TY - JOUR T1 - Evidence That Helix-Loop-Helix Proteins Collaborate with Retinoblastoma Tumor Suppressor Protein to Regulate Cortical Neurogenesis JF - The Journal of Neuroscience JO - J. Neurosci. SP - 7648 LP - 7656 DO - 10.1523/JNEUROSCI.20-20-07648.2000 VL - 20 IS - 20 AU - Jean G. Toma AU - Hiba El-Bizri AU - Fanie Barnabé-Heider AU - Raquel Aloyz AU - Freda D. Miller Y1 - 2000/10/15 UR - http://www.jneurosci.org/content/20/20/7648.abstract N2 - 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. ER -