASO). An ASO binds to a target RNA to in...
Figure 13.4 The mechanism of action of antisense oligonucleotides. (a) RNase H r...
Figure 13.5 Correction of splicing by an antisense oligonucleotide (ASO). In the...
Figure 13.6 Structure of messenger RNAs (mRNAs). mRNAs are often regarded as lin...
Figure 13.7 Structures of modified nucleotides. The figure shows selected struct...
Figure 13.8 Design of a gapmer. In gapmers, modified building blocks are located...
Figure 13.9 Picture of antisense oligonucleotides (ASOs) in the dorsal root gang...
Figure 13.10 Exon-skipping strategy using antisense oligonucleotides (ASOs). The ...
Figure 13.11 Secondary structure model of the hammerhead ribozyme. The ribozyme c...
Figure 13.12 Silencing of green fluorescent protein (GFP) in
Caenorhabditis elega
...
Figure 13.13 Mechanism of RNA interference (RNAi). The nuclease Dicer processes t...
Figure 13.14 Design of a small interfering RNA (siRNA). Standard siRNAs consist o...
Figure 13.15 Comparison of the mechanisms of antisense and RNA interference (RNAi...
Figure 13.16 Small interfering (siRNA)- and short hairpin (shRNA)-induced RNA int...
Figure 13.17 Composition of an artificial MicroRNA (miRNA). On the left side of t...
Figure 13.18 Off-target effects of small interfering RNAs (siRNAs). A study analy...
Figure 13.19 Nonviral delivery of small interfering RNAs (siRNAs). (a) Lipoplex: ...
Figure 13.20 Viral delivery of short hairpin RNA (shRNA) expression cassettes. Le...
Figure 13.21 Structure of the CALAA-01 nanoparticle for the targeted delivery of ...
Figure 13.22 Structure of trimeric
N
-acetylgalactosamine (GalNAc). The GalNAc moi...
Figure 13.23 Permanent hair removal by small interfering RNAs (siRNAs). The siRNA...
Figure 13.24 Comparison of small interfering RNAs (siRNAs) and microRNAs (miRNAs)...
Figure 13.25 MicroRNA (miRNA) pathway. (a) miRNAs are initially generated as long...
Figure 13.26 Mechanisms of microRNA (miRNA)-mediated gene silencing. (a) Repressi...
Figure 13.27 Comparison of microRNA (miRNA) expression levels between normal and ...
Figure 13.28 Association between various disease states and microRNA (miRNA) dysr...
Figure 13.29 Interaction of microRNA 122 with the 5′ untranslated region of the h...
Figure 13.30 The size of aptamers. Aptamers can function as ligands, binding part...
Figure 13.31 Organization of a riboswitch. The riboswitch is usually located in t...
Figure 13.32
S
ystematic
E
volution of
L
igands by
EX
ponential enrichment (SELEX). A...
Figure 13.33 Cell-based aptamer selection. For a cell-based
S
ystematic
E
volution ...
Figure 13.34 Stabilization of aptamers by the introduction of modified nucleotide...
Figure 13.35 Stereochemistry of Spiegelmers. Reciprocal specificities of aptamers...
Figure 13.36 Selection of a Spiegelmer. After the production of the mirror image ...
Figure 13.37 Visual acuity of patients with wet age-related macular degeneration ...
Figure 13.38 Reversal of aptamer activity by an antidote. (a) The PEGylated aptam...
Figure 13.39 Decoy oligonucleotide strategy. The figure shows an approach to sile...
Figure 13.40 Toll-like receptor (TLR) family. TLRs1, 2, 4, 5, and 6 are located a...
Figure 13.41 Activation of plasmacytoid dendritic cells (pDC) and B cells by diff...
Chapter 14
Figure 14.1 Immanuel Kant (1724–1804). Kant was a German philosopher and is ofte...
Figure 14.2 Hans Jonas (1903–1993). The philosopher Hans Jonas was among the fir...
