Protein degradation during endurance exercise and recovery

Dohm, G. Lynis; Tapscott, Edward B.; Kasperek, George J.

doi:10.1249/00005768-198710001-00011

Cited by 84 publications

(69 citation statements)

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“…A similar argument may apply to remodeling of differentiated tissue. Protein degradation in skeletal muscle is increased by heavy exercise (5,12,24,36), which also promotes an increase in MAPK activation (40,57,58). Thus, our results raise the intriguing possibility that the stimulation of proteolysis by Ras-MAPK signaling is an important feature of transformation and/or remodeling in mammalian muscle.…”

Section: Discussionmentioning

confidence: 57%

Activation of Ras and the Mitogen-Activated Protein Kinase Pathway Promotes Protein Degradation in Muscle Cells of Caenorhabditis elegans

Szewczyk

Peterson

Jacobson

2002

Molecular and Cellular Biology

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To discover and study intracellular signals that regulate proteolysis in muscle, we have employed transgenic strains of Caenorhabditis elegans that produce a soluble LacZ reporter protein limited to body-wall and vulval muscles. This reporter protein is stable in well-fed wild-type animals, but its degradation is triggered upon a shift to 25°C in a strain carrying a temperature-sensitive activating mutation in the Ras oncogene homologue let-60. These mutants are not physiologically starved, inasmuch as growth rates are normal at 25°C. Rasinduced degradation is not prevented by the presence of cycloheximide added at or before the temperature shift and thus uses preexisting proteolytic systems and signaling components. Furthermore, degradation is triggered when adult animals are shifted to conditions of 25°C, confirming that Ras acutely promotes protein degradation in muscles whose developmental history is normal. Reduction-of-function mutations in the downstream protein kinase Raf (lin-45), MEK (mek-2), or mitogen-activated protein kinase (MAPK) (mpk-1) prevent Ras-induced protein degradation, whereas activated MPK-1 is sufficient to trigger degradation, indicating that this kinase cascade is the principal route by which Ras signaling triggers protein degradation in muscle. This pathway is activated in hypodermal cells by the LET-23 epidermal growth factor receptor homologue, but an activating mutation in let-23 does not promote proteolysis in muscle. Starvation-induced LacZ reporter degradation is unaffected by reduction-of-function mutations in Ras, Raf, MEK, or MAPK, implying that Ras activation and starvation trigger proteolysis by mechanisms that are at least partially independent. This is the first evidence that Ras-Raf-MEK-MAPK signaling activates protein degradation in differentiated muscle.The regulation of proteolysis in muscle is a clinically significant problem because of its relevance to muscle wasting and atrophy in skeletal muscle and pathological hypertrophy and atrophy in cardiac muscle. Muscle proteolysis is promoted by fasting or chronic starvation (18, 29), by disuse or denervation (19,31), in sepsis (10), and in cancer cachexia (53). Catastrophic loss of muscle protein is associated with increased mortality in patients with cancer, diabetes, sepsis, heart failure, or AIDS (30, 52), and extreme muscle wasting can itself be the proximal cause of death.The molecular mechanisms of proteolysis in muscle have been extensively studied (3, 4, 15, 31-33, 44, 45, 51), although there is considerable uncertainty remaining about the specific roles of the proteolytic systems involved. Moreover, several external signals that regulate muscle proteolysis have been identified but we know little about how intramuscular signaltransduction mechanisms might couple external stimuli to the regulation of protein degradation.We have been developing a genetically tractable model for studying the regulation of proteolysis in muscle, using strains of the nematode Caenorhabditis elegans that express a transgenecoded LacZ ...

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Section: Discussionmentioning

confidence: 57%

Activation of Ras and the Mitogen-Activated Protein Kinase Pathway Promotes Protein Degradation in Muscle Cells of Caenorhabditis elegans

Szewczyk

Peterson

Jacobson

2002

Molecular and Cellular Biology

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“…Postprandial increases in plasma amino acid levels stimulate protein synthesis, while, during exercise, protein synthesis in skeletal muscle is decreased [13][14][15] and protein degradation is elevated 15) . In addition, endurance exercise increases amino acid oxidation 16) .…”

Section: Amino Acid Pool In Skeletal Musclementioning

confidence: 99%

Exercise-induced changes in amino acid levels in skeletal muscle and plasma

Ishikura¹,

Ra²,

Ohmori³

2013

JPFSM

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During exercise, amino acid oxidation and protein breakdown are enhanced while protein synthesis is suppressed, even though protein does not constitute a quantitatively important energy source. In response to exercise-induced stimulation, various changes in free amino acids occur in skeletal muscle to meet physiological demands. Plasma amino acids are also under the influence of various types of stress, including exercise stress. For example, acute exercise increases alanine and glutamine levels, but decreases glutamate levels in skeletal muscle. At the same time, it increases tryptophan and taurine levels, but decreases glutamine levels in plasma. Prolonged exercise decreases glutamine and glutamate levels, while increasing tyrosine and phenylalanine levels in skeletal muscle. Furthermore, when prolonged exercise-induced changes in amino acid levels are compared between trained and untrained individuals, glutamate and taurine levels in skeletal muscle and phenylalanine, leucine, isoleucine, and tyrosine levels in plasma are higher in trained individuals. This review provides an overview of changes in amino acid levels in skeletal muscle and plasma, with a focus on changes induced by exercise.

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“…In ultra-marathoners, however, several reports about an impairment of renal function have been published (4)(5)(6). A net breakdown of body protein during endurance exercise has been shown and the mobilized amino acids were available for increased rates of oxidation and gluconeogenesis during an endurance performance ( 9 ). The increase of parameters of skeletal muscle damage during ultrarunning might be due to a decrease in skeletal muscle mass as has been observed in ultra-marathoners ( 10 ).…”

mentioning

confidence: 98%

Branched-Chain Amino Acid Supplementation during a 100-km Ultra-Marathon^|^mdash;A Randomized Controlled Trial

Knechtle

Mrazek²,

Wirth³

et al. 2012

J Nutr Sci Vitaminol

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Summary Ultra-marathon running is supposed to increase the parameters of skeletal muscle damage and impair renal function. The purpose of this study was to investigate the effect of branched-chain amino acid supplementation on skeletal muscle damage and renal function during a 100-km ultra-marathon. Twenty-eight athletes were randomly divided into two groups, one group using branched-chain amino acid supplementation (BCAA) and a control group (CON). The athletes in the BCAA group were supplemented with a total of 50 g of an amino acid concentrate including 20 g of BCAA. The intake of energy, antioxidants and parameters of both skeletal muscle damage and renal function were determined. Race time was not different between BCAA and CON when controlled for the personal best time in a 100-km ultra-marathon. Neither the intake of energy and antioxidants nor the parameters of skeletal muscle damage and renal function were different between BCAA and CON. We concluded that BCAA-supplementation before and during a 100-km ultra-marathon had no effect on performance, skeletal muscle damage or renal function.

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Protein degradation during endurance exercise and recovery

Cited by 84 publications

References 0 publications

Activation of Ras and the Mitogen-Activated Protein Kinase Pathway Promotes Protein Degradation in Muscle Cells of Caenorhabditis elegans

Activation of Ras and the Mitogen-Activated Protein Kinase Pathway Promotes Protein Degradation in Muscle Cells of Caenorhabditis elegans

Exercise-induced changes in amino acid levels in skeletal muscle and plasma

Branched-Chain Amino Acid Supplementation during a 100-km Ultra-Marathon^|^mdash;A Randomized Controlled Trial

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