Post on 06-Jan-2018
description
The type of target influence the type of drug
• Main drugs’ categories– Small molecules – Biologicals (e.g. antibodies, hormones, etc)
• The drug discovery process for the two categories of drugs is not exactly the same
• In the rest of the presentation we will mainly focus on that for small molecules
Target selection
General criteria for target choice
• Druggability: likelihood of being able to modulate a target with a drug
Target selection
Druggability of small molecules targetsDruggability of small molecules targets
polysaccharides
lipids
nucleic acids
proteins
Problems with toxicity, specificity, and difficulty in creating adequate ligands narrow mainly to protein the druggable targets
Target selection
XX
X
DruggabilityDruggabilityOnly 10% of the human genome represents druggable targets, and only half of those are relevant to disease.
Target selection
GPCR
STY kinases
Zinc peptidases
Serine proteases
PDE
Other 110 families
Cys proteases
Gated ion-channel Ion channels
Nuclear receptor
P450 enzymes
Analysis of current drug targets shows that most targets fall within a few major protein families (GPCRs, kinases, proteases and peptidases)
GPCR
STY kinases
Zinc peptidases
Serine proteases
PDE
Other 110 families
Cys proteases
Gated ion-channel Ion channels
Nuclear receptor
P450 enzymes
Analysis of current drug targets shows that most targets fall within a few major protein families (GPCRs, kinases, proteases and peptidases)
The genome project and the“omics” era
Target identification
The suffix -ome- as used in biology refers to a totality of some sort
Genetic code
Genetic Genetic codecode
GenomeGenome
TrascriptomeTrascriptomeProteomeProteome
MetabolomeMetabolome
PathwaysPathways
static
dynamic
DNADNA RNARNA ProteinsProteins
Complexity
Target identification
Transcriptome: gene expression profiling
However, it should be kept in mind that does not exist a complete match between the trascriptome and the proteome.
Only a part of the genome is expressed in any given moment in both physiological and pathological conditions.
Identification of difference in expression profile between physiological and pathological states could lead to the identification of new targets.
Target identification
Techiniques to measure simoultaneously expression of multiple genes
Differential display
Subtractive cDNA library
S.A.G.E Serial analysis of gene expression
Microarray
Target identification
Gene microarray
Expression level of 20.000 Expression level of 20.000 genes could be measured genes could be measured simoultaneouslysimoultaneously
1,28cm1,28cm
GeneChip Probe Array
18µm18µm
Target gene is present inTarget gene is present inthousands of copiesthousands of copies
* **
**Hybridized Cell
Target identification
Gene microarray applied to target discovery
(Costingan et al., BMC Neuroscience 2002)
Target identification
Gene microarray applied to target discovery
Target identification
Ingenuity’s NetworkCV L5 CGW L5
GENE Rx/Lx Rx/LxAR -2.05 -1.21CACNA2D1 6.63 6.58DLG4 -1.82 -1.63GABRA1 -12.69 -6.88GABRA5 2.74 1.90GABRG2 -6.01 -5.29GRIA2 -8.52 -5.38HTR1D -35.11 -13.23HTR3A -11.38 -6.00HTR3B -81.76 -41.32KCNA4 -5.62 -3.56KCNAB1 -5.67 -3.89KCND3 -5.17 -3.97KCNIP1 -2.61 -2.76KCNIP2 -5.05 -4.15KCNIP3 -5.28 -3.59NTRK1 -3.30 -2.75RET -3.59 -2.76SYT1 -2.28 -1.72SYT9 -3.32 -2.80TAC1 -4.61 -3.61TRPV1 -8.81 -4.93
Target identification
CV L5 Rx vs. Lx fold changes on topCGW L5 Rx vs. Lx fold changes on bottom
Proteomics
• Allow to identify difference in protein expression under different physiological and pathological conditions
• It is possible the identification of post-translation modifications (e.g. phosphorylation and glycosilation)
• It is more time consuming and require more sophisticated instruments than gene expression profiling.
Target identification
2D-gel analysis
pI
MW
ProteomicsTarget identification
Preoteomics applied to target identification
Target identification