<scp>AS160</scp> expression, but not <scp>AS160</scp> Serine‐588, Threonine‐642, and Serine‐704 phosphorylation, is essential for elevated insulin‐stimulated glucose uptake by skeletal muscle from female rats after acute exercise

Wang, Haiyan; Zheng, Amy; Arias, Edward B.; Kwak, Seong Eun; Pan, Xiufang; Duan, Dongsheng; Cartee, Gregory D.

doi:10.1096/fj.202300282rr

Cited by 3 publications

(1 citation statement)

References 54 publications

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“…Consistent with earlier research using the same exercise protocol [ 41 – 43 ], phosphorylation of AMPK and phosphorylation of its substrates ACC and TBC1D1 were markedly elevated IPEX. There was no evidence of a genetic difference between paired muscles for any of the markers of AMPK stimulation.…”

Section: Discussionsupporting

confidence: 90%

A novel genetic model provides a unique perspective on the relationship between postexercise glycogen concentration and increases in the abundance of key metabolic proteins after acute exercise

Kwak,

Zheng,

Arias

et al. 2024

PLoS ONE

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Some acute exercise effects are influenced by postexercise (PEX) diet, and these diet-effects are attributed to differential glycogen resynthesis. However, this idea is challenging to test rigorously. Therefore, we devised a novel genetic model to modify muscle glycogen synthase 1 (GS1) expression in rat skeletal muscle with an adeno-associated virus (AAV) short hairpin RNA knockdown vector targeting GS1 (shRNA-GS1). Contralateral muscles were injected with scrambled shRNA (shRNA-Scr). Muscles from exercised (2-hour-swim) and time-matched sedentary (Sed) rats were collected immediately postexercise (IPEX), 5-hours-PEX (5hPEX), or 9-hours-PEX (9hPEX). Rats in 5hPEX and 9hPEX experiments were refed (RF) or not-refed (NRF) chow. Muscles were analyzed for glycogen, abundance of metabolic proteins (pyruvate dehydrogenase kinase 4, PDK4; peroxisome proliferator-activated receptor γ coactivator-1α, PGC1α; hexokinase II, HKII; glucose transporter 4, GLUT4), AMP-activated protein kinase phosphorylation (pAMPK), and glycogen metabolism-related enzymes (glycogen phosphorylase, PYGM; glycogen debranching enzyme, AGL; glycogen branching enzyme, GBE1). shRNA-GS1 versus paired shRNA-Scr muscles had markedly lower GS1 abundance. IPEX versus Sed rats had lower glycogen and greater pAMPK, and neither of these IPEX-values differed for shRNA-GS1 versus paired shRNA-Scr muscles. IPEX versus Sed groups did not differ for abundance of metabolic proteins, regardless of GS1 knockdown. Glycogen in RF-rats was lower for shRNA-GS1 versus paired shRNA-Scr muscles at both 5hPEX and 9hPEX. HKII protein abundance was greater for 5hPEX versus Sed groups, regardless of GS1 knockdown or diet, and despite differing glycogen levels. At 9hPEX, shRNA-GS1 versus paired shRNA-Scr muscles had greater PDK4 and PGC1α abundance within each diet group. However, the magnitude of PDK4 or PGC1α changes was similar in each diet group regardless of GS1 knockdown although glycogen differed between paired muscles only in RF-rats. In summary, we established a novel genetic approach to investigate the relationship between muscle glycogen and other exercise effects. Our results suggest that exercise-effects on abundance of several metabolic proteins did not uniformly correspond to differences in postexercise glycogen.

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Section: Discussionsupporting

confidence: 90%

A novel genetic model provides a unique perspective on the relationship between postexercise glycogen concentration and increases in the abundance of key metabolic proteins after acute exercise

Kwak,

Zheng,

Arias

et al. 2024

PLoS ONE

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Independent and combined effects of calorie restriction and AICAR on glucose uptake and insulin signaling in skeletal muscles from 24-month-old female and male rats

Wang,

Zheng,

Thorley

et al. 2024

Appl. Physiol. Nutr. Metab.

