Reversal of the relative expression of cardiac and skeletal alpha1 subunit isoforms of L-type calcium channel during in vitro myogenesis

Bulteau, Laurence; Cogné, Michel; Cognard, Christian; Raymond, Guy

doi:10.1007/s004240050291

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…Differentiation of H9c2 cells to myotubes resulted in the expression of both subunits on the transcriptional level. This is in line with a study on subunit expression in primary skeletal muscle cell cultures from hindlimbs of neonatal rats [Bulteau et al, 1997] demonstrating co-expression of both subunits in earlier states of myotube formation during in vitro myogenesis. Reduced transcript levels for phospholamban and the cardiac ryanodine receptor and diminished protein expression of the cardiac subunit of the L-type Ca 2ϩ channel furthermore characterize the skeletal muscle-like phenotype of H9c2 myotubes.…”

Section: Discussionsupporting

confidence: 84%

Differentiation-dependent expression of cardiac δ-CaMKII isoforms

et al. 1998

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Despite their important role in controlling the cardiac Ca2+ homeostasis, presence and functions of individual isoforms of the multifunctional Ca2+/calmodulin-dependent protein kinase in the heart are not well studied. Here we report on expression of isoforms of the delta class in two differentiation states of the embryonic rat heart-derived cell line H9c2 compared to adult rat heart. Reverse transcription coupled polymerase chain reaction analysis revealed specific expression patterns of four variants of the delta class (delta B, delta C, delta 4, delta 9) in adult rat heart, H9c2 myoblasts, and skeletal muscle-like H9c2 myotubes. delta C was identified as a common isoform with higher amounts in H9c2 cells and the prominent one in myoblasts. In contrast, expression of delta 9 accompanied cardiac as well as skeletal muscle differentiation. Expression of delta B, however, was representative for differentiated cardiac muscle, whereas delta 4 expression coincided with differentiation into the skeletal muscle-like state. Our results demonstrate differentiation-dependent isoform expression of the delta class of the multifunctional Ca2+/calmodulin-dependent protein kinase of muscle. The identification of cardiac target proteins for this kinase, e.g. the alpha 1-subunit of the L-type Ca2+ channel, the sarcoplasmic reticulum Ca(2+)-ATPase, phospholamban and the ryanodine receptor define H9c2 myoblasts as a suitable model system for further functional characterization of the identified cardiac delta isoforms.

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Section: Discussionsupporting

confidence: 84%

Differentiation-dependent expression of cardiac δ-CaMKII isoforms

et al. 1998

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“…In this respect, it is important to note that newborn cardiac myocytes in primary culture express functional ␣ 1S that generates contractile activity (42). Conversely, skeletal muscle cells in vitro, as well as developing muscle cells in vivo, do express cardiac ␣ 1C mRNA (43,44). Altogether, our data provide new insights into the tissue-specific expression of L-type Ca 2ϩ channel isotypes and further suggest that the expression of functional skeletal L-type Ca 2ϩ channels can occur within the cardiac cell lineage through a de-differentiation process demonstrated in vitro in a cardiac cell line model.…”

Section: Retinoic Acid Modulation Of Ca 2ϩ Channel Expressionmentioning

confidence: 71%

Modulation of L-type Calcium Channel Expression during Retinoic Acid-induced Differentiation of H9C2 Cardiac Cells

