Abstract 1065: Class-II Histone Deacetylases Regulate Myofilament Calcium Sensitivity in the Mouse Heart

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Stephen H Smith ◽  
Mahesh P Gupta ◽  
Sadhana Samant ◽  
Madhu Gupta ◽  
Sanjeev G Shroff
Keyword(s):  
Contractile Function ◽  
Trichostatin A ◽  
Hdac Inhibitors ◽  
Force Production ◽  
Calcium Sensitivity ◽  
Class Ii ◽  
Skinned Fibers ◽  
Mouse Heart ◽  
Acetyl Coa ◽  
Myofilament Calcium Sensitivity

The role of phosphorylation of myofilaments in regulating cardiac muscle calcium sensitivity and force production is well established. Recently it was shown that trichostatin A (TSA), a class-I and II histone deacetylase (HDAC) inhibitor, improved cardiac contractile function in vivo . Because class-II HDACs are able to translocate to the cytoplasm from the nucleus, it is postulated that some HDACs may interact with contractile proteins and thereby regulate myofilament calcium sensitivity and/or force production. Papillary muscle strips from mouse hearts were skinned for 4 hours and then treated overnight with two structurally dissimilar HDAC inhibitors, TSA and MS275. Both HDAC inhibitors significantly increased myofilament calcium sensitivity as quantified by pCa 50 [Baseline (n=9): 5.75±0.04; TSA (n=6): 5.84±0.02; MS275 (n=7): 5.87±0.03; P <0.05 vs . Baseline], without any significant changes in maximally activated force. Similar increase in calcium sensitivity was also observed when skinned fibers were incubated overnight in a buffer containing acetyl-CoA [acetyl-CoA (n=6): 5.84±0.04; P <0.05 vs . Baseline]. These observations suggest that acetylation of myofilament proteins can regulate myofilament calcium sensitivity. Western blot analyses of skinned fibers revealed that HDAC4 and HDAC5 were specifically associated with myofilament proteins, and acetylation of several myofilament proteins was increased following TSA treatment. One of these acetylated proteins was identified as muscle LIM protein (MLP). Protein-protein interaction analyses and co-localization studies showed that MLP specifically binds to HDAC4. Functional studies with skinned fibers isolated from MLP knock out [MLP −/− ] mice (C57BL6 strain) indicated that TSA-induced increase in calcium sensitivity was completely prevented [MLP −/− -Baseline (n=6): 5.60±0.03; MLP −/− -TSA (n=6): 5.61±0.02; P <NS] compared to wild-type (WT) mice of the same strain [WT-Baseline (n=6): 5.59±0.02; WT-TSA (n=6): 5.70±0.02; P <0.05]. These data demonstrate, for the first time, that class-II HDACs bind to cardiac myofilament proteins, with MLP being one of the binding partners, and play a role in regulating myofilament contractile function.

scholarly journals The Impact of Ovariectomy on Calcium Homeostasis and Myofilament Calcium Sensitivity in the Aging Mouse Heart

PLoS ONE ◽  
2013 ◽  
Vol 8 (9) ◽  
pp. e74719 ◽  
Author(s):  
Elias Fares ◽  
W. Glen Pyle ◽  
Gibanananda Ray ◽  
Robert A. Rose ◽  
Eileen M. Denovan-Wright ◽  
...  
Keyword(s):  
Calcium Homeostasis ◽  
Calcium Sensitivity ◽  
Mouse Heart ◽  
Aging Mouse ◽  
Myofilament Calcium Sensitivity ◽  
The Impact

Determination of the class and isoform selectivity of small-molecule histone deacetylase inhibitors

2007 ◽  
Vol 409 (2) ◽  
pp. 581-589 ◽  
Author(s):  
Nagma Khan ◽  
Michael Jeffers ◽  
Sampath Kumar ◽  
Craig Hackett ◽  
Ferenc Boldog ◽  
...  
Keyword(s):  
Histone Deacetylase ◽  
Histone Deacetylase Inhibitors ◽  
Trichostatin A ◽  
Hdac Inhibitors ◽  
Specific Inhibitor ◽  
Class Ii ◽  
Class I ◽  
Regulation Of Transcription ◽  
Control Of Gene Expression ◽  
Inhibitor Treatment

