NEW HOPE FOR DIABETICS AND THE OBESE
In a recent study from the Columbia University Medical Center, researchers believe they have isolated an enzyme that appears to turn the body’s stores of harmful white fat, into energy burning brown fat. Brown fat dissipates stored energy as heat extremely effectively. Babies have a thicker layer than adults of it, ostensibly to keep their tiny bodies from getting chilly.
The researchers, led by Dr. Domenico Accili, MD, who is a professor of medicine at the university, had been studying a class of drugs called thiazolidazines, or TZD’s, which has been shown to increase insulin sensitivity in humans. These drug did increase the rate of “browning” of the white fat but had serious side effects. These included bone loss, body toxicity as well as, ironically, evidence of significant weight increases.
Accili was not deterred by the disappointing result, however.
"Turning white fat into brown fat is an appealing therapeutic approach to staunching the obesity epidemic, but it has been difficult to do so in a safe and effective way," the doctor admitted in the August 2 edition of the well-regarded website Science Daily.
Accili’s team then began to look at an enzyme that naturally interacted with the body’s metabolic processes. It is called sirtuin and it appeared to be just what the team was looking for.
"When we sought to identify how sirtuins promote browning, we observed many similarities between the effect of sirtuins and that of TZDs," stated the study’s lead author Li Qiang, PhD, who is associate research scientist in Medicine at CUMC.
He explained how sertuin cuts the chemical bonds that hold acetyl groups and proteins together; a process known as deacetylation which is vital to the conversion of white fat cells to brown.
"So the next question was whether sirtuins remove acetyl groups from ppar-gamma and, indeed, that was what we found," Dr. Qiang asserted.
"Our findings have two important implications," said Dr. Accili. "First, they suggest that TZDs may not be so bad -- if you can find a way to tweak their activity. Second, one way to tweak their activity is by using sirtuin agonists -- that is, drugs that promote sirtuin activity.The truth is, making sirtuin agonists has proved to be a real bear -- more promise than fact. But now, for the first time, we have a biomarker for good sirtuin activity: the deacetylation of ppar-gamma (a cell receptor). In other words, any substance that deacetylates ppar-gamma should in turn promote the browning of white fat and have a beneficial metabolic effect."
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