We will continue our development of a detailed, quantitative model of the interaction of the polypeptide growth factor, epidermal growth factor (EGF) with human fibroblasts (HF cells). Using a combination of kinetic and biochemical approaches, we will investigate our recent observations that EGF is able to induce the selective translocation of membrane components to the cell surface and that EGF can regulate subsequent binding to its own receptors. Specifically, we will attempt to answer the following questions: What is the general mechanism by which EGF regulates binding to its own unoccupied receptors? Does EGF treatment induce the translocation of a specific subset of intracellular proteins to the cell surface, or simply accelerate the return of normally recycling proteins? Is the autoregulation of the EGF receptor related to the specific desensitization of the membrane protein translocation response? Can the binding, internalization and the rate of appearance of the EGF receptor at the cell surface be regulated by hormones that modify the response of the cells to EGF? The kinetic studies will use our previously developed computer-assisted techniques for dissecting the individual components of the EGF receptor system. Studies of the effect of EGF on cell surface composition will use double labeling of cell surface components followed by lectin-agarose chromatography and multi-step gel electrophoresis. The relationship between regulators of EGF function and effects of the EGF receptor system will be explored using a completely defined medium in which HF cells are very responsive to the growth-promoting effects of EGF. All of the quantitative information that is obtained from this study will be used to extend and refine our current quantitative model of EGF-cell interactions. This hierarchical model is designed to facilitate our understanding of the role of polypeptide growth factors and receptor dynamics in intercellular communication. Many human diseases involve a dysfunction in growth control and intercellular communication. These studies are expected to provide basic insights into the mechanisms of these processes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK033602-06
Application #
3232016
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1984-04-01
Project End
1990-03-31
Budget Start
1989-04-01
Budget End
1990-03-31
Support Year
6
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Utah
Department
Type
Schools of Medicine
DUNS #
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Yim, D L; Opresko, L K; Wiley, H S et al. (1994) Highly polarized EGF receptor tyrosine kinase activity initiates egg activation in Xenopus. Dev Biol 162:41-55
Wiley, H S; Herbst, J J; Walsh, B J et al. (1991) The role of tyrosine kinase activity in endocytosis, compartmentation, and down-regulation of the epidermal growth factor receptor. J Biol Chem 266:11083-94
Lund, K A; Lazar, C S; Chen, W S et al. (1990) Phosphorylation of the epidermal growth factor receptor at threonine 654 inhibits ligand-induced internalization and down-regulation. J Biol Chem 265:20517-23
Lund, K A; Opresko, L K; Starbuck, C et al. (1990) Quantitative analysis of the endocytic system involved in hormone-induced receptor internalization. J Biol Chem 265:15713-23
Heisermann, G J; Wiley, H S; Walsh, B J et al. (1990) Mutational removal of the Thr669 and Ser671 phosphorylation sites alters substrate specificity and ligand-induced internalization of the epidermal growth factor receptor. J Biol Chem 265:12820-7
Opresko, L K; Wiley, H S (1990) Functional reconstitutional of the human epidermal growth factor receptor system in Xenopus oocytes. J Cell Biol 111:1661-71
Proud, V K; Rizzo, W B; Patterson, J W et al. (1990) Fatty acid alterations and carboxylase deficiencies in the skin of biotin-deficient rats. Am J Clin Nutr 51:853-8
Wiley, H S; Walsh, B J; Lund, K A (1989) Global modulation of the epidermal growth factor receptor is triggered by occupancy of only a few receptors. Evidence for a binary regulatory system in normal human fibroblasts. J Biol Chem 264:18912-20
Wiley, H S (1988) Anomalous binding of epidermal growth factor to A431 cells is due to the effect of high receptor densities and a saturable endocytic system. J Cell Biol 107:801-10
McKinley, D N; Wiley, H S (1988) Reassessment of fluid-phase endocytosis and diacytosis in monolayer cultures of human fibroblasts. J Cell Physiol 136:389-97