|
|
Jonathan A. Javitch, M.D., Ph.D.
Professor of Psychiatry and Pharmacology (in the Center for Molecular Recognition and in Physiology & Cellular Biophysics)
|
Research
Summary
G-protein coupled receptors: structural bases for pharmacological specificity, signal transduction, and oligomerization.Dopamine transporters: structural bases for substrate transport, cocaine binding, and oligomerization. Bacterial and achaeal transporters as models for mammalian neurotransmitter transporters.
A project supported by NIMH focuses on identifying the dimer interface of the dopamine D2 receptor and other G-protein-coupled receptors and on characterizing conformational changes at the dimer interface and their role in receptor function. This project also aims to demonstrate the role of the second extracellular loop in ligand binding and selectivity.
Other projects funded by NIDA focus on the structure of the dopamine transporter, the target for cocaine and amphetamine, as well as on uncovering the mechanism of action of this transporter. We have also established that the transporter appears to be a tetramer in the membrane and that cocaine alters the conformation of one of the interfaces and are studying the interface and its functional role. In a related NIDA-funded project we are studying a series of bacterial transporters as model systems for structural studies of the dopamine and related neurotransmitter transporters.
Current Research
The catecholamine dopamine plays a major role in the regulation of cognitive, emotional and behavioral functions, and abnormalities in its regulation have been implicated in a number of psychiatric and neurological disorders. Dopamine acts through D2-like (D2, D3, D4) and D1-like (D1, D5) receptors, which are members of the seven transmembrane segment G protein-coupled receptor (GPCR) superfamily. The long-term goals of this project are: 1) to understand the
structural bases of agonist and antagonist binding and specificity in dopamine receptors and related biogenic amine receptors and 2) to determine how agonist binding is transduced into G protein activation. Many drugs used to treat psychiatric disorders, including schizophrenia,
attention-deficit hyperactivity disorder (ADHD), and depression, target dopamine receptors, either directly or indirectly.
We propose the following specific aims:
1. To determine the functional stoichiometry of the signaling unit of the dopamine D2 receptor (D2R), a representative Family A GPCR. We will determine whether two
receptors signal through a single heterotrimeric G protein, the number of agonists required to activate a single signaling unit of D2R, and the role of agonist or antagonist binding to the second protomer in homomeric and heteromeric signaling units.
2. To determine the specificity of D2R heterodimerization in neurons in primary culture and in vivo in Drosophila melanogaster using biochemical, biophysical, and optical
methods.
3. To differentiate the role of signaling of D2R homomers and heteromers using a novel resonance energy transfer based-biosensor for G protein activation.
To complete our objectives we will combine experimental, structural, and computational approaches to receptor structure and function. In addition to work in heterologous cells, we will use mouse nucleus accumbens medium spiny neurons in primary culture and Drosophila melanogaster as a model system to dissect further the importance of homo- and heteromeric receptor signaling in vivo. Moreover, we will use our newly developed energy transfer based-biosensor to link biophysically the heteromeric receptor complex with G protein activation in real time.
http://asp.cumc.columbia.edu/facdb/profile_list.asp?uni=jaj2&DepAffil=Psychiatry
|
Selected Publications:
1. Guo W, Shi L, Filizola M, Weinstein H, Javitch JA. (2005) Crosstalk in G protein-coupled receptors: changes at the transmembrane homodimer interface determine activation. Proc Natl Acad Sci U S A
102(48):17499-17500
2. Quick M, Yano H, Goldberg NR, Duan L, Beuming T, Shi L, Weinstein H, Javitch JA. (2006) State-dependent conformations of the translocation pathway in the tyrosine transporter Tyt1, a novel neurotransmitter:sodium symporter from Fusobacterium nucleatum. J Biol Chem.
281(36):26444-26454
3. Beuming T, Shi L, Javitch JA, Weinstein H. (2006) A comprehensive structure-based alignment of prokaryotic and eukaryotic neurotransmitter/Na+ symporters (NSS) aids in the use of the LeuT structure to probe NSS structure and function. Mol Pharmacol.
70(5):1630-1642
4. Fog JU, Khoshbouei H, Holy M, Owens WA, Vaegter CB, Sen N, Nikandrova Y, Bowton E, McMahon DG, Colbran RJ, Daws LC, Sitte HH, Javitch JA, Galli A, Gether U. (2006) Calmodulin kinase II interacts with the dopamine transporter C terminus to regulate amphetamine-induced reverse transport. Neuron
51(4):417-429
5. Quick M, Javitch JA. (2007) Monitoring the function of membrane transport proteins in detergent-solubilized form. Proc Natl Acad Sci U S A
104(9):3603-3608
6. Erreger K, Grewer C, Javitch JA, Galli A. (2008) Currents in response to rapid concentration jumps of amphetamine uncover novel aspects of human dopamine transporter function. J Neuroscience
28(4):976-989
7. Guo W, Urizar E, Kralikova M, Mobarec JC, Shi L, Filizola M, Javitch JA. (2008) Dopamine D2 receptors form higher order oligomers at physiological expression levels. EMBO J
:July 31 (In Press)
8. Beuming T, Kniazeff J, Bergmann ML, Shi L, Gracia L, Raniszewska K, Newman AH, Javitch JA, Weinstein H, Gether U, Loland CJ. (2008) The binding sites for cocaine and dopamine in the dopamine transporter overlap. Nat. Neuroscience
11(7):780-789
9. Klewe IV, Nielsen SM, Tarpo L, Urizar E, Dipace C, Javitch JA, Gether U, Egebjerg J, Christensen KV. (2008) Recruitment of beta-arrestin2 to the dopamine D2 receptor: Insights into anti-psychotic and anti-parkinsonian drug receptor signaling. Neuropharmacology
54(8):1215-1222
10. Shi L, Quick M, Zhao Y, Weinstein H, Javitch JA. (2008) The mechanism of a neurotransmitter:sodium symporter--inward release of Na+ and substrate is triggered by substrate in a second binding site. Mol. Cell.
30(6):667-677
|
|
|
|
|
|
|
top
|
