Genetic analysis of the Caenorhabditis elegans GLH family of P-granule proteins.
The Vasa DEAD-box helicases are widespread markers of germ cells across species, and in some organisms have been shown to be essential for germ-cell formation and development. In contrast to the single Vasa gene in most systems analyzed, Caenorhabditis elegans has four Vasa family members, the germline helicases GLH-1, GLH-2, GLH-3, and GLH-4. Our analysis of deletion alleles of each glh gene demonstrates that GLH-1 is the key member of the family: loss of GLH-1 function causes sterility that is mainly maternal effect, is manifested predominantly at elevated temperature, and is due to reduced germ-cell proliferation and impaired formation of both sperm and oocytes. The other GLHs are not essential. However, GLH-4 serves redundant roles with GLH-1: loss of both genes' function causes glh-1-like sterility at all temperatures. Molecular epistasis analysis demonstrates that GLH-1 and GLH-4 are required for proper association of the PGL family of proteins with P granules, suggesting a pathway of P-granule assembly in which the GLHs are upstream of the PGL proteins and the mRNA cap-binding protein IFE-1. While loss of some P-granule components causes worms to be defective in RNA interference, loss of GLH-1 and GLH-4 does not compromise RNAi. Thus, RNAi likely does not require intact P granules but instead relies on particular P-granule factors. We discuss the evolution of the Vasa/GLH genes and current views of their functions and the assembly and roles of germ granules among species.
Spike
Caroline
C
Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
Meyer
Nicole
N
Racen
Erica
E
Orsborn
April
A
Kirchner
Jay
J
Kuznicki
Kathleen
K
Yee
Christopher
C
Bennett
Karen
K
Strome
Susan
S
D000483:Alleles; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000196:embryology / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000235:genetics*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D005854:Germ Cells / Q000166:cytology; D007246:Infertility; D008938:Mitosis; D005810:Multigene Family / Q000235:genetics*; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D034622:RNA Interference; D011993:Recombinant Fusion Proteins; D013696:Temperature
D029742:Caenorhabditis elegans Proteins; D050505:Mutant Proteins; D011993:Recombinant Fusion Proteins; C524497:GLH-1 protein, C elegans; D053487:DEAD-box RNA Helicases