Effects of Fasting and Refeeding on Expression of Atrogin-1 and Akt/FOXO Signaling Pathway in Skeletal Muscle of Chicks

Nakashima, Kazuki; Yakabe, Yoko; Yamazaki, Makoto; Abé, Hiroyuki

doi:10.1271/bbb.60274

Cited by 39 publications

(41 citation statements)

References 24 publications

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“…Suppression of mRNA expression of the ubiquitin-proteasome-proteolytic related genes, in general, prevents catabolic response produced by catabolic insult (16,17,36). In contradiction to these finding, our data and other studies suggest that atrophic response in skeletal muscle can occur independently of ubiquitin-proteasome-proteolytic related gene expression (37-39).…”

Section: Discussioncontrasting

confidence: 99%

“…The ubiquitin-proteosome system first requires the targeting of specific protein substrates for degradation, which is fulfilled by the activity of a hierarchical cascade containing E1 (ubiquitin-activating), E2 (ubiquitin-conjugating) and E3 (ubiquitin-ligating) enzymes ( 15 ). The gene expression of the two muscle-specific E3 ligases: muscle RING finger (MuRF)1 and muscle atrophy F-box (MAFbx; also known as atrogin-1) is extremely well studied from its relevance to muscular protein degradation following nutrient ingestion (16)(17)(18), but the precise mechanisms and physiological roles have remained to be determined. Furthermore, the contributions of the proteolytic pathway for situations in which AA mixture alone is provided have yet to be addressed.…”

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confidence: 99%

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Enhancement of Myofibrillar Proteolysis Following Infusion of Amino Acid Mixture Correlates Positively with Elevation of Core Body Temperature in Rats

Yamaoka

Mikura

Nishimura

et al. 2008

J Nutr Sci Vitaminol

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Summary Administration of an amino acid (AA) mixture stimulates muscle protein synthesis and elevates core body temperature (T b ), as characteristically found under anesthetic conditions. We tested the hypothesis that not only AA given, but also AA produced by degradation of endogenous muscular protein are provided for muscle protein synthesis, which is further reflected in T b modifications. Rats were intravenously administered an AA mixture or saline in combination with the anesthetic propofol or lipid emulsion. We measured plasma 3-methylhistidine (MeHis) concentrations as an index of myofibrillar protein degradation, rectal temperature and mRNA expression of atrogin-1, MuRF-1 and ubiquitin in gastrocnemius and soleus muscles of rats following 3 h infusion of test solutions. T b did not differ significantly between conscious groups, but was higher in the AA group than in the saline group among anesthetized rats. Plasma MeHis concentrations were higher in the AA group than in the saline group under both conditions. Plasma MeHis levels correlated positively with T b of rats under both conditions. AA administration decreased mRNA levels of atrogin-1 and ubiquitin in gastrocnemius muscle and all mRNA levels in soleus muscle. These results suggest that AA administration enhances myofibrillar protein degradation and that the change is a determinant of T b modification by AA administration. However, the mechanisms underlying AA administration-associated enhancement of myofibrillar proteolysis remains yet to be determined.

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Section: Discussioncontrasting

confidence: 99%

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confidence: 99%

Enhancement of Myofibrillar Proteolysis Following Infusion of Amino Acid Mixture Correlates Positively with Elevation of Core Body Temperature in Rats

Yamaoka

Mikura

Nishimura

et al. 2008

J Nutr Sci Vitaminol

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“…MAFbx and MuRF1 were first demonstrated in muscle atrophy, and were found to be overexpressed in most states involving muscle loss, including paralysis, starvation, diabetes, sepsis, renal failure, and glucocorticoid excess [1]. Previous studies suggested that many genes related to the ubiquitinproteasome system were upregulated by starvation, including 14-kD E2, calpain large subunits, and 20S proteasome subunits [4,9]. The current study demonstrated that, in accord with other components of the ubiquitin-proteasome system, the E3 ligases MAFbx and MuRF1 were significantly induced in chick skeletal muscle at both the RNA and protein levels following starvation for 12 and 24 h. Refeeding normalized the expression of these two genes.…”

Section: Discussionmentioning

confidence: 99%

“…Skeletal muscle protein shows high plasticity and can be mobilized into free amino acids for hepatic gluconeogenesis and energy production during starvation and pathological conditions [5]. Fasting increases the rate of protein degradation in skeletal muscle, while feeding conversely has a suppressive effect on proteolysis [9]. Evidence suggests that the transcription of MAFbx is upregulated by fasting and that refeeding can rescue its overexpression [9].…”

mentioning

confidence: 99%

“…Fasting increases the rate of protein degradation in skeletal muscle, while feeding conversely has a suppressive effect on proteolysis [9]. Evidence suggests that the transcription of MAFbx is upregulated by fasting and that refeeding can rescue its overexpression [9]. However, the effects of fasting on the expression of MuRF1 and the level of MAFbx protein remain to be elucidated.…”

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Effects of fasting and refeeding on expression of MAFbx and MuRF1 in chick skeletal muscle

et al. 2011

Sci. China Life Sci.

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The present study investigated the effects of fasting and refeeding on the expression of proteasome-related genes and their downstream targets in the skeletal muscles of chicks. Seven-day-old chicks were fasted for 24 or 48 h and then refed for 4 h. The expression levels of MAFbx and MuRF1, which function as E3 ligases in the ubiquitin-proteasome system, were investigated at the mRNA and protein levels. MAFbx and MuRF1 expression were increased by fasting and these increases were downregulated by refeeding. The expression of the target proteins of these E3 ligases, MyoD and M-CK, was also analyzed. The levels of these proteins were downregulated by fasting, and these decreases were rescued by refeeding. The results of this study indicate that fasting stimulates MAFbx and MuRF1 expression in chicks, possibly leading to increased degradation of their corresponding target proteins.

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Ubiquitination, phosphorylation, and acetylation—triple threat in muscle wasting

Hasselgren

2007

Journal Cellular Physiology

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Loss of muscle mass is commonly seen in patients with critical illness and is associated with increased expression of multiple genes controlling protein breakdown. Transcription factors that are activated during muscle wasting include NF-kB and members of the FOXO and C/EBP transcription factor families. The activity of these transcription factors is regulated by multiple posttranslational modifications, including ubiquitination, phosphorylation, and acetylation, providing for a complex and integrated network of regulatory mechanisms in muscle wasting. Targeting posttranslational modifications of transcription factors may prove important in the prevention and treatment of the debilitating consequences of muscle wasting.

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Effects of Fasting and Refeeding on Expression of Atrogin-1 and Akt/FOXO Signaling Pathway in Skeletal Muscle of Chicks

Cited by 39 publications

References 24 publications

Enhancement of Myofibrillar Proteolysis Following Infusion of Amino Acid Mixture Correlates Positively with Elevation of Core Body Temperature in Rats

Enhancement of Myofibrillar Proteolysis Following Infusion of Amino Acid Mixture Correlates Positively with Elevation of Core Body Temperature in Rats

Effects of fasting and refeeding on expression of MAFbx and MuRF1 in chick skeletal muscle

Ubiquitination, phosphorylation, and acetylation—triple threat in muscle wasting

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