Pharmacological and functional characterization of the sigma-1 receptor: Studies utilizing sigma-1 receptor photoprobes and the sigma-1 null homozygous mouse.

摘要

The sigma-1 receptor is a ubiquitously expressed unique binding site in the CNS that chaperones at the ER-mitochondrion interface and is involved with cell survival and ER stress. Interestingly, sigma-1 receptor ligands modulate voltage-gated K+ channels independently of G-proteins or kinases, mediate calcium release from intracellular stores, regulate compartmentalization of lipids on the ER, and have antitumour activity in vitro and in vivo.As part of this thesis work, two novel radioiodinated N-subsituted photoprobes were designed and synthesized to further define the sigma-1 receptor binding site. Both photoprobes specifically derivatized the pure guinea pig sigma-1 receptor and were located primarily in the N-terminus and SBDLI-containing peptides of the sigma-1 receptor. Additionally, the endogenous hallucinogen N, N-dimethyltryptamine (DMT), which follows the sigma-1 receptor pharmacophore, was found to regulate the sigma-1 receptor. DMT bound to sigma-1 receptors and inhibited voltage-gated Na+ channels in native cardiac myocytes and heterologous cells expressing sigma-1 receptors. In addition, DMT induced hypermobility in wild type mice but not in sigma-1 receptor knockout mice. Finally, The sigma-1 receptor knockout (KO) mouse was further characterized through metabolomic and genomic studies.Collectively, these studies contribute to the general biological understanding of the sigma-1 receptor at the whole mouse, molecular and cellular, and biochemical levels. The use of two N-substituted novel photoprobes aided in mapping the regions that comprise the sigma-1 receptor binding site. Also, the hallucinogen N, N-dimethyltryptamine (DMT) was discovered to be a potential endogenous ligand for the sigma-1 receptor. Finally, the sigma-1 receptor knockout (KO) mouse was characterized through NMR metabolomics, histology studies, and gene expression microarrays.