@article {2066, title = {The primary cilium dampens proliferative signaling and represses a G2/M transcriptional network in quiescent myoblasts.}, journal = {BMC Mol Cell Biol}, volume = {21}, year = {2020}, month = {2020 Apr 15}, pages = {25}, abstract = {

BACKGROUND: Reversible cell cycle arrest (quiescence/G0) is characteristic of adult stem cells and is actively controlled at multiple levels. Quiescent cells also extend a primary cilium, which functions as a signaling hub. Primary cilia have been shown to be important in multiple developmental processes, and are implicated in numerous developmental disorders. Although the association of the cilium with G0 is established, the role of the cilium in the control of the quiescence program is still poorly understood.

RESULTS: Primary cilia are dynamically regulated across different states of cell cycle exit in skeletal muscle myoblasts: quiescent myoblasts elaborate a primary cilium in vivo and in vitro, but terminally differentiated myofibers do not. Myoblasts where ciliogenesis is ablated using RNAi against a key ciliary assembly protein (IFT88) can exit the cell cycle but display an altered quiescence program and impaired self-renewal. Specifically, the G0 transcriptome in IFT88 knockdown cells is aberrantly enriched for G2/M regulators, suggesting a focused repression of this network by the cilium. Cilium-ablated cells also exhibit features of activation including enhanced activity of Wnt and mitogen signaling and elevated protein synthesis via inactivation of the translational repressor 4E-BP1.

CONCLUSIONS: Taken together, our results show that the primary cilium integrates and dampens proliferative signaling, represses translation and G2/M genes, and is integral to the establishment of the quiescence program.

}, issn = {2661-8850}, doi = {10.1186/s12860-020-00266-1}, author = {Venugopal, Nisha and Ghosh, Ananga and Gala, Hardik and Aloysius, Ajoy and Vyas, Neha and Dhawan, Jyotsna} } @article {1211, title = {Mimicking Muscle Stem Cell Quiescence in Culture: Methods for Synchronization in Reversible Arrest.}, journal = {Methods Mol Biol}, volume = {1556}, year = {2017}, month = {2017}, pages = {283-302}, abstract = {

Growing evidence supports the view that in adult stem cells, the defining stem cell features of potency and self-renewal are associated with the quiescent state. Thus, uncovering the molecular logic of this reversibly arrested state underlies not only a fundamental understanding of adult tissue dynamics but also hopes for therapeutic regeneration and rejuvenation of damaged or aging tissue. A key question concerns how adult stem cells use quiescence to establish or reinforce the property of self-renewal. Since self-renewal is largely studied by assays that measure proliferation, the concept of self-renewal programs imposed during non-proliferating conditions is counterintuitive. However, there is increasing evidence generated by deconstructing the quiescent state that highlights how programs characteristic of this particular cell cycle exit may enhance stem cell capabilities, through both cell-intrinsic and extrinsic programs.Toward this end, culture models that recapitulate key aspects of stem cell quiescence are useful for molecular analysis to explore attributes and regulation of the quiescent state. In this chapter, we review the different methods used to generate homogeneous populations of quiescent muscle cells, largely by manipulating culture conditions that feed into core signaling programs that regulate the cell cycle. We also provide detailed protocols developed or refined in our lab over the past two decades.

}, keywords = {Actins, Adult Stem Cells, Animals, Biomarkers, Cell Culture Techniques, Cell Differentiation, Cell Line, Cell Proliferation, Fluorescent Antibody Technique, Humans, Mice, Microscopy, Fluorescence, Muscle, Skeletal, Myoblasts, Resting Phase, Cell Cycle, Satellite Cells, Skeletal Muscle, Stem Cells}, issn = {1940-6029}, doi = {10.1007/978-1-4939-6771-1_15}, author = {Arora, Reety and Rumman, Mohammed and Venugopal, Nisha and Gala, Hardik and Dhawan, Jyotsna} }