scholarly journals Regulated splicing of the Drosophila sex-lethal male exon involves a blockage mechanism.

1993 ◽  
Vol 13 (3) ◽  
pp. 1408-1414 ◽  
Author(s):  
J I Horabin ◽  
P Schedl
Keyword(s):  
Drosophila Melanogaster ◽  
Alternative Splicing ◽  
Sex Determination ◽  
Splice Site ◽  
Feedback Loop ◽  
Splice Sites ◽  
Alternate Splicing ◽  
Sequence Context ◽  
Sex Lethal ◽  
Hodgkin Cell

In Drosophila melanogaster, sex determination in somatic cells is controlled by a cascade of genes whose expression is regulated by alternative splicing [B. S. Baker, Nature (London) 340:521-524, 1989; J. Hodgkin, Cell 56:905-906, 1989]. The master switch gene in this hierarchy is Sex-lethal. Sex-lethal is turned on only in females, and an autoregulatory feedback loop which controls alternative splicing maintains this state (L. R. Bell, J. I. Horabin, P. Schedl, and T. W. Cline, Cell 65:229-239, 1991; L. N. Keyes, T. W. Cline, and P. Schedl, Cell 68:933-943, 1992). Sex-lethal also promotes female differentiation by controlling the splicing of RNA from the next gene in the hierarchy, transformer. Sosnowski et al. (B. A. Sosnowski, J. M. Belote, and M. McKeown, Cell 58:449-459, 1989) have shown that the mechanism for generating female transformer transcripts is not through the activation of the alternative splice site but by the blockage of the default splice site. We have tested whether an activation or a blockage mechanism is involved in Sex-lethal autoregulation. The male exon of Sex-lethal with flanking splice sites was placed into the introns of heterologous genes. Our results support the blockage mechanism. The poly(U) run at the male exon 3' splice site is required for sex-specific splicing. However, unlike transformer, default splicing to the male exon is sensitive to the sequence context within which the exon resides. This and the observation that the splice signals at the exon are suboptimal are discussed with regard to alternate splicing.

Regulated splicing of the Drosophila sex-lethal male exon involves a blockage mechanism

1993 ◽  
Vol 13 (3) ◽  
pp. 1408-1414
Author(s):  
J I Horabin ◽  
P Schedl
Keyword(s):  
Drosophila Melanogaster ◽  
Alternative Splicing ◽  
Sex Determination ◽  
Splice Site ◽  
Feedback Loop ◽  
Splice Sites ◽  
Alternate Splicing ◽  
Sequence Context ◽  
Sex Lethal ◽  
Hodgkin Cell

In Drosophila melanogaster, sex determination in somatic cells is controlled by a cascade of genes whose expression is regulated by alternative splicing [B. S. Baker, Nature (London) 340:521-524, 1989; J. Hodgkin, Cell 56:905-906, 1989]. The master switch gene in this hierarchy is Sex-lethal. Sex-lethal is turned on only in females, and an autoregulatory feedback loop which controls alternative splicing maintains this state (L. R. Bell, J. I. Horabin, P. Schedl, and T. W. Cline, Cell 65:229-239, 1991; L. N. Keyes, T. W. Cline, and P. Schedl, Cell 68:933-943, 1992). Sex-lethal also promotes female differentiation by controlling the splicing of RNA from the next gene in the hierarchy, transformer. Sosnowski et al. (B. A. Sosnowski, J. M. Belote, and M. McKeown, Cell 58:449-459, 1989) have shown that the mechanism for generating female transformer transcripts is not through the activation of the alternative splice site but by the blockage of the default splice site. We have tested whether an activation or a blockage mechanism is involved in Sex-lethal autoregulation. The male exon of Sex-lethal with flanking splice sites was placed into the introns of heterologous genes. Our results support the blockage mechanism. The poly(U) run at the male exon 3' splice site is required for sex-specific splicing. However, unlike transformer, default splicing to the male exon is sensitive to the sequence context within which the exon resides. This and the observation that the splice signals at the exon are suboptimal are discussed with regard to alternate splicing.

Induction of female Sex-lethal RNA splicing in male germ cells: implications for Drosophila germline sex determination

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5033-5048 ◽  
Author(s):  
J.H. Hager ◽  
T.W. Cline
Keyword(s):  
Sex Determination ◽  
Germ Cells ◽  
Rna Splicing ◽  
Feedback Loop ◽  
Dose Effect ◽  
Male Germ Cells ◽  
Control Female ◽  
Sex Lethal ◽  
Specific Regulation ◽  
Female Specific

