The CRL2LRR-1 ubiquitin ligase regulates cell cycle progression during C. elegans development.
The molecular mechanisms that regulate cell cycle progression in a developmental context are poorly understood. Here, we show that the leucine-rich repeat protein LRR-1 promotes cell cycle progression during C. elegans development, both in the germ line and in the early embryo. Our results indicate that LRR-1 acts as a nuclear substrate-recognition subunit of a Cullin 2-RING E3 ligase complex (CRL2(LRR-1)), which ensures DNA replication integrity. LRR-1 contains a typical BC/Cul-2 box and binds CRL2 components in vitro and in vivo in a BC/Cul-2 box-dependent manner. Loss of lrr-1 function causes cell cycle arrest in the mitotic region of the germ line, resulting in sterility due to the depletion of germ cells. Inactivation of the DNA replication checkpoint signaling components ATL-1 and CHK-1 suppresses this cell cycle arrest and, remarkably, restores lrr-1 mutant fertility. Likewise, in the early embryo, loss of lrr-1 function induces CHK-1 phosphorylation and a severe cell cycle delay in P lineage division, causing embryonic lethality. Checkpoint activation is not constitutive in lrr-1 mutants but is induced by DNA damage, which may arise due to re-replication of some regions of the genome as evidenced by the accumulation of single-stranded DNA-replication protein A (ssDNA-RPA-1) nuclear foci and the increase in germ cell ploidy in lrr-1 and lrr-1; atl-1 double mutants, respectively. Collectively, these observations highlight a crucial function of the CRL2(LRR-1) complex in genome stability via maintenance of DNA replication integrity during C. elegans development.
Institut Jacques Monod, CNRS, Université Paris Diderot, Bâtiment Buffon 15 rue Hélène Brion, 75205 Paris cedex 13, France.
Jorge
J
Merlet
Julien
J
Burger
Nicolas
N
Tavernier
Bénédicte
B
Richaudeau
José-Eduardo
JE
Gomes
Lionel
L
Pintard
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D002453:Cell Cycle; D044842:Cullin Proteins / Q000378:metabolism*; D004261:DNA Replication; D042822:Genomic Instability; D000090263:Leucine-Rich Repeat Proteins; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D044842:Cullin Proteins; D000090263:Leucine-Rich Repeat Proteins; D011506:Proteins; D044767:Ubiquitin-Protein Ligases