Pitt researchers identify key molecular pathway to replicate insulin-producing beta cells

Jun 09, 2009

Researchers at the University of Pittsburgh School of Medicine are trailblazing the molecular pathway that regulates replication of pancreatic beta cells, the insulin-producing cells that are lacking in people who have type 1 or type 2 diabetes.

Building on findings from earlier this year, a research team led by Andrew F. Stewart, M.D., professor of medicine and chief of the Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, has now shown in mouse experiments that knocking out two proteins leads to robust beta . The results were presented today in New Orleans at the 69th Annual Scientific Sessions of the American Diabetes Association, and in an accompanying paper published online in the ADA's journal Diabetes.

"These proteins act like brakes to prevent regeneration of beta cells," Dr. Stewart explained. "It's a redundant system, though, so removing just one of the proteins isn't sufficient to make beta cells replicate."

In earlier studies, Rupangi Vasavada Ph.D., an assistant professor in Pitt's endocrinology division working with Dr. Stewart, assessed mice that lacked a key regulator of cell division called retinoblastoma protein (pRB), so named because mutations in it can lead to the childhood eye cancer. But the loss of pRB alone did not make beta cells regenerate.

In the current study, lead author George Harb, Ph.D., a postdoctoral fellow in Pitt's endocrinology division, engineered mice to lack the gene for another cell cycle protein that is very similar to pRB called p130. Again, there was no impact on beta cell production. The similarity of pRB and p130 hinted that they serve the same purpose, and so his next step was to engineer mice deficient in both proteins. The result was a marked increase in beta cell replication.

"The cell cycle has yet another protein, called p107, that is much like pRB and p130," Dr. Stewart noted. "Now we want to see what happens to beta cell numbers if we knock out any two of the three or all three."

In an online publication in Diabetes in January, another of his research teams demonstrated for the first time that human beta cells could be induced to replicate by boosting levels of cell cycle proteins cdk-6 and cyclin D1 using gene therapy techniques. When study co-author Nathalie Fiaschi-Taesch, Ph.D., assistant professor in Pitt's endocrinology division, transplanted those engineered cells into diabetic mice, blood sugar levels normalized. She will give a symposium at the ADA meeting describing that work.

The Pitt researchers also plan to examine the effects of gain or loss of other cell cycle proteins in an ongoing effort to better understand the regulatory pathway of beta cell replication and to identify targets that might make it possible one day to treat diabetes by giving patients more insulin-producing cells, perhaps by expanding cadaveric donor cells in the lab.

"It's now clear that both type 1 and type 2 diabetes are beta cell deficiency diseases," Dr. Stewart said. "And while we work on making more , our colleagues are trying to tackle the autoimmunity problems that cause a reduction in their number. Ultimately, both issues have to be addressed to develop a cure for ."

Source: University of Pittsburgh Schools of the Health Sciences (news : web)

Explore further: Mutations from Mars: Researchers explain why genetic fertility problems can persist in a population

add to favorites email to friend print save as pdf

Related Stories

Human beta cells can be easily induced to replicate

Jan 13, 2009

Researchers at the University of Pittsburgh School of Medicine have successfully induced human insulin-producing cells, known as beta cells, to replicate robustly in a living animal, as well as in the lab. The discovery not ...

Compounds that trigger beta cell replication identified

Feb 25, 2009

Researchers at the Genomics Institute of the Novartis Research Foundation (GNF) have identified a set of compounds that can trigger the proliferation of insulin-producing cells in the pancreas, using sophisticated high-throughput ...

Stem cell research uncovers mechanism for type 2 diabetes

Feb 12, 2009

Taking clues from their stem cell research, investigators at the University of California San Diego (UC San Diego) and Burnham Institute for Medical Research (Burnham) have discovered that a signaling pathway involved in ...

Elusive pancreatic stem cells found in adult mice

Jan 24, 2008

Just as many scientists had given up the search, researchers have discovered that the pancreas does indeed harbor stem cells with the capacity to generate new insulin-producing beta cells. If the finding made in adult mice ...

Recommended for you

Gene research targets scarring process

7 hours ago

Scientists have identified three genes that may be the key to preventing scar formation after burn injury, and even healing existing scars.

Researchers find new mechanism for neurodegeneration

Jul 24, 2014

A research team led by Jackson Laboratory Professor and Howard Hughes Investigator Susan Ackerman, Ph.D., have pinpointed a surprising mechanism behind neurodegeneration in mice, one that involves a defect in a key component ...

User comments : 0