Exercise type and muscle fiber specific induction of caveolin-1 expression for insulin sensitivity of skeletal muscle

Yoon Sin Oh,Hyo Jeong Kim,Hyon Park,Sung Jin Ryu,Mijung Kim,Sang Chul Park,Chang Keun Kim,Young Sik Park,Kyung A Cho

doi:10.1038/emm.2007.44

Yoon Sin Oh, Hyo Jeong Kim + Show 7 more

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https://doi.org/10.1038/emm.2007.44

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Abstract

It is well known that exercise can have beneficial effects on insulin resistance by activation of glucose transporter. Following up our previous report that caveolin-1 plays an important role in glucose uptake in L6 skeletal muscle cells, we examined whether exercise alters the expression of caveolin-1, and whether exercise-caused changes are muscle fiber and exercise type specific. Fifty week-old Sprague Dawley (SD) rats were trained to climb a ladder and treadmill for 8 weeks and their soleus muscles (SOL) and extensor digitorum longus muscles (EDL) were removed after the last bout of exercise and compared with those from non-exercised animals. We found that the expression of insulin related proteins and caveolins did not change in SOL muscles after exercise. However, in EDL muscles, the expression of insulin receptor beta (IR beta) and glucose transporter-4 (GLUT-4) as well as phosphorylation of AKT and AMPK increased with resistance exercise but not with aerobic exercise. Also, caveolin-1 and caveolin-3 increased along with insulin related proteins only in EDL muscles by resistance exercise. These results suggest that upregulation of caveolin-1 in the skeletal muscle is fiber specific and exercise type specific, implicating the requirement of the specific mode of exercise to improve insulin sensitivity.

Highlights

Exercise increases glucose uptake, and improves glucose homeostasis as well as insulin sensitivity in the skeletal muscle
The enhanced glucose uptake with exercise in skeletal muscle might be related to increased expression and activity of key proteins for insulin signaling such as insulin receptor (IR ), insulin receptor substrate (IRS)-1/2 and phosphatidylinositol 3-kinase (PI3-K) as well
We examined the effect of aerobic and resistance exercise on the expression of caveolins in the skeletal muscles in vivo, employing soleus and extensor digitorum longus muscles (EDL) muscle lysates obtained from the animals exercised as described above

Summary

Introduction

Improves glucose homeostasis as well as insulin sensitivity in the skeletal muscle. The enhanced glucose uptake with exercise in skeletal muscle might be related to increased expression and activity of key proteins for insulin signaling such as insulin receptor (IR ), insulin receptor substrate (IRS)-1/2 and phosphatidylinositol 3-kinase (PI3-K) as well. A wide variety of signaling proteins, recruited following activation of various receptors such as protein kinase C, G proteins, or receptor tyrosine kinase, are found to increase in caveolae (Schlegel et al, 1998). Caveolin-1 has a scaffolding domain within its NH2-terminal region Through this domain, caveolin-1 interacts with G-protein -subunits, HRas, Src-family tyrosine kinases, PKC isoforms, EGF-R, Neu, and eNOS and regulates their activities (Razani and Lisanti, 2001; Abulrob et al, 2004; Cao et al, 2004)

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