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Dr. Nancy Petersen
Department of Molecular Biology
University of Wyoming
Laramie, WY 82071-3944
THE ROLE OF FORKED PROTEINS IN ACTIN FIBER BUNDLE CONSTRUCTION
Actin binding proteins are involved in creating and regulating the different kinds of actin structures in the cell, which determine cell shape and movement. The forked proteins are a new type of actin binding protein which are required for the construction of very long (300 mm) actin fiber bundles during bristle development in Drosophila. These fiber bundles are morphologically very similar to actin fiber bundles present in vertebrate intestinal brush border and in stereocilia in the ear and kidney, but much larger. The forked gene encodes six proteins, with overlapping coding regions, which differ primarily in their amino-terminal ends (Hoover et al. Genetics 135;507, 1993). The forked proteins are actin binding proteins which are homologous to the vertebrate actin binding proteins, the espins. These were originally identified in rat testis ectoplasmic specializations but have now been also found in kidney and intestinal microvilli and in ear stereocilia, reviewed by Bartles, Curr. Opin. Cell Biol. 12;72, 2000. We are studying the role(s) of forked proteins in actin fiber bundle formation in Drosophila bristles and in vertebrate cell lines. We have shown that forked proteins are synthesized and concentrated in bristle tips just prior to the formation of actin bundles, and that they can induce actin bundle formation in transiently transfected vertebrate cells. This suggests that they play a critical role in initiating bundle formation. We plan to use the transfection of vertebrate cells to further define the essential parts of the protein required for bundle formation and to use affinity chromatography and the yeast two-hybrid system to identify the regions of forked which interact with other proteins. P-factor transformation with forked genes mutated in these regions will then be used to clarify the roles of each in actin bundle formation in bristles. A better understanding of the roles played by forked in the construction and maintenance of these actin bundles should provide in formation useful for human health possibly including enhancing hearing and improving kidney and small intestine function.
Grieshaber, S.S., Lankenau, D.H., Talbot, T., Holland, S., and Petersen, N.S. (2001) Expression of the 53 kD forked protein rescues F-actin bundle formation and mutant bristle phenotypes in Drosophila. Cell Motility and the Cytoskeleton. In press.
Grieshaber, S. and Petersen, N.S. (1999) The Drosophila forked protein induces the formation of actin fiber bundles in vertebrate cells. J. Cell Science 12; 2203-2211.
Wulfkuhle, J.D., Petersen, N.S., and Otto, J.J. (1998) Changes in the F-actin Cytoskeleton during Neurosensory Bristle Development in Drosophila: the role of singed and forked proteins. Cell Motility and the Cytoskeleton 40; 119-132.
Williams, J., Moss, G., Hunnicut, L., and Petersen, N.S., (1997) Characterization of the heat shock response and translational thermotolerance in ovine trophoblasts. Theriogenology 47; 1125-1138.
Petersen, N.S., Lankenau, D.-H., Mitchell, H.K., Young, P., and Corces, V.G. (1994) Forked Proteins are Components of Fiber Bundles Present in Developing Bristles of Drosophila melanogaster. Genetics 136:173-182.
Petersen, N.S. (1994) The forked Protein is Most Abundant in the Initial Stages of Actin Fiber Formation in Drosophila Bristles. Mol. Biol. Cell, 5; 273a.
Petersen, N. S. and Mitchell, H.K. (1991) Environmentally Induced Developmental Defects in Drosophila. In "Results and Problems in Cell Differentiation: Heat Shock and Development" eds. L. Hightower and L. Nover. Springer-Verlag, Berlin.
Walter, M.F., Petersen, N.S., and Biessman, H., (1991) Heat shock causes the collapse of the intermediate filament cytoskeleton in Drosophila embryos. Dev. Genetics. 11; 270-279.
Petersen, N.S., and Young, P., (1990) Effects of Heat Shock on Development and Actin mRNA Stability in Drosophila. In "Heat Shock". ed. B. Maresca and S. Lindquist. Springer-Verlag, Berlin.
Petersen, N.S., Bond, B., Mitchell, H.K. and Davidson, N. (1985) Stage specific regulation of actin genes in Drosophila wing cells. Develop. Genetics 5;219-225.
Li, G., Petersen, N.S. and Mitchell, H.K. (1982) Induced thermal tolerance and heat shock protein synthesis in CHO cells. Int. J. Rad. Oncol. Biol. Phys. 8;63-67.
Petersen, N.S. and Mitchell, H.K. (1981) Recovery of protein synthesis following heat shock: Prior heat treatment affects the ability of cells to translate mRNA. Proc. Natl. Acad. Sci. 78; 1708-1711.
H.K., Moller, G., Petersen, N.S. and Lipps-Sarmiento, L. (1979) Specific protection from phenocopy induction by heat shock. Develop. Genet. 1;181-192.
Petersen, N.S., McLaughlin, C. and Nierlich, D. (1976) Messenger RNA half-life in yeast. Nature 260; 70-72.