Acute exercise alters Gαi2 protein expressions through the ubiquitin–proteasome proteolysis pathway in rat adipocytes

• Published in: Biochemical and biophysical research communications 2004-10, Vol.323 (3), p.1109-1115
• Main Authors: Ogasawara, Junetsu, Sakurai, Takuya, Rahman, Nazibur, Kizaki, Takako, Hitomi, Yoshiaki, Ohno, Hideki, Izawa, Tetsuya
• Format: Article
• Language: English
• Subjects: Adipocytes; Exercise; Heterotrimeric G protein; Lactacystin; Proteasome; Rat; Ubiquitin
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2004.08.202

The effects of acute exercise on the protein expressions of heterotrimeric G protein α subunits were examined in rat adipocytes. Gαi2 protein expression was significantly reduced 0 and 3h after exercise but increased 24h after exercise, without alterations in Gαi2 mRNA expressions. The protein expressions of other α subunits, Gαs, Gαi1, and Gαi3, were not influenced. Both the 26S proteasome activity and polyubiquitination of Gαi2 protein were significantly increased 0 and 3h after exercise. Whereas, proteasome activity was decreased, and the polyubiquitination of Gαi2 protein was returned to the control level 24h after exercise. The reductions in Gαi2 protein expressions 0 and 3h after exercise were completely prevented by the injection either of a proteasome inhibitor or of a β-adrenergic receptor blocker prior to exercise. Thus, acute exercise altered the expression of Gαi2 protein via mechanisms which involve the coupling of β-adrenergic receptors to an agonist with subsequent ubiquitin–proteasome-dependent proteolysis.