Abstract
The choice of sexual identity in somatic tissues of the fruit fly Drosophila melanogaster is determined early in embryogenesis by the X-chromosome-to-autosome (X/A) ratio. The system that signals the X/A ratio selects the sexual development pathway by determining the activity state of the binary switch Sex-lethal (Sxl). In 2X/2A animals, the X/A signalling system turns the Sxl gene on, ultimately activating an RNA-splicing autoregulatory feedback loop which serves to maintain the female state during the remainder of development. In 1X/2A animals, this autoregulatory feedback loop is not activated and the male state is subsequently maintained by the default splicing machinery. In the studies reported here, we have examined how the X/A signalling system controls the initial choice of sexual identity through its action on a special early embryonic Sxl promoter, Sxl-Pe. We show that in the early embryo, the activity of Sxl-Pe is controlled in a highly dose-sensitive fashion by the genes on the X chromosome that function as numerator elements and by genes located on the autosomes that function as denominator elements. Functional dissection of Sxl-Pe indicates that activating the promoter in females requires the cumulative action of multiple numerator genes which appear to exert their effects through reiterated cis-acting target sites in the promoter. Conversely, maintaining the promoter silent in males requires the repressive activities of denominator genes, and at least one of the denominator genes also appears to function through target sequences within the promoter.
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- Baker B. S. Sex in flies: the splice of life. Nature. 1989 Aug 17;340(6234):521–524. doi: 10.1038/340521a0. [DOI] [PubMed] [Google Scholar]
- Bell L. R., Horabin J. I., Schedl P., Cline T. W. Positive autoregulation of sex-lethal by alternative splicing maintains the female determined state in Drosophila. Cell. 1991 Apr 19;65(2):229–239. doi: 10.1016/0092-8674(91)90157-t. [DOI] [PubMed] [Google Scholar]
- Bell L. R., Maine E. M., Schedl P., Cline T. W. Sex-lethal, a Drosophila sex determination switch gene, exhibits sex-specific RNA splicing and sequence similarity to RNA binding proteins. Cell. 1988 Dec 23;55(6):1037–1046. doi: 10.1016/0092-8674(88)90248-6. [DOI] [PubMed] [Google Scholar]
- Bellen H. J., O'Kane C. J., Wilson C., Grossniklaus U., Pearson R. K., Gehring W. J. P-element-mediated enhancer detection: a versatile method to study development in Drosophila. Genes Dev. 1989 Sep;3(9):1288–1300. doi: 10.1101/gad.3.9.1288. [DOI] [PubMed] [Google Scholar]
- Berleth T., Burri M., Thoma G., Bopp D., Richstein S., Frigerio G., Noll M., Nüsslein-Volhard C. The role of localization of bicoid RNA in organizing the anterior pattern of the Drosophila embryo. EMBO J. 1988 Jun;7(6):1749–1756. doi: 10.1002/j.1460-2075.1988.tb03004.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bier E., Vaessin H., Younger-Shepherd S., Jan L. Y., Jan Y. N. deadpan, an essential pan-neural gene in Drosophila, encodes a helix-loop-helix protein similar to the hairy gene product. Genes Dev. 1992 Nov;6(11):2137–2151. doi: 10.1101/gad.6.11.2137. [DOI] [PubMed] [Google Scholar]
- Blackwell T. K., Weintraub H. Differences and similarities in DNA-binding preferences of MyoD and E2A protein complexes revealed by binding site selection. Science. 1990 Nov 23;250(4984):1104–1110. doi: 10.1126/science.2174572. [DOI] [PubMed] [Google Scholar]
- Bopp D., Bell L. R., Cline T. W., Schedl P. Developmental distribution of female-specific Sex-lethal proteins in Drosophila melanogaster. Genes Dev. 1991 Mar;5(3):403–415. doi: 10.1101/gad.5.3.403. [DOI] [PubMed] [Google Scholar]
- Cabrera C. V., Alonso M. C. Transcriptional activation by heterodimers of the achaete-scute and daughterless gene products of Drosophila. EMBO J. 1991 Oct;10(10):2965–2973. doi: 10.1002/j.1460-2075.1991.tb07847.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Caudy M., Vässin H., Brand M., Tuma R., Jan L. Y., Jan Y. N. daughterless, a Drosophila gene essential for both neurogenesis and sex determination, has sequence similarities to myc and the achaete-scute complex. Cell. 1988 Dec 23;55(6):1061–1067. doi: 10.1016/0092-8674(88)90250-4. [DOI] [PubMed] [Google Scholar]
