Primary Appointment:
 Pharmacology & Physiology - Associate Chair

GEBS Cluster Affiliations:
 Biochemistry, Molecular Biology, & Genetics - BMBG
 Cell Regulation & Molecular Pharmacology - CRMP

University of Rochester
School of Medicine and Dentistry
601 Elmwood Ave, Box 711
Rochester, New York 14642

E-Mail: hinklep@pharmacol.rochester.edu

Molecular Mechanisms of Cell Regulation

The major goal of Dr. Hinkle's research is to understand how hormone binding to a plasma membrane receptor triggers a characteristic sequence of cellular responses. Established lines of anterior pituitary cells are used as model systems to investigate regulation of cell growth and hormone secretion, particularly by the hypothalamic peptide TRH. Activation of the TRH receptor, which is coupled to G proteins, stimulates phosphoinositide turnover and increases cytoplasmic calcium and protein kinase C activity by well established pathways, but TRH stimulates other kinase cascades by pathways that are currently unknown. Cultures of pancreatic islet cells are used to study the molecular mechanisms involved in regulation of insulin secretion by glucose and other agents. Calcium is a key regulator of exocytosis and transcription in both of these model systems. In order to dissect the complex calcium response to hormones, several fluorescence imaging techniques are used to monitor the free calcium concentration in the cytoplasm and endoplasmic reticulum of individual cells. Many studies focus on how specificity in signaling is achieved. The intracellular signals generated by hormonal activation are transient, and cells undergo rapid and selective desensitization following exposure to hormone. Current work also attempts to understand the mechanisms responsible for the desensitization process. Mutant receptors, dominant-negative mutants of proteins involved in signaling and trafficking, and cells from knockout mice are used in these investigations. The subcellular distribution of membrane receptors and other key signaling molecules is monitored by several approaches, including microscopic localization of fluorescently-labeled hormones and GFP-tagged proteins, in an attempt understand signal transduction, desensitization and resensitization at a cellular level.

Yu, R. and Hinkle, P.M. (1998) Signal transduction, desensitization and recovery of the thyrotropin-releasing hormone receptor after inhibition of receptor internalization. Mol. Endocrinol. 12: 737-749.

Nelson, E.J., Zinkin, N.T. and Hinkle, P.M. (1998) Fluorescence methods to assess multidrug resistance in individual cells. Cancer Chemother. Pharmacol. 42: 292-299.

Fliss, M.S., Hinkle, P.M., and Bancroft, C. (1999) Expression cloning and characterization of PREB, a novel WD motif DNA-binding protein with a capacity to direct basal and protein kinase A-stimulated prolactin promoter activity. Mol. Endocrinol, . 13: 644-657.

Yu, R. and Hinkle, P.M. (1999) Signal transduction and hormone-dependent internalization of the thyrotropin-releasing hormone receptor in cells lacking Gq and G11. J. Biol. Chem. . in press.