Human polyomavirus 7 (HPyV7)-associated dermatoses: novel molecular mechanism driven by viral activation of 4E-BP1 and MEK-ERK-cJun.

A number of pruritic skin conditions arising in immunocompromised patients are associated with viral infection. Recently, human polyomavirus 7 (HPyV7) has been implicated in the pathogenesis of eruptive pruritic parakeratotic and dyskeratotic dermatoses with distinct "peacock plumage" histology. While expression of HPyV7 viral protein, namely small tumor (sT) antigen, is prominent within lesional tissue, the functional role of HPyV7 in cutaneous pathobiology is not yet known. In this study, we demonstrate a novel role for HPyV7 sT antigen in pathways important for the maintenance of keratinocyte structure and function. In particular, HPyV7 sT was found to dysregulate protein phosphatase 2A through physical interactions that led to activation of MEK/ERK/c-Jun and 4E-BP1 (proteins that contribute to disorganized keratinocyte growth as well as hyperproliferative and inflammatory states). Given that HPyV7 actively infects keratinocytes and sT antigen is highly expressed in pruritic dyskeratotic/parakeratotic dermatoses, our data provide important mechanistic evidence supporting a pathogenic role for HPyV7 in cutaneous disease.