The human HDAC (histone deacetylase) family, a well-validated anticancer target, plays a key role in the control of gene expression through regulation of transcription. While HDACs can be subdivided into three main classes, the class I, class II and class III HDACs (sirtuins), it is presently unclear whether inhibiting multiple HDACs using pan-HDAC inhibitors, or targeting specific isoforms that show aberrant levels in tumours, will prove more effective as an anticancer strategy in the clinic. To address the above issues, we have tested a number of clinically relevant HDACis (HDAC inhibitors) against a panel of rhHDAC (recombinant human HDAC) isoforms. Eight rhHDACs were expressed using a baculoviral system, and a Fluor de Lys™ (Biomol International) HDAC assay was optimized for each purified isoform. The potency and selectivity of ten HDACs on class I isoforms (rhHDAC1, rhHDAC2, rhHDAC3 and rhHDAC8) and class II HDAC isoforms (rhHDAC4, rhHDAC6, rhHDAC7 and rhHDAC9) was determined. MS-275 was HDAC1-selective, MGCD0103 was HDAC1- and HDAC2-selective, apicidin was HDAC2- and HDAC3-selective and valproic acid was a specific inhibitor of class I HDACs. The hydroxamic acid-derived compounds (trichostatin A, NVP-LAQ824, panobinostat, ITF2357, vorinostat and belinostat) were potent pan-HDAC inhibitors. The growth-inhibitory effect of the HDACis on HeLa cells showed that both pan-HDAC and class-I-specific inhibitors inhibited cell growth. The results also showed that both pan-HDAC and class-I-specific inhibitor treatment resulted in increased acetylation of histones, but only pan-HDAC inhibitor treatment resulted in increased tubulin acetylation, which is in agreement with their activity towards the HDAC6 isoform.

scholarly journals Acute exposure to progesterone attenuates cardiac contraction by modifying myofilament calcium sensitivity in the female mouse heart

2017 ◽  
Vol 312 (1) ◽  
pp. H46-H59 ◽  
Author(s):  
Hirad A. Feridooni ◽  
Jennifer K. MacDonald ◽  
Anjali Ghimire ◽  
W. Glen Pyle ◽  
Susan E. Howlett
Keyword(s):  
Ventricular Myocytes ◽  
Heart Function ◽  
Calcium Sensitivity ◽  
Cardiac Contraction ◽  
Mouse Heart ◽  
Sodium Pentobarbital ◽  
Serum Progesterone ◽  
Time Courses ◽  
Myofilament Calcium Sensitivity ◽  
In Pregnancy

Acute application of progesterone attenuates cardiac contraction, although the underlying mechanisms are unclear. We investigated whether progesterone modified contraction in isolated ventricular myocytes and identified the Ca2+ handling mechanisms involved in female C57BL/6 mice (6–9 mo; sodium pentobarbital anesthesia). Cells were field-stimulated (4 Hz; 37°C) and exposed to progesterone (0.001–10.0 μM) or vehicle (35 min). Ca2+ transients (fura-2) and cell shortening were recorded simultaneously. Maximal concentrations of progesterone inhibited peak contraction by 71.4% (IC50 = 160 ± 50 nM; n = 12) and slowed relaxation by 75.4%. By contrast, progesterone had no effect on amplitudes or time courses of underlying Ca2+ transients. Progesterone (1 µM) also abbreviated action potential duration. When the duration of depolarization was controlled by voltage-clamp, progesterone attenuated contraction and slowed relaxation but did not affect Ca2+ currents, Ca2+ transients, sarcoplasmic reticulum (SR) content, or fractional release of SR Ca2+. Actomyosin MgATPase activity was assayed in myofilaments from hearts perfused with progesterone (1 μM) or vehicle (35 min). While maximal responses to Ca2+ were not affected by progesterone, myofilament Ca2+ sensitivity was reduced (EC50 = 0.94 ± 0.01 µM for control, n = 7 vs. 1.13 ± 0.05 μM for progesterone, n = 6; P < 0.05) and progesterone increased phosphorylation of myosin binding protein C. The effects on contraction were inhibited by lonaprisan (progesterone receptor antagonist) and levosimendan (Ca2+ sensitizer). Unlike results in females, progesterone had no effect on contraction or myofilament Ca2+ sensitivity in age-matched male mice. These data indicate that progesterone reduces myofilament Ca2+ sensitivity in female hearts, which may exacerbate manifestations of cardiovascular disease late in pregnancy when progesterone levels are high. NEW & NOTEWORTHY We investigated myocardial effects of acute application of progesterone. In females, but not males, progesterone attenuates and slows cardiomyocyte contraction with no effect on calcium transients. Progesterone also reduces myofilament calcium sensitivity in female hearts. This may adversely affect heart function, especially when serum progesterone levels are high in pregnancy. Listen to this article’s corresponding podcast at https://ajpheart.podbean.com/e/acute-progesterone-modifies-cardiac-contraction/ .

