Dataset Information

MicroRNAs 221 and 222 regulate the undifferentiated state in mammalian male germ cells.

ABSTRACT: Continuity of cycling cell lineages relies on the activities of undifferentiated stem cell-containing subpopulations. Transition to a differentiating state must occur periodically in a fraction of the population to supply mature cells, coincident with maintenance of the undifferentiated state in others to sustain a foundational stem cell pool. At present, molecular mechanisms regulating these activities are poorly defined for most cell lineages. Spermatogenesis is a model process that is supported by an undifferentiated spermatogonial population and transition to a differentiating state involves attained expression of the KIT receptor. We found that impaired function of the X chromosome-clustered microRNAs 221 and 222 (miR-221/222) in mouse undifferentiated spermatogonia induces transition from a KIT(-) to a KIT(+) state and loss of stem cell capacity to regenerate spermatogenesis. Both Kit mRNA and KIT protein abundance are influenced by miR-221/222 function in spermatogonia. Growth factors that promote maintenance of undifferentiated spermatogonia upregulate miR-221/222 expression; whereas exposure to retinoic acid, an inducer of spermatogonial differentiation, downregulates miR-221/222 abundance. Furthermore, undifferentiated spermatogonia overexpressing miR-221/222 are resistant to retinoic acid-induced transition to a KIT(+) state and are incapable of differentiation in vivo. These findings indicate that miR-221/222 plays a crucial role in maintaining the undifferentiated state of mammalian spermatogonia through repression of KIT expression.

SUBMITTER: Yang QE

PROVIDER: S-EPMC3597206 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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MicroRNAs 221 and 222 regulate the undifferentiated state in mammalian male germ cells.

Yang Qi-En QE Racicot Karen E KE Kaucher Amy V AV Oatley Melissa J MJ Oatley Jon M JM

Development (Cambridge, England) 20121205 2

Continuity of cycling cell lineages relies on the activities of undifferentiated stem cell-containing subpopulations. Transition to a differentiating state must occur periodically in a fraction of the population to supply mature cells, coincident with maintenance of the undifferentiated state in others to sustain a foundational stem cell pool. At present, molecular mechanisms regulating these activities are poorly defined for most cell lineages. Spermatogenesis is a model process that is support ...[more]

PMID: 23221369

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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.

Dataset Information

MicroRNAs 221 and 222 regulate the undifferentiated state in mammalian male germ cells.

Publications

MicroRNAs 221 and 222 regulate the undifferentiated state in mammalian male germ cells.

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