Gregory Hockerman

Title:

Associate Professor

PhD Granting Institution:

University of Wisconsin-Madison

Contact:

Email Address: hockerma@purdue.edu
Office Phone: 765-496-3874

Primary Training Group:

Integrative Neuroscience

Current Projects:

Voltage-gated calcium channels are key players in a large array of physiological processes including contraction of cardiac, vascular and skeletal muscle, release of neurotransmitters from nerve terminals, gene expression, and hormone secretion. The long-range goal of our studies is to contribute to the development of drugs that can modulate voltage-gated calcium channels in a tissue and type selective manner to treat cardiovascular disease, stroke, and type II diabetes. Recent work in my lab has centered on describing the binding site for the BZP diltiazem in the Cav1.2 L-type channel, as well as the Ca2+ binding site in the channel that modulates the affinity for diltiazem and verapamil. We are currently using chemical oxidizing reagents in conjunction with mutant channels to understand how ischemia my modulate channel activity. Our current research is focused on the role of Cav1.2 and 1.3 channels in insulin secreting cells. My lab has developed mutant versions of Cav1.2 and 1.3 that are resistant to the DHP class of L-type channel blockers (Cav1.2/DHPi and Cav1.3/DHPi), but remain sensitive to the BZP diltiazem. After introducing these mutant channels into insulin-secreting INS-1 cells, we are able to functionally isolate either Cav1.2 or Cav1.3 channels by "turning off" endogenous L-type channels with the DHP nifedipine. Using this approach, we found that Cav1.3, but not Cav1.2, channels are coupled to glucose-stimulated insulin secretion from INS-1 cells. Further, we found that Cav1.3, but not Cav1.2, channels are coupled to glucose-stimulated oscillations in intracellular Ca2+ concentrations. Finally, we found that insulin secretion stimulated by the incretin peptide GLP-1 is preferentially coupled to Cav1.3. Our lab is also collaborating with other groups to study the roles of Cav1.2 and 1.3 channels in cardiac myocytes and endocrine cells using the same strategy