Limits...
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.

Show MeSH

Related in: MedlinePlus

Images of a fiber expressing HDAC4-GFP before and during stimulation with 10-Hz trains. A fiber expressing HDAC4-GFP is shown in Ringer's solution at RT 30 min before stimulation (−30), at the start of stimulation (0), and after stimulation for 60 or 120 minutes with 5-s duration trains of 10-Hz pulses applied every 50 s. After 2-h stimulation there is a significant decline of fluorescence in all the nuclei. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2171787&req=5

fig1: Images of a fiber expressing HDAC4-GFP before and during stimulation with 10-Hz trains. A fiber expressing HDAC4-GFP is shown in Ringer's solution at RT 30 min before stimulation (−30), at the start of stimulation (0), and after stimulation for 60 or 120 minutes with 5-s duration trains of 10-Hz pulses applied every 50 s. After 2-h stimulation there is a significant decline of fluorescence in all the nuclei. Bar, 10 μm.

Mentions: HDAC4-GFP fusion protein was present in both the cytoplasm in a sarcomeric pattern and nucleus of fully differentiated adult flexor digitorum brevis (FDB) skeletal muscle fibers in culture after transduction with adenovirus and expression for ∼3 d (Fig. 1). The mean value of the ratio of nuclear to cytoplasmic mean pixel fluorescence was 2.4 ± 0.2 (28 nuclei from 16 HDAC4-GFP–infected fibers). Hemagglutinin-tagged HDAC4 (HDAC4-HA) showed a similar pattern of distribution as HDAC4-GFP–infected and immunostained FDB fibers (unpublished data). HDAC4-GFP–infected FDB fibers exhibited variable numbers of 1–2-μm-long elongated inclusion bodies in the cytoplasm (Kirsh et al., 2002), generally oriented parallel to the fiber axis, as did HDAC4-HA–infected fibers stained with anti-HA antibody (unpublished data). Thus, these inclusion bodies result from HDAC4 and not the GFP moiety. Inclusion bodies were not included in analyzing the fluorescence of cytoplasmic HDAC4-GFP. Self-aggregation of HDAC4 both in the cytoplasm and nucleus of other cell types has been reported previously, possibly due to an NH2-terminal HDAC4 dimerization domain and sumolyation of HDAC4 (Kirsh et al., 2002).


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)

Images of a fiber expressing HDAC4-GFP before and during stimulation with 10-Hz trains. A fiber expressing HDAC4-GFP is shown in Ringer's solution at RT 30 min before stimulation (−30), at the start of stimulation (0), and after stimulation for 60 or 120 minutes with 5-s duration trains of 10-Hz pulses applied every 50 s. After 2-h stimulation there is a significant decline of fluorescence in all the nuclei. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

fig1: Images of a fiber expressing HDAC4-GFP before and during stimulation with 10-Hz trains. A fiber expressing HDAC4-GFP is shown in Ringer's solution at RT 30 min before stimulation (−30), at the start of stimulation (0), and after stimulation for 60 or 120 minutes with 5-s duration trains of 10-Hz pulses applied every 50 s. After 2-h stimulation there is a significant decline of fluorescence in all the nuclei. Bar, 10 μm.
Mentions: HDAC4-GFP fusion protein was present in both the cytoplasm in a sarcomeric pattern and nucleus of fully differentiated adult flexor digitorum brevis (FDB) skeletal muscle fibers in culture after transduction with adenovirus and expression for ∼3 d (Fig. 1). The mean value of the ratio of nuclear to cytoplasmic mean pixel fluorescence was 2.4 ± 0.2 (28 nuclei from 16 HDAC4-GFP–infected fibers). Hemagglutinin-tagged HDAC4 (HDAC4-HA) showed a similar pattern of distribution as HDAC4-GFP–infected and immunostained FDB fibers (unpublished data). HDAC4-GFP–infected FDB fibers exhibited variable numbers of 1–2-μm-long elongated inclusion bodies in the cytoplasm (Kirsh et al., 2002), generally oriented parallel to the fiber axis, as did HDAC4-HA–infected fibers stained with anti-HA antibody (unpublished data). Thus, these inclusion bodies result from HDAC4 and not the GFP moiety. Inclusion bodies were not included in analyzing the fluorescence of cytoplasmic HDAC4-GFP. Self-aggregation of HDAC4 both in the cytoplasm and nucleus of other cell types has been reported previously, possibly due to an NH2-terminal HDAC4 dimerization domain and sumolyation of HDAC4 (Kirsh et al., 2002).

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