ADVANCES IN CELL BIOLOGY: ADVANCES IN CELL BIOLOGY: CONTRIBUTIONS TO MODERN DRUG CONTRIBUTIONS TO MODERN DRUG DESIGN DESIGN

Esayas AyeleDepartment of Pharmaceutics and Social Pharmacy

Outline2

Introduction Cell biology in drug design Proteins Genomics Proteomics Nucleic Acid as drug target Membrane as drug target Summary

Introduction3

What is cell? The cell is the basic structural, functional,

and biological unit of all known living organisms.

Introduction… Cell biology is a branch of biology that studies the

different structures and functions of the cell. Structure Organelles Physiological properties Metabolic processes Signaling pathways Life cycle Interactions with their environment.

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Introduction…5

Fig 1. Prokaryotic Vs Eukaryotic Cell

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Fig 2. Structure of Animal Cells

Growth and development cell cycle

Transport across cell membrane

Autophagy Adhesion Cell movement

Cell signaling DNA repair Metabolism Transcription and

mRNA splicing

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Processes

Cell Biology in Drug Design Cell biology is a major driver of all aspects of biomedicine.

The diagnosis of a disease increasingly relies on genetic, molecular, and cellular markers, and

Drug discovery has shifted from blind screening to targeted molecular design informed by our genetic, molecular, and cellular understanding of a disease. Identifying and characterization of therapeutic target

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Proteins Enzymes Receptors Membrane Transport Proteins

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G Protein-Coupled Receptors

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GPCRs… Drug discovery programs of many

pharmaceutical companies focus on the G-Protein Coupled Receptor (GPCR) superfamily.

In many diseases GPCRs are known as ‘‘validated

targets’’, i.e. ligands acting at the GPCR are known to affect the disease outcome in human.

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GPCRs… Bioinformatic analysis of the human genome sequence has

revealed several hundred new members of the GPCR family.

As GPCRs are one of the most important families of targets in drug discovery in the pharmaceutical industry, it isexpected that the various newly identified receptors offer similar potential and will also prove to be good drug targets

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GPCRs as a drug target 13

Orphan GPCRs Attempts have been made to deorphanise these receptors

Ligand Hunting: Reverse Pharmacology Approaches to

oGPCRs

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Deorphanised GPCRs reported to be in drug discovery

British Journal of Pharmacology (2008) 153 S339–S346

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Proteins...Enzymes obvious target for therapeutic intervention when

a disease state is associated with production of a biologically active species.

e.g. DHFR vs. Methotrexate, ACE vs. captopril

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Nucleic acid as drug targets DNA

as the receptor for many drugs used in cancer and other diseases;

uses to design sequence-specific reagents for gene therapy. e.g. chemical modification and cross linking of DNA

(cisplatin) or cleavage of the DNA (bleomycin)

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Nucleic acid as drug targets RNA as drug target

Drugs that bind to RNA might produce effects that cannot be achieved by drugs that bind to proteins.

e.g. Aminoglycosides and macrolides are RNA-targeting antibiotics that inhibit prokaryotic translation

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Membranes as drug targets An understanding of the structural and dynamic

functions of the membranes may add to a more rational design of drug molecules with improved permeation characteristics or specific membrane effects. E.g. Amphotericin B

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GenomicsGenomics Structural genomics — the sequence

Information is encoded linearly and digitally in four coding molecules-bases

Three bases = codon = amino acid A number of codons strung together code for a

gene which codes for a protein

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Genomics… Functional genomics — what the

genes do Sequence/structural motifs in proteins i.e.

functional class of protein Microarrays of gene expression Proteomics Pharmacogenomics

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Functional Genomics: Microarrays of Gene Expression

Normal tissue

DNA

Diseased

Diseased associated

normal

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GenomicsGenomics From the Human Genome to New

Drugs Human Genome Project and

Celera

Having the genetic code for the production of an enzyme or a receptor may enable us to over-express that protein and determine its structure and biological function.

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Proteomics “Proteome”-the protein complement encoded by a genome Proteomics is the study of composition, structure,

function and interaction of the proteins directing the activities of each living cell

Identification of the precise 3D-structure of relevant proteins to enable researchers to identify potential drug targets to turn protein “on or off”

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Why Proteomics Beyond the genetic make-up of an individual or organism, many other

factors determine gene and ultimately protein expression and therefore affect proteins directly such as pH, hypoxia, drug treatment…

Proteins can undergo extensive modifications such as glycosylation, acetylation, and phosphorylation which can lead to multiple protein products from the same gene

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Proteomics…The level of any protein in the cell at any given

time is controlled by1. Rate of transcription of the gene2. The efficiency of translation of m RNA into

protein3. The rate of degradation of protein in the cell

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Gel Electrophoresis Mass Spectrometry

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Proteomics Tools

Determining the protein structure/ polypeptide sequence

1. x-ray crystallography2. Nuclear magnetic resonance3. Protein predicting programmes- computer based

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Proteomic Bioinformatics Databases exist for the protein maps of a broad range of

organisms, tissues, and disease states

Ultimately, given the the dynamic nature of the proteome, complex experimental details and related results need to be extrapolated in the context of the relevant biochemical pathways or disease implications

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Databases30

Genome and proteome informations are used to identify the proteins associated with the disease.

That protein will be used by computer software as a target for new drug.

HIV-1 Protease

Proteomics and drug discovery31

Summary The introduction of genomics, proteomics and metabolomics has

paved the way for biology-driven process, leading to plethora of drug targets.

Today, biomedicine sits on the cusp of a new revolution: the use of microbial and human cells as versatile therapeutic engines

Today, biomedical science stands poised at the threshold of another pharmaceutical frontier: cell-based therapies.

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Thank you!