Figure 14.3 Embryo biopsy. At day 3 of its development, the embryo consists of a...
Figure 14.4 Uses of laboratory animals. (a) Percentage of animals used for resea...
List of Tables
Chapter 1
Table 1.1 Eukaryotic RNA polymerases.
Table 1.2 Functions of the eukaryotic general transcription factors.
Table 1.3 The genetic code.
Table 1.4 Characteristics of major neurotransmitters.
Chapter 3
Table 3.1 Examples of single-gene disorders.
Table 3.2 Correlation of repeat numbers, phenotype, and risk to offspring in H...
Table 3.3 Some examples of mitochondrial diseases.
Chapter 4
Table 4.1 Risk factors for HCC.
Table 4.2 New cases and deaths for the most common hematological malignancies ...
Chapter 5
Table 5.1 Selected viruses with high clinical importance.
Table 5.2 Genomic organization and structural characteristics of virus familie...
Table 5.3 Selection of licensed vaccines.
Table 5.4 Selection of approved antiviral drugs.
Chapter 7
Table 7.1 Genome size, protein-coding percentage of the genome, and predicted ...
Chapter 8
Table 8.1 Classification of different medical genetic tests.
Chapter 9
Table 9.1 Examples of drugs for which pharmacogenetic tests are indicated.
Chapter 10
Table 10.1 Selection of PEGylated proteins and peptides in clinical practice.
Table 10.2 Example of host organisms chosen for the recombinant expression of p...
Table 10.3 Comparison of different prokaryotic and eukaryotic host organisms fo...
Table 10.4 Classes of recombinant protein drugs and examples.
Table 10.5 Selected examples of marketed therapeutic mAbs.
Chapter 11
Table 11.1 Summary of the main properties of viral vectors.
Table 11.2 Selection of gene therapy products approved as of 2024.
Chapter 12
Table 12.1 Selected methods for reprogramming somatic cells into induced plurip...
Table 12.2 Selected diseases for which interventional trials of iPSC-based ther...
Chapter 13
Table 13.1 Selection of antisense oligonucleotides (ASOs) with FDA approval.
Table 13.2 Selection of approved siRNAs.
Table 13.3 Selection of miRNA-based therapeutics which have been tested in clin...
Table 13.4 Selection of aptamers that were or are still being tested in clinica...
Guide
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
Acknowledgments
About the Companion Website
Begin Reading
Abbreviations
Glossary
Index
End User License Agreement
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Molecular Medicine
An Introduction
Second Edition
Jens Kurreck
Cy A. Stein
Authors
Jens Kurreck
Technische Universität Berlin
Institute of Biotechnology
Department of Applied Biochemistry, TIB 4/3-2
Gustav-Meyer-Allee 25
13355 Berlin
Germany
Cy A. Stein
11 Dolphin Road
New City
NY 10956
USA
Illustrator
Anke Kurreck, nee Wagner
BioNukleo GmbH
Ackerstraße 76
13355 Berlin
Germany
Cover Image: © Natali_Mis/Shutterstock
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Print ISBN 9783527352395
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Dedicated to our wives, Anke and Myra for their continued and unlimited love, support, and understanding.
Preface
The second edition of Molecular Medicine: An Introduction continues the journey of examining the rapid development in the understanding of human physiology and disease processes at the molecular level. Since the publication of the first edition in 2016, the field has seen remarkable advances. We therefore felt the need to write a second edition that reflects these developments and provides updated insights into the dynamic and evolving landscape of molecular medicine. In the last decade, our understanding of genetic diseases, oncology, infectious diseases, and personalized medicine has deepened significantly. The advent of the CRISPR/Cas-technology has revolutionized our ability to edit the human genome with unprecedented precision. While this approach is still in clinical evaluation, gene therapy has become a routine technology with a continuous number of approvals every year. The same holds true for antisense and RNA interference technologies. Stem cell therapies have made huge strides toward the treatment of previously untreatable diseases. Immunotherapy (checkpoint inhibitors, CAR-T cell therapy) has been established as a powerful tool against cancer, offering new hope to patients. Last, but not least, the COVID-19 pandemic made us aware that new pathogens can arise that pose a global threat. At the same time, the crisis has given rise to a new class of RNA therapeutics, including RNA vaccines.
