Document Detail


Anterograde microtubule transport drives microtubule bending in LLC-PK1 epithelial cells.
MedLine Citation:
PMID:  19403700     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Microtubules (MTs) have been proposed to act mechanically as compressive struts that resist both actomyosin contractile forces and their own polymerization forces to mechanically stabilize cell shape. To identify the origin of MT bending, we directly observed MT bending and F-actin transport dynamics in the periphery of LLC-PK1 epithelial cells. We found that F-actin is nearly stationary in these cells even as MTs are deformed, demonstrating that MT bending is not driven by actomyosin contractility. Furthermore, the inhibition of myosin II activity through the use of blebbistatin results in microtubules that are still dynamically bending. In addition, as determined by fluorescent speckle microscopy, MT polymerization rarely results, if ever, in bending. We suppressed dynamic instability using nocodazole, and we observed no qualitative change in the MT bending dynamics. Bending most often results from anterograde transport of proximal portions of the MT toward a nearly stationary distal tip. Interestingly, we found that in an in vitro kinesin-MT gliding assay, MTs buckle in a similar manner. To make quantitative comparisons, we measured curvature distributions of observed MTs and found that the in vivo and in vitro curvature distributions agree quantitatively. In addition, the measured MT curvature distribution is not Gaussian, as expected for a thermally driven semiflexible polymer, indicating that thermal forces play a minor role in MT bending. We conclude that many of the known mechanisms of MT deformation, such as polymerization and acto-myosin contractility, play an inconsequential role in mediating MT bending in LLC-PK1 cells and that MT-based molecular motors likely generate most of the strain energy stored in the MT lattice. The results argue against models in which MTs play a major mechanical role in LLC-PK1 cells and instead favor a model in which mechanical forces control the spatial distribution of the MT array.
Authors:
Andrew D Bicek; Erkan Tüzel; Aleksey Demtchouk; Maruti Uppalapati; William O Hancock; Daniel M Kroll; David J Odde
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2009-04-29
Journal Detail:
Title:  Molecular biology of the cell     Volume:  20     ISSN:  1939-4586     ISO Abbreviation:  Mol. Biol. Cell     Publication Date:  2009 Jun 
Date Detail:
Created Date:  2009-06-15     Completed Date:  2009-09-21     Revised Date:  2013-06-02    
Medline Journal Info:
Nlm Unique ID:  9201390     Medline TA:  Mol Biol Cell     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2943-53     Citation Subset:  IM    
Affiliation:
Department of Biomedical Engineering and Institute for Mathematics and Its Applications, University of Minnesota, Minneapolis, MN 55455, USA.
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MeSH Terms
Descriptor/Qualifier:
Actins / metabolism
Actomyosin / metabolism
Animals
Biological Assay
Biological Transport
Biomechanics
Cell Line
Cell Survival
Drosophila melanogaster
Epithelial Cells / cytology,  metabolism*
Kymography
Microtubules / metabolism*
Models, Biological
Molecular Motor Proteins / metabolism
Sus scrofa
Chemical
Reg. No./Substance:
0/Actins; 0/Molecular Motor Proteins; 9013-26-7/Actomyosin
Comments/Corrections

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