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Activity-dependent and -independent nuclear fluxes of HDAC4 mediated by different kinases in adult skeletal muscle.

Liu Y, Randall WR, Schneider MF - J. Cell Biol. (2005)

Bottom Line: Class II histone deacetylases (HDACs) may decrease slow muscle fiber gene expression by repressing myogenic transcription factor myocyte enhancer factor 2 (MEF2).Thus, calcium transients for slow, but not fast, fiber stimulation patterns appear to provide sufficient Ca(2+)-dependent activation of nuclear CaMKII to result in net nuclear efflux of HDAC4.Nucleocytoplasmic shuttling of HDAC4-GFP in unstimulated resting fibers was not altered by KN-62, but was blocked by staurosporine, indicating that different kinases underlie nuclear efflux of HDAC4 in resting and stimulated muscle fibers.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

ABSTRACT
Class II histone deacetylases (HDACs) may decrease slow muscle fiber gene expression by repressing myogenic transcription factor myocyte enhancer factor 2 (MEF2). Here, we show that repetitive slow fiber type electrical stimulation, but not fast fiber type stimulation, caused HDAC4-GFP, but not HDAC5-GFP, to translocate from the nucleus to the cytoplasm in cultured adult skeletal muscle fibers. HDAC4-GFP translocation was blocked by calmodulin-dependent protein kinase (CaMK) inhibitor KN-62. Slow fiber type stimulation increased MEF2 transcriptional activity, nuclear Ca(2+) concentration, and nuclear levels of activated CaMKII, but not total nuclear CaMKII or CaM-YFP. Thus, calcium transients for slow, but not fast, fiber stimulation patterns appear to provide sufficient Ca(2+)-dependent activation of nuclear CaMKII to result in net nuclear efflux of HDAC4. Nucleocytoplasmic shuttling of HDAC4-GFP in unstimulated resting fibers was not altered by KN-62, but was blocked by staurosporine, indicating that different kinases underlie nuclear efflux of HDAC4 in resting and stimulated muscle fibers.

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There was no significant change in subcellular distribution of HDAC5-GFP in fibers stimulated with 10-Hz trains. (A) A fiber expressing HDAC5-GFP is shown 30 min before (−30), at the start of (0), and after stimulation for 60 or 120 min. Because of the relatively low cytoplasmic HDAC5, only the nuclei are apparent. (B) The average fluorescent intensity per pixel over whole nuclei (closed circles) or over the cytoplasm (open circles) was quantitated and normalized. After 2 h of 10-Hz train stimulation, there was no significant decline of nuclear fluorescence. Bar, 10 μM.
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fig5: There was no significant change in subcellular distribution of HDAC5-GFP in fibers stimulated with 10-Hz trains. (A) A fiber expressing HDAC5-GFP is shown 30 min before (−30), at the start of (0), and after stimulation for 60 or 120 min. Because of the relatively low cytoplasmic HDAC5, only the nuclei are apparent. (B) The average fluorescent intensity per pixel over whole nuclei (closed circles) or over the cytoplasm (open circles) was quantitated and normalized. After 2 h of 10-Hz train stimulation, there was no significant decline of nuclear fluorescence. Bar, 10 μM.

Mentions: Both HDAC4 and HDAC5 are class II histone deacetylases, exhibiting high levels of expression in skeletal muscle and involvement in muscle differentiation (Lu et al., 2000; McKinsey et al., 2000a). Fibers expressing HDAC5-GFP were repetitively stimulated with 10-Hz trains for 5 s every 50 s, as in fibers expressing HDAC4-GFP. Surprisingly, 2 h of 10-Hz train stimulation, which resulted in ∼49% drop of nuclear HDAC4-GFP, decreased the nuclear HDAC5-GFP by only 11% (Fig. 5, A and B, 10 nuclei from 5 fibers), suggesting a significant difference between HDAC4 and HDAC5 in the sensitivity to the electrical stimulation. Another difference between HDAC4 and 5-GFP was that under resting conditions without electrical stimulation, the mean value of the ratio of cytoplasmic to nuclear mean pixel fluorescence was 51 ± 4% for HDAC4-GFP (28 nuclei from 16 fibers) but only 13 ± 2% for HDAC5-GFP (31 nuclei from 17 fibers), indicating more effective nuclear retention of HDAC5.