Molecular medicine is not only one of the most dynamic areas in all the life sciences, it is also a highly interdisciplinary approach, which combines the disciplines of biology, biochemistry, human biology, and pharmacology, in addition to clinical medicine. The second edition continues to describe the fundamental principles that underpin molecular medicine while integrating the latest research findings and clinical applications. Our goal remains to provide a comprehensive and accessible overview of this rapidly evolving field. We have updated existing chapters to reflect new insights and discoveries, and we have added numerous new subsections to cover emerging topics, some of which were mentioned above. New figures and tables illustrate key concepts of many novel developments. References for further reading were rigorously updated. At the same time, we have shortened sections of those topics that lost relevance.
We are convinced that increasing knowledge of the molecular sources of disease has paved, and will continue to pave, the way for the development of novel diagnostic procedures and therapeutic strategies to treat inherited or acquired diseases. The expanding repertory of therapeutic approaches finally makes it possible to address diseases that hitherto have been untreatable. Molecular medicine will, without doubt, change our disease treatment paradigms; rather than employing standard therapies for every individual and adjusting treatment based on observed efficacy and side effects, personalized approaches based on specific constitutional features of the distressed individual will become possible.
Many universities worldwide have established bachelor’s and master’s degree programs to study molecular medicine. In addition, molecular medicine has become an indispensable component of well-established curricula. Courses of study in medicine, (molecular) biology, biochemistry, human biology, and biotechnology are frequently offered. We thus think that an up-to-date introduction to the entire spectrum of molecular medicine, one written in a clear and uniform style, is valuable to the field. Numerous color figures and expositions of clinical relevance will, we hope, also ensure a systematic introduction to the topic.
We hope this book is of value to readers at different levels of professional development. While it primarily addresses undergraduates and lecturers, we hope that medical and graduate students and researchers in the field of molecular medicine will also benefit from it. The textbook is based on our experience in teaching courses in molecular medicine for many years, in laboratory research, and in medical practice. We assume that students who use this textbook have at least some basic knowledge of molecular and cell biology. If not, we recommend that students first consult appropriate introductory textbooks such as Principles of Biochemistry by Voet et al. or Molecular Biology of the Cell by Alberts et al.
For many reasons, writing a book on molecular medicine is a challenging task. First, there is no common consent on just what molecular medicine actually is. We view molecular medicine as a discipline that investigates normal and pathological cellular processes at the molecular level. Such in-depth analysis will help us to better understand the causes of disease, improve diagnosis, and develop novel therapeutic strategies. This understanding of molecular medicine has led us to the selection of the topics that are covered in this book.
The broad range of topics poses a second challenge, as no two-author team can possibly be experts in all areas of molecular medicine. However, we chose not to edit a book composed of individual specific articles, each written by an expert in a particular field in his or her own style. Instead, we have attempted to present a homogeneous textbook in a uniform and consistent style. Numerous cross-references will help the reader to understand the complex interdependencies between the different fields of molecular medicine.
Despite being rigorously updated, the basic structure of the book remains largely unchanged. It is divided into chapters, each of which can be viewed as one lecture of a one-semester course on molecular medicine. The sections are structured in a logical order. However, each chapter can also stand alone as an introduction to a single topic, for example, gene therapy or stem cell technology. Cross-references will help the reader to find sections in the book that should be consulted for an in-depth understanding of the topic.
