New molecular signaling cascade increases glucose uptake

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New molecular signaling cascade increases glucose uptake

http://news.ku.dk/all_news/2010/2010.8/lucose_uptake/

Scientists from Department of Exercise and Sport Sciences have in collaboration

with colleagues at Harvard University discovered a novel molecular pathway which

is activated in muscles during exercise.

Skeletal muscles combust both lipids and carbohydrates during exercise. The

carbohydrates consist of both glycogen stored in the muscles as well as glucose

extracted from the blood. Being a major sink for glucose disposal, skeletal

muscle represents an important model tissue for studying the intracellular

signaling pathways leading to increased glucose transport.

This is important because it is known that the contraction-induced signaling to

stimulate glucose transport is distinct from that utilized by insulin. Thus, for

individuals in which insulin only has little effect (insulin resistance) the

contraction-induced pathway represents an alternative pathway to increase

glucose uptake. For pharmaceutical companies this pathway represents a possible

and attractive alternative signaling pathway for pharmacological intervention in

regulating glucose homeostasis.

Researchers from Department of Exercise and Sport Sciences, University of

Copenhagen have in collaboration with scientists at the Joslin Diabetes Center,

Harvard University in Boston focused on a novel protein called SNARK which was

found be activated in skeletal muscle in response to contraction and exercise

in both rodents and humans. Furthermore, by the use of transgenic animal models

and by over-expressing an inactive mutant of SNARK in mouse skeletal muscle, it

could be shown that contraction-induced glucose uptake was severely blunted by

40-50% compared with control animals.

The data in this study clearly support a role for SNARK in regulating glucose

transport during muscle contraction and exercise, but it also strongly suggests

that multiple, or redundant signals may mediate the effects of contraction on

activating glucose transport.

These data have now been published in the prominent journal " Proceedings of the

Nation Academy of Sciences " (PNAS).