Robert S. Moreland, Ph.D.
Professor
Ph.D. (1981) Medical College of Virginia
Phone: 215-762-5133  
Email: robert.moreland@drexelmed.edu

Our group is involved in determining how smooth muscle function is regulated. We are currently examining the regulation of vascular and urinary bladder smooth muscle. Our work can be divided into three complementary areas of study: Contraction; Signal Transduction; and Pathophysiology.

Smooth muscle contraction is believed to be initiated by a cascade of events beginning with stimulation-induced increases in cellular calcium and ending with phosphorylation of a protein called the myosin light chain. Our work on contractile regulation is focused on determining if myosin light chain phosphorylation and the resultant activation of the thick filament based protein myosin is necessary and sufficient to initiate contraction or whether the thin filament based protein caldesmon also plays a significant role. To pursue this goal, we use intact and permeabilized (a technique that allows us to control the intracellular environment) strips of smooth muscle to measure force of contraction and velocity of shortening (index of crossbridge cycling rates) as well as biochemical analysis of enzyme activities and protein phosphorylation levels. In addition, we use antisense oligonucleotides and siRNA techniques to "knock-out" specific proteins within a physiologically viable tissue to determine the role that protein plays in regulation.

Our working model for the regulation of contraction in smooth muscle. In the relaxed state, actin and myosin are dissociated, either activation of the myosin light chain kinase or disinhibition of caldesmon will result in the development force.

Our signal transduction studies have centered on the roles of various isoforms of protein kinase C, the mitogen-activated protein (MAP) kinases, Rho kinase, casein kinase II, and the p21-activated protein kinase (PAK). Our experiments are designed to quantitatively determine the magnitude of kinase catalyzed phosphorylation of specific cellular substrates and the role of this phosphorylation in cellular function. We are also investigating how receptor and G-protein activation alters the calcium sensitivity of the contractile filaments and if either protein kinase C, MAP kinase or Rho kinase are involved. Our long term goal is to determine the precise steps involved in the coupling of cellular excitation and contraction and to determine the precise steps of modulatory pathways that alter the contractile response to excitation.

This figure (adapted from Wang, Cell Biochem Biophys 35:275, 2001) shows the complexity of signaling in smooth muscle. Currently we are concentrating on the PAK, MAPK, PKC pathways and how they impact caldesmon (CaD). As we learn more, we are constantly adding more signaling steps to our investigations.

Smooth muscle is the final common pathway for many diseases. Therefore a complete understanding of how smooth muscle changes during the genesis and maintenance of a disease is an important step toward the development of therapeutic approaches. We are currently involved in studies aimed at understanding how urinary bladder smooth muscle cells are altered following partial outlet obstruction similar to that which occurs during benign prostatic hyperplasia. It is known that significant changes occur in the contractile protein content and isoform profile, but how this impacts the physiology and regulation of the tissue is not understood. Recent studies from our lab have shown that bladder outlet obstruction alters the relationship between force and myosin light chain phosphorylation, decreases crossbridge cycling rates, abolishes contractions in response to activation of protein kinase C, and diminishes the G-protein dependent pathways that increase contractile protein sensitivity to calcium. We are currently investigating the precise cellular components involved in these alterations. The goal of these studies is to obtain a better understanding of the role the smooth muscle cell plays in the pathology of the tissue.

Partial bladder outlet obstruction changes the contraction of the smooth muscle cell from a phasic contraction (filled circle) into a tonic contraction (open circles). Outlet obstruction also decreases crossbridge cycling rate, as estimated by velocity of shortening. Control tissues are black bars, tissues from obstructed animals are gray bars.

Selected recent references:

Su X, Stein R, Stanton M, Zedric S, and Moreland RS. Effect of partial outlet obstruction on rabbit urinary bladder smooth muscle function. Am. J. Physiol. 284:F644-F652, 2003.

Adegunloye B, LaMarre, E, and Moreland RS. Quinine inhibits vascular smooth muscle by a calcium and myosin light chain phosphorylation independent mechanism. J. Pharmacol. Exp. Therap. 304:294-300, 2003.

Stanton MC, Clement M., Macarak E. M., Zderic, SA, and Moreland RS. Partial bladder outlet obstruction alters the calcium sensitivity of force but not of myosin light chain phosphorylation in bladder smooth muscle. Am. J. Physiol. 285:F703-F710, 2003.

Adengunloye BJ, Su X, Camper E, and Moreland RS. Sensitivity of rabbit aorta and mesenteric artery to norepinephrine: Role of tyrosine kinases. Eur. J. Pharmacol. 476:201-209, 2003.

Gorenne I, Su X, and Moreland RS. Caldesmon phosphorylation is catalyzed by two kinases in permeabilized and intact vascular smooth muscle. J. Cell. Physiol. 198:461-469, 2004.

Su X*, Smolock E*, Marcel KN, and Moreland RS. Phosphatidylinositol 3-kinase modulates vascular smooth muscle contraction by calcium and myosin light chain phosphorylation independent and dependent pathways (* = equal contribution). Am. J. Physiol. 286:H657-H666, 2004.

Stanton MC, Delaney D, Zderic SA, and Moreland RS. Partial bladder outlet obstruction abolishes the receptor and G-protein dependent increase in calcium sensitivity in rabbit bladder smooth muscle. Am. J. Physiol. 287:F682-F689, 2004.

Su X, Changolkar A, Chacko S, and Moreland RS. Diabetes decreases rabbit bladder smooth muscle contraction while increasing levels of myosin light chain phosphorylation. Am. J. Physiol. 287:F690-F699, 2004.

Soloviev AI, Tishkin SM, Zelensky SN, Ivanova IV, Kizub IV, and Moreland RS. Ionizing radiation alters myofilament calcium sensitivity in vascular smooth muscle: Possible role of protein kinase C. Am. J. Physiol. 289:R755-R762, 2005.

Basha M, Chang S, Smolock E, Moreland RS, Wein A, and Chacko S. Regional differences in myosin isoform _expression and maximum shortening velocity in the vaginal muscularis. Am. J. Physiol. 291:R1076-R1084, 2006.

Stanton MC, Austin JC, Delaney D, Gosfield A, Zderic SA, Chacko S, and Moreland RS. Partial bladder outlet obstruction selectively abolishes protein kinase C induced contraction of rabbit detrusor smooth muscle. J. Urology, 176:2716-2721, 2006 (chosen for an editorial highlight).

Smolock EM, Wang TC, Nolt JC, and Moreland RS. siRNA knock down of casein kinase 2 increases force and crossbridge cycling rates in vascular smooth muscle. Am. J. Physiol., 292:C876-C885, 2007.  (featured in the March 2007 NAVBO Vascular Biology Publications Alert).

Tishkin SM, Rekalov VV, Ivanova IV, Moreland RS and Soloviev AI.  Ionizing non-fatal whole-body irradiation inhibits Ca2+-dependent K+ current in endothelial cells of rat coronary artery: Possible contribution to depression of endothelium-dependent vascular relaxation.  International J. Rad. Biol, 83: 161-169, 2007.