- Cline T. W. A female-specific lethal lesion in an X-linked positive regulator of the Drosophila sex determination gene, Sex-lethal. Genetics. 1986 Jul;113(3):641–663. doi: 10.1093/genetics/113.3.641. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline T. W. A male-specific lethal mutation in Drosophila melanogaster that transforms sex. Dev Biol. 1979 Oct;72(2):266–275. doi: 10.1016/0012-1606(79)90117-9. [DOI] [PubMed] [Google Scholar]
- Cline T. W. A sex-specific, temperature-sensitive maternal effect of the daughterless mutation of Drosophila melanogaster. Genetics. 1976 Dec;84(4):723–742. doi: 10.1093/genetics/84.4.723. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline T. W. Autoregulatory functioning of a Drosophila gene product that establish es and maintains the sexually determined state. Genetics. 1984 Jun;107(2):231–277. doi: 10.1093/genetics/107.2.231. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline T. W. Evidence that sisterless-a and sisterless-b are two of several discrete "numerator elements" of the X/A sex determination signal in Drosophila that switch Sxl between two alternative stable expression states. Genetics. 1988 Aug;119(4):829–862. doi: 10.1093/genetics/119.4.829. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline T. W. Maternal and zygotic sex-specific gene interactions in Drosophila melanogaster. Genetics. 1980 Dec;96(4):903–926. doi: 10.1093/genetics/96.4.903. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cline T. W. The Drosophila sex determination signal: how do flies count to two? Trends Genet. 1993 Nov;9(11):385–390. doi: 10.1016/0168-9525(93)90138-8. [DOI] [PubMed] [Google Scholar]
- Cline T. W. The affairs of daughterless and the promiscuity of developmental regulators. Cell. 1989 Oct 20;59(2):231–234. doi: 10.1016/0092-8674(89)90280-8. [DOI] [PubMed] [Google Scholar]
- Cline T. W. The interaction between daughterless and sex-lethal in triploids: a lethal sex-transforming maternal effect linking sex determination and dosage compensation in Drosophila melanogaster. Dev Biol. 1983 Feb;95(2):260–274. doi: 10.1016/0012-1606(83)90027-1. [DOI] [PubMed] [Google Scholar]
- Cline T. W. Two closely linked mutations in Drosophila melanogaster that are lethal to opposite sexes and interact with daughterless. Genetics. 1978 Dec;90(4):683–698. doi: 10.1093/genetics/90.4.683. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cronmiller C., Cline T. W. The Drosophila sex determination gene daughterless has different functions in the germ line versus the soma. Cell. 1987 Feb 13;48(3):479–487. doi: 10.1016/0092-8674(87)90198-x. [DOI] [PubMed] [Google Scholar]
- Cronmiller C., Cline T. W. The relationship of relative gene dose to the complex phenotype of the daughterless locus in Drosophila. Dev Genet. 1986;7(4):205–221. doi: 10.1002/dvg.1020070406. [DOI] [PubMed] [Google Scholar]
- Cronmiller C., Schedl P., Cline T. W. Molecular characterization of daughterless, a Drosophila sex determination gene with multiple roles in development. Genes Dev. 1988 Dec;2(12A):1666–1676. doi: 10.1101/gad.2.12a.1666. [DOI] [PubMed] [Google Scholar]
- Daga A., Tighe J. E., Calabi F. Leukaemia/Drosophila homology. Nature. 1992 Apr 9;356(6369):484–484. doi: 10.1038/356484b0. [DOI] [PubMed] [Google Scholar]
- Driever W., Nüsslein-Volhard C. A gradient of bicoid protein in Drosophila embryos. Cell. 1988 Jul 1;54(1):83–93. doi: 10.1016/0092-8674(88)90182-1. [DOI] [PubMed] [Google Scholar]
- Driever W., Nüsslein-Volhard C. The bicoid protein determines position in the Drosophila embryo in a concentration-dependent manner. Cell. 1988 Jul 1;54(1):95–104. doi: 10.1016/0092-8674(88)90183-3. [DOI] [PubMed] [Google Scholar]
