Annexin 1 regulation in human epidermal cells.
Annexin 1 (named p35, lipocortin I or calpactin II), initially described as a glucocorticoid induced protein, belongs to a new characterized family of intracellular proteins. In the skin, the role of annexins has still not been elucidated. In a previous study, we reported the localization of annexin 1 in both freshly isolated human epidermal cells and in cultured keratinocytes using immunofluorescence, FACS analysis and immunoblotting techniques. The protein was characterized by Western blot and immunoprecipitation as a 35 kDa protein. Results from in vivo studies confirmed the presence of annexin 1 in basal and suprabasal layers of normal human skin with modified reactivity patterns in hyperproliferative lesions. In the present study, the role of glucocorticoids in annexin 1 regulation was investigated in epidermal cells by Western blot and immunoprecipation assays. In contrast to other studies, we found that glucocorticoid treatment of epidermal cells led to a decrease in annexin 1 content in the cytoplasm and the membranes of cells. As annexin 1 was not detected in the nucleus of cells, we conclude that there was a down regulation of annexin 1 after glucocorticoid treatments rather than a translocation of the protein to the nucleus. Despite the absence of the signal peptide sequence necessary for protein secretion, annexin 1 was released in the keratinocyte culture medium. We found that the protein was secreted only in low Ca2+ medium (0.15 mM), this process required an active metabolism.
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calpactin II annexin 1 annexin 1 annexin 1 Annexin 1 Ca2+ Annexin 1 annexin 1 annexin 1 annexin 1 p35 annexins lipocortin I annexin 1