The long hand of the small RNAs reaches into several levels of gene regulation

Prognostic significance of microRNA-141 expression and its tumor suppressor function in human pancreatic ductal adenocarcinoma

Increasing evidence shows that dysregulation of microRNAs is correlated with tumor development. This study was performed to determine the expression of miR-141 and investigate its clinical significance in pancreatic ductal adenocarcinoma (PDAC). Taqman quantitative RT-PCR was used to detect miR-141 expressions in 94 PDAC tissues and 16 nontumorous pancreatic tissues. Correlations between miR-141 expression and clinicopathologic features and prognosis of patients were statistically analyzed. The effects of miR-141 expression on growth and apoptosis of PDAC cell line (PANC-1) were determined by MTT, colony formation, and flow cytometry assays. Potential target genes were identified by luciferase reporter and Western blot assays. The expression level of miR-141 in PDAC tissues was significantly lower than that in corresponding nontumorous tissues. Downregulation of miR-141 correlated with poorer pT and pN status, advanced clinical stage, and lymphatic invasion. Also, low miR-141 expression in PDAC tissues was significantly correlated with shorter overall survival, and multivariate analysis showed that miR-141 was an independent prognostic factor for PDAC patients. Further, functional researches suggested that miR-141 inhibits growth and colony formation, and enhances caspase-3-dependent apoptosis in PANC-1 cells by targeting Yes-associated protein-1 (YAP1). Therefore, miR-141 is an independent prognostic factor for PDAC patients, and functions as a tumor suppressor gene by targeting YAP1.

Gawky is a component of cytoplasmic mRNA processing bodies required for early Drosophila development

In mammalian cells, the GW182 protein localizes to cytoplasmic bodies implicated in the regulation of messenger RNA (mRNA) stability, translation, and the RNA interference pathway. Many of these functions have also been assigned to analogous yeast cytoplasmic mRNA processing bodies. We have characterized the single Drosophila melanogaster homologue of the human GW182 protein family, which we have named Gawky (GW). Drosophila GW localizes to punctate, cytoplasmic foci in an RNA-dependent manner. Drosophila GW bodies (GWBs) appear to function analogously to human GWBs, as human GW182 colocalizes with GW when expressed in Drosophila cells. The RNA-induced silencing complex component Argonaute2 and orthologues of LSm4 and Xrn1 (Pacman) associated with 5′–3′ mRNA degradation localize to some GWBs. Reducing GW activity by mutation or antibody injection during syncytial embryo development leads to abnormal nuclear divisions, demonstrating an early requirement for GWB-mediated cytoplasmic mRNA regulation. This suggests that gw represents a previously unknown member of a small group of genes that need to be expressed zygotically during early embryo development.

RNA localization mechanisms in oocytes

In many animals, normal development depends on the asymmetric distribution of maternal determinants, including various coding and noncoding RNAs, within the oocyte. The temporal and spatial distribution of localized RNAs is determined by intricate mechanisms that regulate their movement and anchoring. These mechanisms involve cis-acting sequences within the RNA molecules and a multitude of trans-acting factors, as well as a polarized cytoskeleton, molecular motors and specific transporting organelles. The latest studies show that the fates of localized RNAs within the oocyte cytoplasm are predetermined in the nucleus and that nuclear proteins, some of them deposited on RNAs during splicing, together with the components of the RNA-silencing pathway, dictate the proper movement, targeting, anchoring and translatability of localized RNAs.