- Driever W., Nüsslein-Volhard C. The bicoid protein is a positive regulator of hunchback transcription in the early Drosophila embryo. Nature. 1989 Jan 12;337(6203):138–143. doi: 10.1038/337138a0. [DOI] [PubMed] [Google Scholar]
- Driever W., Siegel V., Nüsslein-Volhard C. Autonomous determination of anterior structures in the early Drosophila embryo by the bicoid morphogen. Development. 1990 Aug;109(4):811–820. doi: 10.1242/dev.109.4.811. [DOI] [PubMed] [Google Scholar]
- Duffy J. B., Gergen J. P. The Drosophila segmentation gene runt acts as a position-specific numerator element necessary for the uniform expression of the sex-determining gene Sex-lethal. Genes Dev. 1991 Dec;5(12A):2176–2187. doi: 10.1101/gad.5.12a.2176. [DOI] [PubMed] [Google Scholar]
- Ellis H. M., Spann D. R., Posakony J. W. extramacrochaetae, a negative regulator of sensory organ development in Drosophila, defines a new class of helix-loop-helix proteins. Cell. 1990 Apr 6;61(1):27–38. doi: 10.1016/0092-8674(90)90212-w. [DOI] [PubMed] [Google Scholar]
- Erickson J. W., Cline T. W. A bZIP protein, sisterless-a, collaborates with bHLH transcription factors early in Drosophila development to determine sex. Genes Dev. 1993 Sep;7(9):1688–1702. doi: 10.1101/gad.7.9.1688. [DOI] [PubMed] [Google Scholar]
- Erickson J. W., Cline T. W. Molecular nature of the Drosophila sex determination signal and its link to neurogenesis. Science. 1991 Mar 1;251(4997):1071–1074. doi: 10.1126/science.1900130. [DOI] [PubMed] [Google Scholar]
- Frigerio G., Burri M., Bopp D., Baumgartner S., Noll M. Structure of the segmentation gene paired and the Drosophila PRD gene set as part of a gene network. Cell. 1986 Dec 5;47(5):735–746. doi: 10.1016/0092-8674(86)90516-7. [DOI] [PubMed] [Google Scholar]
- Garrell J., Modolell J. The Drosophila extramacrochaetae locus, an antagonist of proneural genes that, like these genes, encodes a helix-loop-helix protein. Cell. 1990 Apr 6;61(1):39–48. doi: 10.1016/0092-8674(90)90213-x. [DOI] [PubMed] [Google Scholar]
- Gergen J. P. Dosage Compensation in Drosophila: Evidence That daughterless and Sex-lethal Control X Chromosome Activity at the Blastoderm Stage of Embryogenesis. Genetics. 1987 Nov;117(3):477–485. doi: 10.1093/genetics/117.3.477. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gergen J. P., Wieschaus E. Dosage requirements for runt in the segmentation of Drosophila embryos. Cell. 1986 Apr 25;45(2):289–299. doi: 10.1016/0092-8674(86)90393-4. [DOI] [PubMed] [Google Scholar]
- Golic K. G., Lindquist S. The FLP recombinase of yeast catalyzes site-specific recombination in the Drosophila genome. Cell. 1989 Nov 3;59(3):499–509. doi: 10.1016/0092-8674(89)90033-0. [DOI] [PubMed] [Google Scholar]
- Henikoff S. Unidirectional digestion with exonuclease III creates targeted breakpoints for DNA sequencing. Gene. 1984 Jun;28(3):351–359. doi: 10.1016/0378-1119(84)90153-7. [DOI] [PubMed] [Google Scholar]
- Herschlag D., Johnson F. B. Synergism in transcriptional activation: a kinetic view. Genes Dev. 1993 Feb;7(2):173–179. doi: 10.1101/gad.7.2.173. [DOI] [PubMed] [Google Scholar]
- Hodgkin J. Drosophila sex determination: a cascade of regulated splicing. Cell. 1989 Mar 24;56(6):905–906. doi: 10.1016/0092-8674(89)90619-3. [DOI] [PubMed] [Google Scholar]
- Hodgkin J. Sex determination compared in Drosophila and Caenorhabditis. Nature. 1990 Apr 19;344(6268):721–728. doi: 10.1038/344721a0. [DOI] [PubMed] [Google Scholar]
- Inoue K., Hoshijima K., Sakamoto H., Shimura Y. Binding of the Drosophila sex-lethal gene product to the alternative splice site of transformer primary transcript. Nature. 1990 Mar 29;344(6265):461–463. doi: 10.1038/344461a0. [DOI] [PubMed] [Google Scholar]
- Kania M. A., Bonner A. S., Duffy J. B., Gergen J. P. The Drosophila segmentation gene runt encodes a novel nuclear regulatory protein that is also expressed in the developing nervous system. Genes Dev. 1990 Oct;4(10):1701–1713. doi: 10.1101/gad.4.10.1701. [DOI] [PubMed] [Google Scholar]
