Abstract
BackgroundTo form myelin oligodendrocytes expand and wrap their plasma membrane multiple times around an axon. How is this expansion controlled?ResultsHere we show that cell surface area depends on actomyosin contractility and is regulated by physical properties of the supporting matrix. Moreover, we find that chondroitin sulfate proteoglycans (CSPG), molecules associated with non-permissive growth properties within the central nervous system (CNS), block cell surface spreading. Most importantly, the inhibitory effects of CSPG on plasma membrane extension were completely prevented by treatment with inhibitors of actomyosin contractility and by RNAi mediated knockdown of myosin II. In addition, we found that reductions of plasma membrane area were accompanied by changes in the rate of fluid-phase endocytosis.ConclusionIn summary, our results establish a novel connection between endocytosis, cell surface extension and actomyosin contractility. These findings open up new possibilities of how to promote the morphological differentiation of oligodendrocytes in a non-permissive growth environment.See related minireview by Bauer and ffrench-Constant:
Highlights
To form myelin oligodendrocytes expand and wrap their plasma membrane multiple times around an axon
The inhibitory effect of the RGD-peptide on the cell size was completely abolished in cells treated with blebbistatin and to a large extent in cells treated with Y27632 suggesting that the RGD-peptide acts by influencing actomyosin contractility
These experiments provide evidence that integrins are involved in cell surface area control through a pathway that is dependent on contractile forces within the cells
Summary
To form myelin oligodendrocytes expand and wrap their plasma membrane multiple times around an axon. Loss of integrin-mediated adhesion during tumor cell growth triggers the rapid caveolin-mediated endocytosis that leads to cell rounding [1,2,3]. Another example is the cell surface area change that occurs during mitosis. At the onset of mitosis the mother cell starts to round up, and subsequently recovers when entering into anaphase These changes of plasma membrane area are regulated by changes in endosomal membrane traffic [4]
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