Exercise promotes a subcellular redistribution of calcium-stimulated protease activity in striated muscle

1999 ◽  
Vol 77 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Gavin D Arthur ◽  
Timothy S Booker ◽  
Angelo N Belcastro
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Protease Activity ◽  
Striated Muscle ◽  
Contractile Activity ◽  
Particulate Fraction ◽  
Dependent Manner ◽  
Calcium Dependent ◽  
Study Support

The aims of this study were (i) to investigate whether the contractile activity associated with running increases calcium-stimulated, calpastatin-inhibited protease activity (calpain-like) in a time-dependent manner and (ii) to determine whether the changes, if any, are proportionately distributed between soluble (cytosolic) and particulate (bound) fractions of striated muscle in vivo. Calcium-dependent, calpastatin-inhibited caseinolysis (i.e., calpain-like activity) was measured in control and exercised rats (25 m/min, 0% grade) at 2, 5, 15, 30, and 60 min. Total calpain-like activity in skeletal muscle increased by 26% (13.2 ± 1.3 vs. 17.9 ± 2.2 U/g wet wt.) (p < 0.05) after running (60 min), accompanied by an increased activity in the particulate fraction. In cardiac muscle, exercise (60 min) increased total calpain-like activity by 33% (p < 0.05), which was attributable to increases in both the cytosolic and particulate fractions. Both tissues responded with an early (2-5 min) activation of total calpain-like activity (p < 0.05), supported by early increases for particulate fractions from skeletal muscle; whereas for cardiac muscle, a noticeable early drop (p < 0.05) occurred in the particulate fraction. Minimal changes were observed for total, cytosolic, and particulate fractions of noncontracting tissue (i.e., liver). The results of this study support the hypothesis that the total calpain-like activity increases associated with level running occur early on with exercise and that the increases are accompanied by changes in the redistribution of soluble to particulate fractions. The changes would set the stage for enhanced rates of protein degradation known to occur in striated muscle with exercise.Key words: nonlysosomal proteases, calcium-dependent proteolysis, muscle damage.

Skeletal muscle phenotype signaling with ex vivo endurance-type dynamic contractions in rat muscle

2021 ◽  
Author(s):  
Jesper Emil Jakobsgaard ◽  
Jacob Andresen ◽  
Frank V. de Paoli ◽  
Kristian Vissing
Keyword(s):  
Skeletal Muscle ◽  
Translation Initiation ◽  
Ex Vivo ◽  
Contractile Activity ◽  
Specific Protein ◽  
Signaling Proteins ◽  
Dependent Manner ◽  
Metabolic Signaling ◽  
Dynamic Endurance

Skeletal muscle phenotype may influence the response sensitivity of myocellular regulatory mechanisms to contractile activity. To examine this, we employed an ex vivo endurance-type dynamic contraction model to evaluate skeletal muscle phenotype-specific protein signaling responses in rat skeletal muscle. Preparations of slow-twitch soleus and fast-twitch extensor digitorum longus skeletal muscle from 4-wk old female Wistar rats were exposed to an identical ex vivo dynamic endurance-type contraction paradigm consisting of 40 minutes of stretch-shortening contractions under simultaneous low-frequency electrostimulation delivered in an intermittent pattern. Phosphorylation of proteins involved in metabolic signaling and signaling for translation initiation was evaluated at 0, 1, and 4 hours after stimulation by immunoblotting. For both muscle phenotypes, signaling related to metabolic events was upregulated immediately after stimulation, with concomitant absence of signaling for translation-initiation. Signaling for translation-initiation was then activated in both muscle phenotypes at 1-4 hours after stimulation, coinciding with attenuated metabolic signaling. The recognizable pattern of signaling responses support how our ex vivo dynamic muscle contraction model can be utilized to infer a stretch-shortening contraction pattern resembling stretch-shortening contraction of in vivo endurance exercise. Moreover, using this model, we observed that some specific signaling proteins adhering to metabolic events or to translation initation exhibited phosphorylation changes in a phenotype-dependent manner, whereas other signaling proteins exhibited phenotype-independent changes. These findings may aid the interpretation of myocellular signaling outcomes adhering to mixed muscle samples collected during human experimental trials.

scholarly journals Phospholemman is not required for the acute stimulation of Na+-K+-ATPase α2-activity during skeletal muscle fatigue

