Project description:microRNAs in the miR-106b family are overexpressed in multiple tumor types and are correlated with the expression of genes that regulate the cell cycle. Consistent with these observations, miR-106b family gain of function promotes cell cycle progression, whereas loss of function reverses this phenotype. Microarray profiling uncovers multiple targets of the family, including the cyclin-dependent kinase inhibitor p21/CDKN1A. We show that p21 is a direct target of miR-106b and that its silencing plays a key role in miR-106b-induced cell cycle phenotypes. We also show that miR-106b overrides a doxorubicin-induced DNA damage checkpoint. Thus, miR-106b family members contribute to tumor cell proliferation in part by regulating cell cycle progression and by modulating checkpoint functions. HCT116 Dicerex5 cells were transfected with microRNAs in six-well plates, and RNA was isolated 10 h after transfection. Transcripts containing the miR-106b family hexamers in their 3' UTRs were identified. By microarray analysis, 103 transcripts that contained miR-106b family complementary hexamers in their 3' UTRs were down-regulated by miR-106b, miR-106a, miR-20b, and miR-17-5p within 10 h of transfection.
Project description:microRNAs in the miR-106b family are overexpressed in multiple tumor types and are correlated with the expression of genes that regulate the cell cycle. Consistent with these observations, miR-106b family gain of function promotes cell cycle progression, whereas loss of function reverses this phenotype. Microarray profiling uncovers multiple targets of the family, including the cyclin-dependent kinase inhibitor p21/CDKN1A. We show that p21 is a direct target of miR-106b and that its silencing plays a key role in miR-106b-induced cell cycle phenotypes. We also show that miR-106b overrides a doxorubicin-induced DNA damage checkpoint. Thus, miR-106b family members contribute to tumor cell proliferation in part by regulating cell cycle progression and by modulating checkpoint functions.
Project description:Adult beta cells in the pancreas are the sole source of insulin in our body. Beta cell loss or increased demand for insulin, impose metabolic challenges because adult beta cells are generally quiescent and infrequently re-enter the cell division cycle. miR-17-92/106b is a family of proto-oncogene microRNAs, that regulate proliferation in normal tissues and in cancer. Here, we employ mouse genetics to demonstrate a critical role for miR-17-92/106b in glucose homeostasis and in controlling insulin secretion. Mass spectrometry analysis was performed on miR-17-92LoxP/LoxP;106-25-/- MEF lysate, without or with CRE-Adenovirus. miR-17-92LoxP/LoxP;106-25+/+ MEFs with GFP-Adenovirus served as controls. We demonstrate that miR-17-92/106b regulate the adult beta cell mitotic checkpoint and that miR-17-92/106b deficiency results in reduction in beta cell mass in-vivo. Furthermore, protein kinase A (PKA) is a new relevant molecular pathway downstream of miR-17-92/106b in control of adult beta cell division and glucose homeostasis. Therefore, contributes to the understanding of proto-oncogene miRNAs in the normal, untransformed endocrine pancreas, and illustrates new genetic means for regulation of beta cell mitosis and function by non-coding RNAs.
Project description:Studies of human embryonic stem cells (hESCs) commonly describe the non-functional p53-p21 axis of the G1/S checkpoint pathway with subsequent relevance for cell cycle regulation and the DNA damage response (DDR). Importantly, p21 mRNA is clearly present and upregulated after the DDR in hESCs but p21 protein is not detectable. In this article, we provide evidence that expression of p21 protein is directly regulated by the microRNA pathway under standard culture conditions and after DNA damage. The DDR in hESCs leads to upregulation of tens of microRNAs, including hESC-specific microRNAs such as those of the miR-302 family, miR-371-372 family, or C19MC microRNA cluster. Most importantly, we show that the hESC-enriched microRNA family miR-302 (miR-302a, miR-302b, miR-302c, and miR-302d) directly contributes to regulation of p21 expression in hESCs and thus demonstrate a novel function for miR-302s in hESCS. The described mechanism elucidates the role of microRNAs in regulation of important molecular pathway governing the G1/S transition checkpoint before as well as after DNA damage.
