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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Activation of Non-Muscle Myosin IIB Helps Mediate TNF-Alpha Cell Death Signaling

Flynn, Patrick G. 17 March 2010 (has links)
TNF-alpha can stimulate a variety of kinases with the ability to activate non-muscle myosin II. As a result, increases in actin filament formation and actomyosin contractility (AMC) have been reported in response to TNF-alpha. These events are thought to play an important role in mediating TNF-alpha induced apoptosis but how they do so is unclear. In this study we prevented non-muscle myosin II activation in response to TNF-alpha by treating cells with the myosin light chain kinase (MLCK) inhibitor ML-7 or through isoform specific siRNA knockdown of myosin IIA and IIB. We found that treatment with ML-7 or knockdown of myosin IIB, but not IIA, impaired the cleavage of caspase 3 and caspase 8 as well as nuclear condensation in response to TNF-alpha. During this cell death process myosin II seemed to function independent of AMC since treatment of cells with blebbistatin or cytochalasin D failed to inhibit TNF-alpha induced caspase cleavage. Immunoprecipitation studies revealed associations of myosin IIB with clathrin and FADD in response to TNF-alpha suggesting a role for myosin IIB in TNFR1 endocytosis and DISC formation. Taken together these findings suggest that myosin IIB activation promotes TNF-alpha cell death signaling in a manner independent of its force generating property.

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