DIFFERENTIAL EXPRESSION OF THE CALPACTIN-I SUBUNITS ANNEXIN-II AND P11 IN CULTURED KERATINOCYTES AND DURING WOUND REPAIR

Transforming growth factor beta 1 (TGF-beta 1) is an important modulat or of skin morphogenesis and cutaneous wound repair, To gain insight i nto the mechanisms of TGF-beta 1 action in the skin, we used the diffe rential display RT-PCR technique to identify genes that are regulated by this factor in cultured human keratinocytes, We obtained several pa rtial cDNA clones, One of them was identical to the 3'-end of p11, the small and regulatory subunit of the calpactin I complex [(annexin II) (2)(p11)(2)]. RNase protection and northern blot analysis revealed spe cific regulation of expression of both subunits of this heterotetramer ic protein (p11 and annexin II) by TGF-beta 1 as well as by other grow th factors, although the time course and degree of induction or suppre ssion were different for each gene. Furthermore, we analyzed p11 and a nnexin II expression in normal and wounded skin. Both p11 and annexin II mRNAs were found in the dermal and epidermal compartments of normal human skin. Immunohistochemical studies demonstrated the presence of p11 at equally high levels in all layers of normal epidermis and in th e hyper-proliferative epithelium at the wound edge. By contrast, annex in II expression was high in the basal layer of normal epidermis but l ow in the suprabasal layers and in the hyper-proliferative epithelium at the wound edge, suggesting a differentiation-specific regulation of this calpactin I subunit, The differential expression and regulation of p11 and annexin II subunits in keratinocytes suggest the existence of different ratios of monomeric versus p11-complexed annexin II that might be associated with different cellular functions.