A multifunctional protein EWS regulates dermal development

Abstract

EWS (Ewings Sarcoma) gene encodes a RNA/DNA binding protein that is ubiquitously expressed and involved in various cellular processes. EWS is a nuclear protein, whose nuclear localization is dependent upon its transactivating NH2 terminus. Also, the EWS protein stimulates transcription mediated by the COOH terminal transactivation domain of the cofactor CREB-binding protein (CBP)/p300. EWS deficiency leads to impaired development and early senescence through unknown mechanisms. We found that EWS regulates the expression of Drosha and microRNAs. EWS deficiency resulted in increased expression of Drosha, a well known microprocessor, and increased levels of miR-29b and miR-18b. Importantly, miR-29b and miR-18b were directly involved in the posttranscriptional regulation of collagen IV alpha 1 (Col4a1) and connective tissue growth factor (CTGF) in EWS knock-out (KO) mouse embryonic fibroblast (MEFs) cells. The up regulation of Drosha, miR-29b and miR-18b and the sequential down regulation of Col4a1 and CTGF contributed to the deregulation of dermal development in EWS KO mice. Otherwise, knock-down of Drohsa rescued miRNA-dependent down regulation of Col4a1 and CTGF proteins. Taken together, our data indicate that EWS is involved in posttranscriptional regulation of Col4a1 and CTGF via a Drosha-miRNA-dependent pathway. This finding suggests that EWS plays a novel role in dermal morphogenesis through the modulation of miRNA biogenesis.