Activity-dependent and -independent nuclear fluxes of HDAC4 mediated by different kinases in adult skeletal muscle.

Liu Y, Randall WR, Schneider MF - J. Cell Biol. (2005)

There was no significant change in subcellular distribution of HDAC5-GFP in fibers stimulated with 10-Hz trains. (A) A fiber expressing HDAC5-GFP is shown 30 min before (−30), at the start of (0), and after stimulation for 60 or 120 min. Because of the relatively low cytoplasmic HDAC5, only the nuclei are apparent. (B) The average fluorescent intensity per pixel over whole nuclei (closed circles) or over the cytoplasm (open circles) was quantitated and normalized. After 2 h of 10-Hz train stimulation, there was no significant decline of nuclear fluorescence. Bar, 10 μM.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171787&req=5

fig5: There was no significant change in subcellular distribution of HDAC5-GFP in fibers stimulated with 10-Hz trains. (A) A fiber expressing HDAC5-GFP is shown 30 min before (−30), at the start of (0), and after stimulation for 60 or 120 min. Because of the relatively low cytoplasmic HDAC5, only the nuclei are apparent. (B) The average fluorescent intensity per pixel over whole nuclei (closed circles) or over the cytoplasm (open circles) was quantitated and normalized. After 2 h of 10-Hz train stimulation, there was no significant decline of nuclear fluorescence. Bar, 10 μM.
Mentions: Both HDAC4 and HDAC5 are class II histone deacetylases, exhibiting high levels of expression in skeletal muscle and involvement in muscle differentiation (Lu et al., 2000; McKinsey et al., 2000a). Fibers expressing HDAC5-GFP were repetitively stimulated with 10-Hz trains for 5 s every 50 s, as in fibers expressing HDAC4-GFP. Surprisingly, 2 h of 10-Hz train stimulation, which resulted in ∼49% drop of nuclear HDAC4-GFP, decreased the nuclear HDAC5-GFP by only 11% (Fig. 5, A and B, 10 nuclei from 5 fibers), suggesting a significant difference between HDAC4 and HDAC5 in the sensitivity to the electrical stimulation. Another difference between HDAC4 and 5-GFP was that under resting conditions without electrical stimulation, the mean value of the ratio of cytoplasmic to nuclear mean pixel fluorescence was 51 ± 4% for HDAC4-GFP (28 nuclei from 16 fibers) but only 13 ± 2% for HDAC5-GFP (31 nuclei from 17 fibers), indicating more effective nuclear retention of HDAC5.

Bottom Line: Class II histone deacetylases (HDACs) may decrease slow muscle fiber gene expression by repressing myogenic transcription factor myocyte enhancer factor 2 (MEF2).Thus, calcium transients for slow, but not fast, fiber stimulation patterns appear to provide sufficient Ca(2+)-dependent activation of nuclear CaMKII to result in net nuclear efflux of HDAC4.Nucleocytoplasmic shuttling of HDAC4-GFP in unstimulated resting fibers was not altered by KN-62, but was blocked by staurosporine, indicating that different kinases underlie nuclear efflux of HDAC4 in resting and stimulated muscle fibers.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

ABSTRACT
Class II histone deacetylases (HDACs) may decrease slow muscle fiber gene expression by repressing myogenic transcription factor myocyte enhancer factor 2 (MEF2). Here, we show that repetitive slow fiber type electrical stimulation, but not fast fiber type stimulation, caused HDAC4-GFP, but not HDAC5-GFP, to translocate from the nucleus to the cytoplasm in cultured adult skeletal muscle fibers. HDAC4-GFP translocation was blocked by calmodulin-dependent protein kinase (CaMK) inhibitor KN-62. Slow fiber type stimulation increased MEF2 transcriptional activity, nuclear Ca(2+) concentration, and nuclear levels of activated CaMKII, but not total nuclear CaMKII or CaM-YFP. Thus, calcium transients for slow, but not fast, fiber stimulation patterns appear to provide sufficient Ca(2+)-dependent activation of nuclear CaMKII to result in net nuclear efflux of HDAC4. Nucleocytoplasmic shuttling of HDAC4-GFP in unstimulated resting fibers was not altered by KN-62, but was blocked by staurosporine, indicating that different kinases underlie nuclear efflux of HDAC4 in resting and stimulated muscle fibers.

Show MeSH
Related in: MedlinePlus