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Caitlin Bowen, Caitlin Logan, A Sue Menko; A Critical Role for Microtubules in Lens Morphogenesis Through Regulation of Myosin-II Activation. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1710.
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© ARVO (1962-2015); The Authors (2016-present)
Tissue development is known to be dependent on cytoskeletal family members including microtubules, and further understanding of the roles these proteins play will shape the field of tissue morphogenesis. The goal of these studies is to investigate the mechanism by which microtubules (MT) function in lens morphogenesis. We investigate the hypothesis that defects in lens fiber cell elongation when microtubules are disassembled during lens development result from dysregulation of myosin signaling.
For all studies embryonic day 10 chick lenses were isolated and grown in ex vivo culture. MTs were disassembled by exposure to the MT inhibitor Nocodazole (NC) at 1μg/ml and 10μg/ml, the lower dose effecting dynamic MTs and a subpopulation of stable MTs, the higher concentration disassembling both populations of MTs. The vehicle DMSO was used as control. Myosin activation was inhibited with the myosin inhibitor Blebbistatin (Bleb, 50 μM). Whole lens cultures were exposed to NC alone, Bleb alone, or a combination of these two inhibitors where Bleb was added 2hrs prior to NC.
Exposure to NC revealed that microtubule function influences lens morphogenesis by affecting both the extent and directionality of elongation of differentiating fiber cells, with greater dysmorphogenesis at the higher dose of NC. New fiber cells were abnormally curved towards the lens equator and at the lower NC dose these fiber cells failed to establish stable interactions with the apical domains of the opposing lens epithelial cells in the equatorial zone. At the higher concentration of NC this defective interaction between epithelial and fiber cell apical surfaces extended across the Epithelial Fiber Interface (EFI). These morphogenetic defects that occur in the absence of MTs were correlated with increased levels of myosin activation along the EFI. Blocking myosin activation was able to rescue the EFI defect caused by loss of MTs.
Microtubules play an essential role in lens morphogenesis by regulating myosin activity.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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