scholarly journals Activity of a gelsolin-like actin modulator in rat skeletal muscle under protein catabolic conditions

1987 ◽  
Vol 248 (2) ◽  
pp. 397-402 ◽  
Author(s):  
J D'Haese ◽  
M Rutschmann ◽  
B Dahlmann ◽  
H Hinssen
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Molecular Mass ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Proteolytic Degradation ◽  
Rat Skeletal Muscle ◽  
Corticosterone Treatment ◽  
Increased Activity ◽  
Stoichiometric Complex

A gelsolin-like actin-modulating protein was isolated from rat skeletal muscle and characterized with respect to its interaction with actin. The protein, with a molecular mass of approx. 85 kDa, forms a stoichiometric complex with two actin molecules and is activated by micromolar concentrations of Ca2+. It effectively severs actin filaments and promotes nucleation of actin polymerization. The activity of this protein is detectable already in crude extracts by its capability to reduce the steady state viscosity of actin. Actin-modulating activities were determined in muscle extracts of rats kept under protein catabolic conditions, i.e. as generated by corticosterone treatment and starvation. In both cases we found a marked increase of modulator activity. The possibility is discussed that the increased activity of actin modulator indicates a fragmentation of actin filaments prior to the proteolytic degradation of actin.

scholarly journals Catecholamines inhibit Ca2+-dependent proteolysis in rat skeletal muscle through β2-adrenoceptors and cAMP

2001 ◽  
Vol 281 (3) ◽  
pp. E449-E454 ◽  
Author(s):  
Luiz Carlos C. Navegantes ◽  
Neusa M. Z. Resano ◽  
Renato H. Migliorini ◽  
Ísis C. Kettelhut
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Plasma Epinephrine ◽  
Dibutyryl Camp ◽  
Rat Skeletal Muscle ◽  
Adrenergic Agonist ◽  
Norepinephrine Content ◽  
Increased Activity ◽  
Dependent Pathway

Overall proteolysis and the activity of skeletal muscle proteolytic systems were investigated in rats 1, 2, or 4 days after adrenodemedullation. Adrenodemedullation reduced plasma epinephrine by 95% and norepinephrine by 35% but did not affect muscle norepinephrine content. In soleus and extensor digitorum longus (EDL) muscles, rates of overall proteolysis increased by 15–20% by 2 days after surgery but returned to normal levels after 4 days. The rise in rates of protein degradation was accompanied by an increased activity of Ca2+-dependent proteolysis in both muscles, with no significant change in the activity of lysosomal and ATP-dependent proteolytic systems. In vitro rates of Ca2+-dependent proteolysis in soleus and EDL from normal rats decreased by ∼35% in the presence of either 10−5 M clenbuterol, a β2-adrenergic agonist, or epinephrine or norepinephrine. In the presence of dibutyryl cAMP, proteolysis was reduced by 62% in soleus and 34% in EDL. The data suggest that catecholamines secreted by the adrenal medulla exert an inhibitory control of Ca2+-dependent proteolysis in rat skeletal muscle, mediated by β2-adrenoceptors, with the participation of a cAMP-dependent pathway.

scholarly journals Cryo-electron microscopy structures of pyrene-labeled ADP-Pi- and ADP-actin filaments

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Steven Z. Chou ◽  
Thomas D. Pollard
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Active Site ◽  
Actin Filaments ◽  
Actin Polymerization ◽  
Actin Binding ◽  
Muscle Actin ◽  
Hydrophobic Cavity ◽  
Cryo Electron Microscopy ◽  
Kinetics Of

AbstractSince the fluorescent reagent N-(1-pyrene)iodoacetamide was first used to label skeletal muscle actin in 1981, the pyrene-labeled actin has become the most widely employed tool to measure the kinetics of actin polymerization and the interaction between actin and actin-binding proteins. Here we report high-resolution cryo-electron microscopy structures of actin filaments with N-1-pyrene conjugated to cysteine 374 and either ADP (3.2 Å) or ADP-phosphate (3.0 Å) in the active site. Polymerization buries pyrene in a hydrophobic cavity between subunits along the long-pitch helix with only minor differences in conformation compared with native actin filaments. These structures explain how polymerization increases the fluorescence 20-fold, how myosin and cofilin binding to filaments reduces the fluorescence, and how profilin binding to actin monomers increases the fluorescence.