The textbook commences with a short general introduction to molecular and cellular biology and then describes some selected methods widely used in modern life science research. Several chapters deal with the molecular causes of disease, and established as well as new diagnostic approaches are also described. Viral, bacterial, or eukaryotic pathogen infections are also covered, as these are a major cause of suffering and death worldwide, and require continuous improvements in therapeutics for the management of emerging pathogens and drug resistance. The outline of novel therapeutic approaches for the treatment of cancer and genetic disorders developed in the era of molecular medicine will certainly leave the reader impressed by the dynamism of this field: Drugs based on recombinant proteins, particularly monoclonal antibodies, have already become an important element in clinical practice, and immunotherapies have changed the treatment paradigm in oncology. Timely topics such as the newest advances in gene therapy, stem cell research, and RNA technologies will be introduced with numerous helpful figures. The book will conclude with a chapter on the ethical dimensions of molecular medicine.
Every chapter is accompanied by recommendations for further reading. Rather than providing an exhaustive list of bibliographical references that would be of limited use for most students, we selected educationally valuable review articles for each topic. While we initially intended to choose current articles, we also found older reviews that can provide excellent introductions to various subjects. In addition, the reference lists are intended to help students to begin navigating through the jungle known as the modern scientific literature. Furthermore, the second edition includes questions and exercises for each chapter that help students to monitor their learning progress.
We are grateful for the feedback we received from readers of the first edition, which has helped to shape this revised and updated edition. We hope that the readers will enjoy our journey through the field of molecular medicine and share our enthusiasm for this fascinating subject. As the field continues to advance, we look forward to witnessing the new discoveries and breakthroughs that are guaranteed to happen in the near future. We would be very pleased if our textbook helps prepare you for working in this exciting field.
Acknowledgments
This book would not have been possible without the help of many people. We want to thank the team at Wiley for their support. A special thank goes to our managing editor Monica Chandra Sekar for her patience and assistance. We also want to thank Frank Weinreich, Riya Patel, Sairam Soundarajan, and Arun Raj Arumugam from Wiley, who were important for the realization of this book. We are particularly thankful to our graphic designer Anke Kurreck, nee Wagner, for her illustrative figures.
It is impossible for two scientists to cover the whole field of molecular medicine in depth. We are, therefore, thankful to our expert colleagues for reading specific chapters and giving their valuable comments: Thomas Bock (Chapter 5), Henry Fechner (Chapter 13), Birgit Beck (Chapter 14). Furthermore, we thank Ahmed Ali for support with several figures. We also want to thank our research groups for their enthusiasm about molecular medicine.
Last but not least, we express our most heartfelt appreciation and thanks to our families for their patience when we spent far too much time revising this book. Therefore, this book is for Anke, Laura, Malte, Paul; for Myra, Allison and Warren; Lauren and Brian; and Lily Leigh and Margot Nicole, Eli James and Hudson Alexander.
August 2024
Jens Kurreck, Berlin
Cy A. Stein, New York
About the Companion Website
This book is accompanied by a companion website:
www.wiley-vch.de/ISBN9783527352395
This website includes Instructor Manual.
Chapter 1Introduction
Contents List
1.1 The Basics of Molecular Medicine
1.1.1 Topics of Molecular Medicine
1.1.2 Stages of Drug Development
1.2 The Human Cell
1.2.1 Organelles
1.2.1.1 The Nucleus
1.2.1.2 Mitochondria
1.2.1.3 Endoplasmic Reticulum and Golgi Apparatus
1.2.1.4 Peroxisome and Lysosome
1.2.2 Cell Cycle
1.2.3 Apoptosis
1.3 DNA Replication and Gene Expression
1.3.1 DNA Replication
1.3.2 Mutations
1.3.3 Transcription
1.3.4 Epigenetic Regulation of Gene Expression
1.3.5 Translation
1.3.6 Protein Degradation
1.4 Biological Communication
1.4.1 Neurotransmitters
1.4.2 Hormones
1.4.3 Signal Transduction
1.5 The Immune System
1.5.1 The Innate Immune System
1.5.1.1 The Complement System
1.5.2 The Adaptive Immune System
1.5.2.1 Cellular Immunity
1.5.2.2 Humoral Immunity
Summary
Molecular medicine is a highly dynamic field of life science research that uses interdisciplinary approaches to understand normal and pathological cellular processes at the molecular level. The findings of basic research have entered clinical practice, as new diagnostic assays and novel therapeutic strategies focus not only on the symptoms but also on the causes of disease.
