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.

GLH-1, the C. elegans P granule protein, is controlled by the JNK KGB-1 and by the COP9 subunit CSN-5.

The GLHs (germline RNA helicases) are constitutive components of the germline-specific P granules in the nematode Caenorhabditis elegans and are essential for fertility, yet how GLH proteins are regulated remains unknown. KGB-1 and CSN-5 are both GLH binding partners, previously identified by two-hybrid interactions. KGB-1 is a MAP kinase in the Jun N-terminal kinase (JNK) subfamily, whereas CSN-5 is a subunit of the COP9 signalosome.

The GLH proteins, Caenorhabditis elegans P granule components, associate with CSN-5 and KGB-1, proteins necessary for fertility, and with ZYX-1, a predicted cytoskeletal protein.

The GLH proteins belong to a family of four germline RNA helicases in Caenorhabditis elegans. These putative ATP-dependent enzymes localize to the P granules, which are nonmembranous complexes of protein and RNA exclusively found in the cytoplasm of all C. elegans germ cells and germ cell precursors.