CaMKII Potentiates Store-Operated Ca2+ Entry Through Enhancing STIM1 Aggregation and Interaction with Orai1.Cell Physiol Biochem 2018; 46(3):1042-1054CP
Upon Ca2+ store depletion, stromal interaction molecule 1 (STIM1) oligomerizes, redistributes near plasmalemma to interact with Ca2+ selective channel-forming subunit (Orai1) and initiates store-operated Ca2+ entry (SOCE). Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a regulator of SOCE, but how CaMKII regulates SOCE remains obscure.
Using Fura2, confocal microscopy, co-immunoprecipitation, specific blocker and overexpression/knockdown approaches, we evaluated STIM1 aggregation and its interaction with Orai1, and SOCE upon Ca2+ store depletion in thapsigargin (TG) treated HEK293 and HeLa cells.
Overexpression of CaMKIIδ enhanced TG-induced STIM1 co-localization and interaction with Orai1 as well as SOCE. In contrast, CaMKIIδ knockdown and a specific inhibitor of CaMKII suppressed them. In addition, overexpression or knockdown of CaMKIIδ in TG treated cells exhibited increased or reduced STIM1 clustering and plasmalemma redistribution, respectively.
CaMKII up-regulates SOCE by increasing STIM1 aggregation and interaction with Orai1. This study provides an additional insight into SOCE regulation and a potential mechanism for CaMKII involvement in some pathological situations through crosstalk with SOCE.