ANNEXIN-1 LOCALIZATION IN HUMAN SKIN - POSSIBLE ASSOCIATION WITH CYTOSKELETAL ELEMENTS IN KERATINOCYTES OF THE STRATUM-SPINOSUM

Annexin-1 (also called lipocortin-1 or p35), a putative substrate of the epidermal growth factor/receptor kinase, protein kinase C, and transglutaminase, was immunolocalized in embryonic, neonatal, adult, and diseased human epidermis. In embryonic skin intense annexin-1 immunoreactivity was found in the periderm at 54 d estimated gestational age (EGA). Later (EGA = 91-143 d), annexin-1 immunoreactivity was restricted to basal keratinocytes. In neonatal skin, basal cells were often more heavily stained than were suprabasal keratinocytes, which were also stained. Only basal keratinocytes stained in adult plantar skin, but in thin skin annexin-1 was present in the basal, suprabasal, and sometimes even in the granular layers of the epidermis. Often, annexin-1 appeared concentrated around the perimeter of cells, especially tonofilament/desmosome-rich keratinocytes of the spinous-cell layer. At high magnification, annexin-1 appeared associated with distinct structures and was very granular in appearance in the intensely stained ductal keratinocytes ot eccrine sweat glands, cells that are very highly enriched in keratin tonofilaments. This striking distribution in certain keratinocytes enriched in tonofilaments suggests a role for annexin-1 in cytoskeletal functions.