Does acetylcholin play a role in mitosis of V79 Chinese hamster cells?
Sammanfattning: The first stages of mitosis are governed by a cascade of phosphorylations brought about by the universal MPF kinase complex. From a regulatory point of view, less is known about late mitotic events. The present study demonstrates that, firstly, V79 Chinese hamster cells produce acetylcholine and, secondly, that a set of acetylcholine receptor ligands can affect progression throughout mitosis.This was suggested using different approaches. Carbaryl and a-naphthol were used to induce a particular mitotic population consisting of cells with dislocated, unseparated chromosomes. Five distinct cell types can be scored, each representing different mitotic stages. Acetylcholine, as well as other acetylcholine receptor ligands, were found to change the frequencies of the five cell types, implying that mitotic progression be altered.Mitotic cell elongation was studied in more detail, using the experimental system with carbaryl and a-naphthol. The results indicate that cell elongation likely depends on actin filament formation and regulatory proteins functionally coupled to actin, as well as a maintained energy status. Also, some acetylcholine receptor might be involved in this cytoskeletal rearrangement. This was suggested by the finding that the acetylcholine analogue carbachol speeds up the formation of elongated cells and, in addition, that two acetylcholine receptor antagonists can decrease the frequency of elongated cells. Recording cells with a video time-lapse equipment demonstrated that acetylcholine receptor ligands can accelerate or decelerate progression through metaphase as well as anaphase, in line with the previous findings.Three different approaches were used to assess and evaluate the effects of acetylcholine receptor ligands on cell cleavage. Firstly, in the experimental system with carbaryl or a-naphthol complex concentration response curves were obtained for cleavage. Secondly, binuclear cells were induced by a two-hour treatment with five different acetylcholine receptor antagonists. Thirdly, video time-lapse recordings demonstrated that two acetylcholine receptor agonists, carbachol and nicotine, accelerates onset and progression of cleavage, respectively.Since the tested ligands affect different parts of mitosis it might be that there are a number of acetylcholine receptor types or affinity states which elicit signals in a time sequence. The role of acetylcholine could be to fine-tune mitotic progression.
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