About Dr. Holz

Ronald W. Holz, M.D., Ph.D

Dr. Holz has diverse training in membrane biophysics (Ph.D with Dr. Alan Finkelstein, AECOM, Bronx, N. Y) and in neuroscience and neuropharmacology (post-doctoral fellow with Julius Axelrod, NIMH; Guest Investigator with Phillip Nelson, NICHD). His major research interest concerns the mechanisms underlying the late steps in regulated exocytosis. His work has been characterized by the development of innovative and powerful approaches to provide timely insights into the complex pathway including the development of digitonin-permeabilized cells (1983) and co- transfection techniques to study exocytosis (1993). The work is mechanistic with numerous important discoveries including the role of the granule membrane potential in driving catecholamine uptake across the granule membrane, distinct, ATP-dependent priming steps in exocytosis, and the critical role of PIP₂ on the plasma membrane in exocytosis. He has enjoyed a long term, synergistic collaboration with Dr. Daniel Axelrod (Department of Physics, LSA Biophysics, University of Michigan) in which complementary expertise in optical biophysics and cell biology have enabled new insights in secretory cell biology. The collaboration has resulted in discovering the importance of small motions of the granule immediately before fusion and in imaging of the expanding fusion pore with insights into the role of dynamin and lumenal granule proteins in controlling the fusion pore. In addition, the diffusion coefficients of the granule membrane proteins VAMP2 and synaptotagmin have been measured in living cells with the results indicating a possible role of the mobility of these proteins in controlling fusion pore formation and expansion. Dr. Holz has also helped introduce multi-electrode array techniques for the study of adrenal medullary physiology in living animals.

TEACHING AND MENTORING: Dr. Holz has been engaged in medical school and graduate school teaching over many years. He has mentored many PH.D. students and post-doctoral fellows, most of whom have gone on to productive careers in academia and industry.