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Autoregulation of the Drosophila Noncoding roX1 RNA Gene
Chiat Koo Lim1, Richard L Kelley
1Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, USA.
Plos Genetics
|March 23, 2012
Summary
Male-specific lethal (MSL) complex in Drosophila uses roX RNAs to target dosage compensation. Pre-existing roX RNA is required for roX1 gene expression, and MSL complex spreading aids X chromosome targeting.
Area of Science:
- Genetics
- Molecular Biology
- Epigenetics
Background:
- Drosophila X chromosome genes are hypertranscribed twofold in males via the MSL complex.
- The MSL complex utilizes roX1 and roX2 noncoding RNAs for targeting chromatin modifiers.
- roX1 and roX2 are functionally redundant but differ in sequence and regulation.
Purpose of the Study:
- Investigate the regulation of roX1 (RNA on X1) production.
- Determine the role of existing roX RNA in roX1 expression.
- Understand MSL complex spreading and msl2 gene transcription coordination.
Main Methods:
- In situ hybridization specific to endogenous roX1.
- Ectopic expression of MSL2 in wild-type and mutant Drosophila females.
- Analysis of roX1 expression with and without roX2 or functional roX1 variants.
Main Results:
- roX1 expression is unreliable without roX2.
- Pre-existing roX RNA (roX1 or roX2) is necessary for robust roX1 autoregulation.
- MSL complex exhibits massive cis spreading from the roX1 locus.
- msl2 gene transcription is linked to DNA replication.
Conclusions:
- Positive autoregulation by roX RNA is crucial for roX1 expression.
- MSL complex retention and spreading contribute to X chromosome targeting and sustained transcription.
- Coordinated production of roX1 and msl2 supports Drosophila dosage compensation.
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