Drosophila Cyclin J is a mitotically stable Cdk1 partner without essential functions.
Cyclin J is a cyclin family member that appears to have evolved before the metazoan radiation. Its evolutionary conservation argues for an important role but functional characterizations of Cyclin J have remained very limited. In Drosophila, Cyclin J is expressed only in females. Using transgenic Drosophila lines expressing Cyclin J versions with N- or C-terminal GFP extensions, we demonstrate that it is expressed exclusively in the germline. After low level expression in all nuclei within the germarium, it gets highly enriched in the germinal vesicle within the oocyte until stage 12 of oogenesis, followed by disappearance after germinal vesicle breakdown before the first meiotic division. Surprisingly, Cyclin J is not required for female fertility. Chromosome segregation during female meiosis, as well as the rapid early embryonic cell cycles after fertilization, occurs normally in the complete absence of Cyclin J. Cyclin J with EGFP fused at either N- or C-terminus binds to Cdk1 and not to Cdk2. However, in contrast to the other known Cdk1 partners, the A- and B-type cyclins, Cyclin J is not degraded during mitosis.
Althoff
Friederike
F
Institute of Zoology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Viktorinová
Ivana
I
Kastl
Johanna
J
Lehner
Christian F
CF
D000818:Animals; D030801:Animals, Genetically Modified; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D016213:Cyclins / Q000235:genetics* / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics* / Q000502:physiology; D004331:Drosophila melanogaster; D005260:Female; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008540:Meiosis; D008938:Mitosis; D008954:Models, Biological; D008957:Models, Genetic; D009865:Oocytes / Q000378:metabolism; D017434:Protein Structure, Tertiary
D016213:Cyclins; D029721:Drosophila Proteins; C543897:cyclin J, Drosophila; D049452:Green Fluorescent Proteins; D016203:CDC2 Protein Kinase