The Transcription Factors NFAT and CREB Have Different Susceptibilities to the Reduced Ca2+ Responses Caused by the Knock Down of Inositol Trisphosphate Receptor in HEK 293A Cells

Cellular Physiology and Biochemistry

关键词: Inositol trisphosphate receptor;    NFAT;    CREB;    Calcium signaling;   

DOI  :  10.1159/000322330

学科分类：分子生物学，细胞生物学和基因

来源: S Karger AG

【 摘 要 】

Background/Aims The inositol 1,4,5-trisphosphate receptor (IP₃R), a ligand-gated Ca²⁺ channel, plays an important role in the control of intracellular Ca²⁺. Three isoforms of IP₃R have been identified and most cell types express different proportions of these isoforms. The purpose of this study was to investigate how IP₃R signalling is involved in the activation of the Ca²⁺-sensitive transcription factors NFAT and CREB. Methods Each IP₃R isoform expressed in HEK 293A cells was knocked down using selective siRNA. Free intracellular Ca²⁺ was monitored spectrofluometrically. NFAT and CREB activities were measured with luciferase reporter constructs. Results IP₃R-2-knocked down HEK 293A cells showed a deficient CCh-induced Ca²⁺ response that could be rescued by co-stimulation with VIP, a cAMP increasing agonist. NFAT transcriptional activity, but not CREB transcriptional activity, was significantly reduced in IP₃R-2-knocked down HEK 293A cells. Overexpression of IP₃R-1 could fully compensate for IP₃R-2 knock down to mobilize Ca²⁺ and to activate NFAT. Conclusion Our results show that the knock down of IP₃R-2 significantly reduced the intracellular Ca²⁺ response of HEK 293 cells. This reduced Ca²⁺ response did not affect the activation of CREB but significantly decreased the activation of NFAT, suggesting that the Ca²⁺ signals required for the activation of NFAT are stronger than those required for the activation of CREB.

【 授权许可】

CC BY-NC-ND