Concerted actions of distinct nonmuscle myosin II isoforms drive intracellular membrane remodeling in live animals

O Milberg, A Shitara, S Ebrahim, A Masedunskas… - Journal of Cell …, 2017 - rupress.org
O Milberg, A Shitara, S Ebrahim, A Masedunskas, M Tora, DT Tran, Y Chen, MA Conti…
Journal of Cell Biology, 2017rupress.org
Membrane remodeling plays a fundamental role during a variety of biological events.
However, the dynamics and the molecular mechanisms regulating this process within cells
in mammalian tissues in situ remain largely unknown. In this study, we use intravital
subcellular microscopy in live mice to study the role of the actomyosin cytoskeleton in driving
the remodeling of membranes of large secretory granules, which are integrated into the
plasma membrane during regulated exocytosis. We show that two isoforms of nonmuscle …
Membrane remodeling plays a fundamental role during a variety of biological events. However, the dynamics and the molecular mechanisms regulating this process within cells in mammalian tissues in situ remain largely unknown. In this study, we use intravital subcellular microscopy in live mice to study the role of the actomyosin cytoskeleton in driving the remodeling of membranes of large secretory granules, which are integrated into the plasma membrane during regulated exocytosis. We show that two isoforms of nonmuscle myosin II, NMIIA and NMIIB, control distinct steps of the integration process. Furthermore, we find that F-actin is not essential for the recruitment of NMII to the secretory granules but plays a key role in the assembly and activation of NMII into contractile filaments. Our data support a dual role for the actomyosin cytoskeleton in providing the mechanical forces required to remodel the lipid bilayer and serving as a scaffold to recruit key regulatory molecules.
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