Caenorhabditis elegans RBX1 is essential for meiosis, mitotic chromosomal condensation and segregation, and cytokinesis.
BACKGROUND
The RING-H2 finger protein RBX1 (ROC1/HRT1) is a common subunit of SKP1-CDC53/CUL1-F-box (SCF), other cullins and von Hippel-Lindau (VHL) tumour suppressor E3 ubiquitin ligase complexes. RBX1 protein sequences are highly conserved in various species, including yeasts, Drosophila melanogaster, mice and humans. In Saccharomyces cerevisiae, RBX1 is essential for the G1/S transition.


RESULTS
Caenorhabditis elegans RBX1 is strongly expressed in early embryos and in the gonad, including meiotic cells. Depletion of RBX1 by RNA-mediated interference (RNAi) caused pronounced defects in the first meiotic division. Several irregular phenotypes were identified in embryos that escaped from meiotic arrest: defects in mitotic chromosomal condensation and segregation, abnormal chromosome bridges, giant nuclei, abnormal cortical protrusion, multinucleate cells and defects in germ cell proliferation. Moreover, histone H3 phosphorylation at Ser10 and Ser28 was significantly reduced in these embryos. The histone H3 phosphorylation defect of embryos was rescued by the additional depletion of protein phosphatase 1 (GLC7alpha/beta) by RNAi.


CONCLUSIONS
These results indicate that the RBX1 protein participates in diverse functions relevant to chromosome metabolism and cell cycle control.
Sasagawa
Yohei
Y
Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan.
Urano
Takeshi
T
Kohara
Yuji
Y
Takahashi
Hideyuki
H
Higashitani
Atsushi
A
D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D002352:Carrier Proteins / Q000502:physiology*; D002455:Cell Division / Q000502:physiology; D020090:Chromosome Segregation / Q000502:physiology*; D002875:Chromosomes / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D008540:Meiosis / Q000502:physiology*; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000502:physiology; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D016335:Zinc Fingers / Q000502:physiology
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D006657:Histones; C479529:RBX1 protein, human; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1