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:Multiciliated cells possess multiple motile cilia on the cell surface and are widely distributed throughout the vertebrate body to perform important physiological functions by regulating fluid movement in the intercellular space. However the molecular mechanisms underlying multiciliogenesis are not well understood. Although dysregulation of members of the miR-34 family plays a critical role in the progression of various cancers, the physiological function of miR-34b, especially in regulating multiciliogenesis, is largely unknown. Here we focus on the multiciliated cells in the zebrafish kidney to study whether and how miR-34b regulate multiciliogenesis. We performed genome-wide gene expression profiling of zebrafish kidney multiciliated cells in the absence (miR-34b morpholino) or presence of miR-34b (control morpholino). RNA samples for microarray gene expression profiling were collected at 3 days post fertilization.
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:In addition to the glucocorticoids, the glucocorticoid receptor (GR) is regulated by post-translational modifications, including SUMOylation. We have analyzed how SUMOylation influences the activity of endogenous GR target genes and the receptor chromatin binding by using isogenic HEK293 cells expressing wild-type GR (wtGR) or SUMOylation-defective GR (GR3KR). Gene expression profiling revealed that both dexamethasone up- and down-regulated genes are affected by the GR sumoylation and that the affected genes are significantly associated with pathways of cellular proliferation and survival. The GR3KR-expressing cells proliferated more rapidly and their anti-proliferative response to dexamethasone was less pronounced than in the wtGR-expressing cells. ChIP-seq analyses indicated that the SUMOylation modulates the chromatin occupancy of GR on several loci associated with cellular growth in a fashion which parallels with their differential dexamethasone-regulated expression between the two cell lines. Moreover, genome-wide SUMO-2/3 marks, which were generally associated with active chromatin, showed markedly higher overlap with the wtGR cistrome than with the GR3KR cistrome. In sum, our results indicate that the SUMOylation does not simply repress the GR activity, but regulates the activity of the receptor in a target locus selective fashion, playing an important role in controlling the GR activity on genes influencing cell growth. Total RNA isolated from isogenic HEK293 cell lines stably expressing either wild-type GR (wtGR) or SUMOylation-defective GR (GR3KR) treated with either vehicle (EtOH) or 100 nM of dexamethasone (dex) for 6h. All conditions are performed in triplicate
Project description:Genome wide localization of SUMO1 and SUMO2/3 proteins revealed an asscociation of SUMO proetins with active chromatin. SUMO proteins are enriched at super enhancers and enhancers and SUMOylation regulates a subset of these super enhancers. Super enhancers regulated by SUMOylation were enriched for transcription factor TFAP2C and SUMOylation negatively regulates TFAP2C localization to enhancers and super enhancers. Proteomics and ChIP-PCR at MYC SE suggests that chromatin bound TFAP2C recruits histone deacetylation complexes that increases upon SAE2 knockdown. Conversely, SUMOylation promoted TFAP2C asscociation with pre-mRNA splicing machinery components. Taken together, our study revealed a critical role of SUMOylation in chromatin modification through an AP-2 family of transcription factor, TFAP2C and a potential role of TFAP2C in pre-mRNA splicing.
Project description:Genome wide localization of SUMO1 and SUMO2/3 proteins revealed an asscociation of SUMO proetins with active chromatin. SUMO proteins are enriched at super enhancers and enhancers and SUMOylation regulates a subset of these super enhancers. Super enhancers regulated by SUMOylation were enriched for transcription factor TFAP2C and SUMOylation negatively regulates TFAP2C localization to enhancers and super enhancers. Proteomics and ChIP-PCR at MYC SE suggests that chromatin bound TFAP2C recruits histone deacetylation complexes that increases upon SAE2 knockdown. Conversely, SUMOylation promoted TFAP2C asscociation with pre-mRNA splicing machinery components. Taken together, our study revealed a critical role of SUMOylation in chromatin modification through an AP-2 family of transcription factor, TFAP2C and a potential role of TFAP2C in pre-mRNA splicing.