The roX genes encode redundant male-specific lethal transcripts required for targeting of the MSL complex

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• Drosophila roX1 and roX2 genes produce male-specific non-coding RNAs.
• These RNAs co-localize with the Male-Specific Lethal (MSL) protein complex.
• The MSL complex up-regulates the male X chromosome via histone H4 acetylation for gene expression equalization.

Purpose of the Study:

• To investigate the essentiality and function of roX1 and roX2 genes.
• To understand the role of roX RNAs in targeting the MSL complex.
• To explore the redundancy between roX1 and roX2.

Main Methods:

• Generation of flies lacking roX2.
• Simultaneous genetic removal of both roX RNAs.
• Rescue experiments using roX cDNAs from autosomal transgenes.

Main Results:

• Individual roX1 or roX2 gene deletion is non-essential.
• Simultaneous deletion of roX1 and roX2 leads to male-specific lethality.
• MSL proteins and H4 acetylation relocate from the X chromosome to autosomal sites and heterochromatin in roX-deficient males.
• Autosomal roX cDNA transgenes can rescue male viability.

Conclusions:

• roX1 and roX2 genes produce redundant, male-specific lethal transcripts.
• These transcripts are crucial for targeting the MSL complex to the X chromosome.
• Chromatin entry and RNA-encoding functions are genetically separable.