Synaptic vesicle membrane protein VAT-1 homolog
cytoplasm
Human VAT-1: a calcium-regulated activation marker of human epithelial cells.
<h4>Background and aims</h4>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.<h4>Methods</h4>To address this issue, an immunohistological analysis of biopsies of normal epidermis and lesional epidermis of bullous pemphigoid and pemphigus vulgaris patients was undertaken.<h4>Results</h4>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.<h4>Conclusions</h4>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.