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Dr. Alexander K. Murashov, M.D., Ph.D.

Associate Professor Graduate Director Physiology Department

Phone: (252) 744-3111
E-mail:murashoval@ecu.edu

Mailing Address:
Brody School of Medicine, 6N-74
600 Moye Blvd.
Greenville, NC 27834

Laboratory Homepage

Epigenetic effect of paternal high fat diet on offspring susceptibility to glucose intolerance in mice.
Obesity is an important global public health problem (Seidell, 2000), and is a risk factor formorbidity and mortality (Pemberton et al., 2010). National statistics demonstrate continued increases in overweight and obesity among young adults and children over the past three decades (Loomba et al., 2008). Additionally, the obesity epidemic is linked to a startling rise in the incidence of type II diabetes among children. Both obesity and type II diabetes are heritable traits with estimates of >0.70 (Walley et al., 2006), and diabetes heritability estimates ranging from 0.21 to 0.72 (Mathias et al., 2009). Although observations suggest that both genetic and environmental components may play equally important roles in the etiology of type II diabetes, changes in the gene pool of the population over this time frame are not sufficient to explain the recent increase of type II diabetes in adolescents. Rather, such rapid increases in heritable traits are likely due to epigenetic modification of the genome (Permutt et al., 2005) by environment factors (e.g., high fat intake, physical inactivity, etc.). Of particular interest is whether modifications to the genome induced by the environment (i.e., epigenetic effects) may be passed to offspring.  Recent studies demonstrating the perpetuation of type II diabetes into second generation offspring in response to maternal diet, support the heritability of these long-term programming effects (Dunn and Bale, 2009). While most studies of epigenetic effects are focused on maternal influences on susceptibility to diabetes, several new lines of evidence indicate that obese (Loomba et al., 2008) and/or diabetic fathers (Harjutsalo et al., 2006) are also likely to have obese offspring predisposed to diabetes. The molecular basis for these epigenetic transgenerational effects is not known, but is likely to involve epigenetic modifications in the methylation state of the DNA, histones and microRNAs (Handel et al., 2010).  In the current proposal we propose to test the hypothesis that exposure of male mice to a high fat diet will increase susceptibility to obesity and glucose intolerance in offspring. We further presume that these phenotypic changes will be linked to alterations in DNA methylation, gene and miRNA expression.  Aims:

1.To determine effects of paternal high fat diet on offspring postnatal development, post-weaning metabolic profile, and glucose tolerance in comparison to age-matched control offspring of male mice on standard chow. 2.To investigate susceptibility of the offspring from high fat fed fathers to develop obesity and glucose intolerance when fed a high fat diet. 3.To investigate the molecular basis of the epigenetic transgenerational effect of paternal high fat diet by comparing patterns of DNA methylation, gene and miRNA expression of offspring from fathers fed a high fat diet to control offspring from fathers on standard diet.  

Molecular mechanisms of peripheral nerve regeneration and axon growth

The peripheral nerve axons are unique in their robust regeneration capacity. A potential role for intra-axonal translation in axon regeneration is of particular interest, considering the fact that selected mRNAs are delivered to sites, that are long distances away from the neuronal cell body. Although axonally translated mRNAs are being identified with increasing frequency, the mechanisms regulating the localized protein synthesis remain largely unknown. We recently asked if axons in severed peripheral nerve have the potential to regulate local protein synthesis through the RNA interference (RNAi); highlighted in the FASEB Journal press release “Getting on your nerves ... and repairing them” 02/15/2007. Our work has shown that PNS axons in vivo and in vitro contain pivotal miRNA machinery proteins, including Dicer, Ago2, and FMRP. While a recent study uncovered a critical role for the miRNA pathway in regulation of actin filament dynamic and spine development in synapto-dendritic compartment, very little is known at present regarding the role of miRNA biogenesis within the axons. In our laboratory, we investigate the function of the miRNA machinery proteins and micro RNAs in PNS axons with particular focus on individual roles of miRNAs and key biosynthetic enzymes in regulation of intra-axonal translation and axonal regeneration. We employ a murine model of sciatic nerve crush to investigate axon remodeling. We examine the nerve from the level of axon function using electrophysiology to the mRNA and protein level using immunohistochemistry and genomic and proteomic analyses. We also perform cell culture and biochemical assays to help resolve mechanistic questions. Interested people may inquire about possible openings in the laboratory.

 

Treating spinal cord injury with stem cells
Spinal cord injury (SCI) is often followed by chronic pain, which is persistent, intense and refractory to the currently available therapies. While the experiments over the last decade have demonstrated the involvement of a variety of endogenous factors limited success has been achieved in chronic pain treatment. Recent reports revealed a considerable therapeutic potential of embryonic stem (ES) cells. ES cells may be used to generate a variety of cells of adult organism and subsequently applied for treatment of human diseases including injuries of the nervous system. In spite of the recent progress in using ES cell to treat experimental SCI the mechanism of stem cell therapeutic action remains largely unknown. That is why, our long-range goal is to investigate molecular mechanisms of ES cell therapeutic action in the traumatically injured spinal cord. We have recently reported that transplantation of neuronal and glial precursors dramatically improves sensorimotor function after contusion injury. Moreover, our preliminary observations showed that ES cells predifferentiated into dorsal interneurons could restore sensory function and prevent development of chronic pain after SCI. Research from our laboratory indicates that transplantation of ES cells has neurotrophic effects, which can be observed as early as two days after transplantation. This neurotrophic action also persists for a long period, up to 60 days (last examined time point). The initial analyses revealed a decrease in levels of inflammatory cytokines, and increase in neurotrophic factors, and cyclic adenosine monophosphate (cAMP) two days after transplantation. These preliminary data let us to hypothesize that (a) ES cells, predifferentiated into dorsal interneurons, may provide upon transplantation anatomical, neurochemical and physiological recovery and prevent development of chronic pain; and (b) that the mechanism of therapeutic action of ES cells involves secretion of neurotrophins with subsequent activation of cAMP in the host tissue, promoting regeneration of axonal fibers. To verify our hypothesis, we are examining some of the signaling pathways activated in the host cells and stem cells after transplantation. Specifically, we are using the variations of co-culture experiments and molecular biological approaches to determine if there are correlative changes in cell survival and regeneration and the associated signaling pathways.

Associate Professor (2006-present)
Assistant Professor (1999-2006)
Department of Physiology
Brody School of Medicine at East Carolina University
Greenville, NC

Associate Research Scientist (1995-1999)
Postdoctoral Scientist (1992-1995)
Columbia University,
New York, NY, USA

NHMRC Research Officer (1990-1992)
Griffith University
Brisbane, Australia

Visiting Scientist (1990)
Howard Florey Institute of Experimental Physiology and Medicine
University of Melbourne
Australia

Group Leader, Stress Physiology (1988-90)
P.K. Anokhin Institute of Normal Physiology
Academy of Medical Sciences
Moscow, Russia

Assistant Professor (1987-1988)
Department of Normal Physiology,
Sechenov 1st Medical Institute,
Ministry of Health,
Moscow, Russia

Doctor of Philosophy in Physiology (1987)
P.K. Anokhin Institute of Normal Physiology
Academy of Medical Sciences
Moscow, Russia

Doctor of Medicine in Pediatrics (1983)
N.I. Pirogov 2nd Moscow Medical Institute
Ministry of Health
Moscow, Russia