1. Signal Transduction: Dopamine Signaling

2. Outline Dopamine and dopamine receptors cAMP-PKA pathway PLC pathway Regulation of ion channel by dopamine Early signal quench and late signal induction

3. Dopamine Neurotransmitter in Central Neural System Neurohormone in periphery important roles in behavior and cognition, voluntary movement, motivation, sleep, mood, attention, working memory, and learning http://www.3dchem.com/molecules.asp?ID=289

4. Synapse in CNS http://blog.lib.umn.edu/trite001/studyinghumananatomyandphysiology/2008/04/dopamine_excitatory_or_inhibit.html

5. Dopamine signaling related disease Tourette’s syndrome, schizophrenia, and drug and alcohol abuse, Parkinson’s disease etc. depending on the site of their neurobiological correlate http://www.willamette.edu/~gorr/classes/cs449/brain.html

6. G-protein Coupled receptors Ligand binding changing in receptor conformation Facilitate release of GDP and binding of GTP http://openwetware.org/wiki/BIO254:Gprotein

7. Class A (Rhodopsin family) - Highly conserved amino acids (red circles) - Disulphide bridge connecting E1 & E2 - Palmitoylated cysteine in the C-terminal tail - Tilted or kinked due to presence of P’s in TMD’s Class B (Secretin & Adhesion families) -Relatively long N- terminus w/ disulphide cysteine bridges -No palmitoylation site -Conserved residues and motifs (different from A) Class C (Glutamate family) -Long N-terminus and C-tail -Ligand-binding domain (yellow) in N- terminus forms disulphide-linked dimer -2 cys in E1 & E2 form putative disulphide bridge -C1 is short & highly conserved http://www.gpcr.org/7tm/phylo/phylo.html Recall: classfication

8. Dopamine Receptors Class -A : Rhodopsin family D1-like Family: D1 D5 D2-like Family: D2, D3, and D4 Grouped by similarity of signal pathways & structure Two families can have “cross talk”

9. Receptor Structure D3 receptor (homo sapiens) (Ellen Chien, 2010) 400 aa ECL2 forms ligand binding pocket LCL2 is transient, raising the possibility that interactions between ICL2 and the receptor ionic lock

10. Outline Dopamine and dopamine receptors cAMP-PKA pathway PLC pathway Regulation of ion channel by dopamine Early signal quench and late signal induction

11. D1&D2 signaling overview (KA Neve, 2004)

12. D1&D2 signaling overview (KA Neve, 2004)

13. Recall: Families of G  FamilyGene Varients Effectors2 nd Messenger Association GsGs  s(S),  s(L)  adenylyl cyclase cAMP  olf  adenylyl cyclase cAMPOlfactory GiGi  i1,  i2,  i3,  adenylyl cyclase cAMP  0a,  0b  phospholipaseC IP 3, DAGBrain  t1,  t2  cGMP-PDE cGMPRetina  gust  phospholipaseC IP 3, DAGGustatory zz  adenylyl cyclase cAMP GqGq  q,  11,  14,  15,  16  phospholipaseC IP 3, DAG G 12  12,  13  Rho-GEF Rho Adapted from Beckerman, Molecular & Cellular Signaling

14. Alberts MBoC, Fig 15-36, 5th ed. G αs Adenylyl Cyclase 5 cAMP PKA DARPP-32(PP1 R1B) PP2A ( protein phosphatase ) D1-like receptor PP1 cAMP-PKA pathway CREB P on Thr 34 D2-like receptor G αi/0 De-P on Thr 75 Channel/ transporter

15. Protein phosphatase (Y Xu, 2006) Protein Phosphatase 2A Catalytic subunit regulatory subunit scaffolding subunit Protein Phosphatase 1 (A hirschi,2010)

17. cAMP-PKA pathway is in crosstalk and regulated MAPK Epac MAP Kinase MAPK Kinase (JM beaulieu,2011)

19. Outline Dopamine and dopamine receptors cAMP-PKA pathway PLC pathway Regulation of ion channel by dopamine Early signal quench and late signal

20. D1-like receptor activate G q FamilyGene Varients Effectors2 nd Messenger Association GsGs  s(S),  s(L)  adenylyl cyclase cAMP  olf  adenylyl cyclase cAMPOlfactory GiGi  i1,  i2,  i3,  adenylyl cyclase cAMP  0a,  0b  phospholipaseC IP 3, DAGBrain  t1,  t2  cGMP-PDE cGMPRetina  gust  phospholipaseC IP 3, DAGGustatory zz  adenylyl cyclase cAMP GqGq  q,  11,  14,  15,  16  phospholipaseC IP 3, DAG G 12  12,  13  Rho-GEF Rho Adapted from Beckerman, Molecular & Cellular Signaling

