The Caenorhabditis elegans Sex Determination Gene mog-1 Encodes a Member of the DEAH-Box Protein Family

Abstract

In the Caenorhabditis elegans hermaphrodite germ line, the sex-determining gene fem-3 is repressed posttranscriptionally to arrest spermatogenesis and permit oogenesis. This repression requires a cis-acting regulatory element in the fem-3 3 untranslated region; the FBF protein, which binds to this element; and at least six mog genes. In this paper, we report the molecular characterization of mog-1 as well as additional phenotypic characterization of this gene. The mog-1 gene encodes a member of the DEAH-box family. Three mog-1 alleles possess premature stop codons and are likely to be null alleles, and one is a missense mutation and is likely to retain residual activity. mog-1 mRNA is expressed in both germ line and somatic tissues and appears to be ubiquitous. The MOG-1 DEAH-box protein is most closely related to proteins essential for splicing in the yeast Saccharomyces cerevisiae, but splicing appears to occur normally in a mog-1-null mutant. In addition to its involvement in the sperm-oocyte switch and control of fem-3, zygotic mog-1 is required for robust germ line proliferation and for normal growth during development. We suggest that mog-1 plays a broader role in RNA regulation than previously considered.

Roles of theC. eleganscyclophilin-like protein MOG-6 in MEP-1 binding and germline fates

“…We checked whether mog-6 was required for the splicing of several mRNAs but did not detect unprocessed RNAs. A similar result was obtained in mog-1 null mutants (Puoti and Kimble, 1999). If general pre-mRNA splicing was normal in mog-6 mutants, what might be the role of mog-6 in fem-3 regulation?…”

“…Earlier studies have shown that mog-1(0) mutants produce fewer germ cells than normal (Puoti and Kimble, 1999). Similarly, mog-6 animals also made reduced amounts of germ cells (1511±117, n=22 worms analyzed) compared with wildtype hermaphrodites that contain 2400 germ cells (Kimble and White, 1981).…”

“…The findings that some cyclophilins are involved in pre-mRNA splicing (Bourquin et al, 1997;Horowitz et al, 1997;Teigelkamp et al, 1998) and that MOG-1, -4 and -5 are orthologs of well-characterized splicing factors (Puoti and Kimble, 1999;Puoti and Kimble, 2000) led us to consider the possibility that mog-6 might control fem-3 via regulated splicing. To this end, we analyzed several transcripts including fem-3, fbf, nos-3 and gld-3.…”

“…PolyA-enriched RNA and total RNA were isolated from synchronized animals as described (Puoti and Kimble, 1999). Total RNA was treated by DNase for 30 minutes at 37°C (Stratagene).…”

“…The characterization of the mog genes represents one way to understand the molecular basis of fem-3 regulation. mog-1, mog-4 and mog-5 encode proteins of a subclass of nuclear DEAH-box RNA helicases (Puoti and Kimble, 1999;Puoti and Kimble, 2000). The cytoplasmic RNA-binding proteins FBF, NOS-3 and GLD-3 and the nuclear zinc finger protein MEP-1 represent additional regulators of fem-3.…”