Functional dissection of Caenorhabditis elegans CLK-2/TEL2 cell cycle defects during embryogenesis and germline development.
CLK-2/TEL2 is essential for viability from yeasts to vertebrates, but its essential functions remain ill defined. CLK-2/TEL2 was initially implicated in telomere length regulation in budding yeast, but work in Caenorhabditis elegans has uncovered a function in DNA damage response signalling. Subsequently, DNA damage signalling defects associated with CLK-2/TEL2 have been confirmed in yeast and human cells. The CLK-2/TEL2 interaction with the ATM and ATR DNA damage sensor kinases and its requirement for their stability led to the proposal that CLK-2/TEL2 mutants might phenocopy ATM and/or ATR depletion. We use C. elegans to dissect developmental and cell cycle related roles of CLK-2. Temperature sensitive (ts) clk-2 mutants accumulate genomic instability and show a delay of embryonic cell cycle timing. This delay partially depends on the worm p53 homolog CEP-1 and is rescued by co-depletion of the DNA replication checkpoint proteins ATL-1 (C. elegans ATR) and CHK-1. In addition, clk-2 ts mutants show a spindle orientation defect in the eight cell stages that lead to major cell fate transitions. clk-2 deletion worms progress through embryogenesis and larval development by maternal rescue but become sterile and halt germ cell cycle progression. Unlike ATL-1 depleted germ cells, clk-2-null germ cells do not accumulate DNA double-strand breaks. Rather, clk-2 mutant germ cells arrest with duplicated centrosomes but without mitotic spindles in an early prophase like stage. This germ cell cycle arrest does not depend on cep-1, the DNA replication, or the spindle checkpoint. Our analysis shows that CLK-2 depletion does not phenocopy PIKK kinase depletion. Rather, we implicate CLK-2 in multiple developmental and cell cycle related processes and show that CLK-2 and ATR have antagonising functions during early C. elegans embryonic development.
Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, Scotland, United Kingdom.
Sandra C
SC
Moser
Sophie
S
von Elsner
Ingo
I
Büssing
Arno
A
Alpi
Ralf
R
Schnabel
Anton
A
Gartner
D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D049109:Cell Proliferation; D047108:Embryonic Development; D005854:Germ Cells / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D034501:Telomere-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D034501:Telomere-Binding Proteins; C438752:clk-2 protein, C elegans