21. D1 family-PLC pathway PKC Alberts, MBoC, Fig 15-39, 5th ed. (JM beaulieu,2011)

22. D2-like receptor activate via G βγ NATURE REVIEWS | DRUG DISCOVERY 604| JULY 2004 | VOLUME 3 ion channels adenylyl cyclase phospholipases guanine nucleotide exchange factor kinases  binding protein kinases

23. D2 family-PLC pathway (JM beaulieu,2011)

24. Outline Dopamine and dopamine receptors cAMP-PKA pathway PLC pathway Regulation of ion channel by dopamine Early signal quench and late signal induction

25. Four Families of Ion Channels Ion ChannelSelectivitySubunit TopologyChannel assembly 6TM cation6TM, loop 24 TM, 4 loops Tetrameric, Monomeric CalciumCa 2+ HCNNa +, K + PotassiumK+K+ SodiumNa + Voltage-gated ion10-18IMDimeric ClCCl - Cys-loop receptor4TMPentameric nAChRCations GABA A,C Anions (Cl - ) GlycineAnions (Cl - ) 5-HT 3 Cations Glutamate recep’r3TM, loopTetrameric AMPANa +, K + KainateNa +, K + NMDACa 2+ Ligand-gated Voltage-gated RECALL

26. Overview of ion channel regulated (KA Neve, 2004)

27. Dopamine regulated K+ channels G protein-regulated inwardly rectifying K + channels (GIRK) D1 receptor GIRK D2 receptor GIRK voltage-gated K + channels (VGKC) I ks /I A /I D D1 receptor VGKC D2 receptor VGKC G bγ PKA

28. Dopamine regulated Ca 2+ channels Voltage gated calcium Channel D1 receptor L-type channel N,P/Q type channel D2 receptor L,N,P/Q type of channel PKA/PKC PKA G bγ

29. Dopamine regulated Na+ channels Voltage gated Na + Channel (I Nat and I Nap ) D1 receptor  PKA pathway  α-subunit Ser 573 phosphorylation transient Na + current D1 receptor persistent Na + current D2 receptor Na+ channels PKA/PKC PKA inhibition G bγ

30. Dopamine regulated glutamate receptors D1 receptor D2 receptor NMDA AMPA GABA PKA inhibition/ NMDA AMPA GABA PKA G bγ ?

31. Direct interaction between DA receptor and ion channels -- D1 receptor N-type Calcium Channels -- D1 receptor NMDA PKA D2 receptor NMDA D5 receptor GABA

32. Outline Dopamine and dopamine receptors cAMP-PKA pathway PLC pathway Regulation of ion channel by dopamine Early signal quench and late signal induction

33. DA receptor early signal shutdown & late signal induction (JM beaulieu,2011)

34. RGS deactivate G α RGS 9-2 regulates D2- like receptor signaling Probably cooperate with RGS 7, mediated by R7BP

35. GRK deactivate GPCR GPCR Kinase 3 families: GRK1 like (1 and 7) retina specific 1  rhodopsin 7  iodopsin GRK2-like (2 and 3) GRK4-like (4,5 and 6) GRK

36. Arrestin and downstream pathway arrestin 1 (rod) arrestin 4 (cone) β-arrestin 1 2 (widely) β-arrestin 2 (widely) Binds phosphorylated GRK 1.Recruit Clathrin  internalization  recycle or degrade GPCR 2.Scaffold PP2A and Akt(PKB)  dephosphorylate (deactivate)Akt http://www.fz-juelich.de/isb/isb-2/topics/arrestin

37. Akt activation pathway mTOR http://www.nature.com/onc/journal/v24/n50/fig_tab/1209099f1.html

38. NMDA AMPA Glycogen synthase kinase 3 (GSK-3) is a serine/threonine protein kinase (JM beaulieu,2011)

39. Summary D1 and D2 families of dopamine receptor have distinct effect on cAMP-PKA pathway, but also share similar effect in PLC pathway D1 and D2 families have different effect on regulation of ion channels Dopamine receptor signal can be shut down and induce late signal(Akt pathway)

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