The development of drugs is a long-term and expensive process that starts with basic and preclinical research. A candidate drug must then successfully pass through three types of clinical trials in humans before a novel agent can be approved for therapeutic purposes.
The eukaryotic cell is compartmentalized into several cellular organelles by intracellular membranes. The nucleus harbors the genetic material, mitochondria are the cellular power plants, and the endoplasmic reticulum (ER) and the Golgi apparatus are responsible for the glycosylation and sorting of proteins.
Cells follow a tightly regulated cycle of four phases. These include the two gap phases G
1
and G
2
, the S phase in which new DNA is synthesized, and mitosis (M phase), during which the cell divides.
Apoptosis is the process of programmed cell death, which is important as a normal physiological mechanism and for protection against infections and cancer. Apoptosis can be triggered by extrinsic or intrinsic signals.
Genomic DNA is amplified by DNA polymerases in a process known as replication. The synthesis occurs in a semiconservative and semidiscontinuous way.
Expression of genes requires two steps. In the first step, the DNA is transcribed into RNA. Most primary transcripts are posttranscriptionally processed. For mRNAs, this step includes the addition of a cap at the 5′ end and of a poly(A) tail at the 3′ end. Introns are spliced out to link the exons together. Several bases are modified in various types of RNAs. The second step in gene expression is the translation of the genetic information into proteins. This process is carried out by ribosomes. Posttranslational modifications of proteins include activation by proteolytic cleavage and covalent modification of amino acid side chains. This can occur, for example, by glycosylation or reversible phosphorylation.
Sophisticated communication between cells is essential for the functioning of a multicellular organism. Neurons transmit signals at synapses. Hormones are molecules that induce physiological responses over a long distance or in adjacent cells. The extracellular signals are transmitted into the cell-by-cell surface receptors and induce a signaling cascade that leads to a biological response.
The immune system protects an organism against (infectious) diseases. The innate immune response recognizes general patterns of pathogens, while the adaptive immune system is directed against specific targets. The adaptive immune system involves a cellular immune response (T cells) and a humoral immune response (B cells that produce antibodies).
1.1 The Basics of Molecular Medicine
1.1.1 Topics of Molecular Medicine
Molecular medicine is a discipline dedicated to understanding normal and pathological cellular processes at the molecular level. This approach requires the use of many physical, chemical, biological, biochemical, and medical techniques (some of which are introduced in Chapter 2) to understand fundamental molecular mechanisms and how they go awry in disease. Molecular medicine combines classical disciplines such as cell and molecular biology, biochemistry, and medicine. Knowledge is often acquired via interdisciplinary investigation and can be used to develop new forms of molecular diagnosis and therapeutic intervention.
Molecular medicine can be divided into basic research and applied clinical disciplines. The basic research component investigates molecular and genetic mechanisms of cellular function and identifies pathological processes. In many cases, this addresses a specific question with a hypothesis-driven approach and can lead to large-scale investigations of whole genomes and their function (Chapter7). The discipline known as translational research then tries to apply the findings from basic science to the clinic, where it may provide new forms of diagnosis and therapy.
A report published by Linus Pauling in 1949 laid the basis for the establishment of the field of molecular medicine. In his seminal paper, he showed that hemoglobin from patients suffering from sickle-cell anemia had a different electrical charge than hemoglobin from healthy individuals. This study demonstrated that a disease could be traced to an alteration in the molecular structure of a protein. This new perspective opened the possibility of establishing novel forms of diagnosis and therapy at the molecular level. Sickle-cell anemia is not the only case in which a detailed understanding of the molecular etiology of the disease (e.g. of inherited genetic disorders, Chapter3) has led to new diagnostic options (Chapter 8).
