Silencing of sigma-1 receptor induces cell death in human lens cells.
Sigma receptors have no known homology with other receptor systems, have no known natural ligands, but appear to play a critical role in a large diversity of cell functions. In the absence of a conventional pharmacology, siRNA technology provides a direct means of elucidating the major cell signaling pathways influenced by this receptor system. The non-transformed human lens cell line FHL124 was found to express the sigma-1 receptor (Sig-1R) and was employed for these studies. 72 h of transfection with either of the two siRNA directed against the sigma-1 receptor reduced messenger RNA and protein levels by over 70 and 60% respectively. Subsequent incubation for 96 h in culture medium (EMEM) supplemented with 5% serum gave a partial recovery of message, but there was no significant increase in protein. LDH leakage assays showed that significant cell death occurred during this time with an increased expression of caspase-3. Thrombin (10 nM) drives the growth of lens cells with a concomitant increase in ERK and Akt phosphorylation. These increases were inhibited in the cells where knockdown had occurred but not in cells exposed to scrambled siRNA. This study establishes a central role for Sig-1R in cell survival and death.
School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
Lixin
L
Wang
George
G
Duncan
D053148:Caspase 3; D020169:Caspases; D016923:Cell Death / Q000235:genetics; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007908:Lens, Crystalline / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D017480:Receptors, sigma / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism / Q000494:pharmacology; D000097605:Sigma-1 Receptor
D053148:Caspase 3; D020169:Caspases; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017480:Receptors, sigma; D013917:Thrombin; D000097605:Sigma-1 Receptor; C505407:CASP3 protein, human