How are cells regulated to differentiate as one cell type rather than another? How are groups of cells coordinatedly regulated to adopt the same fate? We propose to approach these fundamental problems of metazoan development by analyzing the control of a major fate decision in the nematode Caenorhabditis elegans: determination of sexual fate. Over the past few years, we have laid the groundwork for experiments proposed. First, we have analyzed the tra-2 gene and its RNA products at the molecular level. This work suggests that tra-2 plays a pivotal role in worm sex determination by mediating cell communication and also by regulating transcriptional regulators of cell fate. Second, we have analyzed the fog-1 gene genetically and found that fog-1 is a terminal regulator of sexual fate in the germ line. During the next five years, we propose to investigate the mechanisms by which tra-2 promotes female development throughout the animal and by which fog-1 specifies spermatogenesis in the germ line. First, we will delineate the roles of the individual tra-2 products in sex determination. To this end, we will analyze the phenotypes of transgenic animals that express one of each of the three tra-2 RNAs. Second, we will raise antibodies to the tra-2 proteins, elucidate their cellular locations, and characterize them throughout development in each sex. Third, we will test the idea that the predicted membrane protein pTra2A may serve as a receptor. To this end, we will assay the autonomy of tra-2, either using tissue-specific promoters that drive tra-2 expression in particular cells of transgenic animals or by classic mosaic analysis. Fourth, we will explore the role of maternal tra-2 in early embryonic sex determination, using a combination of genetic maternal effect tests and RNA injection experiments. Fifth, we will identify domains in the tra-2 protein that mediate her-1 control and that promote female development by regulating one or more fem genes. Sixth, we will investigate translational regulation of tra- 2 RNA by its 3'UTR. Seventh, we will clone the fog-1 gene, sequence fog-1 cDNAs, and identify and characterize the fog-1 transcript. These studies will shed light on the mechanisms by which tra-2 and fog-1 are regulated and by which these two genes fulfill their key roles in determination of sexual fate. The health relatedness of this work derives from its contribution to an understanding of fundamental controls of cell fate, including cell communication and transcriptional and translational regulation. These controls are common to all metazoans, including man.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD024663-08
Application #
2199273
Study Section
Genetics Study Section (GEN)
Project Start
1988-08-01
Project End
1997-04-30
Budget Start
1995-05-01
Budget End
1996-04-30
Support Year
8
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Biochemistry
Type
Other Domestic Higher Education
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Kuwabara, P E; Okkema, P G; Kimble, J (1998) Germ-line regulation of the Caenorhabditis elegans sex-determining gene tra-2. Dev Biol 204:251-62
Kadyk, L C; Kimble, J (1998) Genetic regulation of entry into meiosis in Caenorhabditis elegans. Development 125:1803-13
Kuwabara, P E; Kimble, J (1995) A predicted membrane protein, TRA-2A, directs hermaphrodite development in Caenorhabditis elegans. Development 121:2995-3004
Ellis, R E; Kimble, J (1995) The fog-3 gene and regulation of cell fate in the germ line of Caenorhabditis elegans. Genetics 139:561-77
Ellis, R E; Kimble, J (1994) Control of germ cell differentiation in Caenorhabditis elegans. Ciba Found Symp 182:179-88;discussion 189-92
Graham, P L; Kimble, J (1993) The mog-1 gene is required for the switch from spermatogenesis to oogenesis in Caenorhabditis elegans. Genetics 133:919-31
Graham, P L; Schedl, T; Kimble, J (1993) More mog genes that influence the switch from spermatogenesis to oogenesis in the hermaphrodite germ line of Caenorhabditis elegans. Dev Genet 14:471-84
Ahringer, J; Rosenquist, T A; Lawson, D N et al. (1992) The Caenorhabditis elegans sex determining gene fem-3 is regulated post-transcriptionally. EMBO J 11:2303-10
Kuwabara, P E; Okkema, P G; Kimble, J (1992) tra-2 encodes a membrane protein and may mediate cell communication in the Caenorhabditis elegans sex determination pathway. Mol Biol Cell 3:461-73
Okkema, P G; Kimble, J (1991) Molecular analysis of tra-2, a sex determining gene in C.elegans. EMBO J 10:171-6