by Rajashri on  July 8, 2009 at 8:13 PM Genetics & Stem Cells News
 Genetic Switch That may Help Treat Vascular Diseases Identified
A key switch that makes stem cells turn into the type of muscle cells that reside in the wall of blood vessels has been identified by a team led by an Indian-origin scientist at the Gladstone Institute of Cardiovascular Disease (GICD).

Dr. Deepak Srivastava's study claimed that the same switch could be used in the future to limit growth of vascular muscle cells that cause narrowing of arteries leading to heart attacks and strokes, limit formation of blood vessels that feed cancers, or make new blood vessels for organs that are not getting enough blood flow.

It was found that a tiny RNA molecule, called microRNA-145 (miR-145), not only had all the information necessary to turn a stem cell into a vascular smooth muscle cell (VSMC), but could also affect VSMCs in the adult artery.

VSMCs possess the unique property of dividing on their own when an artery is injured or during atherosclerosis, ultimately causing narrowing of the vessel leading to occlusion.

The researchers found that miR-145 and its sister microRNA, miR-143, work together to stop the pathologic division of VSMCs.

But in the setting of vessel disease, their activity was turned down, which made the VSMCs to divide and clog up the artery.

MicroRNAs are small RNA molecules that do not make protein, but instead affect that amount of protein synthesized by the cell from their target mRNAs-the blueprints for translating the genetic code into proteins.

The researchers found that miR-145 and miR-143 together controlled the synthesis of a network of "master regulators" that control VSMCs, and thereby were able to function as a central "switch" for the behaviour of these important cells.

"The ability of miR-145 to efficiently direct the cell fate of vascular smooth muscle cells from stem cells represents the power of these tiny microRNAs to exert major effects on cells. We hope that we can use this knowledge to control when the body makes or does not make new blood vessels," Nature magazine quoted Srivastava as saying.

He added: "Our findings in this study offer insights into regulatory mechanisms that govern the differentiation and proliferation of smooth muscle. They have fundamental implications for the treatment of vessel diseases like atherosclerosis and also may be important for cancer."

The study has been published in the current issue of the journal Nature.

Source: ANI

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