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We assessed the effects of two levels of calorie restriction (CR; eating either 15% or 35% less than ad libitum, AL, food intake for 8 weeks) by 24-month-old female and male rats on glucose uptake (GU) and phosphorylation of key signaling proteins (Akt; AMP-activated protein kinase, AMPK; Akt substrate of 160 kDa, AS160) measured in isolated skeletal muscles that underwent four incubation conditions (without either insulin or AICAR, an AMPK activator; with AICAR alone; with insulin alone; or with insulin and AICAR). Regardless of sex: 1) neither CR group versus the AL group had greater GU by insulin-stimulated muscles; 2) phosphorylation of Akt in insulin-stimulated muscles was increased in 35%-CR versus AL rats; 3) prior AICAR treatment of muscle resulted in greater GU by insulin-stimulated muscles, regardless of diet; and 4) AICAR caused elevated phosphorylation of acetyl CoA carboxylase, an indicator of AMPK activation, in all diet groups. There was a sexually dimorphic diet-effect on AS160 phosphorylation, with 35%-CR exceeding AL for insulin-stimulated muscles in male rats, but not in female rats. Our working hypothesis is that the lack of a CR-effect on GU by insulin-stimulated muscles was related to the extended duration of the ex vivo incubation period (290 minutes compared to 40-50 minutes that was previously reported to be effective). The observed efficacy of prior treatment of muscles with AICAR to improve glucose uptake in insulin stimulated muscles supports the strategy of targeting AMPK with the goal of improving insulin sensitivity in older females and males.

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Phosphorylation of AS160-serine 704 is not essential for exercise-increase in insulin-stimulated glucose uptake by skeletal muscles from female or male rats

Wang,

Kwak,

Zheng

et al. 2024

American Journal of Physiology-Endocrinology and Metabolism

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One exercise session can increase subsequent insulin-stimulated glucose uptake (ISGU) by skeletal muscle from rodents and humans of both sexes. We recently found that concurrent mutation of three key sites to prevent their phosphorylation (Ser588, Thr642, and Ser704) on Akt substrate of 160 kDa (AS160; also known as TBC1D4) reduced the magnitude of the enhancement of postexercise ISGU (PEX-ISGU) by muscle from male, but not female rats. However, we did not test the role of individual phosphorylation sites on PEX-ISGU. Accordingly, our current aim was to test if AS160 Ser704 phosphorylation (pSer704) is required for elevated PEX-ISGU by muscle. AS160-knockout (AS160-KO) rats (female and male) were studied when either sedentary or 3 hours after acute exercise. Adeno-associated virus (AAV) vectors were used to enable muscle expression of wildtype-AS160 (AAV-WT-AS160) or AS160 mutated Ser704 to alanine to prevent phosphorylation (AAV-1P-AS160). Paired epitrochlearis muscles from each rat were injected with AAV-WT-AS160 or AAV-1P-AS160. We discovered that regardless of sex: 1) AS160 abundance in AS160-KO rats was similar in paired muscles expressing WT-AS160 versus 1P-AS160; 2) muscles from exercised versus sedentary rats had greater ISGU, and PEX-ISGU was slightly greater for muscles expressing 1P-AS160 versus contralateral muscles expressing WT-AS160; 3) pAS160 Thr642 was lower in muscles expressing 1P-AS160 versus paired muscles expressing WT-AS160. These results indicate that pAS160 Ser704 was not essential for elevated PEX-ISGU by skeletal muscle from rats of either sex. Furthermore, elimination of the postexercise increase in pAS160 Thr642 did not lessen the postexercise effect on ISGU.

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AS160 expression, but not AS160 Serine‐588, Threonine‐642, and Serine‐704 phosphorylation, is essential for elevated insulin‐stimulated glucose uptake by skeletal muscle from female rats after acute exercise

Cited by 3 publications

References 54 publications

A novel genetic model provides a unique perspective on the relationship between postexercise glycogen concentration and increases in the abundance of key metabolic proteins after acute exercise

A novel genetic model provides a unique perspective on the relationship between postexercise glycogen concentration and increases in the abundance of key metabolic proteins after acute exercise

Independent and combined effects of calorie restriction and AICAR on glucose uptake and insulin signaling in skeletal muscles from 24-month-old female and male rats

Phosphorylation of AS160-serine 704 is not essential for exercise-increase in insulin-stimulated glucose uptake by skeletal muscles from female or male rats

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