Sydney student solves piece of the diabetes puzzle

Nov 9 2008

An important piece in the diabetes puzzle which has perplexed scientists for decades has been uncovered by a Sydney PhD student at Sydney's Garvan Institute of Medical Research.

The novel finding by Freddy Yip has revealed how insulin works and brings researchers one step nearer to understanding just how insulin prompts fat and muscle cells to absorb glucose.

Professor David James, head of Garvan's Diabetes Program says ever since the 1920s, when Banting and Best discovered insulin, scientists have been struggling to discover how insulin actually works and now Freddy Yip has unveiled a completely novel action of insulin which plays a fundamental role in glucose uptake - a process that is defective in type 2 diabetes.

In type 2 diabetes two processes are involved - insufficient production of insulin in the pancreas after a meal and the faulty uptake and storage of glucose in fat and muscle cells, or 'insulin resistance'.

Professor James says Freddy's finding focuses on the intersection between these two processes.

Freddy Yip says in the cell there are a series of motor proteins that have the ability to move other molecules from one place to another along intracellular rail road tracks and he discovered that insulin activates a specific kind of motor protein known as Myo1c, which in turn performs a critical role in glucose uptake.

Insulin controls glucose uptake into the body's fat cells by moving glucose transporter proteins from inside the cell to the surface membrane so that they can pump glucose into the cell and Myo1c aids in this process by helping the transporters slide into the surface membrane.

In healthy people, around 80% of the glucose transporters migrate to the cell membrane after a meal, allowing plenty of glucose into the cell but in people with Type 2 diabetes, that figure drops to around 10%.

Freddy Yip says it was already known that Myo1c was somehow involved in the regulation of glucose transport but his research indicates that Myo1c is a major target of insulin action and helps to accelerate the delivery of transporters to the membrane.

He believes there may be blockages in the signal between insulin and myo1c in people who develop insulin resistance and if he is correct, it should be possible to target that pathway for development of new therapies.

Professor James says the finding is a welcome milestone on a very long road of discovery and while they are not saying they have found a way to cure diabetes,they have found a pretty significant clue.

Freddy Yip believes his study will create a strong foundation for future diabetes research.

His research is published online in the prestigious international journal, Cell Metabolism.