C. elegans hermaphrodites are essentially female worms that have achieved self-fertility. Making sperm in an otherwise female body requires precise regulation of the feminizing gene,
tra-2. While TRA-2 is ubiquitously expressed in the soma, its regulation is of special interest in the germ line where sperm are specified. There are two major mRNA isoforms of
tra-2,
tra-2a (4.7 kb) and
tra-2b (1.8kb) [1]. The 1.8 kb transcript is specific to the hermaphrodite germline [1, 2]. The 4.7 kb transcript is predicted to be a transmembrane receptor for the male-specific protein HER-1 [3]. HER-1 represses
tra-2 activity to allow male cell fates in XO animals, but is not expressed in XX hermaphrodites [4]. Instead, available evidence suggests that hermaphrodites repress
tra-2 by the binding of a GLD-1/FOG-2 heterodimer to its 3' UTR [5, 6]. While
tra-2 mRNA is abundant in the germline, epitope-tagged TRA-2 (TRA-2::HA) was undetectable in the presence of GLD-1 and FOG-2, and only slightly elevated in their absence [7]. We are now investigating the regulation of
tra-2 in two ways. At the mRNA level, we are using single-molecule fluorescence in-situ hybridization (sm-FISH). We hypothesize that the 4.7 kb version of
tra-2 is not present in the hermaphrodite germline, as the 1.8 kb transcript contains all the domains necessary for interaction with both
fem-3 and
tra-1 [8, 9]. We are also investigating the mechanism of FOG-2 action, with an emphasis on identification of additional protein-protein interactions. 1. Okkema, P.G. and J. Kimble, EMBO J., 1991. 10(1): p. 171-176. 2. Kuwabara, P.E., P.G. Okkema, and J. Kimble, Dev. Biol., 1998. 204: p. 251-262. 3. Hamaoka, B.Y., et al., Proc Natl Acad Sci U S A, 2004. 101(32): p. 11673-8. 4. Trent, C., et al., Mech Dev, 1991. 34(1): p. 43-55. 5. Jan, E., et al., EMBO J., 1999. 18(1): p. 258-69. 6. Clifford, R., et al., Development, 2000. 127: p. 5265-5276. 7. Hu, S., et al., Developmental Biology, 2018. 8. Mehra, A., et al., Genes Dev., 1999. 13: p. 1453-1463. 9. Lum, D., et al., Genes Dev, 2000. 14: p. 3153-65.