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Title page for ETD etd-12022011-134648


Type of Document Dissertation
Author Benesh, Andrew Eugene
URN etd-12022011-134648
Title Myosin-1d expression and dynamics in polarized cells
Degree PhD
Department Cell and Developmental Biology
Advisory Committee
Advisor Name Title
David M. Miller Committee Chair
Bruce D. Carter Committee Member
Christopher Janetopolous Committee Member
Irina Kaverina Committee Member
Matthew J. Tyska Committee Member
Robert J. Coffey Committee Member
Keywords
  • Myosin
  • brush border
  • myosin-1d
Date of Defense 2011-08-09
Availability unrestricted
Abstract
Class I myosins are monomeric actin-binding, ATP hydrolyzing molecular motors that are expressed in a variety of cell types, and function at the membrane-actin interface. Myosin-1d, one of eight vertebrate class I myosins, is expressed in polarized cells of the small intestine and nervous system, but subcellular localization and function for the motor remains largely unexplored. Intriguingly, myosin-1d is coexpressed in epithelial cells of the small intestine with myosin-a, where both motors target to the well-defined apical actin array of the brush border. However, how similar class I motors compartmentalize subcellularly is unknown, and raises the question of functional overlap. Interestingly, we found that myosin-1d and myosin1a exhibit differential localization and this partitioning can be explained by differential dynamics. Moreover, myosin-1d redistributes along the microvillar actin bundle in the absence of myosin-1a in MYO1A knockout animals. This suggests that class I myosins do have unique functions in wildtype, but may compensate for loss of activity. Interestingly, our data demonstrates that myosin-1d has a different subcellular localization in the nervous system. In these polarized cells, myosin-1d exhibits a punctate distribution in neuronal dendrites, cell bodies, and axons. We observed prominent expression in Purkinje cells and a subset of granule cells, with both patterns developmentally regulated. However, myosin-1d was not detectable in oligodendrocytes during early development. In the PNS, we observed that myosin-1d is present in neurons, and myelinating Schwann cells. This suggests a differential role for the motor in myelinating cells between the two nervous systems. Our studies also revealed that myosin-1d interacts with aspartoacylase, a catalytic enzyme involved in fatty acid synthesis that is widely expressed in similar polarized cells as myosin-1d. Together, these studies suggest that myosin-1d has distinct localization patterns in different polarized cell types, but may modulate aspartoacylase activity.
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