The integrity of the intestinal mucosal barrier protects hosts against pathological conditions. Early mucosal restitution after wounding refers to epithelial cell migration into a defect. The RNA-binding protein HuR plays an important role in the posttranscriptional regulation of gene expression and is involved in many aspects of cellular physiology. In the present study, we investigated the role of HuR in the regulation of cell migration through the posttranscriptional regulation of Caveolin-1 (Cav-1). Online software was used to identify Cav-1 mRNA as a potential target of HuR. The interaction of HuR with Cav-1 mRNA was investigated via ribonucleoprotein immunoprecipitation (RNP IP) assays and biotin pulldown analysis. HuR was found to bind specifically to the Cav-1 3′-UTR rather than the coding region or 5′-UTR. Transfection of cells with siHuR decreased both HuR protein levels and Cav-1 protein levels; conversely, ectopic overexpression of HuR via infection of cells with an adenoviral vector containing HuR cDNA (AdHuR) increased Cav-1 protein levels without disturbing Cav-1 mRNA levels. Thus, HuR enhanced Cav-1 expression in vitro by stimulating Cav-1 translation. Intestinal epithelium-specific HuR knockout in mice decreased Cav-1 protein levels without changing Cav-1 mRNA levels, consistent with the in vitro results. Decreasing the levels of HuR via siHuR transfection inhibited early epithelial repair, but this effect was reversed by ectopic overexpression of GFP-tagged Cav-1. These results indicate that posttranscriptional regulation of Cav-1 gene expression by HuR plays a critical role in the regulation of rapid epithelial repair after wounding.
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Tumor organoids are a relevant, 3-dimensional, culture method which allows long-term growth preserving the stem cell identity and reconstituting to some extent the morphological and phenotypic heterogeneity of the original tumor. Representative fluorescence image of a tumour organoid derived from patient derived GSCs after 23 days of culture, stained for anti-αTubulin (microtubules, white) and Phalloidin (actin red). In this issue Pinto and colleagues (pp. 21–39) observed that different types of cell protrusions (TMs and TNTs) connecting cells were present and coexist inside the organoid. The image was captured by Inés Saenz-de-Santa-Maria with an inverted confocal microscope LSM700, Pln-Apo 10X/0.45 objective.
The RNA-binding protein HuR regulates intestinal epithelial restitution by modulating Caveolin-1 gene expression
Shan Cao, Lan Xiao, Junyao Wang, Guodong Chen, Yulan Liu; The RNA-binding protein HuR regulates intestinal epithelial restitution by modulating Caveolin-1 gene expression. Biochem J 15 January 2021; 478 (1): 247–260. doi: https://doi.org/10.1042/BCJ20200372
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