title: Evolutionary conservation of regulatory strategies for the sex determination factor transformer-2.
abstract: Sex determination in Drosophila melanogaster is regulated by a cascade of splicing factors which direct the sex-specific expression of gene products needed for male and female differentiation. The splicing factor TRA-2 affects sex-specific splicing of multiple pre-mRNAs involved in sexual differentiation. The tra-2 gene itself expresses a complex set of mRNAs generated through alternative processing that collectively encode three distinct protein isoforms. The expression of these isoforms differs in the soma and germ line. In the male germ line the ratio of two isoforms present is governed by autoregulation of splicing. However, the functional significance of multiple TRA-2 isoforms has remained uncertain. Here we have examined whether the structure, function, and regulation of tra-2 are conserved in Drosophila virilis, a species diverged from D. melanogaster by over 60 million years. We find that the D. virilis homolog of tra-2 produces alternatively spliced RNAs encoding a set of protein isoforms analogous to those found in D. melanogaster. When introduced into the genome of D. melanogaster, this homolog can functionally replace the endogenous tra-2 gene for both normal female sexual differentiation and spermatogenesis. Examination of alternative mRNAs produced in D. virilis testes suggests that germ line-specific autoregulation of tra-2 function is accomplished by a strategy similar to that used in D. melanogaster. The similarity in structure and function of the tra-2 genes in these divergent Drosophila species supports the idea that sexual differentiation in D. melanogaster and D. virilis is accomplished under the control of similar regulatory pathways.
authors.affiliation: Department of Molecular Genetics, M.D. Anderson Cancer Center, University of Texas, Houston 77030, USA.
authors.forename: D
authors.initials: D
authors.lastname: Chandler
authors.forename: M E
authors.initials: ME
authors.lastname: McGuffin
authors.forename: J
authors.initials: J
authors.lastname: Piskur
authors.forename: J
authors.initials: J
authors.lastname: Yao
authors.forename: B S
authors.initials: BS
authors.lastname: Baker
authors.forename: W
authors.initials: W
authors.lastname: Mattox
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D019143:Evolution, Molecular; D005260:Female; D007301:Insect Hormones / Q000235:genetics; D007438:Introns; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics* / Q000302:isolation & purification; D012732:Sex Determination Analysis; D013091:Spermatogenesis / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C070369:DSX protein, Drosophila; D029721:Drosophila Proteins; D007301:Insect Hormones; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C066174:tra2 protein, Drosophila