2015 ◽  
Vol 309 (12) ◽  
pp. C813-C822 ◽  
Author(s):  
Palanikumar Manoharan ◽  
Tatiana L. Radzyukevich ◽  
Hesamedin Hakim Javadi ◽  
Cory A. Stiner ◽  
Julio A. Landero Figueroa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Capacity ◽  
Skeletal Muscles ◽  
Contractile Activity ◽  
Critical Role ◽  
Regulatory Subunit ◽  
Dependent Manner ◽  
Evoked Contractions ◽  
Stimulation Of

The Na+-K+-ATPase α2-isoform in skeletal muscle is rapidly stimulated during muscle use and plays a critical role in fatigue resistance. The acute mechanisms that stimulate α2-activity are not completely known. This study examines whether phosphorylation of phospholemman (PLM/FXYD1), a regulatory subunit of Na+-K+-ATPase, plays a role in the acute stimulation of α2 in working muscles. Mice lacking PLM (PLM KO) have a normal content of the α2-subunit and show normal exercise capacity, in contrast to the greatly reduced exercise capacity of mice that lack α2 in the skeletal muscles. Nerve-evoked contractions in vivo did not induce a change in total PLM or PLM phosphorylated at Ser63 or Ser68, in either WT or PLM KO. Isolated muscles of PLM KO mice maintain contraction and resist fatigue as well as wild type (WT). Rb+ transport by the α2-Na+-K+-ATPase is stimulated to the same extent in contracting WT and contracting PLM KO muscles. Phosphorylation of sarcolemmal membranes prepared from WT but not PLM KO skeletal muscles stimulates the activity of both α1 and α2 in a PLM-dependent manner. The stimulation occurs by an increase in Na+ affinity without significant change in Vmax and is more effective for α1 than α2. These results demonstrate that phosphorylation of PLM is capable of stimulating the activity of both isozymes in skeletal muscle; however, contractile activity alone is not sufficient to induce PLM phosphorylation. Importantly, acute stimulation of α2, sufficient to support exercise and oppose fatigue, does not require PLM or its phosphorylation.

Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle

2015 ◽  
Vol 118 (8) ◽  
pp. 971-979 ◽  
Author(s):  
Andreas Buch Møller ◽  
Mikkel Holm Vendelbo ◽  
Britt Christensen ◽  
Berthil Forrest Clasen ◽  
Ann Mosegaard Bak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Physical Exercise ◽  
Light Chain ◽  
Human Skeletal Muscle ◽  
Transgenic Animal ◽  
Dependent Manner ◽  
Healthy Humans ◽  
Transgenic Animal Models ◽  
Exercise Induced

Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser555 stimulates autophagy, whereas phosphorylation at Ser757 is inhibitory. To determine whether exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1-h cycling exercise at 50% maximal O2 uptake on two occasions: 1) during a 36-h fast, and 2) during continuous glucose infusion at 0.2 kg/h. Physical exercise increased ULK1 phosphorylation at Ser555 and decreased lipidation of light chain 3B. ULK1 phosphorylation at Ser555 correlated positively with AMP-activated protein kinase-α Thr172 phosphorylation and negatively with light chain 3B lipidation. ULK1 phosphorylation at Ser757 was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 min of exercise, independently of nutritional status, and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.

A malonyl-CoA fuel-sensing mechanism in muscle: effects of insulin, glucose, and denervation

1995 ◽  
Vol 269 (2) ◽  
pp. E283-E289 ◽  
Author(s):  
A. K. Saha ◽  
T. G. Kurowski ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Plasma Insulin ◽  
Contractile Activity ◽  
High Plasma ◽  
Muscle Contractions ◽  
Glucose Levels ◽  
Malonyl Coa ◽  
Ad Libitum ◽  
Sciatic Nerve Stimulation

