Epithelial splicing regulatory proteins 1 (ESRP1) and 2 (ESRP2) suppress cancer cell motility via different mechanisms

ESRP1 (epithelial splicing regulatory protein 1) and ESRP2 regulate alternative splicing events associated with epithelial phenotypes of cells, and both are down-regulated during the epithelial-mesenchymal transition. However, little is known about their expression and functions during carcinogenesis. In this study, we found that expression of both ESRP1 and ESRP2 is plastic: during oral squamous cell carcinogenesis, these proteins are up-regulated relative to their levels in normal epithelium but down-regulated in invasive fronts. Importantly, ESRP1 and ESRP2 are re-expressed in the lymph nodes, where carcinoma cells metastasize and colonize. In head and neck carcinoma cell lines, ESRP1 and ESRP2 suppress cancer cell motility through distinct mechanisms: knockdown of ESRP1 affects the dynamics of the actin cytoskeleton through induction of Rac1b, whereas knockdown of ESRP2 attenuates cell-cell adhesion through increased expression of epithelial-mesenchymal transition-associated transcription factors. Down-regulation of ESRP1 and ESRP2 is thus closely associated with a motile phenotype of cancer cells.

RNA binding proteins in the regulation of heart development

In vivo, RNA molecules are constantly accompanied by RNA binding proteins (RBPs), which are intimately involved in every step of RNA biology, including transcription, editing, splicing, transport and localization, stability, and translation. RBPs therefore have opportunities to shape gene expression at multiple levels. This capacity is particularly important during development, when dynamic chemical and physical changes give rise to complex organs and tissues. This review discusses RBPs in the context of heart development. Since the targets and functions of most RBPs--in the heart and at large--are not fully understood, this review focuses on the expression and roles of RBPs that have been implicated in specific stages of heart development or developmental pathology. RBPs are involved in nearly every stage of cardiogenesis, including the formation, morphogenesis, and maturation of the heart. A fuller understanding of the roles and substrates of these proteins could ultimately provide attractive targets for the design of therapies for congenital heart defects, cardiovascular disease, or cardiac tissue repair.