Positive autoregulation of sex-lethal by alternative splicing maintains the female determined state in Drosophila.
Sex-lethal is a binary switch gene that controls all aspects of Drosophila sexual dimorphism. It must be active in females and inactive in males. The on/off regulation reflects alternative RNA splicing in which full-length proteins are produced only in females. Here we investigate the role of Sxl in maintaining sexual pathway commitments. By ectopic expression of a female Sxl cDNA in transgenic male flies, we show that Sxl protein induces a rapid switch from male- to female-specific splicing. The ectopically expressed Sxl protein wil trans-activate an endogenous wild-type Sxl gene. This establishes a feedback loop in which Sxl proteins induce their own synthesis by directing the female-specific splicing of Sxl transcripts. We conclude that the female determined state is maintained by Sxl through positive autoregulation, while the male determined state is maintained by default.
Bell
L R
LR
Department of Biology, Princeton University, New Jersey 08544.
Horabin
J I
JI
Schedl
P
P
Cline
T W
TW
D000483:Alleles; D000818:Animals; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005260:Female; D005786:Gene Expression Regulation; D005812:Genes, Switch; D006706:Homeostasis; D007301:Insect Hormones / Q000032:analysis / Q000235:genetics / Q000502:physiology; D008297:Male; D009154:Mutation; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D012326:RNA Splicing; D016601:RNA-Binding Proteins; D015183:Restriction Mapping; D012732:Sex Determination Analysis; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014170:Transformation, Genetic
D029721:Drosophila Proteins; D007301:Insect Hormones; D016601:RNA-Binding Proteins; C067777:Sxl protein, Drosophila