Small proline-rich protein 4 (SPRR4)

SPRR4 is a member of the small proline-rich protein family, which serve as structural precursors of the cornified cell envelope in the outermost layers of stratified squamous epithelia such as the skin[1][3][4][7]. SPRR4 is typically expressed at very low or undetectable levels in normal skin but is strongly induced by chronic UV light exposure, coinciding with increased formation of the skin barrier[1]. Incorporation of SPRR4 into the cornified envelope is part of the skin's adaptive response to environmental stress, helping compensate for UV-induced damage to the epidermal barrier[1][2]. SPRR family proteins, in general, have emerging roles as antimicrobial proteins, capable of directly killing bacteria by disrupting their membranes (though functional studies for SPRR4 specifically are lacking)[5]. Genetically, SPRR4 is associated with diseases related to barrier dysfunction such as psoriasis and ichthyosis vulgaris[4]. SPRR4 interacts with other cornified envelope proteins (e.g., loricrin, involucrin, KPRP, other SPRRs), indicating its role in epidermal barrier formation[3]. As of this date, SPRR4 is not a recognized therapeutic target and no drugs are known to act specifically on SPRR4[4][5].

Other names

SPRR4small proline-rich protein 4SPRR4 protein, humanSprr4 protein, mouse