Project description:The microRNAs known as miR-34 family suppress the expression of a suit of proteins involved in oncogenesis and pluripotency, including c-Myc. Their expression is frequently down regulated in cancers; however the regulation of their expression is not well understood. Through genome-wide miRNA profiling and mechanistic analysis, we identified an important role of SUMOylation in miR-34b/c expression, regulating the expression of c-Myc and all other tested miR-34 targets.
Project description:The microRNAs known as miR-34 family suppress the expression of a suit of proteins involved in oncogenesis and pluripotency, including c-Myc. Their expression is frequently down regulated in cancers; however the regulation of their expression is not well understood. Through genome-wide miRNA profiling and mechanistic analysis, we identified an important role of SUMOylation in miR-34b/c expression, regulating the expression of c-Myc and all other tested miR-34 targets.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes
Project description:The miR-34 family of microRNAs consisting of miR-34a, miR-34b and miR-34c are tumour suppressors. The annotated human miR-34b-5p has one additional base at the 5’ end of the common miR-34 family seed sequence, compared to miR-34a-5p and miR-34c-5p. This extra base results in a shift of the seed sequence, which would affect the target gene repertoire and have functional consequences. During our studies of miR-34 functions, we investigated the precise sequence of mature miR-34b-5p in human cells by deep sequencing. We found that a miR-34b-5p without the extra base was the predominant form in both non-malignant and malignant cells derived from several human tissues, indicating that the miR-34b annotation is misleading. We evaluated the functional implications of the seed shift, by comparing the effect of mimics representing the alternative miR-34b-5p sequences in MDA-MB-231 cells. In contrast to the annotated miR-34b, the endogenously expressed miR-34b displayed tumour suppressive characteristics in vitro similarly to miR-34c. These data demonstrate the importance of determining the precise sequence of a mature microRNA before exploring miRNA functions.
Project description:To further explore the effect of blood lead on miRNA expression in blood, children (aged 2-5 years) from kindergartens of Shaanxi province were divided into two groups and blood samples were collected. miRNA array was used to testify miRNA expression landscape between low blood lead level (BLL) group (0~ 50.00 g/L) and high BLL group (>50.00 g/L).Our data showed that 27 miRNAs were highly differentially expressed. Expression of miR-34b from this signiture was quantified by qRT-PCR,linear regression analysis showed that the correlation coefficient between blood lead level and miR-34b is 0.247, p <0.001, indicating that miR-34b was correlated with BLL.
Project description:We have sequenced miRNA libraries from human embryonic, neural and foetal mesenchymal stem cells. We report that the majority of miRNA genes encode mature isomers that vary in size by one or more bases at the 3’ and/or 5’ end of the miRNA. Northern blotting for individual miRNAs showed that the proportions of isomiRs expressed by a single miRNA gene often differ between cell and tissue types. IsomiRs were readily co-immunoprecipitated with Argonaute proteins in vivo and were active in luciferase assays, indicating that they are functional. Bioinformatics analysis predicts substantial differences in targeting between miRNAs with minor 5’ differences and in support of this we report that a 5’ isomiR-9-1 gained the ability to inhibit the expression of DNMT3B and NCAM2 but lost the ability to inhibit CDH1 in vitro. This result was confirmed by the use of isomiR-specific sponges. Our analysis of the miRGator database indicates that a small percentage of human miRNA genes express isomiRs as the dominant transcript in certain cell types and analysis of miRBase shows that 5’ isomiRs have replaced canonical miRNAs many times during evolution. This strongly indicates that isomiRs are of functional importance and have contributed to the evolution of miRNA genes Sequence library of miRNAs from a single sample of human foetal mesenchymal stem cells. Results tested and confirmed by northern blotting. Please note that only raw data files are available for the embryonic and neual samples and thus, directly submitted to SRA (SRX547311, SRX548700, respectively under SRP042115/PRJNA247767)