Stem Cell-Intrinsic, Seven-up-Triggered Temporal Factor Gradients Diversify Intermediate Neural Progenitors

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Complex brains require cellular expansion and diversification.
• Drosophila type II neuroblasts, similar to mammalian neural stem cells, use intermediate neural progenitors (INPs) for neuron and glia production.
• Sequential INPs within a lineage produce distinct progeny, suggesting temporal patterning mechanisms.

Purpose of the Study:

• To investigate the temporal fating mechanisms in Drosophila type II neuroblast lineages.
• To identify molecular factors regulating the temporal identity of neural progenitors.

Main Methods:

• Transcriptome profiling of type II neuroblasts over time.
• Analysis of RNA-binding protein gradients (Imp and Syp).
• Investigating the role of the transcription factor Seven-up.

Main Results:

• Opposing temporal gradients of Imp (descending) and Syp (ascending) RNA-binding proteins were identified.
• High Imp levels favor early temporal fates, while precocious Syp upregulation favors late temporal fates.
• The transcription factor Seven-up initiates the Imp/Syp gradients, establishing coarse temporal windows.

Conclusions:

• Seven-up-initiated Imp/Syp gradients create coarse temporal windows in type II neuroblasts.
• These gradients pattern intermediate neural progenitors (INPs) for subsequent fine-tuned subtemporal patterning.
• This mechanism ensures appropriate cellular diversification for complex brain formation.