MARY K. DAHMER
ASSISTANT PROFESSOR

EDUCATION:
B.S. 1977, The University of Michigan, Ann Arbor, Michigan
Ph.D. 1983, The University of Michigan, Ann Arbor, Michigan
Postdoctoral Fellow: 1983-84, The University of Michigan, Ann Arbor, Michigan; 1984-90, The University of Illinois at Chicago and the University of Chicago

RESEARCH INTERESTS: My research has focused on understanding the mechanisms by which hormones, growth factors and neurotransmitters regulate cellular functions. Many of these agents act via second messengers such as cAMP, Ca2+, diacylglycerol and phosphoinositides. My particular interests lie in identifying and studying agents which affect the survival or the differentiated functions of neuronal cells. Recent work in my laboratory is aimed at understanding how insulin-like growth factor-I (IGF-I) affects cells of the nervous system. IGF-I is synthesized by many types of cells and appears to act as an autocrine or paracrine growth factor. IGF-I belongs to the class of polypeptides which binds to membrane receptors with intrinsic tyrosine kinase activity. We have found that IGF-I stimulates proliferation of PC12 pheochromocytoma cells and enhances secretagogue-stimulated catecholamine synthesis and secretion in normal chromaffin cells. Catecholamine synthesis and secretion in chromaffin cells is triggered by a rise in intracellular free Ca2+, primarily due to influx of Ca2+ via voltage-dependent Ca2+ channels. Recent work in my laboratory suggests that protein kinase C (Ca2+, phospholipid dependent protein kinase) is required for the enhanced secretion caused by IGF-I. Another project in the laboratory is aimed at understanding the mechanism by which dopamine agonists acutely inhibit catecholamine secretion.

CURRENT RESEARCH SUPPORT:
"Mechanism of Insulin-Like Growth Factor-I Effects on Chromaffin Cell Function; October 1, 1992 - September 30, 1997; $350,000 TDC.

PUBLICATIONS:
1. Leach, K.L., Dahmer, M.K., Hammond, N.D., Sando, J.J. and Pratt, W.B. (1979) Molybdate inhibition of glucocorticoid receptor inactivation and transformation. J. Biol. Chem., 254, 11884-11890.
2. Dahmer, M.K., Quasney, M.W., Bissen, S.T., and Pratt, W.B. (1981) Molybdate permits resolution of untransformed glucocorticoid receptors from the transformed state. J. Biol. Chem., 256, 9401-9495.
3. England, B.G., Dahmer, M.K., and Webb, R. (1981) Relationships between follicular size and antral fluid steroid concentrations at three stages of the estrous cycle in the ewe. Biol. Reprod., 24, 1068-1075.
4. England, B.G., Webb, R., and Dahmer, M.K. (1981) Follicular steroidogenesis and gonado-tropin binding to ovine follicles during the estrous cycle. Endocrinology, 109, 881-887.
5. Leach, K.L., Housley, P.R., Grippo, J.F., Dahmer, M.K., and Pratt, W.B. (1982) Characteristics of a glucocorticoid receptor stabilizing factor. J. Biol. Chem., 257, 381-388.
6. Housley, P.R., Dahmer, M.K. and Pratt, W.B. (1982) Inactivation of glucocorticoid binding capacity by protein phosphatases in the presence of molybdate and complete reactivation by dithiothreitol. J. Biol. Chem., 257, 8615-8618.
7. Leach, K.L., Dahmer, M.K. and Pratt, W.B. (1983) Unexpected effects of molybdate on glucocorticoid receptors. J. Steroid Biochem., 18, 105-107.
8. Grippo, J.F., Tienrungroj, W., Dahmer, M.K., Housley, P.R., and Pratt, W.B. (1983) Evidence that the endogenous heat stable glucocorticoid receptor activating factor is thioredoxin.
J. Biol. Chem., 258, 13658-13664.
9. Dahmer, M.K., Housley, P.R. and Pratt, W.B. (1984) Effects of molybdate and endogenous inhibitors on steroid receptor inactivation, transformation, and translocation. Ann. Rev. Physiol., 46, 67-81.
10. Housley, P.R., Grippo, J.F., Dahmer, M.K., and Pratt, W.B. (1984) Inactivation, activation and stabilization of glucocorticoid receptors. In G. Litwack (Ed.), Biochemical Actions of Hormones, Vol. 11 (pp. 347-376). New York: Academic Press.
11. Pratt, W.B., Housley, P.R., Dahmer, M.K., and Grippo, J.F. (1984) Phosphorylation of the glucocorticoid receptor. In W. Paton, J. Mitchell and P. Turner (Eds.), IUPHAR Ninth International Congress of Pharmacology (pp. 93-99). London: MacMillan Press.
12. Dahmer, M.K., Tienrungroj, W., and Pratt, W.B. (1985) Purification and preliminary characterization of a macromolecular inhibitor of glucocorticoid receptor binding to DNA.
J. Biol. Chem., 260, 7705-7715.
13. Dahmer, M.K. and Perlman, R.L. (1988) Insulin and insulin-like growth factors stimulate deoxyribonucleic acid synthesis in PC12 pheochromocytoma cells. Endocrinology, 122, 2109-2113.
14. Dahmer, M.K. and Perlman, R.L. (1988) Bovine chromaffin cells have IGF-I receptors: IGF-I enhances catecholamine secretion. J. Neurochem., 51, 321-323.
15. Dahmer, M.K., Ji, L., and Perlman, R.L. (1989) Characterization of insulin-like growth factor-I receptors in PC12 pheochromocytoma cells and bovine adrenal medulla. J. Neurochem., 53, 1036-1042.
16. Dahmer, M.K. and Perlman, R.P. (1989) Effects of insulin-like growth factor-I on chromaffin cells. In M. Raizada and D. LeRoith (Eds.), Molecular and Cellular Aspects of Insulin, Insulin-like Growth Factors and Their Receptors: Implications for the Central Nervous System (pp. 467-472). New York: Plenum Press.
17. Dahmer, M.K., Hart, P.M., and Perlman, R.L. (1990) Studies on the effect of insulin-like growth factor-I on catecholamine secretion from chromaffin cells. J. Neurochem., 54, 931-936.
18. Artalejo, C.R., Dahmer, M.K., Perlman, R.L., and Fox, A.P. (1991) Two types of Ca currents are found in bovine chromaffin cells: Facilitation is due to the recruitment of one type. J. Physiol. (London), 432, 681-707.
19. Dahmer, M.K., Hart, P.M., and Perlman, R.L. (1991) Insulin-like growth factor-I enhances tyrosine hydroxylase activation in bovine chromaffin cells. J. Neurochem., 57, 1347-1353.
20. Penberthy, W.T. and Dahmer, M.K. (1994) Insulin-like growth factor-I enhanced secretion is abolished in protein kinase C-deficient chromaffin cells. J. Neurochem., 62, 1707-1715.
21. Dahmer, M.K. (1995) Down-regulation of protein kinase C activity preferentially attenuates high K+ stimulated tyrosine hydroxylase activity in adrenal chromaffin cells cultured with insulin-like growth factor-I. Neurosci. Lett., in press.
22. Dahmer, M.K. and Senogles, S.E. (1996) Dopaminergic inhibition of catecholamine secretion from chromaffin cells: Evidence that inhibition is mediated by D4 and D5 dopamine receptors.
J. Neurochem., 66, in press.