Post on 14-Dec-2015
Outline
• Dopamine and dopamine receptors• cAMP-PKA pathway• PLC pathway• Regulation of ion channel by dopamine• Early signal quench and late signal induction
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
Synapse in CNS
http://blog.lib.umn.edu/trite001/studyinghumananatomyandphysiology/2008/04/dopamine_excitatory_or_inhibit.html
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
G-protein Coupled receptors
• Ligand binding • changing in
receptor conformation
• Facilitate release of GDP and binding of GTP
http://openwetware.org/wiki/BIO254:Gprotein
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
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”
Receptor Structure• D3 receptor (homo sapiens)
(Ellen Chien, 2010)
400 aa
ECL2 forms ligand binding pocket
LCL2 is transient, raising the possibilitythat interactions between ICL2 and the receptorionic lock
Outline
• Dopamine and dopamine receptors• cAMP-PKA pathway• PLC pathway• Regulation of ion channel by dopamine• Early signal quench and late signal induction
Recall: Families of GFamily Gene
VarientsEffectors 2nd
MessengerAssociation
Gs s(S), s(L) adenylyl cyclase cAMP
olf adenylyl cyclase cAMP Olfactory
Gi i1,i2,i3, adenylyl cyclase cAMP
0a, 0b phospholipaseC IP3, DAG Brain
t1, t2cGMP-PDE cGMP Retina
gust phospholipaseC IP3, DAG Gustatory
z adenylyl cyclase cAMP
Gq q,11,14,
15, 16
phospholipaseC IP3, DAG
G12 12, 13 Rho-GEF Rho
Adapted from Beckerman, Molecular & Cellular Signaling
Alberts MBoC, Fig 15-36, 5th ed.
Gαs
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
Gαi/0
De-P on Thr 75
Channel/transporter
Protein phosphatase
(Y Xu, 2006)
Protein Phosphatase 2A
Catalytic subunit
regulatory subunitscaffolding subunit
Protein Phosphatase 1
(A hirschi,2010)
Outline
• Dopamine and dopamine receptors• cAMP-PKA pathway• PLC pathway• Regulation of ion channel by dopamine• Early signal quench and late signal
D1-like receptor activate GqFamily Gene
VarientsEffectors 2nd
MessengerAssociation
Gs s(S), s(L) adenylyl cyclase cAMP
olf adenylyl cyclase cAMP Olfactory
Gi i1,i2,i3, adenylyl cyclase cAMP
0a, 0b phospholipaseC IP3, DAG Brain
t1, t2cGMP-PDE cGMP Retina
gust phospholipaseC IP3, DAG Gustatory
z adenylyl cyclase cAMP
Gq q,11,14,
15, 16
phospholipaseC IP3, DAG
G12 12, 13 Rho-GEF Rho
Adapted from Beckerman, Molecular & Cellular Signaling
D2-like receptor activate via Gβγ
NATURE REVIEWS | DRUG DISCOVERY 604| JULY 2004 | VOLUME 3
ion channels
adenylyl cyclase
phospholipases
guanine nucleotide exchange factor
kinases
binding protein
kinases
Outline
• Dopamine and dopamine receptors• cAMP-PKA pathway• PLC pathway• Regulation of ion channel by dopamine• Early signal quench and late signal induction
Four Families of Ion ChannelsIon Channel Selectivity Subunit Topology Channel assembly
6TM cation 6TM, loop24 TM, 4 loops
Tetrameric, Monomeric
Calcium Ca2+
HCN Na+, K+
Potassium K+
Sodium Na+
Voltage-gated ion 10-18IM Dimeric
ClC Cl-
Cys-loop receptor 4TM Pentameric
nAChR Cations
GABAA,C Anions (Cl-)
Glycine Anions (Cl-)
5-HT3 Cations
Glutamate recep’r 3TM, loop Tetrameric
AMPA Na+, K+
Kainate Na+, K+
NMDA Ca2+
Liga
nd-g
ated
Vol
tage
-gat
edRECALL
Dopamine regulated K+ channels
• G protein-regulated inwardly rectifying K+
channels (GIRK) D1 receptor GIRK D2 receptor GIRK• voltage-gated K+ channels (VGKC) Iks/IA/ID
D1 receptor VGKC D2 receptor VGKC
Gbγ
PKA
PKA
PKA
PKA
Dopamine regulated Ca2+ 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
Gbγ
Dopamine regulated Na+ channels
• Voltage gated Na+ Channel (INat and INap)• D1 receptor PKA pathwayα-subunit Ser
573 phosphorylation transient Na+ • current D1 receptor persistent Na+
current • D2 receptor Na+ channels
PKA/PKC
PKA inhibition
Gbγ
Dopamine regulated glutamate receptors
• D1 receptor
• D2 receptor
NMDAAMPAGABA
PKA inhibition/NMDAAMPAGABA
PKA
Gbγ
Gbγ
?