The field of oncology also illustrates the paradigm shift caused by a molecular perspective. While cancer treatment is still largely based on the removal of the tumor by surgery (followed by chemotherapy and/or radiation therapy), molecular oncology (Chapter4) tries to elucidate those pathways that lead to cellular transformation. This knowledge also helps produce a comprehensive molecular diagnosis of the disease basis in a single patient so that the treatment can be adjusted accordingly, an approach that has come to be known as “personalized medicine.” Many modern anticancer drugs block specific pathways that lead to uncontrolled cellular proliferation. The development of checkpoint inhibitors and genetically modified T cells (CAR T cells) has revolutionized aspects of modern cancer therapy. Similarly, elucidation of the life cycles of pathogens has helped develop new drugs for the treatment of infections with viruses (Chapter5) and bacteria or eukaryotic pathogens (Chapter 6). For example, advancements in the understanding of virus biology have led to the identification of novel targets for antiviral agents.
Most conventional drugs belong to the class of small molecular compounds. To achieve oral bioavailability and to promote rapid diffusion across cell membranes and intracellular trafficking to their sites of action, the majority of (oral) drugs have molecular weights below 550 Da (although some antibacterial agents fall in the 700–900 Da range). A prominent example is acetylsalicylic acid (trade name Aspirin, Figure 1.1a), a drug mainly used as an analgesic.
Figure 1.1 Small molecular drugs and biologics. (a) The chemical structures of acetylsalicylic acid (Aspirin) and (b) the crystal structure of an antibody, are shown for comparison. The two structures are not drawn to scale.
Source: Part (b) [1] / John Wiley & Sons.
Molecular medicine has broadened the spectrum of entities used as drugs. New medications are now often based on large molecules of biological origin (known as “biologics”). These include, for example, recombinant proteins such as monoclonal antibodies (Figure 1.1b; Chapter10), short pieces of DNA or RNA (Chapter 13), entire genes that can be delivered by viral vectors (Chapter11), or even complete cells (Chapter 12). Pharmacogenetic investigations aim at discovering why the efficacy and toxic side effects of a drug at a given dose vary between individuals (Chapter 9). However, molecular medicine not only develops new diagnostic and therapeutic approaches but can also pose heretofore unknown ethical issues, some of which will be introduced in Chapter14.
1.1.2 Stages of Drug Development
The development of a new drug is a time-consuming and expensive process (Figure 1.2) that may take 12–15 years (and in some cases even longer). The cost calculus of developing a new drug is complex and controversial, but the average cost to bring a new molecular entity (NME) to the market has been estimated to range from US$318 million to US$2.8 billion. Drug development usually starts with the identification of a new target, which, for example, may be a proliferative factor that causes tumor growth. The next step in the process is to characterize the target, its location (extracellular, membrane-bound, cytosolic, and nuclear), and its function. Confirmation that the potential drug target fulfills the expected function is known as target qualification or validation. One way to identify a new compound is to perform what is known as a high-throughput screen (HTS). This approach allows testing a large number (up to millions) of compounds to identify an active molecule that modulates a particular target (e.g. inhibits a proliferative factor). In almost all cases, the primary hit must be optimized by chemical modification to obtain higher binding affinities, better solubility, and so on. The efficacy and toxicology of the substance are then investigated in in vitro studies and animal experiments. The process of drug development may deviate substantially from this path depending on the type of drug being developed. Biologics, for example, are usually not obtained by HTS. Any substance will only be tested in humans after having passed extensive toxicological examination. These tests have conventionally been carried out in different animal species. More recently, alternative in vitro systems composed of human cells have shown to increase the predictability of the toxicity of a substance in humans (Section 2.6).
Figure 1.2 Stages of drug development. The preclinical stages comprise the identification, characterization, and validation of a target, and the identification and optimization of a compound, in addition to toxicological evaluation. The drug then undergoes three main phases of clinical testing before it is approved by the regulatory authorities.
