Protein Kinase C and Calcium/Calmodulin-activated Protein Kinase II (CaMK II) Suppress Nicotinic Acetylcholine Receptor Gene Expression in Mammalian Muscle

Abstract

Nicotinic acetylcholine receptor (nAChR) gene expression is regulated by both muscle activity and increased intracellular calcium. This regulation is an important developmental event that rids receptors from the extrajunctional region of the developing muscle fiber. In avian muscle, it has been proposed that muscle activity suppresses nAChR gene expression via calciumactivated protein kinase C (PKC)-dependent phosphorylation of the myogenic transcription factor, myogenin. Here, we examined the role that PKC and other kinases play in mediating calcium-and activity-dependent suppression of nAChR genes in rat primary myotubes. We found that although activated PKC could regulate nAChR promoter activity and transiently suppressed both nAChR and myogenin gene expression, it did not appear to be required for calcium-or activity-dependent control of nAChR gene expression in mammalian muscle. Neither depletion of PKC from myotubes nor specific pharmacological inhibition of PKC blocked the suppression of nAChR gene expression produced by calcium or muscle depolarization. In contrast, we provide evidence that calcium/calmodulin-activated protein kinase II participates in mediating the effects of muscle depolarization on nAChR and myogenin gene expression. Nicotinic acetylcholine receptors (nAChRs)1 mediate communication between motor neurons and skeletal muscle. They are ligand-gated ion channels that are composed of four different subunits with a stoichiometry of ␣ 2 ␤␥(⑀)␦. The nerve plays an important role in regulating the expression and distribution of nAChRs along the surface of the muscle fiber (reviewed in Ref.

Protein Kinase C Activates Human Lipocalin-type Prostaglandin D Synthase Gene Expression through De-repression of Notch-HES Signaling and Enhancement of AP-2β Function in Brain-derived TE671 Cells

“…Functional Expression of PKC␣-pFLAG-ca.PKC␣ vector carrying the catalytic domain of PKC␣ was constructed as described (38). TE671 cells was transfected with pFLAG-ca.PKC␣ in the presence or absence of L-PGDS promoter-reporter construct.…”

Transcriptional Regulation of Acetylcholinesterase-associated Collagen ColQ

“…Secondly, activation of the Ca 2ϩ /calmodulin-activated protein kinase II (47) and Ser/Thr kinase (48) have been shown to mediate the activity-dependent extrasynaptic repression of AChR, although the regulatory elements responsible for this effect have not been identified. This extrasynaptic repression mediated by nerve activity may be less effective for ColQ-1 than for ColQ-1a.…”

Regulation of a Transcript Encoding the Proline-rich Membrane Anchor of Globular Muscle Acetylcholinesterase

“…In contrast, the mechanism of muscular activity-induced CREB phosphorylation has not yet been determined. CaMKII is one of the downstream effectors of the muscular activity-inducing agents (22,30) and therefore could be responsible for the CREB phosphorylation. In cultured myotubes, application of activity-inducing agents (ACh and A23187) induced a sustained phosphorylation of CaMKII (ϳ50 kDa) that was at least 5-fold stronger (Fig.…”

“…Muscular activity is known to suppress acetylcholine receptor expression via intracellular Ca 2ϩ and CaMKII (22,30). To mimic this muscular activity in myotube cultures, ACh (10 and 100 M), depolarizing agent KCl (10 and 20 mM), and Ca 2ϩ ionophore A23187 (0.2 and 0.5 M) were applied to the myotube cultures for 2 days, and then the expressions of PRiMA and AChE T mRNAs were determined.…”