Functional characterization of beta isoforms of murine Na,K-ATPase. The adhesion molecule on glia (AMOG/beta 2), but not beta 1, promotes neurite outgrowth.
We have previously provided evidence for a dual function of the adhesion molecule on glia (AMOG/beta 2), the beta 2 subunit of the murine Na,K-ATPase, both as neural recognition molecule mediating neuron-glia interactions and as functional beta subunit of the sodium pump. To analyze the functional role of AMOG/beta 2 in neurite outgrowth, AMOG/beta 2-expressing L-cells were generated by transfection and used as substrates for neurite outgrowth of cerebellar and hippocampal neurons. AMOG/beta 2-transfected L-cells led to an increase in neurite length after 6 h, which was specifically inhibited by antibodies to AMOG/beta 2 and a neuronal membrane fraction. Moreover, the extracellular domain of AMOG/beta 2 generated as a soluble recombinant protein in Chinese hamster ovary cells partially inhibited the increase in neurite outgrowth on AMOG/beta 2-transfected L-cells. L-cells transfected with the mouse beta 1 subunit had no effect on neurite extension. Our observations show for the first time differences in functional properties for different beta isoforms of the Na,K-ATPase and suggest that AMOG/beta 2 but not beta 1 is able to interact with an unknown neuronal receptor leading to increased neurite outgrowth, most likely via signal transduction.
Müller-Husmann
G
G
Department of Neurobiology, Swiss Federal Institute of Technology, Zürich.
Gloor
S
S
Schachner
M
M
D000251:Adenosine Triphosphatases; D000818:Animals; D027682:Cation Transport Proteins; D015816:Cell Adhesion Molecules, Neuronal / Q000502:physiology*; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D007739:L Cells / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008813:Mice, Inbred ICR; D008819:Mice, Nude; D009419:Nerve Tissue Proteins / Q000502:physiology*; D016501:Neurites; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology*; D014162:Transfection
C504191:Atp1b2 protein, mouse; D027682:Cation Transport Proteins; D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase