We want to understand the molecular biology of how Drosophila embryo cells collaborate to form a tissue. Basement membranes are fundamental to tissue construction. These thin nets of specialized, conserved extracellular proteins underlie epithelial cells and surround muscles and nerves. We have isolated, cloned and sequenced several of the component proteins, such as laminin and collagen, and are now studying mutant forms, the control of production, and interactions during development. Four new proteins are of special interest: Tiggrin, Peroxidasin, DUGT and Papilin.
Tiggrin is a 220kd connector protein at muscle attachment sites. One end of the protein binds to an integrin receptor in the muscle cell membrane. We are looking for Tiggrin?s molecular neighbor at the other end. Tiggrin also occurs elsewhere in embryos and is an excellent substrate for the differentiation of embryonic muscle cells in vitro, which we are studying.
Peroxidasin is the first combination of an enzyme and an extracellular matrix molecule. The cells which make this (170kd)3 trimer use its peroxidase activity during early embryogenesis to remove other cells that undergo programmed cell death. The secreted peroxidase becomes part of the matrix and probably stabilizes it by cross-linking. We are looking for mutants in Drosophila and for functions of peroxidasin in vertebrates.
DUGT is a universal editor/chaperone protein that we isolated and sequenced from Drosophila. This UDP-Glucose transferase distinguishes glycoproteins that are improperly folded and marks them by attaching a glucose residue. The glucose is the recognition signal for the malfolded proteins to interact with a chaperone system of the endoplasmic reticulum. By molecular manipulation we are investigating its key role as a chaperon/folding controller.
Papilin is a basement membrane protein vital during development.
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Kramerova, I.A., Kramerov, A.A. and Fessler, J.H., "Alternative Splicing of Papilin and the Diversity of Drosophila Extracellular Matrix during Embryonic Morphogenesis", Dev. Dyn 226: 634-642 (2003).
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Kramerova, I., Kawaguchi, N., Fessler, L., Nelson, R, Chen, Y., Kramerov, A., Kusche-Gullberg, M., Kramer, J.M, Ackley, B., Prockop, D., Fessler, J.H, "Papilin in development: a pericellular protein with a homology to the ADAMTS metalloproteinases", Development 127: 5475-5485 (2000).
Bunch, T.A., Graner, M.W., Fessler, L.I., Fessler, J.H., Schneider, K.D., Kerschen, A., Choy, L., Burgess, B.W. and Brower, D., "The PS2 Integrin Ligand Tiggrin is Required for Proper Muscle Function in Drosophila", Development 125: 1679-1687 (1998).
Parker, C.G., Fessler, L.I., Nelson, R.E. and Fessler, J.H., "Drosophila UDP-glucose: glycoprotein glucosyltransferase: Sequence and characterization of an enzyme that distinguishes between denatured and native proteins", EMBO Journal 14: 1294-1303 (1995).
Nelson, R.E., Fessler, L.I., Takagi, Y., Blumberg, B., Keene, E.R., Olson, P.F., Parker, C.G. and Fessler, J.H., "Peroxidasin: a novel enzyme-matrix protein of Drosophila development", EMBO Journal 13: 3438-3447 (1994).
Fogerty, F.J., Fessler, L.I., Bunch, T.A., Yaron, Y., Parker, C.G., Nelson, R.E., Brower, K.L., Gullberg, D. and Fessler, J.H., "Tiggrin, a novel Drosophila extracellular matrix protein that functions as a ligand for Drosophila PS2 integrins", Development 120: 1747-1758 (1994).
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