DNA replication fork speed Acts as A Pacer in Cortical Neurogenesis

DNA replication fork speed, which controls the rate of genome duplication, has emerged as a key regulator of cellular plasticity. However, its role in neurogenesis remains unexplored. Mini-chromosome maintenance complex (MCMs)-binding protein (MCMBP) functions as a chaperone for newly synthesized MCMs, increasing chromatin coverage to restrain fork speed. We demonstrate that selective deletion of MCMBP in neural progenitor radial glial cells (RGCs) accelerates fork speed, triggering widespread apoptosis, DNA damage, and micronuclei formation, ultimately activating p53 and causing microcephaly. Unexpectedly, concurrent deletion of Trp53 and Mcmbp further increased fork speed, leading to extensive RGC detachment from the ventricular zone and acquisition of outer-RGC characteristics. Mechanistically, we found that the MCM3 subunit coordinates DNA and centrosome duplication, thereby mediating RGC attachment. Behavioral analysis revealed that disruption of fork speed results in anxiety-like behavior in mice. These findings unveil a previously unrecognized role for replication fork speed in neurogenesis. Overall design: We sequenced a total of 20 samples of mRNA from E15.5 mouse cerebral cortex. 9 samples were controls (wild type or heterozygote), 6 samples were Emx1-Cre Mcmbp conditional KO, and 5 samples were Emx1-Cre Mcmbp/Trp53 double conditional KO.