Clinical research is usually divided into three main phases. However, these phases are sometimes preceded by an exploratory trial (frequently called as phase 0) in a small number of subjects with a very small, subtherapeutic dose designed to gather data on the agent’s basic properties in humans. This trial does not produce data about safety or efficacy. The actual clinical research starts with a phase I trial, usually carried out with a small number of subjects (20–100). The main purpose of a phase I trial is to assess the safety of the drug. The trial is frequently designed to include a dose escalation to determine the optimal dose and the dose at which unacceptable toxicity supervenes. Although phase I trials are often carried out with healthy volunteers, under some circumstances, sick patients are enrolled. This is done most often with cancer patients, as the drugs to be evaluated are likely to make healthy individuals ill or may carry a significant risk of long-term toxicity.
Phase II trials are carried out with a larger number of individuals (100–300). The central aim of the phase II study is to evaluate the efficacy of the drug. The trial is, therefore, usually performed on sick patients. Phase II studies are sometimes divided into phase IIA and phase IIB. While a phase IIA trial assesses the optimal dosing of the drug, a phase IIB trial is designed to study the efficacy of the drug at the prescribed dose. Another important goal of a phase II trial is to assess drug safety in a larger group of individuals.
Phase III trials are designed to assess the effectiveness and safety of a new drug in clinical practice in a large patient group (300–3000 or more individuals). These studies are carried out in randomized, controlled, multicenter trials. Phase III trials are usually designed as double-blind studies, that is, the patients are randomly assigned to an experimental and a control group (in some trials, the control group may either receive a placebo or standard of care treatment). Neither the patients nor the physicians monitoring the outcome know which treatment the patient is receiving. Phase III trials aim at assessing the efficacy of a drug in comparison to a placebo or the current standard of care treatment.
Just how complicated this process can be is clear when you consider that 90% of all candidates that have shown promise in preclinical studies fail in the three phases of human clinical trials. This is often due to unexpected side effects or a lack of efficacy. However, if drug safety and efficacy have been demonstrated in multiple phase III trial(s), approval for marketing can be applied for from the appropriate regulatory agency such as the US Food and Drug Administration (FDA) in the United States or the European Medicines Agency (EMA) in the European Union. These agencies approve between 40 and 70 new drugs every year. In 2022, the share of biologics reached 50% of all approved drugs for the first time.
After approval, the authorities may request post-marketing monitoring, which is sometimes referred to as a phase IV trial. A phase IV trial involves safety surveillance after the drug has received permission to be marketed. In principle, it is designed to detect rare or long-term adverse effects in a much larger patient population and over a longer time period than was possible during the earlier clinical trial phases. A phase IV trial may also identify interactions with other marketed drugs. Even after marketing, if harmful effects are discovered, any drug may be withdrawn at any time, or its use restricted only to certain conditions.
The term phase V is increasingly used to describe studies that determine whether the therapeutic effect of a new drug is realized in day-to-day clinical practice. Community-based research is employed to survey whether the effects under typical (and somewhat variable) clinical contexts are similar to those that were found in the controlled efficacy studies. A phase V trial may also analyze the cost–benefit ratio of a drug or therapeutic intervention.
1.2 The Human Cell
Despite the extreme complexity of living organisms and the myriad number of functions that each constituent organ must carry out, only a surprisingly limited set of molecules are commonly employed. Typical biomolecules found in living organisms include nucleic acids, proteins, polysaccharides, and lipids. These macromolecules are composed of a relatively limited number of monomeric building blocks such as DNA and RNA nucleotides, amino acids, monosaccharides, and fatty acids. In addition, inorganic ions, organic acids, and a variety of metabolites are also important constituents of cells. While the basic features of biomolecules are extensively covered in the general textbooks of biochemistry listed at the end of this chapter, the cell as the basic functional unit of an organism and the major intracellular processes relevant to human physiology and pathology will be outlined here.
