Regionally restricted expression of the transcription factor c-myc intron 1 binding protein during brain development

Transcription factors regulate proliferation, differentiation, and regionalization of the central nervous system. In a screen of developing cerebral cortex, we identified the transcription factor c-myc intron 1 binding protein (mibp1) due to its abundant expression. In this study, we analyzed the temporal and spatial expression patterns of mibp1 mRNA in developing mouse brain to address the putative role of this transcription factor in neural differentiation. Northern hybridization studies revealed that mibp1 is expressed first in the mouse dorsal telencephalon at embryonic day (E) 14.5, during peak neuronal production. In situ hybridization experiments revealed that mibp1 expression in the cerebral wall is most abundant in postmitotic cells of the cortical plate and absent from proliferative zones. Moreover, mibp1 is restricted to dorsal telencephalon during embryogenesis with expression only in the cerebral wall, olfactory bulb, and hippocampus. N-myc, a potential target of mibp1 regulation, exhibited complementary, nonoverlapping expression patterns in the telencephalon with greatest expression in proliferating cells of the ventricular zone from E12.5 to E14.5; N-myc was absent from the telencephalon by E15.5. The specificity and timing of mibp1 expression in the cerebral cortex suggests a role in maintaining a state of neuronal differentiation in the dorsal telencephalon.