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

Ogasawara, Jun; Sakurai, Takeshi; Rahman, Nazibur; Kizaki, Takako; Hitomi, Yoshiaki; Ohno, Hideki; Izawa, Tetsuya

doi:10.1016/j.bbrc.2004.08.202

Cited by 9 publications

(10 citation statements)

References 32 publications

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“…Lactacystin was administrated 1 h before exercise. We have confirmed that lactacystin blocked the exercise‐induced increase in proteasome activity (32). Under this condition, no change in either GRK‐2 or β‐arrestin‐2 protein was found at any of the designed times after exercise compared with vehicle‐injected rats who were not subjected to exercise (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, the stimulation of β2‐AR resulted in the inhibition of cAMP productions at 24 h after exercise. The former finding most likely results from the enhanced expression of the Gαi2 protein at 24 h after exercise, as shown in a previous study (32). Gαi2 protein predominantly inhibits adenylate cyclase, but β3‐AR can bind to the Gi protein (40–42).…”

Section: Discussionmentioning

confidence: 99%

“…Adipocyte subcellular fractions were prepared by a method described previously (31, 32). Briefly, adipocytes were homogenized in an ice‐cold homogenation buffer (50 mM Tris‐HCl, pH 7.4, 1 mM EDTA, 0.25 M sucrose, 20 μM leupeptin, 20 mM NaF, and 100 μM benzamidine) by 10 passages through a 5/8‐inch, 24 gauge needle attached to a syringe at 4°C.…”

Section: Methodsmentioning

confidence: 99%

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β‐Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G‐protein‐coupled receptor kinase‐2, β‐arrestin‐2, and the ubiquitin‐proteasome pathway

et al. 2005

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The effect of exercise on beta-adrenergic receptor (beta-AR) trafficking was investigated in rat adipocytes. The binding sites of a hydrophilic ligand, [(3)H]CGP12177, increased immediately (0 h) and at 3 h after exercise (3 h) but decreased at 24 h after exercise (24 h). The data of immunoblotting revealed that the alterations in the binding sites mainly paralleled the alterations in the beta2-AR proteins in membrane fractions. The protein expressions of both G-protein-coupled receptor kinase (GRK)-2 and beta-arrestin-2 were reduced, with a decline in beta2-AR ubiquitination at 0 h and 3 h. The protein expressions of beta2-AR, GRK-2, beta-arrestin-2, the beta2-AR/beta-arrestin-2 complex, and beta2-AR ubiquitination returned to their respective control levels at 24 h, whereas the beta2-AR mRNA level was reduced. Administration of either lactacystin or propranolol did not alter GRK-2 and beta2-AR protein expressions after exercise. Thus, the mechanism underlying the increased density of beta2-AR up to at least 3 h may involve alterations in a multistep event involving the coordinate interaction among proteins mediating beta2-AR trafficking, in which both the receptor-agonist interactions and ubiquitin-proteasome pathway have a key role. However, the decreased protein expression of beta2-AR at 24 h might be due to some change occurring at the translational levels.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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β‐Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G‐protein‐coupled receptor kinase‐2, β‐arrestin‐2, and the ubiquitin‐proteasome pathway

et al. 2005

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“…RNA extraction and RT-PCR analysis of mRNAs for ATGL and PPARg-2 and b-actin were performed using an RT-PCR system, as previously described [47], [48]. Twenty-five cycles of amplification were carried out for ATGL and PPARg-2 mRNAs, and 20 cycles were used for b-actin mRNA.…”

Section: Methodsmentioning

confidence: 99%

Higher Levels of ATGL Are Associated with Exercise-Induced Enhancement of Lipolysis in Rat Epididymal Adipocytes

et al. 2012

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BackgroundIn adipose cells, adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte triacylglyceride hydrolysis, thereby regulating both basal and hormone-stimulated lipolysis. However, little is known about the molecular mechanism(s) underlying habitual exercise-induced adaptive modulation of ATGL in white adipocytes via alteration in transcription regulator and lipolytic cofactors.Methodology/Principal ResultsMale Wistar rats were randomly divided into 2 groups a sedentary control group (CG) and a habitual exercise group (EG). The EG was subjected to running on a treadmill set at 5 days per week for 9 weeks. The CG was not subjected to running on a treadmill. In the EG, levels of ATGL mRNA and protein were elevated with a significant increase in lipolysis compared with the CG, accompanied by a significant increase in associations of CGI-58 with ATGL protein. Under these conditions, an upregulation of peroxisome proliferation-activated receptorg-2 (PPARg-2) was observed. In the EG, the addition of rosiglitazone further significantly increased the levels of ATGL protein compared with the CG. However, attenuated levels of the ATGL protein in adipocytes were obtained by the addition of insulin, which is known to inhibit the expression of ATGL, in both types of groups. Actually, levels of plasma insulin were significantly reduced in the EG compared with the CG.ConclusionsThese data suggest that elevated levels of ATGL are involved in the exercise-induced enhancement of lipolysis in primary adipocytes. The exact mechanism(s) underlying this phenomenon is associated, at least in part, with upregulated transcriptional activation of PPARg-2. In addition, exercise-induced lower circulation levels of insulin also correlate with habitual exercise-induced higher levels of ATGL in primary adipocytes.

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“…Well-documented examples include G␣ o , 27 G␣ i3 , 28 G␣ i2 , 93 G␣ s , 26 G␥ 2 , 25 and transducin G␤␥. 24 Among those, direct ubiquitination has been observed for G␣ s , G␥ 2 , and transducin G␥, whereas the others were mainly inferred from studies showing diminished destruction by specific inhibitors of the proteasome.…”

Section: Ubiquitination and Destruction Of Heterotrimeric G-protein Smentioning

confidence: 99%

Regulation of G Protein and Mitogen-Activated Protein Kinase Signaling by Ubiquitination

Wang

Dohlman

2006

Circulation Research

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Abstract-Guanine nucleotide binding proteins (G proteins) and mitogen-activated protein kinases are highly conserved signaling molecules engaged in a wide variety of cellular processes. The strength and duration of signaling mediated by G proteins and mitogen-activated protein kinases are well known to be regulated via phosphorylation of pathway components. Over the past few years, it has become evident that many of the same signaling proteins also undergo ubiquitination, a posttranslational modification that typically leads to protein degradation. Consequently the strength and duration of signaling can also be modulated by regulating the abundance of signaling proteins. This article describes G protein-and mitogen-activated protein kinase-mediated signaling pathways that are known to be regulated by ubiquitination. The focus is on studies performed in the budding yeast Saccharomyces cerevisiae, as many principles governing this new regulatory mechanism were initially discovered in this model organism. Similar mechanisms uncovered in other model systems are also briefly discussed to illustrate the importance and universality of signaling regulation by ubiquitination.

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

Cited by 9 publications

References 32 publications

β‐Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G‐protein‐coupled receptor kinase‐2, β‐arrestin‐2, and the ubiquitin‐proteasome pathway

β‐Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G‐protein‐coupled receptor kinase‐2, β‐arrestin‐2, and the ubiquitin‐proteasome pathway

Higher Levels of ATGL Are Associated with Exercise-Induced Enhancement of Lipolysis in Rat Epididymal Adipocytes

Regulation of G Protein and Mitogen-Activated Protein Kinase Signaling by Ubiquitination

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