GM2 ganglioside regulates the function of ciliary neurotrophic factor receptor in murine immortalized motor neuron-like cells (NSC-34).
We previously reported that ciliary neurotrophic factor (CNTF) increased the serum-free cell survival of immortalized motor neuron-like cells (NSC-34), and addition of the exogenous ganglioside GalNAc beta4(Neu5Ac alpha3)Gal beta4GlcCer (GM2) facilitated cell survival together with CNTF. Moreover beta 1,4 N-acetylgalactosaminyltransferase (GM2 synthase) activity increased in NSC-34 cells cultured with CNTF. We now have examined whether CNTF-induced cell survival is associated with the collaboration between GM2 and the CNTF receptor (CNTF-R). Despite the presence of CNTF (50 ng/ml), anti-CNTF-R antibody caused cell death and prevented the up-regulation of GM2 synthase expression. The addition of GM2 (1 to 20 microM) abrogated the anti-CNTF-R antibody effect which shortened cell survival and blocked GM2 synthase activation. Use of [125I]CNTF showed the specificity of CNTF binding in NSC-34 cells in situ. GM2 produced a 5-fold increase in the CNTF binding affinity per cell but did not change the binding site number. The study by metabolic labeling with [1-(14)C]N-acetyl-D-galactosamine ([14C]GalNAc) showed that biosynthesized GM2 was involved in the immunoprecipitation of CNTF-R. These findings indicate that up-regulated GM2 synthesis induces functional conversion of CNTF-R to the activated state, in which it has affinity for CNTF. We conclude that GM2 is a bio-regulating molecule of CNTF-R in motor neurons.
Usuki
S
S
Tokyo Research Institute, Seikagaku Corporation, Japan.
Ren
J
J
Utsunomiya
I
I
Cashman
N R
NR
Inokuchi
J
J
Miyatake
T
T
D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000187:drug effects; D005678:G(M2) Ganglioside / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011233:Precipitin Tests; D020801:Receptor, Ciliary Neurotrophic Factor / Q000276:immunology / Q000378:metabolism / Q000502:physiology*
D020801:Receptor, Ciliary Neurotrophic Factor; D005678:G(M2) Ganglioside