- Kellum R., Schedl P. A position-effect assay for boundaries of higher order chromosomal domains. Cell. 1991 Mar 8;64(5):941–950. doi: 10.1016/0092-8674(91)90318-s. [DOI] [PubMed] [Google Scholar]
- Keyes L. N., Cline T. W., Schedl P. The primary sex determination signal of Drosophila acts at the level of transcription. Cell. 1992 Mar 6;68(5):933–943. doi: 10.1016/0092-8674(92)90036-c. [DOI] [PubMed] [Google Scholar]
- Lucchesi J. C., Skripsky T. The link between dosage compensation and sex differentiation in Drosophila melanogaster. Chromosoma. 1981;82(2):217–227. doi: 10.1007/BF00286106. [DOI] [PubMed] [Google Scholar]
- Maine E. M., Salz H. K., Schedl P., Cline T. W. Sex-lethal, a link between sex determination and sexual differentiation in Drosophila melanogaster. Cold Spring Harb Symp Quant Biol. 1985;50:595–604. doi: 10.1101/sqb.1985.050.01.072. [DOI] [PubMed] [Google Scholar]
- Mange A. P., Sandler L. A note on the maternal effect mutants daughterless and abnormal oocyte in Drosophila melanogaster. Genetics. 1973 Jan;73(1):73–86. doi: 10.1093/genetics/73.1.73. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Murre C., McCaw P. S., Baltimore D. A new DNA binding and dimerization motif in immunoglobulin enhancer binding, daughterless, MyoD, and myc proteins. Cell. 1989 Mar 10;56(5):777–783. doi: 10.1016/0092-8674(89)90682-x. [DOI] [PubMed] [Google Scholar]
- Murre C., McCaw P. S., Vaessin H., Caudy M., Jan L. Y., Jan Y. N., Cabrera C. V., Buskin J. N., Hauschka S. D., Lassar A. B. Interactions between heterologous helix-loop-helix proteins generate complexes that bind specifically to a common DNA sequence. Cell. 1989 Aug 11;58(3):537–544. doi: 10.1016/0092-8674(89)90434-0. [DOI] [PubMed] [Google Scholar]
- Parkhurst S. M., Bopp D., Ish-Horowicz D. X:A ratio, the primary sex-determining signal in Drosophila, is transduced by helix-loop-helix proteins. Cell. 1990 Dec 21;63(6):1179–1191. doi: 10.1016/0092-8674(90)90414-a. [DOI] [PubMed] [Google Scholar]
- Parkhurst S. M., Ish-Horowicz D. Common denominators for sex. Curr Biol. 1992 Dec;2(12):629–631. doi: 10.1016/0960-9822(92)90097-t. [DOI] [PubMed] [Google Scholar]
- Parkhurst S. M., Lipshitz H. D., Ish-Horowicz D. achaete-scute feminizing activities and Drosophila sex determination. Development. 1993 Feb;117(2):737–749. doi: 10.1242/dev.117.2.737. [DOI] [PubMed] [Google Scholar]
- Parkhurst S. M., Meneely P. M. Sex determination and dosage compensation: lessons from flies and worms. Science. 1994 May 13;264(5161):924–932. doi: 10.1126/science.8178152. [DOI] [PubMed] [Google Scholar]
- Rubin G. M., Spradling A. C. Genetic transformation of Drosophila with transposable element vectors. Science. 1982 Oct 22;218(4570):348–353. doi: 10.1126/science.6289436. [DOI] [PubMed] [Google Scholar]
- Rubin G. M., Spradling A. C. Vectors for P element-mediated gene transfer in Drosophila. Nucleic Acids Res. 1983 Sep 24;11(18):6341–6351. doi: 10.1093/nar/11.18.6341. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Salz H. K., Cline T. W., Schedl P. Functional changes associated with structural alterations induced by mobilization of a P element inserted in the Sex-lethal gene of Drosophila. Genetics. 1987 Oct;117(2):221–231. doi: 10.1093/genetics/117.2.221. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Salz H. K., Maine E. M., Keyes L. N., Samuels M. E., Cline T. W., Schedl P. The Drosophila female-specific sex-determination gene, Sex-lethal, has stage-, tissue-, and sex-specific RNAs suggesting multiple modes of regulation. Genes Dev. 1989 May;3(5):708–719. doi: 10.1101/gad.3.5.708. [DOI] [PubMed] [Google Scholar]
