Human VAT-1: a calcium-regulated activation marker of human epithelial cells

Background and aims: Human VAT-1 (hVAT-1) is a homologue of the synaptic vesicle membrane protein of Torpedo californica. Its coding gene is located near the BRCA1 locus and thus hVAT-1 may be linked to an inherited predisposition to breast and ovary Cancer. However, the hVAT-1 protein expression pattern in normal epithelial tissues such as skin, mammary gland and ovary, as well as in tumours of the mammary gland and ovary, has not been studied.

Methods: To address this issue, an immunohistological analysis of biopsies of normal epidermis and lesional epidermis of bullous pemphigoid and pemphigus vulgaris patients was undertaken.

Results: hVAT-1-expression was observed in basal keratinocytes of lesional epidermis of bullous pemphigoid patients but not in normal epidermis or in lesional epidermis of pemphigus vulgaris patients. Moreover, hVAT-1 expression in HaCaT cells was found to be calcium-dependent. Normal and malignant mammary and ovary epithelium were found to be hVAT-1-negative.

Conclusions: Our results indicate that hVAT-1 exerts a specific function in keratinocyte physiology, in particular in calcium-regulated processes, with no evident deregulation in malignancies of the breast and ovary.