Ménard

Pupier

Mornet

et al. 1999

Journal of Biological Chemistry

167

157

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The molecular mechanisms underlying the developmental regulation of L-type voltage-dependent Ca 2؉ channels (VDCCs) are still unknown. In this study, we have characterized the expression patterns of skeletal (␣ 1S ) and cardiac (␣ 1C ) L-type VDCCs during cardiogenic differentiation in H9C2 cells that derived from embryonic rat heart. We report that chronic treatment of H9C2 cells with 10 nM all-trans-retinoic acid (all-trans-RA) enhanced cardiac Ca 2؉ channel expression, as demonstrated by reverse transcription-polymerase chain reaction, immunoblotting, and indirect immunofluorescence studies, as well as patch-clamp experiments. In addition, RA treatment prevented expression of functional skeletal L-type VDCCs, which were restricted to myotubes that spontaneously appear in control H9C2 cultures undergoing myogenic transdifferentiation. The use of specific skeletal and cardiac markers indicated that RA, by preventing myogenic transdifferentiation, preserves cardiac differentiation of this cell line. Altogether, we provide evidence that cardiac and skeletal subtype-specific L-type Ca 2؉ channels are relevant functional markers of differentiated cardiac and skeletal myocytes, respectively. In conclusion, our data demonstrate that in vitro RA stimulates cardiac (␣ 1C ) L-type Ca 2؉ channel expression, therefore supporting the hypothesis that the RA pathway might be involved in the tissue specific expression of Ca 2؉ channels in mature cardiac cells.

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“…Chaudhari and Beam (1993) showed that mRNA for the cardiac ␣ 1C subunit is abundant in dysgenic and normal muscle. Furthermore, mRNA for ␣ 1C has been reported in a dysgenic cell line (Varadi et al, 1995), as well as in primary cultures of normal myotubes (Bulteau et al, 1977) and in normal adult rodent skeletal muscle (Pereon et al, 1997). Cardiac-type Ca 2ϩ currents are also present in the dysgenic cell line (Varadi et al, 1995).…”

Section: Discussionmentioning

confidence: 99%

Molecular Origin of the L-Type Ca2+ Current of Skeletal Muscle Myotubes Selectively Deficient in Dihydropyridine Receptor β1a Subunit

Strube

Beurg

Sukhareva

et al. 1998

Biophysical Journal

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The origin of Ibetanull, the Ca2+ current of myotubes from mice lacking the skeletal dihydropyridine receptor (DHPR) beta1a subunit, was investigated. The density of Ibetanull was similar to that of Idys, the Ca2+ current of myotubes from dysgenic mice lacking the skeletal DHPR alpha1S subunit (-0.6 +/- 0.1 and -0.7 +/- 0.1 pA/pF, respectively). However, Ibetanull activated at significantly more positive potentials. The midpoints of the GCa-V curves were 16.3 +/- 1.1 mV and 11.7 +/- 1.0 mV for Ibetanull and Idys, respectively. Ibetanull activated significantly more slowly than Idys. At +30 mV, the activation time constant for Ibetanull was 26 +/- 3 ms, and that for Idys was 7 +/- 1 ms. The unitary current of normal L-type and beta1-null Ca2+ channels estimated from the mean variance relationship at +20 mV in 10 mM external Ca2+ was 22 +/- 4 fA and 43 +/- 7 fA, respectively. Both values were significantly smaller than the single-channel current estimated for dysgenic Ca2+ channels, which was 84 +/- 9 fA under the same conditions. Ibetanull and Idys have different gating and permeation characteristics, suggesting that the bulk of the DHPR alpha1 subunits underlying these currents are different. Ibetanull is suggested to originate primarily from Ca2+ channels with a DHPR alpha1S subunit. Dysgenic Ca2+ channels may be a minor component of this current. The expression of DHPR alpha1S in beta1-null myotubes and its absence in dysgenic myotubes was confirmed by immunofluorescence labeling of cells.

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Reversal of the relative expression of cardiac and skeletal alpha1 subunit isoforms of L-type calcium channel during in vitro myogenesis

Cited by 8 publications

References 12 publications

Differentiation-dependent expression of cardiac δ-CaMKII isoforms

Differentiation-dependent expression of cardiac δ-CaMKII isoforms

Modulation of L-type Calcium Channel Expression during Retinoic Acid-induced Differentiation of H9C2 Cardiac Cells

Molecular Origin of the L-Type Ca2+ Current of Skeletal Muscle Myotubes Selectively Deficient in Dihydropyridine Receptor β1a Subunit

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