Genetically-targeted optical control of an endogenous G protein-coupled receptor

G protein-coupled receptors (GPCRs) are membrane proteins that play important roles in biology. However, our understanding of their function in complex living systems is limited because we lack tools that can target individual receptors with sufficient precision. State-of-the-art approaches, including DREADDs, optoXRs, and PORTL gated-receptors, control GPCR signaling with molecular-, cell type-, and temporal-specificity. Nonetheless, these tools are based on engi-neered non-native proteins that may (i) express at non-physiological levels, (ii) localize and turnover incorrectly, and/or (iii) fail to interact with endogenous partners. Alternatively, membrane-anchored ligands (t-toxins, DARTs) target endoge-nous receptors with molecular- and cell type-specificity but cannot be turned on and off. In this study, we used a combina-tion of chemistry, biology, and light to control endogenous metabotropic glutamate receptor 2 (mGluR2), a Family C GPCR, in primary cortical neurons. mGluR2 was rapidly, reversibly, and selectively activated with photoswitchable glutamate teth-ered to a genetically targeted-plasma membrane anchor (membrane anchored Photoswitchable Orthogonal Remotely Teth-ered Ligand; maPORTL). Photoactivation was tuned by adjusting the length of the PORTL as well as the expression level and geometry of the membrane anchor. Our findings provide a template for controlling endogenous GPCRs with cell type-specificity and high spatio-temporal precision

Endogenous antagonists of N-Methyl-D-Aspartate receptor in schizophrenia

Schizophrenia is a chronic neuropsychiatric brain disorder that has a devastating personal impact and rising healthcare costs. Dysregulation of glutamatergic neurotransmission has been implicated in the pathobiology of the disease, attributed largely to the hypofunction of the NMDA receptor. Currently, there is a major gap in the mechanistic analysis as to how endogenous modulators of the NMDA receptors contribute to the onset and progression of the disease. We present a systematic review of the neurobiology and the role of endogenous NMDA receptor antagonists in animal models of schizophrenia, and in patients. We discuss their neurochemical origin, release and action mechanisms, and functional effects, which could contribute to the impairments of neuronal processes underlying this complex pathological state. We consider clinical evidence suggesting dysregulations of endogenous NMDA receptors in schizophrenia, and highlight the pressing need in future studies and emerging directions, to restore the NMDA receptor functions for therapeutic benefits