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MicroRNA-221-222 regulate the cell cycle in mast cells.

ABSTRACT: MicroRNAs (miRNAs) constitute a large family of small noncoding RNAs that have emerged as key posttranscriptional regulators in a wide variety of organisms. Because any one miRNA can potentially regulate expression of a distinct set of genes, differential miRNA expression can shape the repertoire of proteins that are actually expressed during development and differentiation or disease. Here, we have used mast cells as a model to investigate the role of miRNAs in differentiated innate immune cells and found that miR-221-222 are significantly up-regulated upon mast cell activation. Using both bioinformatics and experimental approaches, we identified some signaling pathways, transcription factors, and potential cis-regulatory regions that control miR-221-222 transcription. Overexpression of miR-221-222 in a model mast cell line perturbed cell morphology and cell cycle regulation without altering viability. While in stimulated cells miR-221-222 partially counteracted expression of the cell-cycle inhibitor p27(kip1), we found that in the mouse alternative splicing results in two p27(kip1) mRNA isoforms that differ in their 3' untranslated region, only one of which is subject to miR-221-222 regulation. Additionally, transgenic expression of miR-221-222 from bacterial artificial chromosome clones in embryonic stem cells dramatically reduced cell proliferation and severely impaired their accumulation. Our study provides further insights on miR-221-222 transcriptional regulation as well as evidences that miR-221-222 regulate cell cycle checkpoints in mast cells in response to acute activation stimuli.

SUBMITTER: Mayoral RJ

PROVIDER: S-EPMC2610349 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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MicroRNA-221-222 regulate the cell cycle in mast cells.

Mayoral Ramon J RJ Pipkin Matthew E ME Pachkov Mikhail M van Nimwegen Erik E Rao Anjana A Monticelli Silvia S

Journal of immunology (Baltimore, Md. : 1950) 20090101 1

MicroRNAs (miRNAs) constitute a large family of small noncoding RNAs that have emerged as key posttranscriptional regulators in a wide variety of organisms. Because any one miRNA can potentially regulate expression of a distinct set of genes, differential miRNA expression can shape the repertoire of proteins that are actually expressed during development and differentiation or disease. Here, we have used mast cells as a model to investigate the role of miRNAs in differentiated innate immune cell ...[more]

PMID: 19109175

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Project description:BACKGROUND:MicroRNAs (miRNAs) are a class of small non-coding RNAs that have recently emerged as important regulators of gene expression. They negatively regulate gene expression post-transcriptionally by translational repression and target mRNA degradation. miRNAs have been shown to play crucial roles in muscle development and in regulation of muscle cell proliferation and differentiation. METHODOLOGY/PRINCIPAL FINDINGS:By comparing miRNA expression profiling of proliferating myoblasts versus differentiated myotubes, a number of modulated miRNAs, not previously implicated in regulation of myogenic differentiation, were identified. Among these, miR-221 and miR-222 were strongly down-regulated upon differentiation of both primary and established myogenic cells. Conversely, miR-221 and miR-222 expression was restored in post-mitotic, terminally differentiated myotubes subjected to Src tyrosine kinase activation. By the use of specific inhibitors we provide evidence that expression of miR-221 and miR-222 is under the control of the Ras-MAPK pathway. Both in myoblasts and in myotubes, levels of the cell cycle inhibitor p27 inversely correlated with miR-221 and miR-222 expression, and indeed we show that p27 mRNA is a direct target of these miRNAs in myogenic cells. Ectopic expression of miR-221 and miR-222 in myoblasts undergoing differentiation induced a delay in withdrawal from the cell cycle and in myogenin expression, followed by inhibition of sarcomeric protein accumulation. When miR-221 and miR-222 were expressed in myotubes undergoing maturation, a profound alteration of myofibrillar organization was observed. CONCLUSIONS/SIGNIFICANCE:miR-221 and miR-222 have been found to be modulated during myogenesis and to play a role both in the progression from myoblasts to myocytes and in the achievement of the fully differentiated phenotype. Identification of miRNAs modulating muscle gene expression is crucial for the understanding of the circuits controlling skeletal muscle differentiation and maintenance.

Project description:Breast malignancy remains one of the most common causes of cancer-associated mortalities among women. MicroRNA (miR)-221 and miR-222 are homologous miRs and have a substantial impact on cancer progression. In the present study, the regulatory mechanisms of miR-221/222 and its target annexin A3 (ANXA3) in breast cancer cells were investigated. Breast tissue samples were collected to evaluate the expression patterns of miR-221/222 levels in breast cancer cell lines and cancer tissues according to clinical characteristics. The levels of miR-221/222 were increased or decreased in cancer cell lines compared with normal breast cell lines according to cell line subtype. Subsequently, the changes in the progression and invasion of breast cancer cells were investigated using cell proliferation, invasion assay, gap closure and colony formation assays. Western blotting of cell cycle proteins and flow cytometry were performed to evaluate the possible pathway of miR-221/222 and ANXA3 axis. Chemosensitivity tests were performed to explore the suitability of the miR-221/222 and ANXA3 axis as a therapeutic target in breast cancer. The expression levels of miR-221/222 were associated with aggressive characteristics of breast cancer subtypes. Cell transfection assay demonstrated the regulation of breast cancer proliferation and invasiveness by miR-221/222. MiR-221/222 directly targeted the 3'-untranslated region of ANXA3 and suppressed the expression of ANXA3 at the mRNA and protein levels. In addition, miR-221/222 negatively regulated cell proliferation and the cell cycle pathway in breast cancer cells by targeting ANXA3. In combination with adriamycin, downregulation of ANXA3 may sensitize adriamycin-induced cell death to induction of persistent G2/M and G0/G1 arrest. Decreased expression of ANXA3 through increased expression of miR-221/222 reduced breast cancer progression and increased the effectiveness of the chemotherapy drug. The present results indicated the miR-221/222 and ANXA3 axis to be a possible novel therapeutic target for the treatment of breast cancer.

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MicroRNA-221-222 regulate the cell cycle in mast cells.

Publications

MicroRNA-221-222 regulate the cell cycle in mast cells.

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