Diet-induced obesity and acute hyperlipidemia reduce IκBα levels in rat skeletal muscle in a fiber-type dependent manner

2006 ◽  
Vol 290 (1) ◽  
pp. R233-R240 ◽  
Author(s):  
Bankim A. Bhatt ◽  
John J. Dube ◽  
Nikolas Dedousis ◽  
Jodie A. Reider ◽  
Robert M. O’Doherty
Keyword(s):  
Skeletal Muscle ◽  
P38 Mapk ◽  
Fiber Type ◽  
Dependent Manner ◽  
Rat Skeletal Muscle ◽  
Diet Induced Obesity ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Fat Feeding ◽  
Increased Activity

Increased activity of proinflammatory/stress pathways has been implicated in the pathogenesis of insulin resistance in obesity. However, the effects of obesity on the activity of these pathways in skeletal muscle, the major insulin-sensitive tissue by mass, are poorly understood. Furthermore, the mechanisms that activate proinflammatory/stress pathways in obesity are unknown. The present study addressed the effects of diet-induced obesity (DIO; 6 wk of high-fat feeding) and acute (6-h) hyperlipidemia (HL) in rats on activity of IKK/IκB/NF-κB c-Jun NH2-terminal kinase, and p38 MAPK in three skeletal muscles differing in fiber type [superficial vastus (Vas; fast twitch-glycolytic), soleus (Sol; slow twitch-oxidative), and gastrocnemius (Gas; mixed)]. DIO decreased the levels of the IκBα in Vas (24 ± 3%, P = 0.001, n = 8) but not in Sol or Gas compared with standard chow-fed controls. Similar to DIO, HL decreased IκBα levels in Vas (26 ± 5%, P = 0.006, n = 6) and in Gas (15 ± 4%, P = 0.01, n = 7) but not in Sol compared with saline-infused controls. Importantly, the fiber-type-dependent effects on IκBα levels could not be explained by differential accumulation of triglyceride in Sol and Vas. HL, but not DIO, decreased phospho-p38 MAPK levels in Vas (41 ± 7% P = 0.004, n = 6) but not in Sol or Gas. Finally, skeletal muscle c-Jun NH2-terminal kinase activity was unchanged by DIO or HL. We conclude that diet-induced obesity and acute HL reduce IκBα levels in rat skeletal muscle in a fiber-type-dependent manner.

scholarly journals Noninactivating tension in rat skeletal muscle. Effects of thyroid hormone.

1989 ◽  
Vol 94 (1) ◽  
pp. 183-203 ◽  
Author(s):  
M Chua ◽  
A F Dulhunty
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Membrane Potential ◽  
Extensor Digitorum Longus ◽  
Voltage Dependence ◽  
Surface Membrane ◽  
Membrane Potentials ◽  
Resting Membrane Potential ◽  
Rat Skeletal Muscle ◽  
Contraction Coupling

Inactivation of excitation-contraction coupling was examined in extensor digitorum longus (EDL) and soleus muscle fibers from rats injected daily with tri-iodothyronine (T3, 150 micrograms/kg) for 10-14 d. Steady-state activation and inactivation curves for contraction were obtained from measurements of peak potassium contracture tension at different surface membrane potentials. The experiments tested the hypothesis that noninactivating tension is a "window" tension caused by the overlap of the activation and inactivation curves. Changes in the amplitude and voltage dependence of noninactivating tension should be predicted by the changes in the activation and inactivation curves, if noninactivating tension arises from their overlap. After T3 treatment, the area of overlap increased in EDL fibers and decreased in soleus fibers and the overlap region was shifted to more negative potentials in both muscles. Noninactivating tension also appeared at more negative membrane potentials after T3 treatment in both EDL and soleus fibers. The effects of T3 treatment were confirmed with a two microelectrode voltage-clamp technique: at the resting membrane potential (-80 mV) contraction in response to a brief test pulse required less than normal depolarization in EDL, but more than normal depolarization in soleus fibers. After T3 treatment, the increase in contraction threshold at depolarized holding potentials (attributed to inactivation) occurred at more depolarized holding potentials in EDL, or less depolarized holding potentials in soleus. The changes in contraction threshold could be accounted for by the effects of T3 on the activation and inactivation curves. In conclusion, (a) T3 appeared to affect the expression of both activation and inactivation characteristics, but the activation effects could not be cleanly distinguished from T3 effects on the sarcoplasmic reticulum and contractile proteins, and (b) the experiments provided evidence for the hypothesis that the noninactivating tension is a steady-state "window" tension.

