Redundant control of the Caenorhabditis elegans sperm/oocyte switch by PUF-8 and FBF-1, two distinct PUF RNA-binding proteins.
PUF proteins control both growth and differentiation in the C. elegans germ line. These conserved RNA-binding proteins inhibit expression of target mRNAs, either by repressing translation or promoting degradation. Previous studies showed that PUF-8, a PUF protein with striking similarity to human Pumilio, prevents return of primary spermatocytes to the mitotic cell cycle [Subramaniam, K. & Seydoux, G. (2003) Curr. Biol. 13, 134-139]. We now report that PUF-8 is also critical for the hermaphrodite sperm/oocyte switch. Most puf-8 mutant hermaphrodites make both sperm and oocytes and are self-fertile, but some make a vast excess of sperm and fail to switch into oogenesis. This puf-8 defect is dramatically enhanced by removal of another puf gene called fbf-1: all fbf-1 puf-8 double mutants fail in the hermaphrodite sperm/oocyte switch. Therefore, puf-8 and fbf-1 act redundantly to control this decision. Epistasis analyses place puf-8 and fbf-1 upstream of fog-2, a gene near the top of the germ-line sex determination pathway. Furthermore, the abundance of FOG-2 increases dramatically in the distal region of fbf-1 puf-8 double mutants. We suggest that PUF-8 and FBF-1 may control fog-2 expression, and that the sperm/oocyte decision occurs in the distal germ line.
Bachorik
Jennifer L
JL
Program in Cellular and Molecular Biology, Department of Biochemistry, and Howard Hughes Medical Institute, University of Wisconsin, Madison, WI 53706, USA.
Kimble
Judith
J
D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012734:Disorders of Sex Development / Q000235:genetics / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017238:Genes, Helminth; D008297:Male; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D009866:Oogenesis / Q000235:genetics / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019849:Sex Determination Processes; D013091:Spermatogenesis / Q000235:genetics / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D004268:DNA-Binding Proteins; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C109286:fem-3-binding protein, C elegans; C492171:fog-2 protein, C elegans