- Samuels M. E., Bopp D., Colvin R. A., Roscigno R. F., Garcia-Blanco M. A., Schedl P. RNA binding by Sxl proteins in vitro and in vivo. Mol Cell Biol. 1994 Jul;14(7):4975–4990. doi: 10.1128/mcb.14.7.4975. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Samuels M. E., Schedl P., Cline T. W. The complex set of late transcripts from the Drosophila sex determination gene sex-lethal encodes multiple related polypeptides. Mol Cell Biol. 1991 Jul;11(7):3584–3602. doi: 10.1128/mcb.11.7.3584. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schröder C., Tautz D., Seifert E., Jäckle H. Differential regulation of the two transcripts from the Drosophila gap segmentation gene hunchback. EMBO J. 1988 Sep;7(9):2881–2887. doi: 10.1002/j.1460-2075.1988.tb03145.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spradling A. C., Rubin G. M. Transposition of cloned P elements into Drosophila germ line chromosomes. Science. 1982 Oct 22;218(4570):341–347. doi: 10.1126/science.6289435. [DOI] [PubMed] [Google Scholar]
- Steinmann-Zwicky M., Amrein H., Nöthiger R. Genetic control of sex determination in Drosophila. Adv Genet. 1990;27:189–237. doi: 10.1016/s0065-2660(08)60026-7. [DOI] [PubMed] [Google Scholar]
- Struhl G. Differing strategies for organizing anterior and posterior body pattern in Drosophila embryos. Nature. 1989 Apr 27;338(6218):741–744. doi: 10.1038/338741a0. [DOI] [PubMed] [Google Scholar]
- Struhl G., Struhl K., Macdonald P. M. The gradient morphogen bicoid is a concentration-dependent transcriptional activator. Cell. 1989 Jun 30;57(7):1259–1273. doi: 10.1016/0092-8674(89)90062-7. [DOI] [PubMed] [Google Scholar]
- Sánchez L., Nöthiger R. Sex determination and dosage compensation in Drosophila melanogaster: production of male clones in XX females. EMBO J. 1983;2(4):485–491. doi: 10.1002/j.1460-2075.1983.tb01451.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tautz D. Regulation of the Drosophila segmentation gene hunchback by two maternal morphogenetic centres. Nature. 1988 Mar 17;332(6161):281–284. doi: 10.1038/332281a0. [DOI] [PubMed] [Google Scholar]
- Thummel C. S., Boulet A. M., Lipshitz H. D. Vectors for Drosophila P-element-mediated transformation and tissue culture transfection. Gene. 1988 Dec 30;74(2):445–456. doi: 10.1016/0378-1119(88)90177-1. [DOI] [PubMed] [Google Scholar]
- Tomlinson A., Kimmel B. E., Rubin G. M. rough, a Drosophila homeobox gene required in photoreceptors R2 and R5 for inductive interactions in the developing eye. Cell. 1988 Dec 2;55(5):771–784. doi: 10.1016/0092-8674(88)90133-x. [DOI] [PubMed] [Google Scholar]
- Torres M., Sánchez L. The scute (T4) gene acts as a numerator element of the X:a signal that determines the state of activity of sex-lethal in Drosophila. EMBO J. 1989 Oct;8(10):3079–3086. doi: 10.1002/j.1460-2075.1989.tb08459.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Torres M., Sánchez L. The segmentation gene runt is needed to activate Sex-lethal, a gene that controls sex determination and dosage compensation in Drosophila. Genet Res. 1992 Jun;59(3):189–198. doi: 10.1017/s0016672300030470. [DOI] [PubMed] [Google Scholar]
- Torres M., Sánchez L. The sisterless-b function of the Drosophila gene scute is restricted to the stage when the X:A ratio determines the activity of Sex-lethal. Development. 1991 Oct;113(2):715–722. doi: 10.1242/dev.113.2.715. [DOI] [PubMed] [Google Scholar]
- Valcárcel J., Singh R., Zamore P. D., Green M. R. The protein Sex-lethal antagonizes the splicing factor U2AF to regulate alternative splicing of transformer pre-mRNA. Nature. 1993 Mar 11;362(6416):171–175. doi: 10.1038/362171a0. [DOI] [PubMed] [Google Scholar]
- Van Doren M., Ellis H. M., Posakony J. W. The Drosophila extramacrochaetae protein antagonizes sequence-specific DNA binding by daughterless/achaete-scute protein complexes. Development. 1991 Sep;113(1):245–255. doi: 10.1242/dev.113.1.245. [DOI] [PubMed] [Google Scholar]
- Villares R., Cabrera C. V. The achaete-scute gene complex of D. melanogaster: conserved domains in a subset of genes required for neurogenesis and their homology to myc. Cell. 1987 Jul 31;50(3):415–424. doi: 10.1016/0092-8674(87)90495-8. [DOI] [PubMed] [Google Scholar]
- Younger-Shepherd S., Vaessin H., Bier E., Jan L. Y., Jan Y. N. deadpan, an essential pan-neural gene encoding an HLH protein, acts as a denominator in Drosophila sex determination. Cell. 1992 Sep 18;70(6):911–922. doi: 10.1016/0092-8674(92)90242-5. [DOI] [PubMed] [Google Scholar]