Fasting-related autophagic response in slow- and fast-twitch skeletal muscle.
This study investigated regulation of autophagy in slow-twitch soleus and fast-twitch plantaris muscles in fasting-related atrophy. Male Fischer-344 rats were subjected to fasting for 1, 2, or 3 days. Greater weight loss was observed in plantaris muscle than in soleus muscle in response to fasting. Western blot analysis demonstrated that LC3-II, a marker protein for macroautophagy, was expressed at a notably higher level in plantaris than in soleus muscle, and that the expression level was fasting duration-dependent. To identify factors related to LC3-II enhancement, autophagy-related signals were examined in both types of muscle. Phosphorylated mTOR was reduced in plantaris but not in soleus muscle. FOXO3a and ER stress signals were unchanged in both muscle types during fasting. These findings suggest that preferential atrophy of fast-twitch muscle is associated with induction of autophagy during fasting and that differences in autophagy regulation are attributable to differential signal regulation in soleus and plantaris muscle.
Ogata
Tomonori
T
Comprehensive Research Institutes, Waseda University, Saitama, Japan. ogata096@gmail.com
Oishi
Yasuharu
Y
Higuchi
Mitsuru
M
Muraoka
Isao
I
D000818:Animals; D001343:Autophagy; D015536:Down-Regulation; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005215:Fasting; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism / Q000502:physiology*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D058570:TOR Serine-Threonine Kinases
D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C499515:FOXO3 protein, rat; C526109:Anxa3 protein, rat; C546845:mTOR protein, rat