RNAi Screen Identifies Novel Regulators of RNP Granules in the Caenorhabditis elegans Germ Line.
Complexes of RNA and RNA binding proteins form large-scale supramolecular structures under many cellular contexts. In Caenorhabditis elegans, small germ granules are present in the germ line that share characteristics with liquid droplets that undergo phase transitions. In meiotically-arrested oocytes of middle-aged hermaphrodites, the germ granules appear to aggregate or condense into large assemblies of RNA-binding proteins and maternal mRNAs. Prior characterization of the assembly of large-scale RNP structures via candidate approaches has identified a small number of regulators of phase transitions in the C. elegans germ line; however, the assembly, function, and regulation of these large RNP assemblies remain incompletely understood. To identify genes that promote remodeling and assembly of large RNP granules in meiotically-arrested oocytes, we performed a targeted, functional RNAi screen and identified over 300 genes that regulate the assembly of the RNA-binding protein MEX-3 into large granules. Among the most common GO classes are several categories related to RNA biology, as well as novel categories such as cell cortex, ER, and chromosome segregation. We found that arrested oocytes that fail to localize MEX-3 into cortical granules display reduced oocyte quality, consistent with the idea that the larger RNP assemblies promote oocyte quality when fertilization is delayed. Interestingly, a relatively small number of genes overlap with the regulators of germ granule assembly during normal development, or with the regulators of solid RNP granules in cgh-1 oocytes, suggesting fundamental differences in the regulation of RNP granule phase transitions during meiotic arrest.
Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859.
Megan P
MP
Wood
Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859.
Angela
A
Hollis
Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859.
Ashley L
AL
Severance
Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859.
Megan L
ML
Karrick
Department of Biology, Central Michigan University, Mount Pleasant, Michigan 48859 schis1j@cmich.edu.
Jennifer A
JA
Schisa
D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D020090:Chromosome Segregation; D002875:Chromosomes / Q000235:genetics; D003594:Cytoplasmic Granules / Q000235:genetics* / Q000378:metabolism; D003599:Cytoskeleton / Q000235:genetics; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D005260:Female; D005854:Germ Cells; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D034622:RNA Interference; D012316:RNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D019849:Sex Determination Processes
D029742:Caenorhabditis elegans Proteins; C102175:MEX-3 protein, C elegans; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C524497:GLH-1 protein, C elegans; D012316:RNA Nucleotidyltransferases; C490618:cgh-1 protein, C elegans; D053487:DEAD-box RNA Helicases
C. elegans; RNP granule; aging; germ line; oocyte quality