Role of calcium in the regulation of acetylcholine receptor synthesis in cultured muscle cells

Birnbaum, Miriam; Reis, Moshe; Shainberg, Asher

doi:10.1007/bf00583913

Cited by 66 publications

(23 citation statements)

References 25 publications

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“…Protein kinase C has been implicated in the down-regulation of AChR synthesis by electrical activity (32,33). Changes in the levels of intracellular calcium have also been shown to influence muscle AChR synthesis (32,34). The action of ARIA probably does not involve changes in cAMP and/or Ca2+ levels.…”

Section: Resultsmentioning

confidence: 99%

ARIA, a protein that stimulates acetylcholine receptor synthesis, also induces tyrosine phosphorylation of a 185-kDa muscle transmembrane protein.

Corfas

Falls

Fischbach

1993

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

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Motoneurons promote the accumulation of acetylcholine receptors (AChRs) at developing neuromuscular synapses. The AChR-mdudng activity protein ARIA, which is purified from chicken brain and increases the synthesis of AChRs in chicken myotubes, may play a crucial role in this process. Here we show that ARIA induces the rapid tyrosine phosphorylation of a Mr 185,000 protein (p185) in muscle cells. Phosphorylation of p185 correlates with AChR induction at each stage of ARIA purification. Moreover, medium conditioned by spinal cord motoneurons stimulates AChR synthesis and p185 phosphorylation. Studies with membrane-impermeant reagents and 125I-labeled ARIA indicate that p185 is a transmembrane ARIA-receptor tyrosine kinase. Our data suggests that muscle AChR synthesis can be regulated through tyrosine phosphorylation.During formation of the neuromuscular junction, embryonic motor nerve terminals promote the accumulation of acetylcholine receptors (AChRs) and other synaptic proteins in the postsynaptic muscle membrane and cytoplasm. The increase in postsynaptic AChR density is due primarily to an increase in local AChR synthesis (1) and to the aggregation of receptors already present in the membrane at the time of nervemuscle contact (2). There is strong evidence that a form ofthe protein agrin plays a role in AChR aggregation (3,4). Less is known about factors that induce AChR gene expression. We have purified a 42-kDa glycoprotein from chicken brain that stimulates AChR synthesis in cultured embryonic myotubes (5,6). Our hypothesis is that this protein, named ARIA for its acetylcholine receptor inducing activity, regulates receptor synthesis at developing neuromuscular junctions. ARIA stimulation of AChR synthesis is associated with an increase in the level of the a-subunit mRNA in chicken muscle (7). In mouse muscle a prominent effect on the E-subunit mRNA was observed (8). The local increase in AChR synthesis is remarkable because it occurs despite a dramatic decrease in AChR synthesis in extrasynaptic regions of the same muscle cells, as synaptic transmission drives muscle electrical/ mechanical activity.We have begun to study the mechanism by which ARIA regulates AChR subunit gene expression. In this paper we present evidence suggesting that ARIA regulates muscle AChR synthesis by activating a receptor tyrosine kinase. MATERIALS AND METHODSTissue Culture. Chicken myoblasts were dissociated from embryonic day 11 (Eli) pectoral muscle and seeded in 96-or 48-well culture dishes (20,000 and 80,000 cells per well, respectively) in Eagle's minimum essential medium (MEM)/ 10%o horse serum/2% chicken embryo extract. L6 cells were grown in Dulbecco's MEM (DMEM)/10% fetal bovine serum. Motoneurons were dissociated from chicken spinal cords (E5) and purified through metrizamide gradients (9) before plating. Cells were plated in DMEM/F-12 (GIBCO), supplemented with glucose to 4 g/liter, 10%o fetal bovine serum, and chicken muscle extract at 10 ,ug/ml (9).ARIA Purification. ARIA was purified by a modification of ou...

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Section: Resultsmentioning

confidence: 99%

ARIA, a protein that stimulates acetylcholine receptor synthesis, also induces tyrosine phosphorylation of a 185-kDa muscle transmembrane protein.