With a focus on Sex-lethal (Sxl), the master regulator of Drosophila somatic sex determination, we compare the sex determination mechanism that operates in the germline with that in the soma. In both cell types, Sxl is functional in females (2X2A) and nonfunctional in males (1X2A). Somatic cell sex is determined initially by a dose effect of X:A numerator genes on Sxl transcription. Once initiated, the active state of SXL is maintained by a positive autoregulatory feedback loop in which Sxl protein insures its continued synthesis by binding to Sxl pre-mRNA and thereby imposing the productive (female) splicing mode. The gene splicing-necessary factor (snf), which encodes a component of U1 and U2 snRNPs, participates in this RNA splicing control. Here we show that an increase in the dose of snf+ can trigger the female Sxl RNA splicing mode in male germ cells and can feminize triploid intersex (2X3A) germ cells. These snf+ dose effects are as dramatic as those of X:A numerator genes on Sxl in the soma and qualify snf as a numerator element of the X:A signal for Sxl in the germline. We also show that female-specific regulation of Sxl in the germline involves a positive autoregulatory feedback loop on RNA splicing, as it does in the soma. Neither a phenotypically female gonadal soma nor a female dose of X chromosomes in the germline is essential for the operation of this feedback loop, although a female X-chromosome dose in the germline may facilitate it. Engagement of the Sxl splicing feedback loop in somatic cells invariably imposes female development. In contrast, engagement of the Sxl feedback loop in male germ cells does not invariably disrupt spermatogenesis; nevertheless, it is premature to conclude that Sxl is not a switch gene in germ cells for at least some sex-specific aspects of their differentiation. Ironically, the testis may be an excellent organ in which to study the interactions among regulatory genes such as Sxl, snf, ovo and otu which control female-specific processes in the ovary.

scholarly journals hnRNP A1 Regulates Alternative Splicing of Tau Exon 10 by Targeting 3′ Splice Sites

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 936 ◽  
Author(s):  
Yongchao Liu ◽  
Donggun Kim ◽  
Namjeong Choi ◽  
Jagyeong Oh ◽  
Jiyeon Ha ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Ontology ◽  
Alternative Splicing ◽  
Splice Site ◽  
Hnrnp A1 ◽  
Gene Ontology Analysis ◽  
Splice Sites ◽  
Neuronal Function ◽  
Brain Functions ◽  
Exon 10

The ratio control of 4R-Tau/3R-Tau by alternative splicing of Tau exon 10 is important for maintaining brain functions. In this study, we show that hnRNP A1 knockdown induces inclusion of endogenous Tau exon 10, conversely, overexpression of hnRNP A1 promotes exon 10 skipping of Tau. In addition, hnRNP A1 inhibits splicing of intron 9, but not intron 10. Furthermore, hnRNP A1 directly interacts with the 3′ splice site of exon 10 to regulate its functions in alternative splicing. Finally, gene ontology analysis demonstrates that hnRNP A1-induced splicing and gene expression targets a subset of genes with neuronal function.

scholarly journals The Sex-lethal early splicing pattern uses a default mechanism dependent on the alternative 5' splice sites.

1997 ◽  
Vol 17 (3) ◽  
pp. 1674-1681 ◽  
Author(s):  
C Zhu ◽  
J Urano ◽  
L R Bell
Keyword(s):  
Tissue Culture ◽  
Splice Site ◽  
Site Preference ◽  
Splice Sites ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Important Region ◽  
Splicing Pattern ◽  
Sex Lethal ◽  
Splicing Patterns

The Sex-lethal (Sxl) early transcripts have a unique 5' exon and a splicing pattern that differs from that of the late transcripts. While the late transcripts are regulated sex specifically by control of exon 3 inclusion, the early transcripts are not. While the late transcripts include exon 3 by default, the early transcripts skip exon 3. Splicing patterns of a reporter gene that mimics the early transcript, and its variants, were analyzed in Drosophila transformants and tissue culture cells. The results demonstrate that the early, in contrast to the late, splicing pattern is not regulated by stage-specific or sex-specific trans-acting factors, and so the pattern appears to arise from some type of intrinsic splice site preference or compatibility. Inclusion or exclusion of exon 3 is determined by the identity of the upstream 5' splice site region as late or early. The important region of the early exon lies within 233 nucleotides of the immediately adjacent intron.

scholarly journals Two forms of Drosophila melanogaster Gs alpha are produced by alternate splicing involving an unusual splice site.

1990 ◽  
Vol 10 (3) ◽  
pp. 910-917 ◽  
Author(s):  
F Quan ◽  
M A Forte
Keyword(s):  
Drosophila Melanogaster ◽  
Splice Site ◽  
Sodium Dodecyl ◽  
Receptor Activation ◽  
In Vitro Translation ◽  
Alternate Splicing ◽  
Molecular Weights ◽  
Intron Structure ◽  
Gs Alpha

G proteins are responsible for modulating the activity of intracellular effector systems in response to receptor activation. The stimulatory G protein Gs is responsible for activation of adenylate cyclase in response to a variety of hormonal signals. In this report, we describe the structure of the gene for the alpha subunit of Drosophila melanogaster Gs. The gene is approximately 4.5 kilobases long and is divided into nine exons. The exon-intron structure of the Drosophila gene shows substantial similarity to that of the human gene for Gs alpha. Alternate splicing of intron 7, involving either use of an unusual TG or consensus AG 3' splice site, results in transcripts which code for either a long (DGs alpha L) or short (DGs alpha S) form of Gs alpha. These subunits differ by inclusion or deletion of three amino acids and substitution of a Ser for a Gly. The two forms of Drosophila Gs alpha differ in a region where no variation in the primary sequence of vertebrate Gs alpha subunits has been observed. In vitro translation experiments demonstrated that the Drosophila subunits migrate anomalously on sodium dodecyl sulfate-polyacrylamide gels with apparent molecular weights of 51,000 and 48,000. Additional Gs alpha transcript heterogeneity reflects the use of multiple polyadenylation sites.

