Evidence that helix-loop-helix proteins collaborate with retinoblastoma tumor suppressor protein to regulate cortical neurogenesis.
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.
Toma
J G
JG
Center for Neuronal Survival, Montreal Neurological Institute, Montreal, Canada H3A 2B4.
El-Bizri
H
H
Barnabe-Heider
F
F
Aloyz
R
R
Miller
F D
FD
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis; D002454:Cell Differentiation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D018257:Helix-Loop-Helix Motifs / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D051797:Inhibitor of Differentiation Protein 2; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D012097:Repressor Proteins; D016160:Retinoblastoma Protein / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014404:Tubulin / Q000378:metabolism
D004268:DNA-Binding Proteins; C497452:Idb2 protein, mouse; D051797:Inhibitor of Differentiation Protein 2; D012097:Repressor Proteins; D016160:Retinoblastoma Protein; D014157:Transcription Factors; D014404:Tubulin