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Asymmetric Division in Muscle Stem Cells. Christian Elabd, Ph.D. Joey Pham, B.A. Muscle System. - The muscle system is a model for quiescence (resting) and activity - Satellite cells, or muscle stem cells, can regenerate repeatedly
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Asymmetric Division in Muscle Stem Cells Christian Elabd, Ph.D. Joey Pham, B.A.
Muscle System - The muscle system is a model for quiescence (resting) and activity • - Satellite cells, or muscle stem cells, can regenerate repeatedly - Satellite cells give rise to myoblasts (mostly), and fibroblasts, adipocytes, chondrocytes. injured muscle intact muscle regenerated muscle myonuclei intact muscle satellite cells myofiber Histology 2 weeks after injury Hematoxylinandeosin cross section Pictures from MJ Conboy, UC Berkeley
Muscle Regeneration Quiescent Muscle Stem Cell Myotrauma Resting muscleFiber 1) Activation Multi-nucleation Self Renewal Return to resting state Fusion to repair damaged muscle fibers 2) Proliferation Fusion to produce new muscle fibers 3) Regeneration
Symmetric versus Asymmetric Division Symmetry Asymmetry Stem Stem Stem Stem Diff self renewal differentiation Asymmetric Division = Segregation of DNA, RNA or Proteins in one daughter cell
Symmetric versus Asymmetric Division in the Context of Muscle + = Satellite Satellite Option 1 + = Option 2 Myoblast Myoblast Satellite Dividing Satellite + = Option 3 Satellite Myoblast
Asymmetric Division in the Context of Muscle Hoechst Desmin Sca-1 Merge Differentiated cells are Desminpositive. Non-differentiated cells areSca-1positive. Conboy MJ et al. PLoS Biol. 2007 Jul;5(7):e182
Summary of Asymmetric Division Hoechst While most cells in the body divide strictly symmetrically, stem cells have the ability to divide asymmetrically as well. In the context of muscle regeneration, asymmetric division may allow for muscle regeneration without exhausting the pool of satellite cells (or muscle stem cells). Understanding the mechanism of asymmetric division is essential to advancing the control of stem cell self-renewal versus differentiation. Such control is necessary for the use of stem cells in regenerative medicine. Desmin Sca-1 Merge