Project description:The microRNAs encoded by the miR-17~92 polycistron are commonly overexpressed in cancer and orchestrate a wide range of oncogenic functions. Here, we identify a novel mechanism for miR-17~92 oncogenic function through the disruption of endogenous miRNA processing. We show that upon oncogenic overexpression of the miR-17~92 primary transcript (pri-miR-17~92), the Microprocessor complex remains associated with partially processed intermediates that aberrantly accumulate. These intermediates reflect a series of hierarchical and conserved steps in the early processing of the pri-miR-17~92 transcript. Encumbrance of the Microprocessor by miR-17~92 intermediates leads to the broad, but selective, downregulation of co-expressed polycistronic miRNAs, including miRNAs derived from tumour suppressive miR-34b/c, and from the Dlk1-Dio3 polycistrons. We propose that the newly identified steps of polycistronic miR-17~92 biogenesis contribute to the oncogenic re-wiring of gene regulation networks. Our results reveal new functional paradigms for polycistronic miRNAs in cancer.
Project description:The precise control of miR-17~92 microRNA (miRNA) is essential for normal development and overexpression of certain miRNAs from this cluster is oncogenic. Here we find the relative expression of the six miRNAs processed from the primary (pri-miR-17~92) transcript is dynamically regulated during embryonic stem cell differentiation. We identify a new miRNA biogenesis intermediate, termed ‘progenitor-miRNA’ (pro-miRNA), that is an efficient substrate for Microprocessor. An autoinhibitory 5’ RNA fragment is cleaved to generate pro-miRNA and selectively license Microprocessor-mediated production of pre-miR-17, -18a, -19a, 20a, and -19b. Using genetic, biochemical, and structural methods we define two complementary cis-regulatory repression domains required for the formation of this inhibitory RNA conformation. We find the endonuclease CPSF3 (CPSF73), and the Spliceosome-associated ISY1 are required for pro-miRNA biogenesis and expression of all miRNAs within the cluster except miR-92. Thus, developmentally regulated generation of pro-miRNA explains the posttranscriptional control of miR-17~92 expression in development. Illumina RNAseq in WT, dgcr8-/- and dicer-/- mESCs and small RNA seq in WT mESCs
Project description:The precise control of miR-17~92 microRNA (miRNA) is essential for normal development and overexpression of certain miRNAs from this cluster is oncogenic. Here we find the relative expression of the six miRNAs processed from the primary (pri-miR-17~92) transcript is dynamically regulated during embryonic stem cell differentiation. We identify a new miRNA biogenesis intermediate, termed ‘progenitor-miRNA’ (pro-miRNA), that is an efficient substrate for Microprocessor. An autoinhibitory 5’ RNA fragment is cleaved to generate pro-miRNA and selectively license Microprocessor-mediated production of pre-miR-17, -18a, -19a, 20a, and -19b. Using genetic, biochemical, and structural methods we define two complementary cis-regulatory repression domains required for the formation of this inhibitory RNA conformation. We find the endonuclease CPSF3 (CPSF73), and the Spliceosome-associated ISY1 are required for pro-miRNA biogenesis and expression of all miRNAs within the cluster except miR-92. Thus, developmentally regulated generation of pro-miRNA explains the posttranscriptional control of miR-17~92 expression in development.
Project description:A network of gene regulatory factors such as transcription factors and microRNAs establish and maintain the gene expression pattern during hematopoiesis. In this network transcription factors regulate each other and are involved in regulatory loops with microRNAs.The microRNA cluster miR-17-92 is located within the MIR17HG gene and encodes for six mature microRNAs. It is important for hematopoietic differentiation and plays a central role in malignant disease. However, the transcription factors downstream of miR-17-92 are largely elusive and the transcriptional regulation of miR-17-92 is not fully understood. Here we show that miR-17-92 forms a regulatory loop with the transcription factor TAL1. The miR-17-92 cluster inhibits expression of TAL1 and indirectly leads to decreased stability of the TAL1 transcriptional complex. We found that TAL1 and its heterodimerization partner E47 regulate miR-17-92 transcriptionally. Furthermore, miR-17-92 negatively influences erythroid differentiation, a process that depends on gene activation by the TAL1 complex. Our data give example of how transcription factor activity is fine-tuned during normal hematopoiesis. We postulate that disturbance of the regulatory loop between TAL1 and the miR-17-92 cluster could be an important step in cancer development and progression.
2021-09-09 | PXD018052 | Pride
Project description:Oncogenic biogenesis of pri-miR-17~92
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.