Direct interaction between DA receptor and ion channels
-- D1 receptor N-type Calcium Channels-- D1 receptor NMDA PKA D2 receptor NMDA D5 receptor GABA
Outline
• Dopamine and dopamine receptors• cAMP-PKA pathway• PLC pathway• Regulation of ion channel by dopamine• Early signal quench and late signal induction
RGS deactivate Gα
RGS 9-2 regulates D2-like receptor
signaling
Probably cooperate with
RGS 7, mediated by
R7BP
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
Arrestin and downstream pathway
• arrestin 1 (rod) arrestin 4 (cone) β-arrestin 1 2 (widely) β-arrestin 2 (widely)
• Binds phosphorylated GRK1.Recruit Clathrininternalizationrecycle or degrade GPCR2.Scaffold PP2A and Akt(PKB) dephosphorylate (deactivate)Akt
http://www.fz-juelich.de/isb/isb-2/topics/arrestin
NMDA
AMPA
Glycogen synthase kinase 3 (GSK-3) is a serine/threonine protein kinase
(JM beaulieu,2011)
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)
Reference• Beaulieu, J. M. and R. R. Gainetdinov (2011). "The Physiology, Signaling, and Pharmacology of Dopamine
Receptors." Pharmacological Reviews 63(1): 182.• Cave, J. W. and H. Baker (2009). "Dopamine systems in the forebrain." Development and Engineering of
Dopamine Neurons: 15-35.• Chien, E. Y. T., W. Liu, et al. (2010). "Structure of the human dopamine D3 receptor in complex with a D2/D3
selective antagonist." Science 330(6007): 1091.• Hirschi, A., M. Cecchini, et al. (2010). "An overlapping kinase and phosphatase docking site regulates activity
of the retinoblastoma protein." Nature structural & molecular biology• Kienast, T. and A. Heinz (2006). "Dopamine and the diseased brain." Current Drug Targets-CNS &# 38;
Neurological Disorders 5(1): 109-131.• Kurachi, Y. and M. Ishii (2004). "Cell signal control of the G protein-gated potassium channel and its
subcellular localization." The Journal of Physiology 554(2): 285.• Lüscher, C. and P. A. Slesinger (2010). "Emerging roles for G protein-gated inwardly rectifying potassium
(GIRK) channels in health and disease." Nature Reviews Neuroscience 11(5): 301-315.• Missale, C., C. Fiorentini, et al. (2010). "The neurobiology of dopamine receptors: evolution from the dual
concept to heterodimer complexes." Journal of Receptors and Signal Transduction 30(5): 347-354.• Neve, K. A., J. K. Seamans, et al. (2004). "Dopamine receptor signaling." Journal of Receptors and Signal
Transduction 24(3): 165-205.• Xu, Y., Y. Xing, et al. (2006). "Structure of the protein phosphatase 2A holoenzyme." Cell 127(6): 1239-1251.