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Associate Dean for Research and Graduate Studies, Penn State Capital College
Ph.D.: University of Houston
Postdoctoral: University of California, Riverside; Baylor College of Medicine

My laboratory studies cell and molecular aspects of steroid hormone and vitamin D receptor signal transduction in a variety of physiological systems. Prior research projects included several aspects of vitamin D receptor signal transduction, role of protein kinase C in vitamin D effects in breast cancer, and the molecular basis of vitamin D receptor heterogeneity.

Cross-talk between B-adrenergic stimulation and estrogen receptors in cardiovascular targets: Recent studies in our laboratory have shown that the B-adrenergic receptor agonist isoproterenol abolishes estrogen-induced reporter gene expression in vascular smooth muscle cells. Since the vasoactive agent adrenomedullin does not inhibit the estrogen-induced gene expression, this effect is specific with respect to the B-adrenergic receptor agonist. The isoproterenol effect is also specific in that it does not affect gene expression induced by the nuclear vitamin D receptor and is tissue specific in that it does not occur in breast cancer cells.

Ongoing studies of this membrane-nuclear receptor cross-talk include studies of the B adrenergic receptor signaling pathway that induces the effect, as well as molecular studies to determine what step in the estrogen receptor response pathway is specifically inhibited.

Vitamin D-Induced Calmodulin Binding Proteins:  The nuclear vitamin D receptor (VDR) has been cloned and is well characterized. One of the most striking effects of the hormonal form of vitamin D in many targets is the induction of one or more calcium binding proteins. Studies related to these effects resulted in the unexpected discovery that vitamin D treatment induces at least four biochemically distinct calmodulin binding proteins in the rat. This effect is hormone and tissue specific. Future studies of the CaMBP-Ds will be directed at defining a cellular model for their study and using gene array techniques to determine their identity. In addition, it will be important to establish whether this effect is a direct consequence of vitamin D receptor action, or a secondary effect of hypercalcemia and/or renal damage in this model.

Recent Publications:

A PubMed listing of research publications for Marian R. Walters, Ph.D.

mrw16@psu.edu

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