Functional autoradiography: Incorporation of [ 35 S]-GTP γ S

1. [35S]GTPγS In vitro target function Functional autoradiography:Incorporation of [35S]-GTPγS X

2. Functional autoradiography: incorporation of [35S]-GTPγS (Laitinen et al 2001) In vitro target function A case study SP1999

3. Stimulation of hippocampal slices with ADP induces microglia process extension and cell migration (Haynes et al. 2006) In vitro target function A case study SP1999 Time-lapse confocal microscopy

4. A patient with a phase shift mutation in the gene showed a reduced and reversable platelet aggregration after ADP stimulation (Hollopeter et al 2001 and Humbert et al 1996) In vitro target function A case study SP1999 Linking gene to function: platelet aggregation

5. In vivo target function Functional imaging in vivo • Light imaging • Bioluminescence • Fluorescence • Magnetic resonance • MRI • fMRI • Poistron emission tomography (PET)

6. Extension of microglia processess after ATP injection (a) or focal laser ablation (c) (Haynes et al 2006) In vivo target function A case study SP1999 Two photons laser microscopy in vivo

7. Target validation SP1999 target validation summary Receptor identification • SP1999 is a receptor for ADP, belong to the purinergic receptor family and has been named P2Y12 Expression profile • mRNA is present in brain and platelets (northern blot, PCR, and in situ hybridization) • The protein is expressed in several brain region and is localized in microglia cells (immunocytochemistry) • Protein expression is increased in a disease models of chronic pain (immunocytochemistry) Functional activity • Activation of Gi protein (cAMP and GTPγS) • Modulation of microglia activation (live cell imaging) • Role in platelet aggregration (genetic analysis and in vitro assay)

8. To perform these studies it is necessary to develop appropriate disease models In vivo target function Linking a target to a pathology: in vivo function • Genetic manipulation • Pharmacological manipulation

9. In vivo target function Animal Models “A laboratory animal model is a model in which basic biology or behavior can be studied, or in which a spontaneous or induced pathological process can be investigated (including the therapeutic effect of drugs), and in which the phenomenon in one or more respects resembles the same phenomenon in humans or other species of animal.”

10. Animal models are used in various phases of the drug discovery process Use of animal models CANDIDATE TARGET POC I D E A DRUG Exploratory research Therapeutic research Exploratory development Full development • Target validation • Screening/optimization/efficacy profile • Evaluation of tolerability and toxicity

11. In vivo target function Type of animal models Experimentally induced disease. • Behavior (e.g stress) • Pharmacology (e.g. CFA) • Genetic manipulation (e.g. transgenics, knockouts, knock-ins) • Surgery (e.g. nerve cuts, vessels’ ligature) Spontaneous disease Naturally occurring with similar mechanisms to human diseases (e.g. asthma in cat; Factor VIII deficiency in Irish setter equivalent to hemophilia A, etc..) Negative The disease is not developed by the animal “why DOESN’T - models”. (e.g.no atherosclerosis in dog, no AIDS in HIV infected chimpanzees )

12. In vivo target function Essential features of an animal disease model • Predictive validity • The effects of a test drug in this model correspond to that of clinically effective drugs. • Face validity • Phenomenological similarities between the model and the clinic. • Construct validity • The primary cause of the disease is similar in man

13. In vivo target function Learning and memory: Water Maze

14. Rotarod Activity Cage In vivo target function Lomotor activity and coordination This model is used to assess horizontal and vertical locomotor activity. This model is used to assess motor coordination, balance, and motor learning.

15. In vivo target function Target Knockdown

16. X No gene X No protein X No phenotype In vivo target function The central tenet

17. Deletion of target gene Gene KO Reduction of protein transcription Oligoantisense RNA Interference Reduction of protein activity Aptamers In vivo target function Techniques to KO a gene product

18. readout Mechanical or tactile allodynia von Frey hair test P2Y12 KO mice do not develop tactile allodynia after L5 spinal nerve transection (Tozaki-Saitoh et al 2008) In vivo target function A case study SP1999

19. KO mice showed a reduced platelet aggregration and a prolonged bleeding time (Foster et al 2006) In vivo target function A case study SP1999

20. Target validation SP1999 target validation summary Receptor identification • SP1999 is a receptor for ADP, belong to the purinergic receptor family and has been named P2Y12 Expression profile • mRNA is present in brain and platelets (northern blot, PCR, and in situ hybridization) • The protein is expressed in several brain region and is localized in microglia cells (immunocytochemistry) • Gene expression is increased in some disease models (in situ hybridization) Functional activity • Activation of Gi protein (GTPγS) • Modulation of microglia activation (live cell imaging) • Role in platelet aggregration (Genetic analysis and in vitro assay) Potential role in diseases • Bleeding disorder/Thrombosis • Chronic pain