Depletion of a novel SET-domain protein enhances the sterility of mes-3 and mes-4 mutants of Caenorhabditis elegans.
Four maternal-effect sterile genes, mes-2, mes-3, mes-4, and mes-6, are essential for germline development in Caenorhabditis elegans. Homozygous mes progeny from heterozygous mothers are themselves fertile but produce sterile progeny with underproliferated and degenerated germlines. All four mes genes encode chromatin-associated proteins, two of which resemble known regulators of gene expression. To identify additional components in the MES pathway, we used RNA-mediated interference (RNAi) to test candidate genes for enhancement of the Mes mutant phenotype. Enhancement in this assay was induction of sterility a generation earlier, in the otherwise fertile homozygous progeny of heterozygous mothers, which previous results had suggested represent a sensitized genetic background. We tested seven genes predicted to encode regulators of chromatin organization for RNAi-induced enhancement of mes-3 sterility and identified one enhancer, called set-2 after the SET domain encoded by the gene. Depletion of SET-2 also enhances the sterile phenotype of mes-4 but not of mes-2 or mes-6. set-2 encodes two alternatively spliced transcripts, set-2(l) and set-2(s), both of which are enriched in the germline of adults. In the adult germline, SET-2(L) protein is localized in mitotic and mid-late-stage meiotic nuclei but is undetectable in early pachytene nuclei. SET-2(L) protein is localized in all nuclei of embryos. The localization of SET-2(L) does not depend on any of the four MES proteins, and none of the MES proteins depend on SET-2 for their normal localization. Our results suggest that SET-2 participates along with the MES proteins in promoting normal germline development.
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Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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D000483:Alleles; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005260:Female; D005838:Genotype; D018095:Germ-Line Mutation; D015801:Helminth Proteins / Q000235:genetics* / Q000502:physiology; D017403:In Situ Hybridization; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D029742:Caenorhabditis elegans Proteins; D002843:Chromatin; D018076:DNA, Complementary; D015801:Helminth Proteins; D007211:Indoles; C098864:Mes-3 protein, C elegans; C449639:Mes-4 protein, C elegans; D009687:Nuclear Proteins; D012333:RNA, Messenger; C449640:SET-2 protein, C elegans; C007293:DAPI; D012313:RNA