Expression of cyclin A decreases during neuronal apoptosis in cultured rat cerebellar granule neurons.
Cultured cerebellar granule neurons died in an apoptotic manner when the K+ concentration in culture medium was lowered to the normal level (5 mM) after maturation of cells with a high concentration of K+ (26 mM). The changes in expression of 14 cell cycle-related genes in this CNS apoptosis model were analyzed by quantitative RT-PCR. Most of the genes analyzed were stable during apoptosis. The expression of cyclin A mRNA, however, transiently decreased 1 h after the induction of apoptosis, and recovered within 3 h to above the basal level. In this system, the level of cyclin D1, which has been reported to be up-regulated in apoptosis of NGF-deprived cultured sympathetic neurons, did not change. These results suggest that the molecular mechanisms in these two apoptosis models are different. To determine cyclin A protein level, we used an immunostaining method. The number of cyclin A-positive neurons decreased during apoptosis. Moreover, the numbers of MAP2- and cdk2-positive neurons also decreased in a similar manner. Taken together, these results suggest that there is a relationship between apoptosis and cell cycle, and that morphological changes during apoptosis result from cytoskeletal structure degradation.
Oka
T
T
Division of Protein Biosynthesis, Osaka University, Japan.
Kubo
T
T
Enokido
Y
Y
Hatanaka
H
H
D000367:Age Factors; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured / Q000502:physiology; D002531:Cerebellum / Q000166:cytology; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication / Q000502:physiology; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D007150:Immunohistochemistry; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology* / Q000201:enzymology; D011188:Potassium / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
D016213:Cyclins; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D011188:Potassium