Store-operated calcium entry promotes the degradation of the transcription factor Sp4 in resting neurons

Expression of ORAII, a plasma membrane resident subunit of the CRAC channel, in rodent and non-rodent species

We determined the expression of ORAI1 protein in rodent and non-rodent tissues using a monoclonal antibody directed against an extracellular loop of the protein. Previous reports using antibodies directed at the C-terminus of ORAI1 have not detected central nervous system (CNS) expression. Our results demonstrate broad tissue expression that includes the CNS using a unique monoclonal antibody specific to an extracellular loop of ORAI1. In addition, we present in situ hybridization (ISH) results using a probe within the middle of the mouse coding region showing CNS expression of Orai1 RNA. We contrast the patterns of rodent and human tissue expression and conclude that rodents have similar expression of ORAI1 in most tissue types when compared to primates, with an important exception being the male reproductive system, where human-specific expression is observed.

Neuronal STIMulation at rest

Almost a decade has passed since first STIM, and later Orai, proteins were identified as the molecular constituents of store-operated calcium entry (SOCE). Their roles in immune function have been intensely investigated, but the roles of STIM and Orai in neuronal cells have been much less clear. Lalonde et al. show that when neurons are hyperpolarized or "at rest," constitutive endoplasmic reticulum (ER) Ca(2+) release leads to SOCE-mediated activation of neuronal transcription factors. Precisely why ER Ca(2+) release is constitutive in neurons remains an important question. Irrespective of the answer, this observation provides an intriguing new perspective on why a relatively low-abundance, small-conductance channel such as Orai1 would be important in neurons, which contain a relative abundance of voltage-operated Ca(2+) channels.