Stim1, an endoplasmic reticulum Ca2+ sensor, negatively regulates 3T3-L1 pre-adipocyte differentiation

Abstract

Ca 2+ plays a complex role in the differentiation of committed pre-adipocytes into mature, fat laden adipocytes. Stim1 is a single pass transmembrane protein that has an essential role in regulating the influx of Ca 2+ ions through specific plasma membrane store-operated Ca 2+ channels. Stim1 is a sensor of endoplasmic reticulum Ca 2+ store content and when these stores are depleted ERlocalized Stim1 interacts with molecular components of store-operated Ca 2+ channels in the plasma membrane to activate these channels and induce Ca 2+ influx. To investigate the potential role of Stim1 in Ca 2+ -mediated adipogenesis, we investigated the expression of Stim1 during adipocyte differentiation and the effects of altering Stim1 expression on the differentiation process. Western blotting revealed that Stim1 was expressed at low levels in 3T3-L1 preadipocytes and was upregulated 4 days following induction of differentiation. However, overexpression of Stim1 potently inhibited their ability to differentiate and accumulate lipid, and reduced the expression of C/EBP alpha and adiponectin. Stim1-mediated differentiation was shown to be dependent on store-operated Ca 2+ entry, which was increased upon overexpression of Stim1. Overexpression of Stim1 did not disrupt cell proliferation, mitotic clonal expansion or subsequent growth arrest. siRNA-mediated knockdown of endogenous Stim1 had the opposite effect, with increased 3T3-L1 differentiation and increased expression of C/EBP alpha and adiponectin. We thus demonstrate for the first time the presence of store-operated Ca 2+ entry in 3T3-L1 adipocytes, and that Stim1-mediated Ca 2+ entry negatively regulates adipocyte differentiation. We suggest that increased expression of Stim1 during 3T3-L1 differentiation may act, through its ability to modify the level of Ca 2+ influx through store-operated channels, to balance the level of differentiation in these cells in vitro.

An Adenosine Receptor-Krüppel-like Factor 4 Protein Axis Inhibits Adipogenesis

“…7E), contribute to its significant inhibitory effect on adipogenesis. Indeed, increased intracellular calcium has been shown to inhibit adipogenesis (40,41 (42). Intriguingly, we now found a strong positive correlation between mRNA expression of A2bAR and KLF4 in both subcutaneous (Fig.…”

“…The differential effect of cAMP inducers on adipocyte differentiation may be due to different timing and levels of cAMP induction or due to compartmentalization of the A2bAR, adenylate cyclase, and effector molecules in microdomains (59). Increased intracellular calcium has been shown to inhibit adipogenesis (40,41,60). Therefore, the ability of A2bAR to increase cAMP as well as intracellular calcium via coupling to both G s and G q (39) may allow a more effective inhibition of adipogenesis.…”

Activation of TRPV2 negatively regulates the differentiation of mouse brown adipocytes

“…These reports demonstrated that elevation of [Ca 2+ ] i has negative effects on white adipocyte differentiation similar to that seen in other cell types [2]. A previous report showed that increased Ca 2+ influx via a store-operated Ca 2+ channel, Orai1, upon activation of an ER membrane protein, stromal interaction molecule-1 (Stim1), inhibited the differentiation of 3T3-L1 pre-adipocytes [11]. However, the effect of a [Ca 2+ ] i increase on the differentiation of brown adipocytes is unknown.…”

Airway smooth muscle STIM1 and Orai1 are upregulated in asthmatic mice and mediate PDGF-activated SOCE, CRAC currents, proliferation, and migration

“…Numerous studies have documented increased ASMC mass in asthma [2, 4, 16, 17, 22, 24, 30, 39, 50]. This pathophysiological remodeling of ASMC is a phenotypic change from a quiescent to a migratory and proliferative/hypertrophic phenotype [24, 50] and is the major cause of decreased pulmonary function in asthmatic patients [2, 4, 23, 43].…”