Involvement of the Dihydropyridine Receptor and Internal Ca2+Stores in Myoblast Fusion

Seigneurin-Venin, Sophie; Parrish, Elaine; Marty, Isabelle; Rieger, François; Romey, Georges; Villaz, Michel; Garcı́a, Luis

doi:10.1006/excr.1996.0085

Cited by 35 publications

(37 citation statements)

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“…The mechanism by which Ca 2ϩ enters myoblasts before fusion is still a matter of debate (7)(8)(9)(10). Using clonal myoblast cultures, we have examined how Ca 2ϩ enters human myoblasts at the onset of fusion.…”

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confidence: 99%

T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

Bijlenga¹,

Liu²,

Espinos³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

177

194

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Mechanisms underlying Ca 2؉ signaling during human myoblast terminal differentiation were studied using cell cultures. We found that T-type Ca 2؉ channels (T-channels) are expressed in myoblasts just before fusion. Their inhibition by amiloride or Ni 2؉ suppresses fusion and prevents an intracellular Ca 2؉ concentration increase normally observed at the onset of fusion. The use of antisense oligonucleotides indicates that the functional T-channels are formed by ␣1H subunits. At hyperpolarized potentials, these channels allow a window current sufficient to increase [Ca 2؉ ]i. As hyperpolarization is a prerequisite to myoblast fusion, we conclude that the Ca 2؉ signal required for fusion is produced when the resting potential enters the T-channel window. A similar mechanism could operate in other cell types of which differentiation implicates membrane hyperpolarization.

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confidence: 99%

T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

Bijlenga¹,

Liu²,

Espinos³

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

177

194

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“…The close relation between cytosolic Ca 2ϩ increase and fusion was analyzed by Constantin et al (11): the observed increase of cytosolic Ca 2ϩ was not attributed to voltage-dependent or voltage-gated channels but to other mechanisms such as cholinergic action (11). A model of cytosolic Ca 2ϩ control during L6 myoblast fusion involving cardiac L-type Ca 2ϩ channels [dihydropyridine-sensitive voltage-operated Ca 2ϩ channels (DHPR)] and intracellular Ca 2ϩ stores was proposed by Seigneurin-Venin et al (28). Recently, a careful analysis of ionic transmembrane currents has shown that an increase of myoblast membrane potential represents the preliminary step for fusion and differentiation.…”

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confidence: 99%

Increase in cytosolic Ca²⁺ induced by elevation of extracellular Ca²⁺ in skeletal myogenic cells

Naro

Arcangelis

Coletti

et al. 2003

American Journal of Physiology-Cell Physiology

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The identification of proteins supporting the Ca 2ϩ influx through the cell membrane or the Ca 2ϩ release from intracellular stores in mononucleated cells with myogenic potential is still controversial. A recent detailed study carried out on human myoblasts showed the expression of the L-type Ca 2ϩ channels (DHPR) and, although at a very low level, of ryanodine receptors (RyR) (32), suggesting that proteins involved in the control of [Ca 2ϩ ] i are already present in undifferentiated myoblasts. In this latter study, however, no substantial Ca 2ϩ transient was observed in mononucleated cells. The presence of T-type Ca 2ϩ channels and their role in triggering myoblast fusion was demonstrated by Bijlenga et al. (6) in human myogenic cells.A simple and direct way to address the question about the mechanism supporting the increase in cytosolic Ca 2ϩ is to record [Ca 2ϩ ] i using a Ca 2ϩ indicatorAddress for reprint requests and other correspondence: F. Naro, Dipartimento Istologia ed Embriologia Medica, Università "La Sapienza" via Scarpa 14, 00161 Rome, Italy (E-mail: fabio.naro @uniroma1.it).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked ''advertisement'' in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. J Physiol Cell Physiol 284: C969-C976, 2003. First published December 21, 2002 10.1152/ajpcell.00237.2002 Am

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“…One intriguing observation is that part of the same basic sequence involved in translocation also appears to mediate the interaction with RyR1. For instance, mutation of Arg 24 of MCa, which belongs to the putative CPP sequence, results in a complete loss of interaction with RyR1 (4). Interestingly, part of the PTD of HIV-1 Tat, the Gly-Arg-Lys-LysArg-Arg sequence, is also a potential nuclear localization sequence (12).…”

Section: Discussionmentioning

confidence: 99%

“…Differentiation of L6 cells was induced by a shift to differentiation medium (Dulbecco's modified Eagle's medium ϩ 5% horse serum) when they reached confluence, as described previously (24).…”

Section: (23) Protein Concentration Was Measured By the Biuret Methodmentioning

confidence: 99%

Transduction of the Scorpion Toxin Maurocalcine into Cells

Estève

Mabrouk

Dupuis

et al. 2005

Journal of Biological Chemistry

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Maurocalcine (MCa) is a 33-amino-acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. External application of MCa to cultured myotubes is known to produce Ca 2؉ release from intracellular stores. MCa binds directly to the skeletal muscle isoform of the ryanodine receptor, an intracellular channel target of the endoplasmic reticulum, and induces long lasting channel openings in a mode of smaller conductance. Here we investigated the way MCa proceeds to cross biological membranes to reach its target. A biotinylated derivative of MCa was produced (MCa b ) and complexed with a fluorescent indicator (streptavidine-cyanine 3) to follow the cell penetration of the toxin. The toxin complex efficiently penetrated into various cell types without requiring metabolic energy (low temperature) or implicating an endocytosis mechanism. MCa appeared to share the same features as the so-called cell-penetrating peptides. Our results provide evidence that MCa has the ability to act as a molecular carrier and to cross cell membranes in a rapid manner (1-2 min), making this toxin the first demonstrated example of a scorpion toxin that translocates into cells.

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Involvement of the Dihydropyridine Receptor and Internal Ca2+Stores in Myoblast Fusion

Cited by 35 publications

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T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

Increase in cytosolic Ca²⁺ induced by elevation of extracellular Ca²⁺ in skeletal myogenic cells

Transduction of the Scorpion Toxin Maurocalcine into Cells

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Involvement of the Dihydropyridine Receptor and Internal Ca2+Stores in Myoblast Fusion

Cited by 35 publications

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T-type α1H Ca 2+ channels are involved in Ca 2+ signaling during terminal differentiation (fusion) of human myoblasts

T-type α1H Ca 2+ channels are involved in Ca 2+ signaling during terminal differentiation (fusion) of human myoblasts

Increase in cytosolic Ca2+ induced by elevation of extracellular Ca2+ in skeletal myogenic cells

Transduction of the Scorpion Toxin Maurocalcine into Cells

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T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

T-type α1H Ca ²⁺ channels are involved in Ca ²⁺ signaling during terminal differentiation (fusion) of human myoblasts

Increase in cytosolic Ca²⁺ induced by elevation of extracellular Ca²⁺ in skeletal myogenic cells