Project description:Post-transcriptional modifications of tumor suppressors, including microRNA-mediated downregulation, are important events in tumor progression. To identify microRNAs involved in oncogenic transformation, we examined global microRNA profiles of three ras transgenic zebrafish models. Four microRNAs are upregulated in all transgenic systems. Analysis of the predicted targets shows that three of them target Jmjd6, and overexpression of Jmjd6 in ras transformed melanocytes blocks proliferation and melanoma development. We found that Jmjd6 functions to regulate splicing of the tumor suppressor cdkn1a/p21. Truncated cdkn1a/p21 transcripts, lacking the PCNA binding domain, accumulate in ras-expressing melanocytes during melanoma development. These findings implicate Jmjd6 in a novel mechanism for inactivation of a major tumor suppressor pathway in melanoma.
Project description:TAF15 (formerly TAFII68) is a member of the TET family of RNA and DNA binding proteins whose genes are frequently translocated in sarcomas. Consistent with a functional role in cell viability, TAF15 depletion had a growth-inhibitory effect and increased apoptosis. Interestingly, one of the genes affected by TAF15 depletion is CDKN1A/p21, a key regulator of cell cycle. Here we show that TAF15 down-regulates CDKN1A/p21 expression through a pathway involving miRNAs.
Project description:p53-mediated cell cycle arrest during DNA damage is dependent on the induction of p21 protein, encoded by the CDKN1A gene. p21 inhibits cyclin-dependent kinases required for cell cycle progression to guarantee accurate repair of DNA lesions. Hence, fine-tuning of p21 levels is crucial to preserve genomic stability. Currently, the multilayered regulation of p21 levels during DNA damage is not fully understood. Herein, we identified the human RNA binding motif protein 42 (RBM42) as a novel regulator of p21 levels during DNA damage. Genome-wide transcriptome and interactome analysis revealed that RBM42 alters the expression of p53-regulated genes during DNA damage. Specifically, we demonstrated that RBM42 facilitates CDKN1A splicing by counteracting the splicing inhibitory effect of RBM4 protein. Unexpectedly, we also show that RBM42, underpins translation of various splicing targets, including CDKN1A. Concordantly, transcriptome-wide mapping of RBM42-RNA interactions using eCLIP further substantiates the dual function of RBM42 in regulating splicing and translation of its target genes, including CDKN1A. Collectively, our data show that RBM42 couples splicing and translation machineries to fine-tune gene expression during DNA damage response.
Project description:microRNAs (miRNAs) are abundant, ~21 nucleotide (nt) non-coding regulatory RNAs. Each miRNA may regulate hundreds of mRNA targets, but the identities of these targets and the processes they regulate are poorly understood. Here we have explored the use of microarray profiling and functional screening to identify targets and biological processes triggered by transfection of miRNAs into human cells. We demonstrate that a family of miRNAs sharing sequence identity with miR-16 negatively regulates cellular growth and cell cycle progression. miR-16 down-regulated transcripts were enriched for genes whose silencing by siRNAs causes cell cycle accumulation at G0/G1. Simultaneous silencing of these genes was more effective at blocking cell cycle progression than disruption of the individual genes. Thus, miR-16 coordinately regulates targets that may act in concert to control cell cycle progression. Keywords: miRNA, microRNA, miR-16, target, cell cycle, G0/G1, microarray profiling, functional screen,
Project description:p53 suppresses tumor progression and metastasis by regulating a large set of genes and microRNAs. By profiling 92 primary hepatocellular carcinomas (HCCs) and 9 HCC cell lines, we found that p53 upregulates microRNAs including miR-200 and miR-192 family members. By sequencing TP53 in 92 HCC samples, we classified the 92 samples into two groups (wt and mut). We also classified 9 HCC cell lines by testing p21 expression after DNA-damage mediated p53 activation. We then profiled microRNA expression in 92 HCC tissue samples and 9 HCC celll lines to identify p53-regulated microRNAs.
Project description:TAF15 (formerly TAFII68) is a member of the TET family of RNA and DNA binding proteins whose genes are frequently translocated in sarcomas. Consistent with a functional role in cell viability, TAF15 depletion had a growth-inhibitory effect and increased apoptosis. Interestingly, one of the genes affected by TAF15 depletion is CDKN1A/p21, a key regulator of cell cycle. Here we show that TAF15 down-regulates CDKN1A/p21 expression through a pathway involving miRNAs. We performed a gene expression profiling upon TAF15 knock down by RNA interference.Total RNAs purified from four biological replicates of HeLa GL3 luc cells transfected either with si-TAF15 or control si-LUC were hybridized to the array.