Increases in the concentration of malonyl-CoA in skeletal muscle have been observed in the KKAy mouse, an obese rodent with high plasma insulin and glucose levels [Saha et al. Am. J. Physiol. 267 (Endocrinol. Metab. 30): E95-E101, 1994]. To assess whether insulin and glucose directly regulate malonyl-CoA in muscle, soleus muscles from young rats were incubated with insulin and glucose at various concentrations, and their content of malonyl-CoA was determined. In addition, the effect on malonyl-CoA of denervation and electrically induced muscle contractions was assessed. The concentration of malonyl-CoA in the soleus, taken directly from a rat fed ad libitum, was 2.0 +/- 0.2 nmol/g. In muscles incubated for 20 min in a medium devoid of added insulin and glucose, the concentration was decreased to 0.8 +/- 0.2 nmol/g. When the medium contained 0.5, 7.5, or 30 mM glucose, malonyl-CoA levels were 1.3 +/- 0.1, 1.8 +/- 0.1, or 2.4 +/- 0.2 nmol/g, respectively, in the absence of insulin and 1.7 +/- 0.1, 4.6 +/- 0.3, or 5.5 +/- 0.6 nmol/g in its presence (10 mU/ml). Compared with its level in a control muscle, the concentration of malonyl-CoA was increased threefold in the soleus 6-8 h after denervation and remained twofold higher for > or = 48 h. In contrast, muscle contractions induced by sciatic nerve stimulation, in vivo, acutely decreased the concentration of malonyl-CoA by 30-35%. The results indicate that insulin and glucose, and probably contractile activity, regulate the concentration of malonyl-CoA in muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Inhibiting myosin-ATPase reveals a dynamic range of mitochondrial respiratory control in skeletal muscle

2011 ◽  
Vol 437 (2) ◽  
pp. 215-222 ◽  
Author(s):  
Christopher G. R. Perry ◽  
Daniel A. Kane ◽  
Chien-Te Lin ◽  
Rachel Kozy ◽  
Brook L. Cathey ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dynamic Range ◽  
Energy Charge ◽  
Respiratory Control ◽  
Basic Research ◽  
Dependent Manner ◽  
Atpase Inhibitor ◽  
Wide Range ◽  
The Impact

Assessment of mitochondrial ADP-stimulated respiratory kinetics in PmFBs (permeabilized fibre bundles) is increasingly used in clinical diagnostic and basic research settings. However, estimates of the Km for ADP vary considerably (~20–300 μM) and tend to overestimate respiration at rest. Noting that PmFBs spontaneously contract during respiration experiments, we systematically determined the impact of contraction, temperature and oxygenation on ADP-stimulated respiratory kinetics. BLEB (blebbistatin), a myosin II ATPase inhibitor, blocked contraction under all conditions and yielded high Km values for ADP of >~250 and ~80 μM in red and white rat PmFBs respectively. In the absence of BLEB, PmFBs contracted and the Km for ADP decreased ~2–10-fold in a temperature-dependent manner. PmFBs were sensitive to hyperoxia (increased Km) in the absence of BLEB (contracted) at 30 °C but not 37 °C. In PmFBs from humans, contraction elicited high sensitivity to ADP (Km<100 μM), whereas blocking contraction (+BLEB) and including a phosphocreatine/creatine ratio of 2:1 to mimic the resting energetic state yielded a Km for ADP of ~1560 μM, consistent with estimates of in vivo resting respiratory rates of <1% maximum. These results demonstrate that the sensitivity of muscle to ADP varies over a wide range in relation to contractile state and cellular energy charge, providing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state.

scholarly journals The subcellular distribution of dystrophin in mouse skeletal, cardiac, and smooth muscle.

1991 ◽  
Vol 115 (2) ◽  
pp. 411-421 ◽  
Author(s):  
T J Byers ◽  
L M Kunkel ◽  
S C Watkins
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Plasma Membrane ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Adherens Junctions ◽  
Myotendinous Junction ◽  
Elevated Concentration ◽  
Western Blots ◽  
Functional Roles

We use a highly specific and sensitive antibody to further characterize the distribution of dystrophin in skeletal, cardiac, and smooth muscle. No evidence for localization other than at the cell surface is apparent in skeletal muscle and no 427-kD dystrophin labeling was detected in sciatic nerve. An elevated concentration of dystrophin appears at the myotendinous junction and the neuromuscular junction, labeling in the latter being more intense specifically in the troughs of the synaptic folds. In cardiac muscle the distribution of dystrophin is limited to the surface plasma membrane but is notably absent from the membrane that overlays adherens junctions of the intercalated disks. In smooth muscle, the plasma membrane labeling is considerably less abundant than in cardiac or skeletal muscle and is found in areas of membrane underlain by membranous vesicles. As in cardiac muscle, smooth muscle dystrophin seems to be excluded from membrane above densities that mark adherens junctions. Dystrophin appears as a doublet on Western blots of skeletal and cardiac muscle, and as a single band of lower abundance in smooth muscle that corresponds most closely in molecular weight to the upper band of the striated muscle doublet. The lower band of the doublet in striated muscle appears to lack a portion of the carboxyl terminus and may represent a dystrophin isoform. Isoform differences and the presence of dystrophin on different specialized membrane surfaces imply multiple functional roles for the dystrophin protein.

