The long term objective of this project is to understand the signaling pathways which regulate the activity of serine racemase (SR), a glial enzyme that catalyzes the conversion of L-serine to D-serine. D-serine formed by the action of SR has been proposed to function as a neuromodulator. Activation of the alpha-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA)-type glutamate receptors on glial cells releases D-serine from astrocytic cultures. D- serine then enters the synaptic cleft and activates post-synaptic glutamate N-methyl-D-aspartate (NMDA) receptors in conjunction with L-glutamate. The D-serine regulatory pathway could therefore represent therapeutic targets for diseases involving glutamate excitotoxicity such as Alzheimer's, stroke, epilepsy and ALS among others as well as for conditions involving hypofunction of NMDA receptors such as Schizophrenia.
The specific aims of this project are twofold: 1) I wish to determine the functional effects of protein kinase C-alpha (PKCalpha) phosphorylation on the enzymatic activity of SR and examine the role of the protein interactor of C kinase-1 (PICK1) in this regulatory process. 2) I will develop a novel assay to rapidly and accurately measure D-Serine levels in vitro and from intact cells and monitor SR activity specifically with respect to phosphorylation by PKCa and interaction with PICK1. The assay will be done using D-serine deaminase (DsdA), a bacterial enzyme that specifically converts D-serine to pyruvate, in conjunction with the lactate dehydrogenase (LDH) fluorescence shift assay. All this will primarily be accomplished by a combination of radiolabeling experiments, the use of pharmacological agents, mass spectrometry analysis, site-directed mutagenesis and the DsdA-LDH assay. ? ? ?
| Sen, Nilkantha; Paul, Bindu D; Gadalla, Moataz M et al. (2012) Hydrogen sulfide-linked sulfhydration of NF-?B mediates its antiapoptotic actions. Mol Cell 45:13-24 |
| Mustafa, Asif K; Sikka, Gautam; Gazi, Sadia K et al. (2011) Hydrogen sulfide as endothelium-derived hyperpolarizing factor sulfhydrates potassium channels. Circ Res 109:1259-68 |
| Mustafa, Asif K; Ahmad, Abdullah S; Zeynalov, Emil et al. (2010) Serine racemase deletion protects against cerebral ischemia and excitotoxicity. J Neurosci 30:1413-6 |
| Mustafa, Asif K; van Rossum, Damian B; Patterson, Randen L et al. (2009) Glutamatergic regulation of serine racemase via reversal of PIP2 inhibition. Proc Natl Acad Sci U S A 106:2921-6 |
| Mustafa, Asif K; Gadalla, Moataz M; Sen, Nilkantha et al. (2009) H2S signals through protein S-sulfhydration. Sci Signal 2:ra72 |
| Hikida, Takatoshi; Mustafa, Asif K; Maeda, Kazuhisa et al. (2008) Modulation of D-serine levels in brains of mice lacking PICK1. Biol Psychiatry 63:997-1000 |
