68 research outputs found
Staurosporine Inhibits Frequency-Dependent Myofilament Desensitization in Intact Rabbit Cardiac Trabeculae
Myofilament calcium sensitivity decreases with frequency in intact healthy rabbit trabeculae and associates with Troponin I and Myosin light chain-2 phosphorylation. We here tested whether serine-threonine kinase activity is primarily responsible for this frequency-dependent modulations of myofilament calcium sensitivity. Right ventricular trabeculae were isolated from New Zealand White rabbit hearts and iontophoretically loaded with bis-fura-2. Twitch force-calcium relationships and steady state force-calcium relationships were measured at frequencies of 1 and 4 Hz at 37 °C. Staurosporine (100 nM), a nonspecific serine-threonine kinase inhibitor, or vehicle (DMSO) was included in the superfusion solution before and during the contractures. Staurosporine had no frequency-dependent effect on force development, kinetics, calcium transient amplitude, or rate of calcium transient decline. The shift in the pCa50 of the force-calcium relationship was significant from 6.05 ± 0.04 at 1 Hz versus 5.88 ± 0.06 at 4 Hz under control conditions (vehicle, P < 0.001) but not in presence of staurosporine (5.89 ± 0.08 at 1 Hz versus 5.94 ± 0.07 at 4 Hz, P = NS). Phosphoprotein analysis (Pro-Q Diamond stain) confirmed that staurosporine significantly blunted the frequency-dependent phosphorylation at Troponin I and Myosin light chain-2. We conclude that frequency-dependent modulation of calcium sensitivity is mediated through a kinase-specific effect involving phosphorylation of myofilament proteins
Nf-κb Inhibition Rescues Cardiac Function By Remodeling Calcium Genes In A Duchenne Muscular Dystrophy Model
Duchenne muscular dystrophy (DMD) is a neuromuscular disorder causing progressive muscle degeneration. Although cardiomyopathy is a leading mortality cause in DMD patients, the mechanisms underlying heart failure are not well understood. Previously, we showed that NF-κB exacerbates DMD skeletal muscle pathology by promoting inflammation and impairing new muscle growth. Here, we show that NF-κB is activated in murine dystrophic (mdx) hearts, and that cardiomyocyte ablation of NF-κB rescues cardiac function. This physiological improvement is associated with a signature of upregulated calcium genes, coinciding with global enrichment of permissive H3K27 acetylation chromatin marks and depletion of the transcriptional repressors CCCTC-binding factor, SIN3 transcription regulator family member A, and histone deacetylase 1. In this respect, in DMD hearts, NF-κB acts differently from its established role as a transcriptional activator, instead promoting global changes in the chromatin landscape to regulate calcium genes and cardiac function
Role of nitric oxide/cyclic GMP in the depressed function of myocytes from rejecting transplanted hearts.
Role of nitric oxide/cyclic GMP in the depressed function of myocytes from rejecting transplanted hearts
Expression levels of sarcolemmal membrane repair proteins following prolonged exercise training in mice
428-435Membrane repair is a conserved cellular
process, where intracellular vesicles translocate to sites of plasma membrane
injury to actively reseal membrane disruptions. Such membrane disruptions
commonly occur in the course of normal physiology, particularly in skeletal
muscles due to repeated contraction producing small tears in the sarcolemmal
membrane. Here, we investigated whether prolonged exercise could produce
adaptive changes in expression levels of proteins associated with the membrane
repair process, including mitsugumin 53/tripartite motif-containing protein 72
(MG53/TRIM72), dysferlin and caveolin-3 (cav3). Mice were exercised using a
treadmill running protocol and protein levels were measured by immunoblotting.
The specificity of the antibodies used was established by immunoblot testing of
various tissue lysates from both mice and rats. We found that MG53/TRIM72
immunostaining on isolated mouse skeletal muscle fibers showed protein
localization at sites of membrane disruption created by the isolation of these
muscle fibers. However, no significant changes in the expression levels of the
tested membrane repair proteins were observed following prolonged treadmill
running for eight weeks (30 to 80 min/day). These findings suggest that any
compensation occurring in the membrane repair process in skeletal muscle
following prolonged exercise does not affect the expression levels of these
three key membrane repair proteins
Expression levels of sarcolemmal membrane repair proteins following prolonged exercise training in mice
428-435Membrane repair is a conserved cellular
process, where intracellular vesicles translocate to sites of plasma membrane
injury to actively reseal membrane disruptions. Such membrane disruptions
commonly occur in the course of normal physiology, particularly in skeletal
muscles due to repeated contraction producing small tears in the sarcolemmal
membrane. Here, we investigated whether prolonged exercise could produce
adaptive changes in expression levels of proteins associated with the membrane
repair process, including mitsugumin 53/tripartite motif-containing protein 72
(MG53/TRIM72), dysferlin and caveolin-3 (cav3). Mice were exercised using a
treadmill running protocol and protein levels were measured by immunoblotting.
The specificity of the antibodies used was established by immunoblot testing of
various tissue lysates from both mice and rats. We found that MG53/TRIM72
immunostaining on isolated mouse skeletal muscle fibers showed protein
localization at sites of membrane disruption created by the isolation of these
muscle fibers. However, no significant changes in the expression levels of the
tested membrane repair proteins were observed following prolonged treadmill
running for eight weeks (30 to 80 min/day). These findings suggest that any
compensation occurring in the membrane repair process in skeletal muscle
following prolonged exercise does not affect the expression levels of these
three key membrane repair proteins
- …