Autoregulation of transformer-2 alternative splicing is necessary for normal male fertility in Drosophila.
In the male germline of Drosophila the transformer-2 protein is required for differential splicing of pre-mRNAs from the exuperantia and att genes and autoregulates alternative splicing of its own pre-mRNA. Autoregulation of TRA-2 splicing results in production of two mRNAs that differ by the splicing/retention of the M1 intron and encode functionally distinct protein isoforms. Splicing of the intron produces an mRNA encoding TRA-2(226), which is necessary and sufficient for both male fertility and regulation of downstream target RNAs. When the intron is retained, an mRNA is produced encoding TRA-2(179), a protein with no known function. We have previously shown that repression of M1 splicing is dependent on TRA-2(226), suggesting that this protein quantitatively limits its own expression through a negative feedback mechanism at the level of splicing. Here we examine this idea, by testing the effect that variations in the level of tra-2 expression have on the splicing of M1 and on male fertility. Consistent with our hypothesis, we observe that as tra-2 gene dosage is increased, smaller proportions of TRA-2(226) mRNA are produced, limiting expression of this isoform. Feedback regulation is critical for male fertility, since it is significantly decreased by a transgene in which repression of M1 splicing cannot occur and TRA-2(226) mRNA is constitutively produced. The effect of this transgene becomes more severe as its dosage is increased, indicating that fertility is sensitive to an excess of TRA-2(226). Our results suggest that autoregulation of TRA-2(226) expression in male germ cells is necessary for normal spermatogenesis.
McGuffin
M E
ME
Department of Molecular Genetics, The University of Texas, M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Chandler
D
D
Somaiya
D
D
Dauwalder
B
B
Mattox
W
W
D017398:Alternative Splicing; D000818:Animals; D030801:Animals, Genetically Modified; D003433:Crosses, Genetic; D004251:DNA Transposable Elements; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D029721:Drosophila Proteins; D005260:Female; D005298:Fertility / Q000235:genetics; D018628:Gene Dosage; D005786:Gene Expression Regulation; D006706:Homeostasis; D008297:Male; D012333:RNA, Messenger / Q000096:biosynthesis; D012261:Ribonucleoproteins / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic
D004251:DNA Transposable Elements; D029721:Drosophila Proteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C066174:tra2 protein, Drosophila