Corfas

Falls

Fischbach

1993

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

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“…The dramatic decrease in surface AChR was accounted for by an inhibition of assembly of oe subunits into mature receptor and an inhibition of transport of assembled AChR to the cell surface. In another example, primary cultures of embryonic chick myotubes, the level of AChR falls dramatically with the onset of spontaneous contractile activity (Shainberg et al, 1976;Birnbaum, Reis & Shainberg, 1980), and inhibition of activity with the sodium channel blocker, tetrodotoxin, results in an increase in AChR levels. Recently, analyses employing a cloned fragment of the chick a subunit gene to quantitate mRNA levels have shown that tetrodotoxin treatment of active chick myotubes resulted in a 17-fold increase in a subunit mRNA but only a twofold increase in AChR levels (Klarsfeld & Changeux, 1985).…”

Section: Biosynthesis Of Achrmentioning

confidence: 98%

Synthesis and assembly of acetylcholine receptor, a multisubunit membrane glycoprotein

Merlie

Smith

1986

J. Membrain Biol.

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“…A regulatory role of calcium in the expression of sodium channels, acetylcholinesterase, and nicotinic acetylcholine receptor has been suggested (12)(13)(14)(15)(16). In addition, it has recently been shown that calcium influx blocks the expression of nicotinic acetylcholine receptor ␣-subunit gene in chick skeletal muscle (17).…”

mentioning

confidence: 99%

Opposite Effect of Intracellular Ca2+ and Protein Kinase C on the Expression of Inwardly Rectifying K+Channel 1 in Mouse Skeletal Muscle

Shin

Park

Kwon

et al. 1997

Journal of Biological Chemistry

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The level of inwardly rectifying K ؉ channel 1 (IRK1) mRNA decreased upon denervation and increased during muscle differentiation in mouse skeletal muscle. To identify the mechanism(s) underlying the regulation of IRK1 mRNA expression, we examined its expression using the well differentiated C2C12 mouse skeletal muscle cell line as a model system. Since nerve-induced muscle activity results in contraction, it was questioned whether the changes in IRK1 expression might be relevant to the increased intracellular calcium that functions as a cytoplasmic messenger in excitation-contraction coupling. Indeed, activation of either L-type calcium channels or ryanodine receptors increased the level of IRK1 mRNA. More directly, ionomycin activated the IRK1 expression in time-and dose-dependent manners, which was abolished by treatment with EGTA. Genistein, a tyrosine kinase inhibitor, also abolished the stimulating effect of ionomycin. Meanwhile, activation of protein kinase C by 12-O-tetradecanoylphorbol acetate (TPA) markedly decreased the level of IRK1 mRNA, which required ongoing protein synthesis. Actinomycin D experiments revealed that ionomycin increased the half-life of IRK1 mRNA from 0.86 to 1.97 h, but TPA decreased it to 0.38 h. However, neither ionomycin nor TPA appreciably altered the rate of IRK1 gene transcription. Based on these observations, we conclude that intracellular calcium and protein kinase C are oppositely involved in the muscle activity-dependent regulation of IRK1 gene expression and that both act at the level of mRNA stability.It has been known that denervation influences many biophysical and biochemical properties of skeletal muscle fibers (1-7). The mechanisms by which denervation initiates these changes are still unclear. They may be caused by the loss of neurotrophic factors normally released from the nerve terminals (8, 9). Alternatively, the electrical inactivity of the denervated muscle might be responsible, since direct electrical stimulation to the denervated muscle restores all passive electrical parameters of the membrane that were observed without denervation (10, 11). Considering the importance of calcium in the process of muscle contraction induced by neural activity, calcium may play a critical role in linking the biochemical and biophysical changes with muscle activity.Calcium is known to be involved in many cellular events as a second messenger. A regulatory role of calcium in the expression of sodium channels, acetylcholinesterase, and nicotinic acetylcholine receptor has been suggested (12-16). In addition, it has recently been shown that calcium influx blocks the expression of nicotinic acetylcholine receptor ␣-subunit gene in chick skeletal muscle (17). There are reports that coupling of the electrical activity with altered gene expression is mediated by protein kinase C (PKC) 1 pathway (18, 19). Gonoi and Hasegawa (20) demonstrate by using a patch clamp method that innervation of skeletal muscle fibers plays a key role in the induction and maintenance of inwardly rectifyin...

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Role of calcium in the regulation of acetylcholine receptor synthesis in cultured muscle cells

Cited by 66 publications

References 25 publications

ARIA, a protein that stimulates acetylcholine receptor synthesis, also induces tyrosine phosphorylation of a 185-kDa muscle transmembrane protein.

ARIA, a protein that stimulates acetylcholine receptor synthesis, also induces tyrosine phosphorylation of a 185-kDa muscle transmembrane protein.

Synthesis and assembly of acetylcholine receptor, a multisubunit membrane glycoprotein

Opposite Effect of Intracellular Ca2+ and Protein Kinase C on the Expression of Inwardly Rectifying K+Channel 1 in Mouse Skeletal Muscle

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