Muscle protection during hibernation of Daurian ground squirrels (Spermophilus dauricus): role of atrogin-1, MuRF1, and fiber-type transition

Dang, Kai; Feng, Ban; Gao, Yunfang; Hu, Naifei; Jiang, Shuai; Fu, Weiwei; Hinghofer‐Szalkay, Helmut

doi:10.1139/cjz-2015-0242

Cited by 6 publications

(1 citation statement)

References 52 publications

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“…In our previous studies, it has been reported that the phosphorylation levels of AKT and mTOR, two proteins related to protein synthesis, decreased significantly during hibernation in SOL, suggesting inhibition of protein synthesis during hibernation. The mRNA expression of atrogin‐1 and MuRF1, two proteins related to protein degradation, remained unchanged during hibernation in both skeletal muscles, indicating unaltered protein degradation during hibernation (Dang, Feny, et al, ; Dang, Li, et al, ). Therefore, the inhibition of protein synthesis during hibernation may be the main reason of vacuolation in skeletal muscle.…”

Section: Discussionmentioning

confidence: 99%

Novel findings on ultrastructural protection of skeletal muscle fibers during hibernation of Daurian ground squirrels: Mitochondria, nuclei, cytoskeleton, glycogen

Wang

Jiang

Cao

et al. 2019

Journal Cellular Physiology

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We examined ultrastructure protective phenomena and mechanisms of slow and fast muscles in hibernating Daurian ground squirrels (Spermophilus dauricus). Some degenerative changes such as slightly decreased sarcomere length and vacuolization occurred in hibernation, but periaxonal capsular borders in intrafusal fibers remained distinct and the arrangement of extrafusal fibers and Z‐lines unscathed. In soleus samples, the number of glycogenosomes more than tripled during hibernation. The expression of phosphorylated glycogen synthase remained unaltered while that of glycogen phosphorylase decreased during hibernation. The number of extensor digitorum longus glycogenosomes decreased and the expression of phosphorylated glycogen synthase decreased, while glycogen phosphorylase expression remained unaltered. The nuclei number remained unchanged. Kinesin and desmin, preventors of nuclear loss and damage, were maintained or just slightly reduced in hibernation. The single‐fiber mitochondrial concentration and sub‐sarcolemmal mitochondrial number increased in both muscle types. The expression of vimentin, which anchors mitochondria and maintains Z‐line integrity, was increased during and after hibernation. Also, dynamin‐related protein 1, mitochondrial fission factor, and adenosine triphosphate synthase were elevated in both muscle types. These findings confirm a remarkable ultrastructure preservation and show an unexpected increase in mitochondrial capacity in hibernating squirrels.

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Section: Discussionmentioning

confidence: 99%

Novel findings on ultrastructural protection of skeletal muscle fibers during hibernation of Daurian ground squirrels: Mitochondria, nuclei, cytoskeleton, glycogen

Wang

Jiang

Cao

et al. 2019

Journal Cellular Physiology

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A dramatic blood plasticity in hibernating and 14-day hindlimb unloading Daurian ground squirrels (Spermophilus dauricus)

et al. 2017

J Comp Physiol B

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We compared the effects of hibernation inactivity and 14-day hindlimb unloading in non-hibernating period on biochemical, rheological, and hematological parameters of blood in Daurian ground squirrels (Spermophilus dauricus). Twenty-four squirrels were randomly divided into four groups: control (CON), hibernation (HIB), post-hibernation (POST), and 14-day hindlimb unloading (HU). The results showed that serum enzymes (L-lactate dehydrogenase, alanine aminotransferase, and aspartate aminotransferase) activities decreased in HIB, POST, and HU squirrels compared with CON. Total protein (including albumin and globulin) maintained in HIB but decreased in HU compared with CON. Total cholesterol and high-density lipoprotein-cholesterol increased in HIB but maintained in HU and POST compared with CON. Meanwhile, serum creatinine decreased and urea increased in HU compared with CON. All blood ions concentrations were unchanged in HIB, POST, and HU squirrels compared with CON except calcium which increased in HIB compared with CON, and phosphorus which increased in HIB and POST compared with CON. Most of detected serum biochemical analytes in POST recovered to the CON level. Blood viscosity, which was unchanged in all shear rates in HU, increased in HIB and recovered in POST in lower shear rates compared with CON. Erythrocyte and corpuscular volume decreased in HIB and HU but maintained in POST compared with CON. All the routine hematological parameters recovered in POST as compared with CON except platelet, which decreased in HIB and POST but maintained in HU compared with CON. In conclusion, our results suggested a remarkable ability to maintain blood homeostasis in hibernating squirrels.

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Muscle-specific activation of calpain system in hindlimb unloading rats and hibernating Daurian ground squirrels: a comparison between artificial and natural disuse

Chang

Lei

et al. 2018

J Comp Physiol B

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To determine whether the regulation of calpain system is involved in non-hibernators and hibernators in disused condition, the soleus (SOL) and extensor digitorum longus (EDL) muscles were used for investigating the muscle mass, the ratio of muscle wet weight/body weight (MWW/BW), fiber-type distribution, fiber cross-sectional area (CSA), and the protein expression of MuRF1, calpain-1, calpain-2, calpastatin, desmin, troponin T, and troponin C in hindlimb unloading rats and hibernating Daurian ground squirrels. The muscle mass, MWW/BW, and fiber CSA were found significantly decreased in SOL and EDL of hindlimb unloading rats, but unchanged in hibernating ground squirrels. The MuRF1 expression was increased in both SOL and EDL of unloading rats, while it was only increased in SOL, but maintained in EDL of hibernating ground squirrels. The expression levels of calpain-1 and calpain-2 were increased in different degrees in unloaded SOL and EDL in rats, while they were maintained in EDL and even reduced in SOL of hibernating ground squirrels. Besides, the expression of calpastatin was decreased in unloaded rats, but increased in hibernating ground squirrels. The desmin expression was decreased in unloaded rats, but maintained in hibernating squirrels. Interestingly, the levels of troponin T and troponin C were decreased in both SOL and EDL of unloaded rats, but increased in hibernating ground squirrels with muscle-type specificity. In conclusion, differential calpain activation and substrate-selective degradation in slow and fast muscles are involved in the mechanisms of muscle atrophy of unloaded rats and remarkable ability of muscle maintenance of hibernating ground squirrels.

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Muscle protection during hibernation of Daurian ground squirrels (Spermophilus dauricus): role of atrogin-1, MuRF1, and fiber-type transition

Cited by 6 publications

References 52 publications

Novel findings on ultrastructural protection of skeletal muscle fibers during hibernation of Daurian ground squirrels: Mitochondria, nuclei, cytoskeleton, glycogen

Novel findings on ultrastructural protection of skeletal muscle fibers during hibernation of Daurian ground squirrels: Mitochondria, nuclei, cytoskeleton, glycogen

A dramatic blood plasticity in hibernating and 14-day hindlimb unloading Daurian ground squirrels (Spermophilus dauricus)

Muscle-specific activation of calpain system in hindlimb unloading rats and hibernating Daurian ground squirrels: a comparison between artificial and natural disuse

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