Activity of the hSPCA1 Golgi Ca2+ pump is essential for Ca2+-mediated Ca2+ response and cell viability in Darier disease

Abstract

Keratinocyte differentiation, adhesion and motility are directed by extracellular Ca2+ concentration increases, which in turn increase intracellular Ca2+ levels. Normal keratinocytes, in contrast to most non-excitable cells, require Ca2+ release from both Golgi and endoplasmic reticulum Ca2+ stores for efficient Ca2+ signaling. Dysfunction of the Golgi human secretory pathway Ca2+-ATPase hSPCA1, encoded by ATP2C1, abrogates Ca2+ signaling and causes the acantholytic genodermatosis, Hailey-Hailey disease. We have examined the role of the endoplasmic reticulum Ca2+ store, established and maintained by the sarcoplasmic and endoplasmic reticulum Ca2+-ATPase SERCA2 encoded by ATP2A2, in Ca2+ signaling. Although previous studies have shown acute SERCA2 inactivation to abrogate Ca2+ signaling, we find that chronic inactivation of ATP2A2 in keratinocytes from patients with the similar acantholytic genodermatosis, Darier disease, does not impair the response to raised extracellular Ca2+ levels. This normal response is due to a compensatory upregulation of hSPCA1, as inactivating ATP2C1 expression with siRNA blocks the response to raised extracellular Ca2+ concentrations in both normal and Darier keratinocytes. ATP2C1 inactivation also diminishes Darier disease keratinocyte viability, suggesting that compensatory ATP2C1 upregulation maintains viability and partially compensates for defective endoplasmic reticulum Ca2+-ATPase in Darier disease keratinocytes. Keratinocytes thus are unique among mammalian cells in their ability to use the Golgi Ca2+ store to mediate Ca2+ signaling.

A P IIB -type Ca 2+ -ATPase is essential for stress adaptation in Physcomitrella patens

“…These studies suggest similar fundamental functions of P-type Ca 2+ -ATPases in plants and animals as the generation of KO mice revealed perturbations upon the targeted ablation of specific Ca 2+ -ATPases including lethality, tumorigenesis, skin and muscle diseases, deafness, balance disorders, and male infertility (20). It is assumed that these defects rely on the role of animal Ca 2+ -ATPases in the clearance of [Ca 2+ ] cyt , making them critical factors in Ca 2+ -mediated signaling cascades (21)(22)(23).…”

Darier’s disease: a calcium-signaling perspective

“…Our recent study on the involvement of TRPC1 in DD was based on the hypothesis that in SERCA2-compromised keratinocytes, expression and function of TRPC1 would be augmented to compensate for the prolonged state of depleted stores [44]. Interestingly, in DD, similar upregulation of Ca 2+ signaling elements has been envisioned and reported [31,48]. In a mouse model of DD, the expression and activity of a plasma membrane isoform of Ca 2+ ATPase (PMCA) was significantly higher [31], perhaps as a compensatory adaptation toward SERCA2 haploinsufficiency.…”

Up-Regulation of Transient Receptor Potential Canonical 1 (TRPC1) following Sarco(endo)plasmic Reticulum Ca2+ATPase 2 Gene Silencing Promotes Cell Survival: A Potential Role for TRPC1 in Darier's Disease

“…Cells were maintained in complete media, until reaching 90% confluence and then trypsinized, centrifuged, and resuspended in the same medium as described above. Primary keratinocytes from normal and DD subjects were grown in EpiLife medium supplemented with 0.06 mM Ca 2ϩ and human keratinocyte growth supplement (Cascade Biologics, Portland, OR) as described previously (Foggia et al, 2006). HaCaT cells were infected using adenovirus encoding trpc1 gene or SERCA2-siRNA as described previously (Singh et al, 2001;Seth et al, 2004).…”

“…It has been hypothesized that a single copy of the gene is insufficient to encode adequate amount of SERCA protein, and significant changes in cellular Ca 2ϩ regulation and cell growth are seen in these cells (Sakuntabhai et al, 1999;Ahn et al, 2003;Foggia et al, 2006). To examine the possible consequences of SERCA2 hypofunction, we knocked down SERCA2 in HaCaT cells using adenovirus encoding either SERCA2-siRNA or control-siRNA.…”

“…Based on our observation that TRPC1 is overexpressed in the proliferative layer of the epidermis, we suggest that TRPC1-induced resistance to apoptosis might play a role in the abnormal keratosis associated with this disease. Interestingly, Foggia et al (2006) also showed that capacitative Ca 2ϩ influx was increased in DD patients; however, cytosolic Ca 2ϩ was decreased as a result of overexpressed ATP2C1 (a Golgi Ca 2ϩ pump). These results complement our data and indicate perhaps ATP2C1 and TRPC1 could work together to maintain Ca 2ϩ homeostasis in long-term DD condition; however, it remains to be investigated whether TRPC1 regulate or interact with ATP2C1 protein.…”