NG108-15 cells express neuregulin that induces AChR alpha-subunit synthesis in cultured myotubes.
A cholinergic neuroblastoma x glioma hybrid cell line NG108-15 is able to form functional synapses, and contains both AChR-aggregating and AChR-inducing activities when cocultured with myotubes. Several lines of evidence indicate that the AChR-inducing activity of NG108-15 cells is derived from neuregulin. The conditioned medium of cultured NG108-15 cells induced the expression of AChR alpha-subunit as well as the tyrosine phosphorylation of erbB-3 receptor. NG108-15 cells expressed neuregulin with a protein of approximately 100 kDa in size and transcripts of approximately 6.8 kbp, approximately 2.6 kbp and approximately 1.8 kbp; mRNAs encoding beta1 and alpha2 isoforms of neuregulin were revealed. NG108-15 cells were induced to differentiate by chemicals, and the chemical-induced differentiation of NG108-15 cells increased the level of neuregulin mRNA expression approximately 3-fold while the expression of a housekeeping gene remained relatively unchanged. The activity of neuregulin in the conditioned medium of NG108-15 cells was reduced by treating the medium with heparin and anti-neuregulin antibody. In addition, NG108-15 cells were transfected with antisense neuregulin cDNA and its expression of neuregulin was reduced, while its neuregulin-induced tyrosine phosphorylation activity was markedly decreased. This is the first direct demonstration that the NG108-15 cell-induced AChR upregulation on cultured myotubes is mediated by neuron-derived neuregulin.
Pun
S
S
Department of Biology and Biotechnology Research Institute, The Hong Kong University of Science and Technology, China.
Yang
J F
JF
Ng
Y P
YP
Tsim
K W
KW
D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D018920:Coculture Techniques; D005910:Glioma / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism; D009414:Nerve Growth Factors / Q000096:biosynthesis; D020880:Neuregulins; D009447:Neuroblastoma / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000096:biosynthesis*; D015398:Signal Transduction
D006023:Glycoproteins; D009414:Nerve Growth Factors; D020880:Neuregulins; D011950:Receptors, Cholinergic