Susan Bonner-Weir, Ph.D., Becomes AAAS Fellow Member
Wednesday, June 12, 2013
Susan Bonner-Weir, Ph.D., studies beta cells—those cells in the pancreas responsible for secreting insulin.
For over twenty-five years her research has specifically focused around these cells that are subject to autoimmune onslaught in type 1 diabetes as well as dysfunction in type 2 diabetes. By looking at these cells both in living bodies and in petri dishes, she has examined how beta cells function and grow normally, and what happens to the cells in people with diabetes.
In February, the American for the Advancement of Science (AAAS) inducted Dr. Bonner-Weir as a Fellow for her major contributions made in the areas of architecture and function of the islet, in vivo regulation of β-cell mass, and islet growth and differentiation.
“When I first started in this field, researchers thought you were born with all the beta cells you would ever have. But in collaboration with a lot of different people, I’ve shown through different experimental situations, both the number and the size of beta cells can change. The beta cell mass can be modulated, as well as the function, but the amount can be changed as needed,” said Dr. Bonner-Weir.
For example, as a human or animal becomes bigger or obese, the islets get bigger or more numerous. Or when a woman or an animal becomes pregnant, they get an increased mass of beta cells (though after the pregnancy ends, studies show beta cells return to their original, pre-pregnancy level).
Dr. Bonner-Weir’s laboratory currently concentrates on two main areas of research. In the first, they are identifying possible cells that can give rise to new beta cells after birth. The pancreas is composed of several cell types other than the hormone producing islet cells. They are focusing on the pancreatic duct cell. These cells usually serve as the plumbing to direct the digestive enzymes made in the bulk of the pancreas to the intestine for digestion of our food.
“However, these cells have a plasticity and can be stimulated to regress to a more progenitor state from which they can give rise to all the pancreatic cells, those that make the digestive enzymes, the islet hormones, or even more duct cells,” said Dr. Bonner-Weir.
The second area of focus is understanding the regulation of function of the beta cell. In the body, beta cells sense glucose in the blood stream and then release the appropriate amount of insulin to pull that glucose into the cells to be used for energy. Even so, newly formed beta cells do not respond to glucose and so must be considered as immature.
“Researchers who have worked using stem cells to make beta cells in vitro, can get them to express insulin, but they cannot get the beta cells to respond to glucose in a dish. However, if they transplant them into an animal and wait, they can get them to secrete insulin in response to glucose. This process of acquiring the glucose responsiveness is called maturation,” explained Dr. Bonner-Weir.
This process of maturation intrigued her and her colleagues and got them interested in the process of how the beta cell becomes responsive to glucose. This course of study could contribute to understand how replacement beta cells will work after being transplanted.
Her research brings us closer to a cure for diabetes because the more we understand the lifecycle of a beta cell, the closer we get to being able to either generate them ex vivo (outside of the body) or generate them in vivo (within the body).
She was recognized and honored for her major efforts in advancing science and technology in the field of diabetes research on Feb. 16 at the AAAS Annual Meeting in Boston, MA. She received a certificate and a blue and gold rosette as a symbol of her distinguished accomplishments in diabetes research.
Dr. Bonner-Weir has been with Joslin since 1984 and is Senior Investigator in the Section on Islet Transplantation and Cell Biology. She is Professor of Medicine at Harvard Medical School.
She received her doctorate in biology at Case Western Reserve University. She did some postdoctoral training at Joslin, about ten years before returning to work here as faculty.
Dr. Bonner-Weir serves or has served on the editorial boards of the American Journal of Physiology, Journal of Biological Chemistry, Endocrinology, Cell Transplant, and Diabetes. Also, she is or has been a member of the grant review panels for the NIH, Juvenile Diabetes Research Foundation, the American Diabetes Association, the California Institute of Regenerative Medicine, and the European Research Council.
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