Evaluation of RNA polymerase activities in nuclei isolated from slow and fast skeletal muscles

Epigenetic regulation of gene expression differs between fast- and slow-twitch skeletal muscles in adult rats, although the precise mechanisms are still unknown. The present study investigates the differences in responses of RNA polymerase II (Pol II) and histone acetylation during transcriptional activation in the plantaris and soleus muscles of adult rats after acute treadmill running. We targeted the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) gene to analyze epigenomic changes by chromatin immunoprecipitation. The mRNA expression of the PGC-1α-b isoform was significantly upregulated in both plantaris and soleus muscles 2 h after acute running, although the magnitude of the upregulation was more pronounced in the plantaris muscle. The sequences of proximal exons of the PGC-1α locus were expressed more in the plantaris muscle after acute running. Accumulation of Pol II was noted near the alternative exon 1 in both plantaris and soleus muscles in association with the enhanced distribution of acetylated histone 3. Accumulation of Pol II was also observed at the transcription start site, exon 2, and exon 3 in the plantaris muscle, but not the soleus muscle. It was noted that in the soleus muscle, acetylation of histone 3 at lysine 27 was enhanced throughout the PGC-1α locus in response to transcriptional activation, suggesting that elongating Pol II was capable of traveling through to the end of the locus. These results indicate that the mobility of Pol II during PGC-1α transcription differed between fast- and slow-twitch skeletal muscles, affecting the strength of the transcriptional activity. NEW & NOTEWORTHY Fast- and slow-twitch skeletal muscles have distinct characteristics in both force production and metabolism. Epigenetic regulations also largely differ in these muscles. Here we show that RNA polymerase II is distributed extensively at the proximal regions downstream of transcription start site during the transcriptional activation of PGC-1α in fast-twitch muscles, but it accumulates at the first exon in slow-twitch muscles. These findings will provide a basis to understand type-specific mechanisms in skeletal muscle.

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RNA polymerase: Preparation and structural analysis of helical polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010011091x ◽

1984 ◽

Vol 42 ◽

pp. 152-153

Author(s):

E. Loren Buhle ◽

Pamela Rew ◽

Ueli Aebi

Keyword(s):

Structural Analysis ◽

Rna Polymerase ◽

Molecular Level ◽

X Ray Diffraction ◽

Helical Polymers ◽

X Ray ◽

E Coli ◽

The Past ◽

Ordered Arrays ◽

Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

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Distribution of c-protein isoforms in sarcomeres of developing chick skeletal muscle

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010319x ◽

1988 ◽

Vol 46 ◽

pp. 226-227

Author(s):

D. A. Fischman ◽

J. E. Dennis ◽

T. Obinata ◽

H. Takano-Ohmuro

Keyword(s):

Skeletal Muscles ◽

Thick Filament ◽

Protein Isoforms ◽

Actin Binding ◽

Striated Muscles ◽

C Protein ◽

Sarcomeric Protein ◽

Thick Filaments ◽

Cross Bridges ◽

Bridge Bearing

C-protein is a 150 kDa protein found within the A bands of all vertebrate cross-striated muscles. By immunoelectron microscopy, it has been demonstrated that C-protein is distributed along a series of 7-9 transverse stripes in the medial, cross-bridge bearing zone of each A band. This zone is now termed the C-zone of the sarcomere. Interest in this protein has been sparked by its striking distribution in the sarcomere: the transverse repeat between C-protein stripes is 43 nm, almost exactly 3 times the 14.3 nm axial repeat of myosin cross-bridges along the thick filaments. The precise packing of C-protein in the thick filament is still unknown. It is the only sarcomeric protein which binds to both myosin and actin, and the actin-binding is Ca-sensitive. In cardiac and slow, but not fast, skeletal muscles C-protein is phosphorylated. Amino acid composition suggests a protein of little or no αhelical content. Variant forms (isoforms) of C-protein have been identified in cardiac, slow and embryonic muscles.

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The effect of ionophore A23178 on the α-actinin crosslinks in the z-band of frog skeletal muscle: An EM study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100142396 ◽

1986 ◽

Vol 44 ◽

pp. 154-155

Author(s):

F.T. Llados ◽

V. Krlho ◽

G.D. Pappas

Keyword(s):

Muscle Damage ◽

Transmitter Release ◽

Skeletal Muscles ◽

Calcium Uptake ◽

Muscle Membrane ◽

Frog Skeletal Muscle ◽

Ach Release ◽

Sustained Action ◽

Calcium Deposits ◽

Intense Stimulation

It Is known that Ca++ enters the muscle fiber at the junctional area during the action of the neurotransmitter, acetylcholine (ACh). Pappas and Rose demonstrated that following Intense stimulation, calcium deposits are found In the postsynaptic muscle membrane, Indicating the existence of calcium uptake In the postsynaptic area following ACh release. In addition to this calcium uptake, when mammal Ian skeletal muscles are exposed to a sustained action of the neurotransmitter, muscle damage develops. These same effects, l.e., Increased transmitter release, calcium uptake and finally muscle damage, can be obtained by Incubating the muscle with lonophore A23178.

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Nutrient-regulated gene expression in eukaryotes

Biochemical Society Symposium ◽

10.1042/bss0730085 ◽

2006 ◽

Vol 73 ◽

pp. 85-96 ◽

Cited By ~ 8

Author(s):

Richard J. Reece ◽

Laila Beynon ◽

Stacey Holden ◽

Amanda D. Hughes ◽

Karine Rébora ◽

...

Keyword(s):

Gene Expression ◽

Rna Polymerase ◽

Rna Polymerase Ii ◽

Transcriptional Control ◽

Direct Interaction ◽

Signalling Pathways ◽

A Cell ◽

One Step ◽

Higher Eukaryotes ◽

Regulated Gene Expression

The recognition of changes in environmental conditions, and the ability to adapt to these changes, is essential for the viability of cells. There are numerous well characterized systems by which the presence or absence of an individual metabolite may be recognized by a cell. However, the recognition of a metabolite is just one step in a process that often results in changes in the expression of whole sets of genes required to respond to that metabolite. In higher eukaryotes, the signalling pathway between metabolite recognition and transcriptional control can be complex. Recent evidence from the relatively simple eukaryote yeast suggests that complex signalling pathways may be circumvented through the direct interaction between individual metabolites and regulators of RNA polymerase II-mediated transcription. Biochemical and structural analyses are beginning to unravel these elegant genetic control elements.

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