Hypoxia causes glycogenolysis without an increase in percent phosphorylase a in rat skeletal muscle

1992 ◽  
Vol 263 (6) ◽  
pp. E1086-E1091 ◽  
Author(s):  
J. M. Ren ◽  
E. A. Gulve ◽  
G. D. Cartee ◽  
J. O. Holloszy
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Strenuous Exercise ◽  
Rat Skeletal Muscle ◽  
Glycogen Breakdown ◽  
Stimulation Of

Stimulation of skeletal muscle to contract activates phosphorylase b-to-a conversion and glycogenolysis. Despite reversal of the increase in percentage of phosphorylase a after a few minutes, continued glycogen breakdown can occur during strenuous exercise. Hypoxia causes sustained glycogenolysis in skeletal muscle without an increase in percentage of phosphorylase a. We used this model to obtain insights regarding how glycogenolysis is mediated in the absence of an increase in percentage of phosphorylase a. Hypoxia caused a 70% decrease in glycogen in epitrochlearis muscles during an 80-min incubation despite no increase in percentage of phosphorylase a above the basal level of approximately 10%. Muscle Pi concentration increased from 3.8 to 8.6 mumol/g muscle after 5 min and 15.7 mumol/g after 20 min. AMP concentration doubled, attaining a steady state of 0.23 mumol/g in 5 min. Incubation of oxygenated muscles with 0.1 microM epinephrine induced an approximately sixfold increase in percentage of phosphorylase a but resulted in minimal glycogenolysis. Muscle Pi concentration was not altered by epinephrine. Despite no increase in percentage of phosphorylase a, hypoxia resulted in a fivefold greater depletion of glycogen over 20 min than did epinephrine. To evaluate the role of phosphorylase b, muscles were loaded with 2-deoxyglucose 6-phosphate, which inhibits phosphorylase b. The rate of glycogenolysis during 60 min of hypoxia was reduced by only approximately 14% in 2-deoxyglucose 6-phosphate-loaded muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Intramitochondrial control of the oxidation of hexadecanoate in skeletal muscle. A study of the acyl-CoA esters which accumulate during rat skeletal-muscle mitochondrial β-oxidation of [U-14C]hexadecanoate and [U-14C]hexadecanoyl-carnitine

1993 ◽  
Vol 289 (1) ◽  
pp. 161-168 ◽  
Author(s):  
S Eaton ◽  
A K M J Bhuiyan ◽  
R S Kler ◽  
D M Turnbull ◽  
K Bartlett
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Complex I ◽  
Rat Skeletal Muscle ◽  
Beta Oxidation ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Fractions ◽  
Nadh Ratio ◽  
14Co2 Production ◽  
Small Pool

1. We describe the acyl-CoA and acyl-carnitine esters which arise from the incubation of well-coupled State 3 rat skeletal-muscle mitochondrial fractions with [U-14C]hexadecanoate and [U-14C]hexadecanoyl-carnitine. 2. Acyl-CoA ester intermediates of chain length 16, 14, 12, 10 and 8 carbons were detected. 3. Although incubations were in steady state in respect of oxygen consumption, 14CO2 production and generation of acid-soluble radioactivity, quantitative analysis of acyl-CoA esters showed that steady state was not achieved in respect of all intermediates. 4. 3-Hydroxyacyl- and 2-enoyl-CoA and -carnitine esters were found under normoxic conditions. 5. Direct measurement of NAD+ and NADH shows that under identical incubation conditions our observations cannot be explained by gross perturbation of the [NAD+]/[NADH] ratio. 6. We hypothesize that there is a small pool of rapidly recycling NAD+ channelled between complex I of the respiratory chain and the newly described mitochondrial-inner-membrane-associated beta-oxidation trifunctional enzyme [Uchida, Izai, Orii and Hashimoto (1992) J. Biol. Chem. 267, 1034-1041].

ATP-activated, high-molecular-mass proteinase-I from rat skeletal muscle is a cysteineproteinase-α1-macroglobulin complex

1989 ◽  
Vol 991 (2) ◽  
pp. 253-262 ◽  
Author(s):  
Burkhardt Dahlmann ◽  
Lothar Kuehn ◽  
Peter C. Heinrich ◽  
Heidrun Kirschke ◽  
Bernd Wiederanders
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mass ◽  
High Molecular Mass ◽  
Rat Skeletal Muscle

Non - Lysosomal, High - Molecular - Mass Cysteine Proteinases from Rat Skeletal Muscle

1988 ◽  
pp. 215-223 ◽  
Author(s):  
Burkhardt Dahlmann ◽  
Lothar Kuehn ◽  
Friedrich Kopp ◽  
Hans Reinauer ◽  
William T. Stauber
Keyword(s):  
Skeletal Muscle ◽  
Molecular Mass ◽  
High Molecular Mass ◽  
Cysteine Proteinases ◽  
Rat Skeletal Muscle
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