Reticulon 3-mediated Chk2/p53 activation suppresses hepatocellular carcinogenesis and is blocked by hepatitis B virus

Gut ◽  
2020 ◽  
pp. gutjnl-2020-321386
Author(s):  
Shushu Song ◽  
Yinghong Shi ◽  
Weicheng Wu ◽  
Hao Wu ◽  
Lei Chang ◽  
...  
Keyword(s):  
Cellular Proliferation ◽  
Dependent Manner ◽  
Mice Model ◽  
Calcium Dependent ◽  
B Virus ◽  
P53 Activation ◽  
Underlying Mechanisms ◽  
Induced Apoptosis

ObjectiveDysfunction of endoplasmic reticulum (ER) proteins is closely related to homeostasis disturbance and malignant transformation of hepatocellular carcinoma (HCC). Reticulons (RTN) are a family of ER-resident proteins critical for maintaining ER function. Nevertheless, the precise roles of RTN in HCC remain largely unclear. The aim of the study is to examine the effect of reticulon family member RTN3 on HCC development and explore the underlying mechanisms.DesignClinical HCC samples were collected to assess the relationship between RTN3 expression and patients’ outcome. HCC cell lines were employed to examine the effects of RTN3 on cellular proliferation, apoptosis and signal transduction in vitro. Nude mice model was used to detect the role of RTN3 in modulating tumour growth in vivo.ResultsWe found that RTN3 was highly expressed in normal hepatocytes but frequently downregulated in HCC. Low RTN3 expression predicted poor outcome in patients with HCC in TP53 gene mutation and HBV infection status-dependent manner. RTN3 restrained HCC growth and induced apoptosis by activating p53. Mechanism studies indicated that RTN3 facilitated p53 Ser392 phosphorylation via Chk2 and enhanced subsequent p53 nuclear localisation. RTN3 interacted with Chk2, recruited it to ER and promoted its activation in an ER calcium-dependent manner. Nevertheless, the tumour suppressive effects of RTN3 were abrogated in HBV-positive cells. HBV surface antigen competed with Chk2 for RTN3 binding and blocked RTN3-mediated Chk2/p53 activation.ConclusionThe findings suggest that RTN3 functions as a novel suppressor of HCC by activating Chk2/p53 pathway and provide more clues to better understand the oncogenic effects of HBV.

Selective chronic regulation of GLUT1 and GLUT4 content by insulin, glucose, and lipid in rat cardiac muscle in vivo

1997 ◽  
Vol 273 (3) ◽  
pp. H1309-H1316 ◽  
Author(s):  
D. R. Laybutt ◽  
A. L. Thompson ◽  
G. J. Cooney ◽  
E. W. Kraegen
Keyword(s):  
Cardiac Muscle ◽  
Plasma Glucose ◽  
Glucose Transporter ◽  
Close Association ◽  
Nonesterified Fatty Acid ◽  
Control Group ◽  
Dependent Manner ◽  
Energy Status ◽  
Glut1 Expression

