Navegando por Autor "Gonçalves, Dawit Alberto Pinheiro"

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CAMP-dependent protein kinase inhibits FoxO activity and regulates skeletal muscle plasticity in mice.
(2020) Silveira, Wilian de Assis; Gonçalves, Dawit Alberto Pinheiro; Machado, Juliano; Silva, Natalia Lautherbach Ennes da; Borges, Danilo Lustrino; Gomes, Sílvia de Paula; Pereira, Marcelo G.; Miyabara, Elen Haruka; Sandri, Marco; Kettelhut, Isis do Carmo; Navegantes, Luiz Carlos Carvalho
Although we have shown that catecholamines suppress the activity of the Ubiquitin- Proteasome System (UPS) and atrophy-related genes expression through a cAMP-de- pendent manner in skeletal muscle from rodents, the underlying mechanisms remain unclear. Here, we report that a single injection of norepinephrine (NE; 1 mg kg−1; s.c) attenuated the fasting-induced up-regulation of FoxO-target genes in tibialis anterior (TA) muscles by the stimulation of PKA/CREB and Akt/FoxO1 signaling pathways. In addition, muscle-specific activation of PKA by the overexpression of PKA catalytic subunit (PKAcat) suppressed FoxO reporter activity induced by (1) a wild-type; (2) a non-phosphorylatable; (3) a non-phosphorylatable and non-acet- ylatable forms of FoxO1 and FoxO3; (4) downregulation of FoxO protein content, and probably by (5) PGC-1α up-regulation. Consistently, the overexpression of the PKAcat inhibitor (PKI) up-regulated FoxO activity and the content of Atrogin-1 and MuRF1, as well as induced muscle fiber atrophy, the latter effect being prevented by the overexpression of a dominant negative (d. n.) form of FoxO (d.n.FoxO). The sustained overexpression of PKAcat induced fiber-type transition toward a smaller, slower, and more oxidative phenotype and improved muscle resistance to fatigue. Taken together, our data provide the first evidence that endogenous PKA activity is required to restrain the basal activity of FoxO and physiologically important to maintain skeletal muscle mass.
Sympathetic innervation suppresses the autophagic-lysosomal system in brown adipose tissue under basal and cold-stimulated conditions.
(2020) Mioranza, Franciele Przygodda; Silva, Natalia Lautherbach Ennes da; Buzelle, Samyra Lopes; Gonçalves, Dawit Alberto Pinheiro; Assis, Ana Paula; Gomes, Sílvia de Paula; Garófalo, Maria Antonieta Rissato; Heck, Lilian Carmo; Matsuo, Flávia Sayuri; Mota, Ryerson Fonseca; Osako, Mariana Kiomy; Kettelhut, Isis do Carmo; Navegantes, Luiz Carlos Carvalho
The sympathetic nervous system (SNS) activates cAMP signaling and promotes trophic effects on brown adipose tissue (BAT) through poorly understood mechanisms. Because norepinephrine has been found to induce antiproteolytic effects on muscle and heart, we hypothesized that the SNS could inhibit autophagy in interscapular BAT (IBAT). Here, we describe that selective sympathetic denervation of rat IBAT kept at 25°C induced atrophy, and in parallel dephosphorylated forkhead box class O (FoxO), and increased cathepsin activity, autophagic flux, autophagosome formation, and expression of autophagy-related genes. Conversely, cold stimulus (4°C) for up to 72 h induced thermogenesis and IBAT hypertrophy, an anabolic effect that was associated with inhibition of cathepsin activity, autophagic flux, and autophagosome formation. These effects were abrogated by sympathetic denervation, which also upregulated Gabarapl1 mRNA. In addition, the cold-driven sympathetic activation stimulated the mechanistic target of rapamycin (mTOR) pathway, leading to the enhancement of protein synthesis, evaluated in vivo by puromycin incorporation, and to the inhibitory phosphorylation of Unc51-like kinase-1, a key protein in the initiation of autophagy. This coincided with a higher content of exchange protein-1 directly activated by cAMP (Epac1), a cAMP effector, and phosphorylation of Akt at Thr308, all these effects being abolished by denervation. Systemic treatment with norepinephrine for 72 h mimicked most of the cold effects on IBAT. These data suggest that the noradrenergic sympathetic inputs to IBAT restrain basal autophagy via suppression of FoxO and, in the setting of cold, stimulate protein synthesis via the Epac/Akt/mTOR-dependent pathway and suppress the autophagosome formation, probably through posttranscriptional mechanisms.
Urocortin 2 promotes hypertrophy and enhances skeletal muscle function through cAMP and insulin/IGF-1 signaling pathways.
(2022) Silva, Natalia Lautherbach Ennes da; Gonçalves, Dawit Alberto Pinheiro; Silveira, Wilian de Assis; Gomes, Sílvia de Paula; Valentim, Rafael Rossi; Zanon, Neusa Maria; Pereira, Marcelo G.; Miyabara, Elen Haruka; Navegantes, Luiz Carlos Carvalho; Kettelhut, Isis do Carmo
Objective: Although it is well established that urocortin 2 (Ucn2), a peptide member of the corticotrophin releasing factor (CRF) family, and its specific corticotrophin-releasing factor 2 receptor (CRF2R) are highly expressed in skeletal muscle, the role of this peptide in the regulation of skeletal muscle mass and protein metabolism remains elusive. Methods: To elucidate the mechanisms how Ucn2 directly controls protein metabolism in skeletal muscles of normal mice, we carried out genetic tools, physiological and molecular analyses of muscles in vivo and in vitro. Results: Here, we demonstrated that Ucn2 overexpression activated cAMP signaling and promoted an expressive muscle hypertrophy associated with higher rates of protein synthesis and activation of Akt/mTOR and ERK1/2 signaling pathways. Furthermore, Ucn2 induced a decrease in mRNA levels of atrogin-1 and in autophagic flux inferred by an increase in the protein content of LC3-I, LC3-II and p62. Accordingly, Ucn2 reduced both the transcriptional activity of FoxO in vivo and the overall protein degradation in vitro through an inhibition of lysosomal proteolytic activity. In addition, we demonstrated that Ucn2 induced a fast-to-slow fiber type shift and improved fatigue muscle resistance, an effect that was completely blocked in muscles co-transfected with mitogen-activated protein kinase phosphatase 1 (MKP-1), but not with dominant-negative Akt mutant (Aktmt). Conclusions: These data suggest that Ucn2 triggers an anabolic and anti-catabolic response in skeletal muscle of normal mice probably through the activation of cAMP cascade and participation of Akt and ERK1/2 signaling. These findings open new perspectives in the development of therapeutic strategies to cope with the loss of muscle mass.