Biological And Biochemical Characterization Of Sigma Rec

Sigma Rec 的生物学和生化特征

• 批准号: 6987742
• 负责人: Tsung-Ping Ping Su
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON DRUG ABUSE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6987742
• 关键词: ankyrins; biological signal transduction; calcium; cytoskeleton; drug receptors; epidermal growth factor; nerve growth factors; neuropharmacology; psychopharmacology; receptor expression

This project delineates biochemical and pharmacological properties of sigma-1 receptors (s-1R). S-1R are one-transmembrane proteins at the endoplasmic reticulum (ER) that bind neurosteroids, dextrobenzomorphans, and certain psychostimulants such as cocaine. We previously demonstrated that overexpression of s-1R potentiated neurite sprouting caused by nerve growth factor in PC12 cells (Takebayashi et al., 2002). In this study we examined if s-1R may be involved in the action of epidermal growth factor (EGF). EGF is conventionally recognized as a mitogenic factor that stimulates only the proliferation of various types of cells including PC12 cells. We found here that in s-1 receptor-overexpressing PC12 cells (s-1R OE cells), EGF markedly stimulates neuritogenesis without affecting cellular proliferation. EGF receptors (EGFR) are largely reduced in lipid rafts and are enriched in non-raft regions in s-1R OE cells. The enrichment of EGFR in the non-raft region is correlated with enhanced downstream signaling of EGFR including the phosphorylation of both EGFR and extracellular signal-regulated kinases (ERKs). Destruction of cholesterol-containing rafts by treating cells with methyl-b-cyclodextrin also causes a reduction of EGFR in lipid rafts, a concomitant increase in the phosphorylation of both EGFR and ERK, and an increase in the EGF-induced neurite sprouting in wild type cells. Furthermore, while overexpression of s-1R increases the level of lipid raft-associated cholesterol, the overexpression alters the levels of gangliosides in lipid rafts: GM1 and GM2 are decreased, whereas GD1a is increased. We conclude that s-1R cause the remodeling of lipid rafts, at least by increasing the level of lipid raft-associated cholesterol and by altering the levels of certain critical lipid raft-forming gangliosides. s-1R may thus play an important role in directing EGF signaling towards neuritogenesis perhaps by shifting EGFR from the lipid raft into non-raft regions.

本项目描述了Sigma-1受体(S-1R)的生化和药理学特性。S-1R是一种位于内质网(ER)的跨膜蛋白，可与神经类固醇、右旋苯并吗啉和某些精神刺激剂(如可卡因)结合。我们先前证明过表达S-1R可以促进神经生长因子在PC12细胞中引起的轴突萌发(Takebayashi等人，2002年)。在本研究中，我们检测了S-1R是否参与了表皮生长因子的作用。EGF传统上被认为是一种有丝分裂因子，只刺激包括PC12细胞在内的各种类型的细胞的增殖。我们在此发现，在高表达S-1受体的PC12细胞(S-1R-OE细胞)中，表皮生长因子显著刺激神经发生而不影响细胞增殖。在S-1R-OE细胞中，表皮生长因子受体(EGFR)在脂筏中大量减少，在非RAFT区丰富。EGFR在非RAFT区的丰富与EGFR下游信号的增强有关，包括EGFR和细胞外信号调节激酶(ERKs)的磷酸化。用甲基-b-环糊精处理细胞破坏含胆固醇的筏，也会导致脂筏中EGFR的减少，伴随而来的是EGFR和ERK的磷酸化增加，以及EGF诱导的野生型细胞突起萌发的增加。此外，虽然S-1R的过表达增加了脂筏相关胆固醇的水平，但过表达改变了脂筏中神经节苷脂的水平：GM1和GM2减少，而GD1a增加。我们的结论是，S-1R至少通过增加脂筏相关胆固醇的水平和改变某些关键的脂筏形成神经节苷脂的水平而导致脂筏重塑。因此，S-1R可能通过将表皮生长因子受体从脂筏转移到非脂筏区域，在引导表皮生长因子信号转导神经发生中发挥重要作用。