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. 2021 Oct 20;9:753175. doi: 10.3389/fcell.2021.753175

FIGURE 1.

FIGURE 1

Expression profiles of cell cycle-related proteins in the brain. Schematic illustration of the cell cycle and DNA repair in neural progenitors (A) and differentiated neurons (B). During the S and G2 phases, damaged DNA is predominantly repaired via homology-directed repair (HDR), whereas non-homologous end-joining (NHEJ) is utilized at the G1 and G0 phases (see the text for details). (C–I) Relative mRNA expression levels of cell cycle-related proteins in cerebral cortices of mice at embryonic day 10 (E10), E18, and 2 months old. Total RNA was extracted from the cerebral cortices of E10, E18, and 2-month-old ICR mice (SLC Japan) using an RNeasy Mini Kit (Qiagen) and transcribed into first-strand cDNA using ReverTra Ace qPCR RT Master Mix (TOYOBO), according to the manufacturer’s instructions. Quantitative real-time PCR was performed with a QuantStudio 3 Real-Time PCR System (Applied Biosystems) using TaqMan Array Fast Plates for cell cycle-related and DNA repair genes (Applied Biosystems) (see also Supplementary Table 1). Relative expression levels were calculated by the comparative Ct (ΔΔCt) method using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA as an internal control. Animals were handled in accordance with guidelines established by RIKEN-BDR and Institute of Biomedical Research and Innovation, FBRI. Each Y-axis shows the mean ratio ± standard deviation (SD). Significance of differences between the relative mRNA expression levels at E10 and that of E18 or 2 months old was determined by applying Student’s t test. *P < 0.05, **P < 0.01, ***P < 0.001, and n.s., no significant difference.