[PMC free article] [PubMed] [Google Scholar] 19
[PMC free article] [PubMed] [Google Scholar] 19. of the receptor. While p11 overexpression potentiates mGluR5 agonist-induced calcium responses, overexpression of mGluR5 mutant, which does not interact with p11, diminishes the calcium responses in cultured cells. Knockout of mGluR5 or p11 specifically in glutamatergic neurons in mice causes depression-like behaviors. Conversely, knockout of mGluR5 or p11 in GABAergic neurons causes antidepressant-like behaviors. Inhibition of mGluR5 with an antagonist, MPEP, induces antidepressant-like behaviors in a p11-dependent manner. Notably, the antidepressant-like action of MPEP is mediated by parvalbumin-positive GABAergic interneurons, resulting in a decrease of inhibitory neuronal firing with a resultant increase of excitatory neuronal firing. These results identify a molecular and cellular basis by which mGluR5 antagonism achieves its antidepressant-like activity. INTRODUCTION Major depressive disorder (MDD) is a devastating psychiatric disease with an estimated lifetime incidence of more than 12 % in men and 20% in women in the United States1. Although dysfunction of monoaminergic and glutamatergic transmission has been implicated in Cilliobrevin D MDD1, the pathogenic mechanisms underlying the disease are not well understood. Currently available antidepressant drugs, which influence monoaminergic systems, are effective only for 30%C50% of patients and have critical drawbacks such as delayed onset of therapeutic efficacy. Thus, the development of improved therapies is necessary. p11 has been implicated in the etiology of depression and in the mechanism of action of selective serotonin reuptake inhibitors (SSRIs)2. p11 was initially identified as a binding protein for serotonin receptors 1B, 1D and 4 (5-HTR 1B, 1D and 4) using a yeast two hybrid screen3, 4. The levels of p11 mRNA and protein in the brain are down-regulated in depressed humans and in a mouse model of depression3, 5. In contrast, the levels of p11 are increased by electroconvulsive therapy or chronic administration of monoaminergic antidepressants including SSRIs2, 3, 6. p11 null mice showed depression-like behaviors, and reduced neurogenic and behavioral responses to the SSRIs2, 3, 7, 8. Conversely, mice overexpressing p11 showed antidepressant-like behaviors3. Recently we have found a chromatin-remodeling factor, called SMARCA3, as a binding partner of p11 and showed a central role for SMARCA3 in p11-dependent neurogenic and behavioral responses to the SSRIs6. Metabotropic glutamate receptors (mGluRs), a sub-family of glutamate receptors, are G protein-coupled receptors. mGluRs are divided into three groups based on the modes of G-protein coupling and signaling pathways: group I (mGluR1 and 5), group Rabbit Polyclonal to MRGX1 II (mGluR 2 and 3), and group III (mGluR4, 6, 7 and 8)9. Previous studies have shown that antagonists acting on mGluR5 or mGluR2/3 exert antidepressant-like activities in mice10C12. We became particularly interested in mGluR5 because we have found a potential p11 binding motif in the cytoplasmic tail of mGluR5. Thus, we aimed at investigating the potential interaction between mGluR5 and p11, and Cilliobrevin D a possible role for p11 in antidepressant-like activities of an mGluR5 antagonist. In this study, we have performed a variety of biochemical, cell biological, imaging, electrophysiological and behavioral experiments, and elucidated a mechanism by which mGluR5 antagonism achieves its antidepressant-like activity. MATERIALS AND METHODS Animals Cilliobrevin D and drug treatments All procedures for biochemical and behavioral experiments involving animals were approved by the Rockefeller University Institutional Animal Care and Use Committee and were in accordance with the National Institutes of Health guidelines. electrophysiology experiments were conducted in accordance with the directives of the Animal Care and Use Committee of the Korea Advanced Institute of Science and Technology (KAIST, Korea). p11 null mice 3, floxed p11 line 13, and floxed mGluR5 line 14 were generated previously. EMX-Cre (stock# 005628), GAD-Cre (stock# 10802), and PV-Cre (stock# 008069) lines were purchased from The Jackson Laboratory (Bar Harbor, Maine, USA). We produced the progeny for each line by fertilization (IVF) and embryo transfer (ET) techniques to produce a number of animals with the same age sufficient for the behavioral tests (Transgenic facility, Rockefeller University). 10C16 week old male mice were used for behavioral tests, and housed 2C4 per cage with a 12:12-hr light/dark cycle and access to food and water. Mice were assigned to experimental groups based on their genotype. Selection of animal for different drug-treatment was performed randomly and in a blinded fashion. mGluR5 antagonist MPEP (Tocris, Minneapolis, MN, USA) or mGluR2/3 antagonist “type”:”entrez-nucleotide”,”attrs”:”text”:”LY341495″,”term_id”:”1257705759″,”term_text”:”LY341495″LY341495 (Tocris) was IP injected at 30 min (for FST )15, 16 and 24 hr (for NSF)17 prior to behavioral tests. Plasmid constructs pGEX-6P1-p11, pGEX-6P1-p11-AnxA2 fusion protein, pIRESneo-Flag/HA-EGFP expressing p11-Flag/HA (WT p11) and pIRESneo-Flag/HA-EGFP expressing p11C83Q-Flag-HA (C83Q p11) were previously generated 6. pRK5-Myc-mGluR5 and pRK5-cytoplasmic tail of mGluR5 (aa 826C1171) were generated previously 18. pRK5-cytoplasmic tail of mGluR5 was used Cilliobrevin D as a template to generate p11 binding-defective mutants by site-directed mutagenesis (Genewiz, South Plainfield, NJ, USA). pRK5-Myc-mGluR5 was digested with NheI (1704 of.