The myogenic response is a critical homeostatic mechanism of vasculature smooth muscle that maintains constant blood flow and capillary pressure to the brain and kidney despite fluctuations in perfusion pressure. There is evidence that the myogenic response is impaired in aging populations, especially in the presence of comorbidities of hypertension and diabetes. Hypertension and diabetes are leading causes of end stage renal disease (ESRD) and stroke;however, not all hypertensive or diabetic patients develop ESRD or stroke and very little is known about the genetic factors that determine an individual's risk. The Fawn Hooded Hypertensive (FHH) rat is a genetic model of hypertension and ESRD. We have shown that they exhibit an impaired myogenic response in both renal and cerebral circulation with aging. However, the genes and pathways involved are unknown. The goals of this project are to use molecular, genetic and transgenic approaches to identify the gene and associated pathways responsible for impaired myogenic response in FHH rats. The 1st aim of this project is to characterize a congenic FHH.1BN strain with a narrowed region of interest for myogenic response in renal and cerebral vessels. The 2nd aim is to perform DNA sequencing and PCR expression studies of all the genes in the region to obtain the molecular evidence needed to prioritize which of the positional candidate genes to investigate further. The 3rd aim is to evaluate the ability of sequence variants in Add3 and Dusp5 and any other positional candidate genes to alter myogenic tone in the renal and cerebral vasculature of FHH rats using a transposon-based transgenic rescue, targeted Zn-finger nuclease gene knockout strategies and siRNA knockdown techniques in the FHH genetic background. The research training and methods related to these aims will provide me with experience using techniques ranging from in vivo and vitro studies of vascular function to cutting edge molecular biology and transgenic manipulation. Completion of these studies will put me in a very competitive position to obtain a post-doc position at a well respected research institution to continue work on the genetic basis of vascular disease.

Public Health Relevance

With an increasing elderly population in the U.S., there is increasing incidence and cost of treating chronic and progressive diseases such as hypertension and diabetes which are predictors of other serious and costly conditions;notably stroke and end stage renal disease (ESRD). There are around 750,000 strokes annually in the US with an estimated cost of caring for survivors at $51 billion annually. Hypertension and diabetic induced ESRD disease, traditionally considered a disease of old age, now accounts for over 67% of US cases with a cost to the US government of over $20 billion a year for dialysis alone.

National Institute of Health (NIH)
National Institute on Aging (NIA)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1-F10A-S (20))
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Zieman, Susan
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University of Mississippi Medical Center
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Burke, Marilyn; Pabbidi, Malikarjuna; Fan, Fan et al. (2013) Genetic basis of the impaired renal myogenic response in FHH rats. Am J Physiol Renal Physiol 304:F565-77