Global transcriptional repression in C. elegans germline precursors by regulated sequestration of TAF-4.
In C. elegans, four asymmetric divisions, beginning with the zygote (P0), generate transcriptionally repressed germline blastomeres (P1-P4) and somatic sisters that become transcriptionally active. The protein PIE-1 represses transcription in the later germline blastomeres but not in the earlier germline blastomeres P0 and P1. We show here that OMA-1 and OMA-2, previously shown to regulate oocyte maturation, repress transcription in P0 and P1 by binding to and sequestering in the cytoplasm TAF-4, a component critical for assembly of TFIID and the pol II preinitiation complex. OMA-1/2 binding to TAF-4 is developmentally regulated, requiring phosphorylation by the DYRK kinase MBK-2, which is activated at meiosis II after fertilization. OMA-1/2 are normally degraded after the first mitosis, but ectopic expression of wild-type OMA-1 is sufficient to repress transcription in both somatic and later germline blastomeres. We propose that phosphorylation by MBK-2 serves as a developmental switch, converting OMA-1/2 from oocyte to embryo regulators.
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Tugba
T
Guven-Ozkan
Yuichi
Y
Nishi
Scott M
SM
Robertson
Rueyling
R
Lin
D000595:Amino Acid Sequence; D000818:Animals; D001757:Blastomeres / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000378:metabolism; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D015053:Zygote / Q000166:cytology / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D006657:Histones; C440205:OMA-1 protein, C elegans; D012097:Repressor Proteins; C532583:TAF-12 protein, C elegans; C532582:TAF-4 protein, C elegans; D014157:Transcription Factors; C473076:oma-2 protein, C elegans; C478059:MBK-2 protein, C elegans; D011505:Protein-Tyrosine Kinases