The glucose transporter GLUT1 may play a more important role in cardiac than in skeletal muscle, but its regulation is unclear. During fasting, cardiac GLUT1 declines in the presence of low plasma insulin and glucose and high nonesterified fatty acid (NEFA) levels, whereas GLUT4 is unchanged. We investigated insulin, glucose, and NEFA levels as regulatory factors of cardiac GLUT content in chronically cannulated rats. Fasting rats were infused for 24 h with saline or insulin (2 rates) while plasma glucose was equalized by a glucose clamp; final transporter content was compared with a fed control group. There was a close association of GLUT1 content with insulin (r2 = 0.83, P < 0.001), with GLUT1 varying over a threefold range, under equivalent fasting glycemic conditions (plasma glucose, 5.1 +/- 0.1 mM). Maintenance of fed insulin levels during fasting prevented the GLUT1 fall (P < 0.01), whereas hyperinsulinemia (117 +/- 10 mU/l) led to significant overexpression of GLUT1 (155 +/- 12% of control, P < 0.01). When high glucose (7.6 +/- 0.1 mM) or high NEFA (0.76 +/- 0.05 mM) levels accompanied the hyperinsulinemia, upregulation of GLUT1 was blocked. GLUT1 content correlated with an estimate of cardiac glucose clearance across the groups. Cardiac GLUT4 content, hexokinase, and acyl-CoA synthase activities were unaffected by fasting, insulin, or substrate manipulation. In conclusion, insulin preferentially upregulates GLUT1 (but not GLUT4) in a dose-dependent manner in cardiac muscle in vivo, and substrate supply modulates this response, since upregulation can be effectively blocked by increased glucose or lipid availability. Therefore, both insulin exposure and energy status of cardiac muscle may be important determinants of cardiac GLUT1 expression.

scholarly journals THE ULTRASTRUCTURE OF FROG VENTRICULAR CARDIAC MUSCLE AND ITS RELATIONSHIP TO MECHANISMS OF EXCITATION-CONTRACTION COUPLING

1968 ◽  
Vol 38 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Nancy A. Staley ◽  
Ellis S. Benson
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Structural Features ◽  
Mammalian Skeletal Muscle ◽  
Striated Muscles ◽  
Thin Filaments ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Dense Granules

Frog ventricular cardiac muscle has structural features which set it apart from frog and mammalian skeletal muscle and mammalian cardiac muscle. In describing these differences, our attention focused chiefly on the distribution of cellular membranes. Abundant inter cellular clefts, the absence of tranverse tubules, and the paucity of sarcotubules, together with exceedingly small cell diameters (less than 5 µ), support the suggestion that the mechanism of excitation-contraction coupling differs in these muscle cells from that now thought to be characteristic of striated muscle such as skeletal muscle and mammalian cardiac muscle. These structural dissimilarities also imply that the mechanism of relaxation in frog ventricular muscle differs from that considered typical of other striated muscles. Additional ultrastructural features of frog ventricular heart muscle include spherical electron-opaque bodies on thin filaments, inconstantly present, forming a rank across the I band about 150 mµ from the Z line, and membrane-bounded dense granules resembling neurosecretory granules. The functional significance of these features is not yet clear.

scholarly journals Disruption of the striated muscle glycogen-targeting subunit of protein phosphatase 1: influence of the genetic background

2007 ◽  
Vol 40 (2) ◽  
pp. 47-59 ◽  
Author(s):  
James Paterson ◽  
Ian R Kelsall ◽  
Patricia T W Cohen
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Muscle Glycogen ◽  
Protein Phosphatase ◽  
Striated Muscle ◽  
Protein Phosphatase 1 ◽  
Phosphorylase Kinase ◽  
Donor Strain ◽  
Key Factor

A prediabetic phenotype of glucose intolerance, insulin resistance and obesity was observed at ∼12 months of age in mice homozygous for a null allele of the major skeletal muscle glycogen-targeting subunit GM of protein phosphatase 1 (PP1) and derived from a 129/Ola donor strain. In this study, backcrossing of these mice (termed obese mice) onto two different genetic backgrounds gave rise to lean, glucose-tolerant, insulin-sensitive mice (termed lean mice), indicating that at least one variant gene in the 129/Ola background, not present in the C57BL/6 or 129s2/sV background, is required for the development of the prediabetic phenotype of obese mice. Slightly elevated AMP-activated protein kinase α2 activity in the skeletal muscle of lean C57BL/6 mice was also observed to a lesser extent in the obese mice. Normal or slightly raised in vivo glucose transport in lean C57BL/6 mice compared with decreased glucose transport in the obese mice supports the tenet that adequate transport of glucose may be a key factor in preventing the development of the prediabetic phenotype. The pH 6.8/pH 8.6 activity ratio of phosphorylase kinase was increased in lean C57BL/6 mice compared with controls indicating that phosphorylase kinase is an in vivo substrate of PP1-GM.

Sign in / Sign up

Export Citation Format

Share Document