MicroRNAs involved in the browning process of adipocytes

The present review focuses on the role of miRNAs in the control of white adipose tissue browning, a process which describes the recruitment of adipocytes showing features of brown adipocytes in white adipose tissue. MicroRNAs (miRNAs) are a class of short non-coding RNAs (19-22 nucleotides) involved in gene regulation. Although the main effect of miRNAs is the inhibition of the translational machinery, thereby preventing the production of the protein product, the activation of protein translation has also been described in the literature. In addition to modifying translation, miRNAs binding to its target mRNAs also trigger the recruitment and association of mRNA decay factors, leading to mRNA destabilization, degradation, and thus to the decrease in expression levels. Although a great number of miRNAs have been reported to potentially regulate genes that play important roles in the browning process, only a reduced number of studies have demonstrated experimentally an effect on this process associated to changes in miRNA expressions, so far. These studies have shown, by using either primary adipocyte cultures or experimental models of mice (KO mice, mice overexpressing a specific miRNA) that miR-196a, miR-26 and miR-30 are needed for browning process development. By contrast, miR-155, miR-133, miR-27b and miR-34 act as negative regulators of this process. Further studies are needed to fully describe the miRNA network-involved white adipose tissue browning regulation (AU)

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Erratum to: MicroRNAs involved in the browning process of adipocytes

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Selecting housekeepping genes as references for the normalization of quantitative PCR data in breast cancer

OBJECTIVE: The common reference genes of choice in relative gene expression studies based on quantitative real time polymerase chain reaction, ACTB and B2M, were shown to be regulated differently in respect to tissue type. In this study, the stability of the selected housekeeping genes for normalizing the qPCR data were identified in the tumor and its adjacent tissues in invasive breast cancer, and the variability of their levels according to the stages and the histopathologic subtypes was analyzed. METHODS: Four housekeeping genes: PUM1, RPL13A, B2M, and ACTB were analyzed in 99 surgically excised tissue specimens (50 tumor, 45 tumor adjacent and 4 normal breast tissues). Three of the most common softwares (GeNorm, NormFinder, and BestKeeper) were used for calculation purposes. RESULTS: When all of the tissue samples were included in analyses, PUM1 was the most stable gene according to calculations made with both NormFinder and BestKeeper; while PUM1/RPL13A combination was the most stable by GeNorm software. The PUM1 gene was also identified as the most stable gene among the four in all sample groups (in both Estrogen Receptor positive and Estrogen Receptor negative subgroups of invasive breast carcinoma and in normal breast tissue) according to calculations made using the NormFinder software. CONCLUSION: While suggesting PUM1 is one of the most stable single gene and the PUM1/RPL13A pair as one of the best housekeeping genes for the normalization of expression studies in invasive breast tumor studies, it will be more practical to evaluate stability once more and decide upon the reference gene accordingly within the sample group itself (AU)

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Aberrant mRNA stability regulation in human diseases

La estabilidad del ARN mensajero está surgiendo como instrumento celular fundamental y efectivo para regular la expresión génica a nivel post-transcripcional. La estabilidad del ARNm se controla vía interacciones coordinadas entre componentes estructurales del ARNm (elementos cis) y factores trans específicos. Los determinantes de estabilidad de ARNm más conocidos y eficientes son los elementos ricos en adenina y uridina (ARE) que, a través de su unión con proteínas de unión a ARE (AUBPS), modulan la estabilidad de los transcritos y/o su traducción. Alteraciones en cualquiera de estos componentes puede dar lugar a enfermedades. Aquí revisamos las alteraciones genéticas en elementos regulatorios del 3’UTR, así como las aberraciones en los niveles, localización subcelular y modificaciones posttraslacionales de AUBPs que están asociadas a enfermedades humanas. Un conocimiento detallado de estas alteraciones y su impacto en la regulación de la estabilidad del ARNm revelará nuevas dianas para su aplicación terapéutica

mRNA stability is emerging as a fundamental and effective cellular tool to regulate gene expression at posttranscriptional levels. mRNA stability is controlled via orchestrated interactions between mRNA structural components (cis-elements) and specific trans-acting factors. The most widespread and efficient determinant of RNA stability are the adenylate and uridylate-rich elements (ARE) that, through binding of ARE-binding proteins (AUBPs), modulate the stability of transcripts and/or their translation. Alterations in any of these components can lead to disease. Here, we review the genetic alterations in 3’UTR regulatory sequences as well as the aberrant levels, subcellular localization, and posttranslational modifications of AUBPs that are linked to human diseases. A thorough understanding of these alterations and their impact on mRNA stability regulation will uncover promising new targets for therapeutic intervention