Abstract-Recent breakthroughs in the store-operated calcium (Ca 2ϩ ) entry (SOCE) pathway have identified Stim1 as the endoplasmic reticulum Ca 2ϩ sensor and Orai1 as the pore forming subunit of the highly Ca 2ϩ -selective CRAC channel expressed in hematopoietic cells. Previous studies, however, have suggested that endothelial cell (EC) SOCE is mediated by the nonselective canonical transient receptor potential channel (TRPC) family, TRPC1 or TRPC4. Here, we show that passive store depletion by thapsigargin or receptor activation by either thrombin or the vascular endothelial growth factor activates the same pathway in primary ECs with classical SOCE pharmacological features. ECs possess the archetypical Ca 2ϩ release-activated Ca 2ϩ current (I CRAC ), albeit of a very small amplitude. Using a maneuver that amplifies currents in divalent-free bath solutions, we show that EC CRAC has similar characteristics to that recorded from rat basophilic leukemia cells, namely a similar time course of activation, sensitivity to 2-aminoethoxydiphenyl borate, and low concentrations of lanthanides, and large Na ϩ currents displaying the typical depotentiation. RNA silencing of either Stim1 or Orai1 essentially abolished SOCE and I CRAC in ECs, which were rescued by ectopic expression of either Stim1 or Orai1, respectively. Surprisingly, knockdown of either TRPC1 or TRPC4 proteins had no effect on SOCE and I CRAC . Ectopic expression of Stim1 in ECs increased their I CRAC to a size comparable to that in rat basophilic leukemia cells. Knockdown of Stim1, Stim2, or Orai1 inhibited EC proliferation and caused cell cycle arrest at S and G2/M phase, although Orai1 knockdown was more efficient than that of Stim proteins. These results are first to our knowledge to establish the requirement of Stim1/Orai1 in the endothelial SOCE pathway. ATPase inhibitors such as thapsigargin activates SOCE. 1,2 Under physiological conditions SOCE is initiated by inositol 1,4,5 triphosphate (IP 3 )-mediated depletion of ER Ca 2ϩ in response to a plethora of stimuli acting through phospholipase C-coupled receptors. The best characterized SOC current is the Ca 2ϩ release-activated Ca 2ϩ current (I CRAC ), first recorded in rat basophilic leukemia (RBL) mast cells, 3 and later described in other cell types. 4 SOCE is necessary for the replenishment of ER Ca 2ϩ content and is a key regulator of many Ca 2ϩ -dependent physiological processes. 4 Recently, high-throughput RNA silencing (siRNA) screens by several laboratories have identified 2 molecules, Stim1 and Orai1, as key components of the I CRAC pathway in mast cells, lymphocytes, and HEK293 cells. 5-8 On ER Ca 2ϩ depletion, Ca 2ϩ -sensing Stim1 proteins translocate to close proximity of the plasma membrane, where they aggregate into multiple puncta. Strikingly, Orai1 molecules also translocate to the same Stim1-containing structures on store depletion, where they open to mediate Ca 2ϩ influx. 9 -12 In endothelial cells (ECs), SOCE in response to passive store depletion was reported for several EC ...

Introduction: In this multicenter study on subjective cognitive decline (SCD) in community-based and memory clinic settings, we assessed the (1) incidence of Alzheimer’s disease (AD) and non-AD dementia and (2) determinants of progression to dementia. Methods: Eleven cohorts provided 2978 participants with SCD and 1391 controls. We estimated dementia incidence and identified risk factors using Cox proportional hazards models. Results: In SCD, incidence of dementia was 17.7 (95% Poisson confidence interval 15.2–20.3)/1000 person-years (AD: 11.5 [9.6–13.7], non-AD: 6.1 [4.7–7.7]), compared with 14.2 (11.3–17.6) in controls (AD: 10.1 [7.7–13.0], non-AD: 4.1 [2.6–6.0]). The risk of dementia was strongly increased in SCD in a memory clinic setting but less so in a community-based setting. In addition, higher age (hazard ratio 1.1 [95% confidence interval 1.1–1.1]), lower Mini-Mental State Examination (0.7 [0.66–0.8]), and apolipoprotein E ε4 (1.8 [1.3–2.5]) increased the risk of dementia. Discussion: SCD can precede both AD and non-AD dementia. Despite their younger age, individuals with SCD in a memory clinic setting have a higher risk of dementia than those in community-based cohorts.

Calcium (Ca 2+ ) is a highly versatile second messenger that controls vascular smooth muscle cell (VSMC) contraction, proliferation, and migration. By means of Ca 2+ permeable channels, Ca 2+ pumps and channels conducting other ions such as potassium and chloride, VSMC keep intracellular Ca 2+ levels under tight control. In healthy quiescent contractile VSMC, two important components of the Ca 2+ signaling pathways that regulate VSMC contraction are the plasma membrane voltageoperated Ca 2+ channel of the high voltage-activated type (L-type) and the sarcoplasmic reticulum Ca 2+ release channel, Ryanodine Receptor (RyR). Injury to the vessel wall is accompanied by VSMC phenotype switch from a contractile quiescent to a proliferative motile phenotype (synthetic phenotype) and by alteration of many components of VSMC Ca 2+ signaling pathways. Specifically, this switch that culminates in a VSMC phenotype reminiscent of a non-excitable cell is characterized by loss of L-type channels expression and increased expression of the low voltage-activated (T-type) Ca 2+ channels and the canonical transient receptor potential (TRPC) channels. The expression levels of intracellular Ca 2+ release channels, pumps and Ca 2+ -activated proteins are also altered: the proliferative VSMC lose the RyR3 and the sarcoplasmic/endoplasmic reticulum Ca 2+ ATPase isoform 2a pump and reciprocally regulate isoforms of the ca 2+ /calmodulin-dependent protein kinase II. This review focuses on the changes in expression of Ca 2+ signaling proteins associated with VSMC proliferation both in vitro and in vivo. The physiological implications of the altered expression of these Ca 2+ signaling molecules, their contribution to VSMC dysfunction during vascular disease and their potential as targets for drug therapy will be discussed.

Potassium channels have been involved in epithelial tumorigenesis but the role of small-conductance Ca 2+ -activated K + channels is unknown. We report here that small-conductance Ca 2+ -activated K + channels are expressed in a highly metastasizing mammary cancer cell line, MDA-MB-435s. Patch-clamp recordings showed typical small-conductance Ca 2+ -activated K + channelmediated currents sensitive to apamin, 4-aminopyridine, and tetraethylammonium. Moreover, the cells displayed a high intracellular calcium concentration, which was decreased after 24 hours of apamin treatment. By regulating membrane potential and intracellular calcium concentration, these channels were involved in MDA-MB435s cell migration, but not in proliferation. Only SK3 protein expression was observed in these cells in contrast to SK2, which was expressed both in cancer and noncancer cell lines. Whereas small interfering RNA directed against SK3 almost totally abolished MDA-MB435s cell migration, transient expression of SK3 increased migration of the SK3-deficient cell lines, MCF-7 and 184A1. SK3 channel was solely expressed in tumor breast biopsies and not in nontumor breast tissues. Thus, SK3 protein channel seems to be a new mediator of breast cancer cell migration and represents a potential target for a new class of anticancer agents.