PT  - JOURNAL ARTICLE
AU  - Jean G. Toma
AU  - Hiba El-Bizri
AU  - Fanie Barnabé-Heider
AU  - Raquel Aloyz
AU  - Freda D. Miller
TI  - Evidence That Helix-Loop-Helix Proteins Collaborate with Retinoblastoma Tumor Suppressor Protein to Regulate Cortical Neurogenesis
AID  - 10.1523/JNEUROSCI.20-20-07648.2000
DP  - 2000 Oct 15
TA  - The Journal of Neuroscience
PG  - 7648--7656
VI  - 20
IP  - 20
4099  - http://www.jneurosci.org/content/20/20/7648.short
4100  - http://www.jneurosci.org/content/20/20/7648.full
SO  - J. Neurosci.2000 Oct 15; 20
AB  - The retinoblastoma tumor suppressor protein (pRb) family is essential for cortical progenitors to exit the cell cycle and survive. In this report, we test the hypothesis that pRb collaborates with basic helix-loop-helix (bHLH) transcription factors to regulate cortical neurogenesis, taking advantage of the naturally occurring dominant-inhibitory HLH protein Id2. Overexpression of Id2 in cortical progenitors completely inhibited the induction of neuron-specific genes and led to apoptosis, presumably as a consequence of conflicting differentiation signals. Both of these phenotypes were rescued by coexpression of a constitutively activated pRb mutant. In contrast, Id2 overexpression in postmitotic cortical neurons affected neither neuronal gene expression nor survival. Thus, pRb collaborates with HLHs to ensure the coordinate induction of terminal mitosis and neuronal gene expression as cortical progenitors become neurons.