scholarly journals Combinatorial Control of Exon Recognition

2007 ◽  
Vol 283 (3) ◽  
pp. 1211-1215 ◽  
Author(s):  
Klemens J. Hertel
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Cell Types ◽  
Splice Sites ◽  
Splice Site Selection ◽  
Multiple Parameters ◽  
Splicing Regulators ◽  
Eukaryotic Genes ◽  
Different Cell Types ◽  
Mature Mrnas

Pre-mRNA splicing is a fundamental process required for the expression of most metazoan genes. It is carried out by the spliceosome, which catalyzes the removal of noncoding intronic sequences to assemble exons into mature mRNAs prior to export and translation. Given the complexity of higher eukaryotic genes and the relatively low level of splice site conservation, the precision of the splicing machinery in recognizing and pairing splice sites is impressive. Introns ranging in size from <100 up to 100,000 bases are removed efficiently. At the same time, a large number of alternative splicing events are observed between different cell types, during development, or during other biological processes. This extensive alternative splicing implies a significant flexibility of the spliceosome to identify and process exons within a given pre-mRNA. To reach this flexibility, splice site selection in higher eukaryotes has evolved to depend on multiple parameters such as splice site strength, the presence or absence of splicing regulators, RNA secondary structures, the exon/intron architecture, and the process of pre-mRNA synthesis itself. The relative contributions of each of these parameters control how efficiently splice sites are recognized and flanking introns are removed.

Factor interactions with the simian virus 40 early pre-mRNA influence branch site selection and alternative splicing

1989 ◽  
Vol 9 (5) ◽  
pp. 2007-2017
Author(s):  
J C Noble ◽  
H Ge ◽  
M Chaudhuri ◽  
J L Manley
Keyword(s):  
Alternative Splicing ◽  
Splice Site ◽  
Rnase Protection Assay ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Splice Sites ◽  
Rnase Protection ◽  
Branch Site ◽  
Factor Interactions ◽  
Selection Of

To study the interaction of splicing factors with the simian virus 40 early-region pre-RNA, which can be alternatively spliced to produce large T and small t mRNAs, we used an in vitro RNase protection assay that defines the 5' boundaries of factor-RNA interactions. Protection products reflecting factor interactions with the large T and small t 5' splice sites and with the multiple lariat branch site region were characterized. All protection products were detected very early in the splicing reaction, before the appearance of spliced RNAs. However, protection of the large T 5' splice site was detected well before small t 5' splice site and branch site protection products, which appeared simultaneously. Oligonucleotide-targeted degradation of small nuclear RNAs (snRNAs) revealed that protection of the branch site region, which occurred at multiple sites, required intact U2 snRNA and was enhanced by U1 snRNA, while protection of the large T and small t 5' splice sites required both U1 and U2 snRNAs. Analysis of several pre-RNAs containing mutations in the branch site region suggests that factor interactions involving the multiple copies of the branch site consensus determine the selection of branch points, which is an important factor in the selection of alternative splicing pathways.

A Theoretical Model for the Regulation of Sex-lethal, a Gene That Controls Sex Determination and Dosage Compensation in Drosophila melanogaster

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1355-1384
Author(s):  
Matthieu Louis ◽  
Liisa Holm ◽  
Lucas Sánchez ◽  
Marcelle Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
Theoretical Model ◽  
Sex Determination ◽  
Numerical Simulations ◽  
Cell Fate ◽  
Regulatory Gene ◽  
Experimental Studies ◽  
Formal Basis ◽  
Sex Lethal ◽  
Specific Regulation

Abstract Cell fate commitment relies upon making a choice between different developmental pathways and subsequently remembering that choice. Experimental studies have thoroughly investigated this central theme in biology for sex determination. In the somatic cells of Drosophila melanogaster, Sex-lethal (Sxl) is the master regulatory gene that specifies sexual identity. We have developed a theoretical model for the initial sex-specific regulation of Sxl expression. The model is based on the well-documented molecular details of the system and uses a stochastic formulation of transcription. Numerical simulations allow quantitative assessment of the role of different regulatory mechanisms in achieving a robust switch. We establish on a formal basis that the autoregulatory loop involved in the alternative splicing of Sxl primary transcripts generates an all-or-none bistable behavior and constitutes an efficient stabilization and memorization device. The model indicates that production of a small amount of early Sxl proteins leaves the autoregulatory loop in its off state. Numerical simulations of mutant genotypes enable us to reproduce and explain the phenotypic effects of perturbations induced in the dosage of genes whose products participate in the early Sxl promoter activation.

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