Effects of temperature and concomitant change in pH on muscle

1990 ◽  
Vol 259 (2) ◽  
pp. R204-R209 ◽  
Author(s):  
E. D. Stevens ◽  
R. E. Godt
Keyword(s):  
Ambient Temperature ◽  
Calcium Sensitivity ◽  
Skinned Fibers ◽  
Concomitant Increase ◽  
Concomitant Change ◽  
Effects Of Temperature ◽  
Contractile Performance

Contractile performance decreases with a decrease in temperature and increases with an increase in pH. In general, a decrease in ambient temperature is associated with an increase of the pH of the intracellular and extracellular fluids of ectotherms. Thus the concomitant increase in pH will to some extent counteract the effect of the decrease in temperature. We review the magnitude of this effect and show that it is modest for force (24%) but is small or negligible for speed or for variables involving time. Experiments with skinned fibers yield similar results to those with intact fibers. We argue that one important effect of the concomitant increase in pH is that it causes an increase in calcium sensitivity and that there may be a considerable metabolic saving associated with releasing less calcium at lower temperatures.

scholarly journals Computational modeling of Takotsubo cardiomyopathy: effect of spatially varying β-adrenergic stimulation in the rat left ventricle

2014 ◽  
Vol 307 (10) ◽  
pp. H1487-H1496 ◽  
Author(s):  
Sander Land ◽  
Steven A. Niederer ◽  
William E. Louch ◽  
Åsmund T. Røe ◽  
Jan Magnus Aronsen ◽  
...  
Keyword(s):  
Left Ventricle ◽  
Takotsubo Cardiomyopathy ◽  
Troponin I ◽  
Contractile Function ◽  
Single Cells ◽  
Apical Ballooning ◽  
Calcium Sensitivity ◽  
Takotsubo Syndrome ◽  
Adrenergic Stimulation ◽  
Inotropic Effects

In Takotsubo cardiomyopathy, the left ventricle shows apical ballooning combined with basal hypercontractility. Both clinical observations in humans and recent experimental work on isolated rat ventricular myocytes suggest the dominant mechanisms of this syndrome are related to acute catecholamine overload. However, relating observed differences in single cells to the capacity of such alterations to result in the extreme changes in ventricular shape seen in Takotsubo syndrome is difficult. By using a computational model of the rat left ventricle, we investigate which mechanisms can give rise to the typical shape of the ventricle observed in this syndrome. Three potential dominant mechanisms related to effects of β-adrenergic stimulation were considered: apical-basal variation of calcium transients due to differences in L-type and sarco(endo)plasmic reticulum Ca2+-ATPase activation, apical-basal variation of calcium sensitivity due to differences in troponin I phosphorylation, and apical-basal variation in maximal active tension due to, e.g., the negative inotropic effects of p38 MAPK. Furthermore, we investigated the interaction of these spatial variations in the presence of a failing Frank-Starling mechanism. We conclude that a large portion of the apex needs to be affected by severe changes in calcium regulation or contractile function to result in apical ballooning, and smooth linear variation from apex to base is unlikely to result in the typical ventricular shape observed in this syndrome. A failing Frank-Starling mechanism significantly increases apical ballooning at end systole and may be an important additional factor underpinning Takotsubo syndrome.

