Acetylcholine-induced phosphorylation in isolated outer hair cells.
Two groups of isolated, surviving outer hair cells (OHCs) of guinea pig cochleas (n = 20, for each group) were treated with 10 microM acetylcholine or acetylcholine plus strichnine (an alpha9 nAChR antagonist), respectively, under short-term tissue culture conditions. The protein content of the cell homogenates was separated by SDS-polyacrylamide gel electrophoresis, Western blotted and labelled with an antibody against phosphoserine residues. Signals were detected using the ECL system. Acetylcholine challenge of the OHCs resulted in a difference in the pattern of phosphorylated proteins from those of strichnine pretreated cells. A 220 kDa and a 120 kDa protein expressed a more intense phosphorylated state in the ACh group compared with the ACh plus strichnine group. The 220 kDa phosphoprotein is in the range of the cytoskeletal protein beta-fodrin, whereas the 120 kDa fraction is similar to alpha-fodrin or an ankyrin isoform. Phosphorylation of proteins due to activation of the AChR by agonist can play a role in the signalling mechanism between receptor activation and increase in the electromotile capability of isolated OHCs.
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects* / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010766:Phosphorylation; D011950:Receptors, Cholinergic / Q000187:drug effects; D013331:Strychnine / Q000494:pharmacology; D013049:Spectrin