Store-operated Ca2+ entry regulates Ca2+-activated chloride channels and eccrine sweat gland function

Abstract

Eccrine sweat glands are essential for sweating and thermoregulation in humans. Loss-of-function mutations in the Ca2+ release-activated Ca2+ (CRAC) channel genes ORAI1 and STIM1 abolish store-operated Ca2+ entry (SOCE), and patients with these CRAC channel mutations suffer from anhidrosis and hyperthermia at high ambient temperatures. Here we have shown that CRAC channel-deficient patients and mice with ectodermal tissue-specific deletion of Orai1 (Orai1K14Cre) or Stim1 and Stim2 (Stim1/2K14Cre) failed to sweat despite normal sweat gland development. SOCE was absent in agonist-stimulated sweat glands from Orai1K14Cre and Stim1/2K14Cre mice and human sweat gland cells lacking ORAI1 or STIM1 expression. In Orai1K14Cre mice, abolishment of SOCE was associated with impaired chloride secretion by primary murine sweat glands. In human sweat gland cells, SOCE mediated by ORAI1 was necessary for agonist-induced chloride secretion and activation of the Ca2+-activated chloride channel (CaCC) anoctamin 1 (ANO1, also known as TMEM16A). By contrast, expression of TMEM16A, the water channel aquaporin 5 (AQP5), and other regulators of sweat gland function was normal in the absence of SOCE. Our findings demonstrate that Ca2+ influx via store-operated CRAC channels is essential for CaCC activation, chloride secretion, and sweat production in humans and mice.

Hemophagocytic lymphohistiocytosis as presenting manifestation of profound combined immunodeficiency due to an ORAI1 mutation

“…Other signs of CRAC-channelopathy, such as ectodermal dysplasia with anhidrosis 4 were not obvious in our patient, but it was noted that his fever in the course of the CMV infections was particularly responsive to physical measures, while antipyretics had only little effect. While muscular hypotonia, another feature of CRAC-channelopathy, was difficult to assess on mechanical ventilation, the mother reported reduced fetal child movements and hypotonia after birth.…”

“…Flow cytometric analysis of the patient's PBMC showed that the mutant ORAI1 protein was expressed (Fig.2B). Thus, this is the first human mutation described in the II-III intracellular loop of ORAI1 resulting in sustained protein expression 4, 6 . Srikanth et al had previously demonstrated that engineered mutations of ORAI1 residues P146 and E149 neighboring I148 abolish SOCE in vitro 7 .…”

Store-operated Ca2+ entry controls ameloblast cell function and enamel development

“…To address the effect of SOCE deficiency in enamel, we used mice with conditional deletion of Stim1 and Stim2 in keratin expressing ectodermally derived tissues, such as epidermis, salivary glands, and dental enamel, that were generated as described previously (13 ) mice showed drastically reduced mRNA levels of Stim1 and Stim2 relative to control cells, as expected ( Figure 1A). To further confirm deletion of protein expression, tissues from 5-week-old WT controls and Stim1/2 K14cre mice were isolated for immunohistochemical analysis.…”

“…Mice were generated as described previously (13). Briefly, Stim1 fl/fl Stim2 fl/fl mice that had been previously generated as reported (14) were crossed with K14-Cre mice obtained from Jackson Laboratory (strain 004782).…”

The STIM-Orai Pathway: Orai, the Pore-Forming Subunit of the CRAC Channel

“…These scattered observations foreshadowed the broad tissue distribution of Orai proteins (Gwack et al 2007, 2008; Vig et al 2008; McCarl et al 2009) and the physiological role of Orai1 in tissues from the skin to secretory epithelia to muscle (Gwack et al 2008; McCarl et al 2009; Davis et al 2015; Concepcion et al 2016). …”