Orb2 enables rare-codon-enriched mRNA expression during Drosophila neuron differentiation.

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Codon optimality is a key regulator of cell- and tissue-specific protein expression.
• Understanding how gene expression is controlled during neural stem cell differentiation is crucial for developmental biology.

Purpose of the Study:

• To investigate the role of codon optimality in Drosophila neural stem cell differentiation.
• To identify regulators of rare-codon-enriched gene expression in neurons.
• To elucidate the function of Orb2 in regulating mRNA stability and its impact on neuronal function.

Main Methods:

• Utilized codon-modified reporters to assess protein expression.
• Performed candidate screening to identify regulatory proteins.
• Employed RNA sequencing to analyze mRNA profiles in the brain.
• Investigated the impact of rare-codon enrichment on mRNA stability and gene function.

Main Results:

• Drosophila neural stem cell differentiation promotes protein expression from rare-codon-enriched genes.
• Identified Orb2 (cytoplasmic polyadenylation element binding protein) as a positive regulator of rare-codon-dependent mRNA stability in neurons.
• Orb2-upregulated mRNAs in the brain exhibit a rare-codon bias and contain Orb2 binding sites.
• Rare-codon enrichment is essential for the stability and social behavior function of the metabotropic glutamate receptor (mGluR).

Conclusions:

• Neural stem cell differentiation triggers a shift in genetic code regulation, favoring rare-codon usage.
• Orb2-mediated stabilization of rare-codon-enriched mRNAs is a critical mechanism for enabling protein expression in neurons.
• This regulatory pathway is important for the function of specific genes, such as mGluR, and influences complex behaviors like social interaction.