In order to dissect differential expression on a finer temporal scale, we LY2157299 TGF-beta inhibitor selected 2 genes for further analysis, namely Catechol-O-methyltransferase 1 and Dual specificity protein phosphatase 1 , which were either downregulated or up-regulated at both P3 and P21 . We monitored Comt1 and Dusp1/MPK1 mRNA levels in the brain of wild-type and mutant mice by qRT-PCR at several postnatal timepoints from P1 to P60. Interestingly, whereas no difference in Comt1 mRNA levels was observed between wild-type and mutant mice at P1, Comt1 mRNA level in mutant mice was down-regulated soon after birth and remained lower compared to wild-type mice for at least 3 weeks , followed by normal levels in adult mutant mice . This underlines the transient abnormality of Comt1 gene expression during early postnatal brain high throughput screening development due to Eif2b5 mutation. Analysis of Dusp1/ Mkp1 mRNA levels also showed transient mutation-induced differences. Importantly, our analysis revealed that during normal brain development, Dusp1/Mkp1 expression is down-regulated in the first week after birth followed by gradual up-regulation in the second and third weeks until it returns to its initial high levels in the adult brain . Dusp1/Mkp1 mRNA levels were similar in wild-type and Eif2b5-mutated mice during the first two postnatal weeks. However, while Dusp1/Mpk1 mRNA levels increased in a moderate fashion during the third postnatal week in the wild-type mice, its levels ascended more drastically in the mutant mice, building abnormal up-regulation specifically during the peak of white matter formation . To better understand the spatial distribution of abnormal gene expression, 12 genes were selected for further analysis of mRNA levels in the cerebrum and brain-stem of wild-type and Eif2b5- mutated mice at P21. The expression level of 2 of these genes was altered only in the brain stem but not the cerebrum, whereas the expression level of others was altered only in the cerebrum but not the brain stem. In contrast, the expression level of yet another group of genes was altered in both brain regions . Of these, Comt1 was downregulated in both regions while Hspa12a and Hyou12 were upregulated in the brain stem but down-regulated in the cerebrum at P21 . To test if Hspa12a and Hyou12 also share similar age-specific alterations, their mRNA levels were quantitated by qRT-PCR at P3 in both brain regions. This analysis revealed that at both time points during early postnatal development, the mutation in Eif2b5 led to lower levels of Hspa12a and Hyou1 mRNAs in the cerebrum and higher levels of both mRNAs in the brain stem .