Hayashi T, Su T P
Cellular Pathobiology Unit, Cellular Neurobiology Research Branch, Intramural Research Program, National Institute on Drug Abuse/National Institutes of Health, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
Proc Natl Acad Sci U S A. 2001 Jan 16;98(2):491-6. doi: 10.1073/pnas.98.2.491. Epub 2001 Jan 9.
Ankyrin is a cytoskeletal adaptor protein that controls important cellular functions, including Ca(2+) efflux at inositol 1,4,5-trisphosphate receptors (IP(3)R) on the endoplasmic reticulum. The present study found that sigma-1 receptors (Sig-1R), unique endoplasmic reticulum proteins that bind certain steroids, neuroleptics, and psychotropic drugs, form a trimeric complex with ankyrin B and IP(3)R type 3 (IP(3)R-3) in NG-108 cells. The trimeric complex could be coimmunoprecipitated by antibodies against any of the three proteins. Sig-1R agonists such as pregnenolone sulfate and cocaine caused the dissociation of an ankyrin B isoform (ANK 220) from IP(3)R-3. This effect caused by Sig-1R agonists was blocked by a Sig-1R antagonist. The degree of dissociation of ANK 220 from IP(3)R-3 caused by Sig-1R ligands correlates excellently with the ligands' efficacies in potentiating the bradykinin-induced increase in cytosolic free Ca(2+) concentration. Immunocytohistochemistry showed that Sig-1R, ankyrin B, and IP(3)R-3 are colocalized in NG-108 cells in perinuclear areas and in regions of cell-to-cell communication. These results suggest that Sig-1R and associated ligands may play important roles in cells by controlling the function of cytoskeletal proteins and that the Sig-1R/ANK220/IP(3)R-3 complex regulating Ca(2+) signaling may represent a site of action for neurosteroids and cocaine.
锚蛋白是一种细胞骨架衔接蛋白，可控制重要的细胞功能，包括内质网上肌醇1,4,5 - 三磷酸受体（IP(3)R）处的Ca(2+)外流。本研究发现，σ-1受体（Sig-1R）是一种独特的内质网蛋白，可结合某些类固醇、抗精神病药物和精神药物，在NG-108细胞中与锚蛋白B和3型IP(3)R（IP(3)R-3）形成三聚体复合物。该三聚体复合物可被针对这三种蛋白质中任何一种的抗体共免疫沉淀。Sig-1R激动剂如硫酸孕烯醇酮和可卡因会导致一种锚蛋白B异构体（ANK 220）从IP(3)R-3上解离。Sig-1R激动剂引起的这种效应被Sig-1R拮抗剂阻断。Sig-1R配体引起的ANK 220从IP(3)R-3上的解离程度与配体增强缓激肽诱导的胞质游离Ca(2+)浓度增加的效力密切相关。免疫细胞化学显示，Sig-1R、锚蛋白B和IP(3)R-3在NG-108细胞的核周区域和细胞间通讯区域共定位。这些结果表明，Sig-1R及其相关配体可能通过控制细胞骨架蛋白的功能在细胞中发挥重要作用，并且调节Ca(2+)信号的Sig-1R/ANK220/IP(3)R-3复合物可能代表神经甾体和可卡因的作用位点。
