Sex-specific transcript complexity in the neural system of Drosophila melanogaster

Hochschulschrift

Abstract: Post-transcriptional alternative splicing (AS) of precursor messenger RNA (pre-mRNA) is a fundamental process in the gene expression cascade. Via alternative splicing, transcriptome and proteome diversity is massively increased in higher organisms, and recent studies revealed that over 95 % of human and 60 % of Drosophila genes are alternatively spliced (Graveley et al., 2011; Pan et al., 2008; Wang et al., 2008). However, in general little is known about the impact of AS on developmental processes, about regulatory mechanisms underlying AS, and about the biological role of alternative transcripts. The sex determination pathway of Drosophila serves as a prime example and is the best analyzed splicing network to date. Sex-lethal (Sxl) as the master regulator on top of the sex determination cascade directly regulates sex-specific AS of its own transcript and the pre mRNAs of male-specific lethal 2 (msl-2) which is crucial for dosage compensation, and transformer (tra) encoding another splicing factor (Bashaw & Baker, 1995; Bell et al., 1991; Inoue et al., 1990; Kelley et al., 1997; Nagoshi et al., 1988). Subsequently, Tra together with Transformer2 (Tra2) controls AS of doublesex (dsx) and fruitless (fru) which in turn encode sex-specific transcription factors (Burtis & Baker, 1989; Ito et al., 1996; Ryner & Baker, 1991; Ryner et al., 1996).
In this thesis, Drosophila was used as a model organism to explore the level of sex-specific transcripts in the neural system, to investigate the regulation of AS, and to explore the biological relevance of these transcripts. For this purpose, genome-wide approaches were combined with in vivo genetic and molecular studies. Whole-transcriptome RNA-Sequencing (RNA-Seq) analyses revealed that many more genes besides the classical sex determination factors are sex-specific alternatively spliced in the adult fly head. Further experiments showed that these AS changes are not significantly influenced by signals of the germline or factors which are transferred during mating. The absence of sex-specific transcripts in third instar larval brains further supported the idea of a functional relevance of sex-specific transcripts in adult fly heads.
As for most of these alternatively spliced transcripts no prove of functional isoforms already existed, we investigated whether sex-specific isoforms of one of our candidate genes, Tango13, fulfill specific functions. Firstly, we showed that Tango13 transcripts encode two sex-specific protein isoforms. Next, we illustrated the potential of alternative Tango13 isoforms to influence the behavior of the fly in a sex-specific manner. We postulate that in the case of Tango13, sex-specific AS might also interfere with signaling via the sulfation pathway.
Using dual-fluorescence reporter minigenes to monitor AS in vivo, we observed the exciting phenomenon of tissue-specific regulated isoform expression. Often, one isoform was exclusively expressed in one tissue, whereas the alternative isoform was expressed in another tissue. While this observation hindered the assessment of sex-specific isoform levels, we investigated cis- and trans acting regulatory elements underlying tissue-specific AS of Tango13. Here, ELAV was identified as a potential trans-acting regulator of Tango13 alternative splice site choice.
Taken together, in this thesis I could show that sex-specific AS targets various other genes next to the classical sex determinants, has important biological functions, and features interesting regulatory mechanisms

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: IN COPYRIGHT http://rightsstatements.org/page/InC/1.0 rs ; Albert-Ludwigs-Universität Freiburg, Dissertation, 2016

Classification and Topics

• Classification: Biowissenschaften, Biologie
• Keyword: RNS-Spleißen ; Spleißfaktor ; Taufliege

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2016
• Creator: Mohr, Carmen
• Contributor: Hartmann, Britta ; Albert-Ludwigs-Universität Freiburg. Fakultät für Biologie ; Albert-Ludwigs-Universität Freiburg

Further information

• DOI: 10.6094/UNIFR/10809
• URN: urn:nbn:de:bsz:25-freidok-108092
• Rights: Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:49 PM CET