PT  - JOURNAL ARTICLE
AU  - Qingzhong Ren
AU  - Ching-Po Yang
AU  - Zhiyong Liu
AU  - Ken Sugino
AU  - Kent Mok
AU  - Yisheng He
AU  - Tzumin Lee
TI  - Stem cell intrinsic, Seven-up-triggered temporal factor gradients diversify intermediate neural progenitors
AID  - 10.1101/121863
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 121863
4099  - http://biorxiv.org/content/early/2017/03/29/121863.short
4100  - http://biorxiv.org/content/early/2017/03/29/121863.full
AB  - Drosophila type II neuroblasts produce numerous neurons and glia due to transiently amplifying, intermediate neural progenitors (INP). Consecutively born INPs produce morphologically distinct progeny, presumably due to temporal patterning in type II neuroblasts. We therefore profiled type II neuroblasts’ transcriptome across time. Our results reveal opposing temporal gradients of Imp and Syp RNA-binding proteins (descending and ascending, respectively). Maintaining Imp expression throughout brain development expands the number of neurons/glia with early temporal fate at the expense of cells with late fate. Conversely, precocious upregulation of Syp reduces the number of cells with early fate. Further, we reveal that the transcription factor, Seven-up initiates progression of the Imp/Syp gradients. Interestingly, genetic manipulations that fix Imp or Syp levels still yield progeny with a small range of early fates. We propose that the Seven-up-initiated Imp/Syp gradients create coarse temporal windows within type II neuroblasts to pattern INPs, which subsequently undergo fine-tuned subtemporal patterning.