Hailey–Hailey disease and tight junctions: Claudins 1 and 4 are regulated by ATP2C1 gene encoding Ca²⁺/Mn²⁺ATPase SPCA1 in cultured keratinocytes

Abstract

Mutations in the ATP2C1 gene encoding Ca2+/Mn2+ ATPase SPCA1 cause Hailey-Hailey disease (HHD, OMIM 16960). HHD is characterized by epidermal acantholysis. We attempted to model HHD using normal keratinocytes in which the SPCA1 mRNA was down-regulated with the small inhibitory RNA (siRNA) method. SiRNA inhibition significantly down-regulated the SPCA1 mRNA, as demonstrated by qPCR, and decreased the SPCA1 protein beyond detectable level, as shown by western analysis. The expression of selected desmosomal, adherens and tight junction (TJ) proteins was then studied in the SPCA1-deficient and control keratinocytes cultured in low (0.06 mM) or high (1.2 mM) calcium concentration. The mRNA and protein levels of most TJ components were up-regulated in non-treated control keratinocyte cultures upon switch from low to high calcium concentration. In contrast, SPCA1-deficient keratinocytes displayed high levels of TJ proteins claudin 1 and 4 even in low calcium. ZO-1 did not however follow similar expression patterns. Protein levels of occludin, betacatenin, E-cadherin, desmoplakin, desmogleins 1-3, desmocollin 2/3 and plakoglobin did not show marked changes in SPCA1 deficient keratinocytes. Indirect immunofluorescence labeling revealed delayed translocation of desmoplakin and desmoglein 3 in desmosomes, and increased intracellular pools of TJ and desmosomal components in SPCA1 inhibited keratinocytes. The results show that SPCA1 regulates the levels of claudins 1 and 4, but does not affect desmosomal protein levels, indicating that TJ proteins are differently regulated. The results also suggest a potential role for claudins in HHD.

Desmosome assembly and dynamics

“…In this case mutation in Ca 2+ /Mn 2+ -ATPases (SPCA1) located in the Golgi apparatus cause similar clinical and histological symptoms as those observed in Darier’s disease [60,71]. Additionally, translocation of DP and Dsg3 into desmosomes was reported to be delayed in SPCA1-deficient keratinocytes [72]. A more detailed mechanism explaining how defective function of SPCA1 affects desmosome assembly awaits further study.…”

Mutation‐dependent effects on mRNA and protein expressions in cultured keratinocytes of Hailey–Hailey disease

“…Abnormal cytoplasmic Ca 2+ caused by haploinsufficiency of SPCA1 may alter post-translational modifications, including glycosylation, folding, trafficking and sorting, in cell adhesion molecules, leading to acantholytic changes seen in HHD (11)(12)(13). This study showed that different mutations in HHD result in distinct expression of mRNA and protein, which may relate to clinical phenotypes.…”

Cell-Cell Adhesions and Cell Contractility Are Upregulated upon Desmosome Disruption

“…Desmoplakin null epidermis showed a similar increase in claudin-1 levels. While there have not been reports of tight junction activity in pemphigus patients, it is noteworthy that an upregulation of claudin 1 was found in Hailey-Hailey disease [32]. Hailey-Hailey disease results in blistering of the epidermis and is caused by a mutation in the ATP2C1 gene, resulting in desmosomal defects.…”