Dr. Haj is scheduled to present at the UC Davis Graduate Group in Nutritional Biology Seminar Series. His talk is titled “Regulation of Systemic Glucose Homeostasis by Protein-Tyropsine Phosphatases.”(9/26/2011)
Dr. Haj will be a collaborator on a new National Institutes of Health grant that awarded $3.8 million to the University of California, Davis, to fund a new mouse-based research center devoted to studies of the physiology and genetics of obesity, diabetes and cardiovascular health.
A major focus for the new Mouse Metabolic Phenotyping Center will be cardiovascular disease, which affects more than 82 million Americans, costs an estimated $444 billion annually and is the nation’s leading cause of death.
The new center will provide scientists worldwide with complete physiologic characterizations of mice that have been genetically altered for metabolic studies. It will be one of only six such centers in the United States, and the only one that can create the mice for researchers.
Collaborating in the new center are UC Davis School of Medicine researchers Craig Warden, scientific director of the Mouse Metabolic Phenotyping Center and a professor of pediatrics, and neurobiology, physiology and behavior; Amparo Villablanca and Nipavan Chiamvimovat, both professors of cardiovascular medicine; Liming Jin, an assistant professor of endocrinology; and Thomas Huser, an adjunct professor of endocrinology.
Collaborators from the School of Veterinary Medicine include clinical professor Stephen Griffey; Peter Havel, a professor of molecular bioscience; Philip Kass, a professor of statistics; Jon Ramsey, an associate professor of molecular bioscience; Helen Raybould, a professor of physiology; and assistant clinical professor Katherine Wasson.
Other collaborators include adjunct assistant nutrition professor Sean H. Adams, a supervisory research physiologist at the USDA-Agricultural Research Service’s Western Human Nutrition Research Center at UC Davis; and Mari Golub, an adjunct professor of toxicology.
The hormone leptin, naturally produced by fat cells and long known to play an important role in regulating appetite and fat metabolism, may prove to be successful in treating Type 2 diabetes, a disease that affects more than 21 million people in the United States, reports a team of scientists led by researchers at the University of California, Davis.
The findings from their study, involving rats predisposed to Type 2 diabetes — formerly known as adult-onset diabetes — appear in the Aug. 30 issue of the journal the Proceedings of the National Academy of Sciences.
“One of leptin’s important effects is in signaling the brain to decrease food intake, and recent animal studies have shown that the hormone also lowers blood sugar in Type 1 diabetes,” said lead author Peter Havel, a veterinary endocrinologist.
“Our study, however, is the first to demonstrate that twice-daily injections of leptin lower blood sugar levels and circulating triglycerides in an animal model with the more common form of diabetes — Type 2 diabetes,” Havel said.
Triglycerides are compounds containing three fatty acids; they primarily circulate in the bloodstream and, at high levels, can increase the risk of heart disease.
“The data from this study indicate that leptin improves blood sugar control, in part, by increasing the animals’ sensitivity to insulin, the hormone responsible for maintaining normal blood sugar levels,” said co-author Bethany Cummings, a veterinary molecular physiologist in the Havel laboratory.
The results suggest that the improved insulin sensitivity may be due to reduced stress in a specialized part of the cell called the endoplasmic reticulum. Previous studies have shown that stress to the endoplasmic reticulum can cause insulin resistance, which can lead to Type 2 diabetes.
The study also showed that the leptin treatments resulted in decreased levels of circulating glucagon, a hormone produced in the pancreas that stimulates an increase in blood-sugar levels and works in opposition to insulin.
Other co-authors of this study are: postdoctoral fellow Ahmed Bettaieb, Associate Professor Fawaz G. Haj, and undergraduate assistant Riva Dill, all of the UC Davis Department of Nutrition; research scientists James L. Graham and Kimber L. Stanhope, both of the School of Veterinary Medicine and the Department of Nutrition; and Research Assistant Professor Gregory J. Morton of the University of Washington School of Medicine.
Funding for the study was provided by the National Institutes of Health and UC Davis’ Center for Nutrition and Health Research.