STIM Proteins: The Gas and Brake of Calcium Entry in Neurons.

Stromal interaction molecules (STIM)s are Ca sensors in internal Ca stores of the endoplasmic reticulum. They activate the store-operated Ca channels, which are the main source of Ca entry in non-excitable cells. Moreover, STIM proteins interact with other Ca channel subunits and active transporters, making STIMs an important intermediate molecule in orchestrating a wide variety of Ca influxes into excitable cells.

Calcium chelation independent effects of BAPTA on endogenous ANO6 channels in HEK293T cells.

Selective calcium chelator 1,2-Bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) is a common tool to investigate calcium signaling. However, BAPTA expresses various effects on intracellular calcium signaling, which are not related to its ability to bind Ca. In patch clamp experiments, we investigated calcium chelation independent effects of BAPTA on endogenous calcium-activated chloride channels ANO6 (TMEM16F) in HEK293T cells.

The STIM1/2-Regulated Calcium Homeostasis Is Impaired in Hippocampal Neurons of the 5xFAD Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common cause of age-related dementia. Neuronal calcium homeostasis impairment may contribute to AD. Here we demonstrated that voltage-gated calcium (VGC) entry and store-operated calcium (SOC) entry regulated by calcium sensors of intracellular calcium stores STIM proteins are affected in hippocampal neurons of the 5xFAD transgenic mouse model.

Increased Calcium Influx through L-Type Calcium Channels in Hippocampal Neurons with Exogenous Expression of Presenilin-1 ΔE9 Mutant.

Mutations in the PSEN1 gene encoding presenilin-1 (PS1) protein are the most common cause of familial Alzheimer's disease. One of these, deletion of exon 9, results in the production of shortened PS1 protein (PS1ΔE9). Neuronal hyperexcitability and hyperactivation of L-type calcium channels were observed in cellular and animal models of familial Alzheimer's disease.

Role of STIM2 and Orai proteins in regulating TRPC1 channel activity upon calcium store depletion.

Store-operated calcium channels are the major player in calcium signaling in non-excitable cells. Store-operated calcium entry is associated with the Orai, stromal interaction molecule (STIM), and transient receptor potential canonical (TRPC) protein families. Researchers have provided conflicting data about TRPC1 channel regulation by Orai and STIM.