Protein translation rate determines neocortical neuron fate

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mammalian neocortex exhibits remarkable diversity in cell types, morphology, and connectivity.
• Understanding the mechanisms driving this cellular diversity is crucial for comprehending brain development.

Purpose of the Study:

• To investigate post-transcriptional gene regulation, specifically protein translation, as a determinant of cortical neuron identity.
• To identify key molecular players and pathways involved in regulating translation for neuronal diversity.

Main Methods:

• Conducted small molecule screening to identify regulators of gene expression and neuronal characteristics.
• Utilized techniques to measure protein synthesis rates and protein half-lives in developing neurons.
• Investigated the role of Ire1α (Inositol-requiring enzyme 1 alpha) and eIF4A1 (eukaryotic initiation factor 4A1) in regulating translation and gene expression.

Main Results:

• Discovered that increased protein synthesis in progenitors of later-born neurons contributes to neuronal identity.
• Identified Ire1α as a regulator of Satb2 expression and neuronal polarity, influencing global translation rates and ribosome traffic.
• Demonstrated that Satb2 mRNA translation is dependent on eIF4A1 helicase activity, highlighting its role in post-transcriptional regulation.

Conclusions:

• Cortical neuron diversity arises from mechanisms operating beyond gene transcription, including post-transcriptional regulation of protein synthesis.
• Ire1α-mediated proteostasis is essential for regulating translation and plays a critical role in mammalian brain development and neuronal subtype specification.