The human body consists of approximately 36 trillion cells in a typical male (70 kg), approximately 28 trillion cells in a typical female (60 kg), and approximately 17 trillion cells in a 10-year-old child (32 kg). These cells divide into more than 1200 separate cell groups, comprising 400 major cell types across 60 tissues. Although all cells of a given organism carry (almost) the same genome, these cells have different functions and are highly specialized. A typical eukaryotic (animal) cell is illustrated in Figure 1.3. The most prominent characteristic that distinguishes eukaryotic cells from prokaryotes is its compartmentalization. The main membrane-bound organelles of animal cells are the nucleus, the ER, the Golgi apparatus, the mitochondrion, the lysosome, and the peroxisome. Each of these organelles contains a specific set of proteins that fulfill a specific function. These organelles are embedded in a gelatinous fluid called the cytosol.
Figure 1.3 Diagram of a typical eukaryotic cell. Membrane-bound organelles include the nucleus, endoplasmic reticulum (ER), Golgi apparatus, mitochondrion, lysosome, and peroxisome.
Source: [2] / Taylor & Francis Group.
1.2.1 Organelles
1.2.1.1 The Nucleus
The central organelle of a eukaryotic cell is the nucleus, which contains the genetic material. The nucleus is surrounded by the nuclear envelope consisting of two membranes: the inner and the outer nuclear membranes (Figure 1.4a). The outer nuclear membrane is continuous with the rough endoplasmic reticulum (RER). Proteins referred to as nucleoporins form aqueous channels, called nuclear pores, through the envelope. These pores allow small water-soluble molecules to pass into and out of the nucleus, while larger molecules must be actively transported in or out. A filamentous network of lamin proteins provides mechanical support but is also involved in the regulation of replication and cell division. A distinct structure found in the cell nucleus is the nucleolus (indicated in Figure 1.3). The nucleolus occupies up to one-fourth of the volume of the nucleus and forms around specific chromosomal regions. In the nucleolus, ribosomal RNA is transcribed and assembled with proteins to give (incomplete) ribosomes.
Figure 1.4 Cell nucleus and chromatin organization. (a) The nucleus is surrounded by the nuclear envelope consisting of two membranes. Pores in the envelope allow the exchange of small water-soluble molecules. The outer nuclear membrane is continuous with the membrane of the endoplasmic reticulum (ER). (b) Schematic representation of a eukaryotic metaphase chromosome. Each chromosome has a specific banding pattern after staining. (c) DNA winds around histone proteins to form nucleosomes that fold into a 30 nm fiber. Loops of chromatin are then attached to a protein scaffold to form the metaphase chromosome.
Source: Part (a) [2] / Taylor & Francis Group. Part (c) [1] / John Wiley & Sons.
The DNA together with DNA-binding proteins and RNA molecules is organized in chromosomes. The human genome consists of 46 chromosomes that can be identified based on the specific banding pattern after staining. Figure 1.4b shows a schematic representation of a condensed metaphase chromosome. The ends of the chromosome are called telomeres. The centromere is the point where the two identical chromosomes touch and the microtubules attach for separation during mitosis. Most chromosomes are asymmetric; the centromere separates a short arm (p for the French word petit) and a long arm (q, chosen as the next letter in the alphabet after p). The position of a gene or a DNA sequence in the human genome (denoted as the locus) is indicated by the chromosome number, the arm, and three numbers that refer to the region, the band, and the sub-band. For example, the locus 11p15.3 indicates that a DNA sequence is located on the short arm of chromosome 11, in region 1, band 5, and sub-band 3.
If the DNA of every cell in the human body were lined up end to end, it would stretch from the Earth to the Sun and back 100 times. This means that a single cell must package DNA strands with a combined length of approximately 2 m into a nucleus with a volume in the cubic micrometer (μm3) range.
Chromosomes consist of the DNA complexed with proteins, together known as chromatin (
