University researchers study diabetes in flies

When it comes to diabetes, university scientists have found fruit flies and humans aren’t that different.

By removing several genes from the genome of a fruit fly, a team of researchers created insects demonstrating human symptoms of diabetes. This research could pave the way to discovering the genetic causes of diabetes and developing treatments, according to research published online Nov. 2 in the Proceedings of the National Academy of Sciences.

During three years of experiments and study, lead researcher and entomology professor Leslie Pick worked with a five-person team — four of whom work or worked at this university — to delete five of the seven genes in fruit flies that encode a protein similar to mammalian insulin, causing the flies’ cells to stop producing those proteins.

The team’s results showed the fruit flies, known by the scientific name Drosophila melanogaster, exhibited hallmark symptoms of human diabetes: higher blood-sugar levels, less body fat and a breakdown of fat tissue.

“We didn’t really know what we’d see,” Pick said. “But if we did find things that were very similar, we could say these flies were diabetic.”

When a person eats a meal, glucose — a sugar — is released into the bloodstream during digestion and causes certain cells to release the hormone insulin, which triggers other cells to absorb and store the glucose as an energy source.

In a person with genetically derived Type 1 diabetes, also known as insulin-dependent or juvenile diabetes, the cells that release insulin are gradually destroyed so the body’s tissues expel, rather than absorb, glucose. Blood sugar levels rise when the body is not using glucose as an energy source, forcing it to eat away at its own fat stores.

“Even though the [diabetic] person is eating, the body can’t really tell, so their body is behaving as if they were starving,” Pick said.

The fruit flies whose insulin-producing genes were deleted developed a form of diabetes similar to Type 1.

Environmental science professor Bahram Momen’s calorimetry analysis — measurement of the flies’ metabolic activity — showed less growth in the flies whose insulin genes were deleted.

“These results are proof of principle — we can get diabetic flies,” Pick said. “Then we can start to think about using the flies to look at new genes and interactions that could modulate diabetes.”

Type 1 diabetes is fatal unless sufferers regularly inject themselves with insulin to regulate their own glucose levels. If people with the illness maintain a strict schedule of injections, they can live normal lives. However, no cure to the disease exists.

Diabetes also exists in a second form, in which insulin exists but the body does not react to it. Type 2 diabetes is often preventable through diet and exercise, but researchers are looking at the environmental and genetic factors that make some more susceptible to it than others.

According to a 2007 Centers for Disease Control study, an estimated 23.6 million Americans have some form of diabetes. With these results, Pick said she hopes to continue researching how genes trigger diabetes in flies and to invite collaborators to find the gene pathways in mammals that cause diabetes. Eventual findings could apply to humans and potentially result in the development of pharmacological or genetic intervention to prevent the disease.

“If you understand the process, you can solve the problem,” Momen said. “These little findings here and there can be pieced together to solve a puzzle. These small pieces are instrumental to finding the whole picture.”

kraftery at umdbk dot com