PKC catalytic subunit and phenylephrine induce a comparable decrease in myofilament calcium sensitivity

2007 ◽  
Vol 42 (6) ◽  
pp. S46
Author(s):  
Judit Barta ◽  
Jolanda van der Velden ◽  
Nicky M. Boontje ◽  
Ruud Zaremba ◽  
Ger J.M. Stienen
Keyword(s):  
Calcium Sensitivity ◽  
Catalytic Subunit ◽  
Myofilament Calcium Sensitivity

scholarly journals Fission yeast myosin Myo2 is down-regulated in actin affinity by light chain phosphorylation

2017 ◽  
Vol 114 (35) ◽  
pp. E7236-E7244 ◽  
Author(s):  
Luther W. Pollard ◽  
Carol S. Bookwalter ◽  
Qing Tang ◽  
Elena B. Krementsova ◽  
Kathleen M. Trybus ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Light Chain ◽  
Force Production ◽  
Class Ii ◽  
Cell System ◽  
Cell Cortex ◽  
Animal Cells ◽  
Contractile Ring ◽  
Biophysical Studies

Studies in fission yeast Schizosaccharomyces pombe have provided the basis for the most advanced models of the dynamics of the cytokinetic contractile ring. Myo2, a class-II myosin, is the major source of tension in the contractile ring, but how Myo2 is anchored and regulated to produce force is poorly understood. To enable more detailed biochemical/biophysical studies, Myo2 was expressed in the baculovirus/Sf9 insect cell system with its two native light chains, Rlc1 and Cdc4. Milligram yields of soluble, unphosphorylated Myo2 were obtained that exhibited high actin-activated ATPase activity and in vitro actin filament motility. The fission yeast specific chaperone Rng3 was thus not required for expression or activity. In contrast to nonmuscle myosins from animal cells that require phosphorylation of the regulatory light chain for activation, phosphorylation of Rlc1 markedly reduced the affinity of Myo2 for actin. Another unusual feature of Myo2 was that, unlike class-II myosins, which generally form bipolar filamentous structures, Myo2 showed no inclination to self-assemble at approximately physiological salt concentrations, as analyzed by sedimentation velocity ultracentrifugation. This lack of assembly supports the hypothesis that clusters of Myo2 depend on interactions at the cell cortex in structural units called nodes for force production during cytokinesis.

scholarly journals HDAC2 Is Involved in the Regulation of BRN3A in Melanocytes and Melanoma

2022 ◽  
Vol 23 (2) ◽  
pp. 849
Author(s):  
Markus V. Heppt ◽  
Anja Wessely ◽  
Eva Hornig ◽  
Claudia Kammerbauer ◽  
Saskia A. Graf ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Histone Acetyltransferase ◽  
Trichostatin A ◽  
Hdac Inhibitors ◽  
Melanoma Cells ◽  
Distal Enhancer ◽  
Aberrant Expression ◽  
Expression Levels ◽  
Epigenetic Regulator ◽  
Class I Hdacs

The neural crest transcription factor BRN3A is essential for the proliferation and survival of melanoma cells. It is frequently expressed in melanoma but not in normal melanocytes or benign nevi. The mechanisms underlying the aberrant expression of BRN3A are unknown. Here, we investigated the epigenetic regulation of BRN3A in melanocytes and melanoma cell lines treated with DNA methyltransferase (DNMT), histone acetyltransferase (HAT), and histone deacetylase (HDAC) inhibitors. DNMT and HAT inhibition did not significantly alter BRN3A expression levels, whereas panHDAC inhibition by trichostatin A led to increased expression. Treatment with the isoform-specific HDAC inhibitor mocetinostat, but not with PCI-34051, also increased BRN3A expression levels, suggesting that class I HDACs HDAC1, HDAC2, and HDAC3, and class IV HDAC11, were involved in the regulation of BRN3A expression. Transient silencing of HDACs 1, 2, 3, and 11 by siRNAs revealed that, specifically, HDAC2 inhibition was able to increase BRN3A expression. ChIP-Seq analysis uncovered that HDAC2 inhibition specifically increased H3K27ac levels at a distal enhancer region of the BRN3A gene. Altogether, our data suggest that HDAC2 is a key epigenetic regulator of BRN3A in melanocytes and melanoma cells. These results highlight the importance of epigenetic mechanisms in regulating melanoma oncogenes.

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