Researchers at Wake Forest Baptist Medical Center's Institute for
Regenerative Medicine and colleagues have discovered a new protein that
may play a critical role in how the human body regulates blood sugar
levels. Reporting in the current issue of Pancreas, the research team says the protein may represent a new target for treating type 1 diabetes.
"This data may change the current thinking about what causes type 1
diabetes," said Bryon E. Petersen, Ph.D., professor of regenerative
medicine and senior author. "Much more research is needed to understand
exactly how the protein functions, but its discovery opens a new door to
better understand and hopefully develop new treatments for this
currently incurable disease."
The protein, which the scientists have named Islet Homeostasis
Protein (IHoP), has so far been isolated in the pancreas of both humans
and rodents. It is located in the pancreatic islets, clusters of cells
that secrete the hormones insulin and glucagon that work together to
regulate blood sugar. In healthy individuals, glucagon raises blood
sugar levels and insulin helps lower gluocose levels by moving sugar
from the blood into the body's cells. In people with type 1 diabetes,
which affects about 5 percent of people with diabetes, the pancreas does
not produce enough insulin and blood sugar levels are too high.
The researchers determined that IHoP is found within the
glucagon-producing cells of the islets. In both humans and mice that
haven't yet developed diabetes, the researchers found high levels of
IHoP. But after the onset of diabetes, there was no expression of IHoP,
suggesting that the protein may work to regulate blood sugar levels by
regulating the balance between insulin and glucagon.
When the researchers inhibited production of the protein in
rodents, there was loss of glucagon expression, which caused a chain of
events that led to decreased insulin, increased levels of glucagon and
death of insulin-producing cells.
"In a nutshell," said lead author Seh-Hoon Oh, Ph.D., "IHoP appears
to keep blood sugar regulation in check. When IHoP isn't present, it
throws the pancreas into a critical state and starts the process that
results in type 1 diabetes." Oh is an instructor of regenerative
medicine at Wake Forest Baptist.
It is currently believed that type 1 diabetes is caused by a viral
or environmental trigger in genetically susceptible people that results
in the body's white cells mistakenly attacking the insulin producing
cells. Within 10 to 15 years of diagnosis, the insulin-producing cells
are completely destroyed.
The current research supports the idea that cell death plays a role
in type 1 diabetes, but the results suggest that IHoP may influence the
process. Next steps in the research will be to explore how IHoP controls
the interaction of insulin and glucagon.
