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  • American Physiological Society  (3)
  • 1
    Online Resource
    Online Resource
    Activating cAMP/PKA signaling in skeletal muscle suppresses the ubiquitin-proteasome-dependent proteolysis: implications for sympathetic regulation
    American Physiological Society ; 2014
    In:  Journal of Applied Physiology Vol. 117, No. 1 ( 2014-07-01), p. 11-19
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 117, No. 1 ( 2014-07-01), p. 11-19
    Abstract: Although we have recently demonstrated that plasma catecholamines induce antiproteolytic effects on skeletal muscle (Graça FA, Gonçalves DAP, Silveira WA, Lira EC, Chaves VE, Zanon NM, Garófalo MAR, Kettelhut IC, Navegantes LCC. Am J Physiol Endocrinol Metab. 305: E1483-E1494, 2013), the role of the muscle sympathetic innervation and, more specifically, norepinephrine (NE) in regulating the ubiquitin (Ub)-proteasome system (UPS) remains unknown. Based on previous findings that chemical sympathectomy acutely reduces UPS activity, we hypothesized that muscle NE depletion induces adrenergic supersensitivity in rat skeletal muscles. We report that surgical sympathetic denervation (SDEN), a condition in which only muscle NE from both hindlimbs is depleted, transiently reduced the overall proteolysis and the UPS activity (∼25%) in both soleus and extensor digitorum longus muscles. This antiproteolytic response was accompanied by increased activity of adenylyl cyclase (112%), levels of cyclic adenosine monophosphate (cAMP; 191%), and the serine phosphorylation of cAMP response element-binding protein (32%). In extensor digitorum longus from normal rats, NE (10 −4 M) in vitro increased the levels of cAMP (115%) and the serine phosphorylation of both cAMP response element-binding protein (2.7-fold) and forkhead box class O1 transcription factor. Similar effects were observed in C 2 C 12 cells incubated with forskolin (10 μM). In parallel, NE significantly reduced the basal UPS (21%) activity and the mRNA levels of atrophy-related Ub-ligases. Similar responses were observed in isolated muscles exposed to 6-BNZ-cAMP (500 μM), a specific PKA activator. The phosphorylation levels of Akt were not altered by SDEN, NE, forskolin or 6-BNZ-cAMP. Our results demonstrate that SDEN induces muscle adrenergic supersensitivity for cAMP leading to the suppression of UPS, and that the suppressive effects of NE on UPS activity and expression of Ub-ligases can be mediated by the activation of cAMP/PKA signaling, with the inhibition of forkhead box class O1 transcription factor.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.01055.2013
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2014
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Adrenodemedullation activates the Ca 2+ -dependent proteolysis in soleus muscles from rats exposed to cold
    American Physiological Society ; 2017
    In:  Journal of Applied Physiology Vol. 122, No. 2 ( 2017-02-01), p. 317-326
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 122, No. 2 ( 2017-02-01), p. 317-326
    Abstract: Previous studies have shown that catecholamines in vivo and in vitro inhibit the activity of Ca 2+ -dependent proteolysis in skeletal muscles under basal conditions. In the present study we sought to investigate the role of catecholamines in regulating the Ca 2+ -dependent proteolysis in soleus and extensor digitorum longus (EDL) muscles from rats acutely exposed to cold. Overall proteolysis, the activity of proteolytic systems, protein levels and gene expression of different components of the calpain system were investigated in rats submitted to adrenodemedullation (ADMX) and exposed to cold for 24 h. ADMX drastically reduced plasma epinephrine and promoted an additional increase in the overall proteolysis, which was already increased by cold exposure. The rise in the rate of protein degradation in soleus muscles from adrenodemedullated cold-exposed rats was caused by the high activity of the Ca 2+ -dependent proteolysis, which was associated with the generation of a 145-kDa cleaved α-fodrin fragment, a typical calpain substrate, and lower protein levels and mRNA expression of calpastatin, the endogenous calpain inhibitor. Unlike that observed for soleus muscles, the cold-induced muscle proteolysis in EDL was not affected by ADMX. In isolated soleus muscle, clenbuterol, a selective β 2 -adrenoceptor agonist, reduced the basal Ca 2+ -dependent proteolysis and completely abolished the activation of this pathway by the cholinergic agonist carbachol. These data suggest that catecholamines released from the adrenal medulla inhibit cold-induced protein breakdown in soleus, and this antiproteolytic effect on the Ca 2+ -dependent proteolytic system is apparently mediated through expression of calpastatin, which leads to suppression of calpain activation. NEW & NOTEWORTHY Although many effects of the sympathetic nervous system on muscle physiology are known, the role of catecholamines in skeletal muscle protein metabolism has been scarcely studied. We suggest that catecholamines released from adrenal medulla may be of particular importance for restraining the activation of the Ca 2+ -dependent proteolysis in soleus muscles during acute cold exposure. This finding helps us to understand the adaptive changes that occur in skeletal muscle protein metabolism during cold stress.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00198.2016
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2017
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Effect of short-term cold exposure on skeletal muscle protein breakdown in rats
    American Physiological Society ; 2013
    In:  Journal of Applied Physiology Vol. 115, No. 10 ( 2013-11-15), p. 1496-1505
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 115, No. 10 ( 2013-11-15), p. 1496-1505
    Abstract: Although it is well established that carbohydrate and lipid metabolism are profoundly altered by cold stress, the effects of short-term cold exposure on protein metabolism in skeletal muscle are still poorly understood. Because cold acclimation requires that an organism adjust its metabolic flux, and muscle amino acids may be an important energy source for heat production, we hypothesize that muscle proteolysis is increased and protein synthesis is decreased under such a stress condition. Herein, cold exposure for 24 h decreased rates of protein synthesis and increased overall proteolysis in both soleus and extensor digitorum longus (EDL) muscles, but it did not affect muscle weight. An increase in proteolysis was accompanied by hyperactivity of the ubiquitin-proteasome system (UPS) in both soleus and EDL, and Ca 2+ -dependent proteolysis in EDL. Furthermore, muscles of rats exposed to cold showed increased mRNA and protein levels of atrogin-1 and muscle RING finger enzyme-1 (MuRF1). Additionally, cold stress reduced phosphorylation of Akt and Forkhead box class O1 (FoxO1), a well-known effect that increases FoxO translocation to the nucleus and leads to activation of proteolysis. Plasma insulin levels were lower, whereas catecholamines, corticosterone, and thyroid hormones were higher in cold-exposed rats compared with control rats. The present data provide the first direct evidence that short-term cold exposure for 24 h decreases rates of protein synthesis and increases the UPS and Ca 2+ -dependent proteolytic processes, and increases expression of atrogin-1 and MuRF1 in skeletal muscles of young rats. The activation of atrophy induced by acute cold stress seems to be mediated at least in part through the inactivation of Akt/FoxO signaling and activation of AMP-activated protein kinase.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00474.2013
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2013
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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