STIM1 tyrosine-phosphorylation is required for STIM1-Orai1 association in human platelets

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• 作者：Esther Lopez^a ; Isaac Jardin^a ; Alejandro Berna-Erro^a ; Nuria Bermejo^c ; Giné ; s M. Salido^a ; Stewart O. Sage^b ; Juan A. Rosado^a ; Pedro C. Redondo^a ; ^b ; ^pcr@unex.es
• 关键词：STIM1 ; Stromal interaction molecule 1 ; SOCE ; operated Ca2+ entry mechanism ; SERCA2b ; sarco-endoplasmic Ca2+-ATPase isotype 2b ; IP3R II ; inositol trisphosphate receptor ; TRPC ; transient receptor potential channel ; SKFs ; Src family of tyrosine kinases ; Btk
• 刊名：Cellular Signalling
• 出版年：2012
• 期刊代码：42_08986568
• 类别：bio
• 出版时间：June, 2012
• 卷：24
• 期：6
• 页码：1315-1322
• 文件大小：997 K

摘要

Stromal interaction molecule 1 (STIM1) is a key element of the store-operated Ca²⁺ entry mechanism (SOCE). Recently, regulation of STIM1 by glycosylation and phosphorylation on serine/threonine or proline residues has been described; however other modes of phosphorylation that are important for activating SOCE in platelets, such as tyrosine phosphorylation, have been poorly investigated. Here we investigate the latency of STIM1 phosphorylation on tyrosine residues during the first steps of SOCE activation.

Human platelets were stimulated and fixed at desired times using rapid kinetic assays instruments, and immunoprecipitation and western blotting techniques were then used to investigate the pattern of STIM1 tyrosine phosphorylation during the first steps of SOCE activation. We have found that maximal STIM1 tyrosine phosphorylation occurred 2.5 s after stimulation of human platelets with thapsigargin (Tg). STIM1 localized in the plasma membrane were also phosphorylated in platelets stimulated with Tg. By using chemical inhibitors that target different members of the Src family of tyrosine kinases (SKFs), two independent signaling pathways involved in STIM1 tyrosine phosphorylation during the first steps of SOCE activation were identified. We finally conclude that STIM1 tyrosine phosphorylation is a key event for the association of STIM1 with plasma membrane Ca²⁺ channels such as Orai1, hence it is required for conducting SOCE activation.