MCPH1 has been identified as the causal gene for primary microcephaly type 1, a neurodevelopmental disorder characterized by reduced brain size and delayed growth. As a multifunction protein, MCPH1 has been reported to repress the expression of TERT and interact with transcriptional regulator E2F1. However, it remains unclear whether MCPH1 regulates brain development through its transcriptional regulation function. This study showed that the knockout of Mcph1 in mice leads to delayed growth as early as the embryo stage E11.5. Transcriptome analysis (RNA-seq) revealed that the deletion of Mcph1 resulted in changes in the expression levels of a limited number of genes. Although the expression of some of E2F1 targets, such as Satb2 and Cdkn1c, was affected, the differentially expressed genes (DEGs) were not significantly enriched as E2F1 target genes. Further investigations showed that primary and immortalized Mcph1 knockout mouse embryonic fibroblasts (MEFs) exhibited cell cycle arrest and cellular senescence phenotype. Interestingly, the upregulation of p19ARF was detected in Mcph1 knockout MEFs, and silencing p19Arf restored the cell cycle and growth arrest to wild-type levels. Our findings suggested it is unlikely that MCPH1 regulates neurodevelopment through E2F1-mediated transcriptional regulation, and p19ARF-dependent cell cycle arrest and cellular senescence may contribute to the developmental abnormalities observed in primary microcephaly.

Influenza viruses are characterized by their high variability and pathogenicity, and effective therapeutic options remain limited. Given these challenges, targeting host cell proteins that facilitate viral replication presents a promising strategy for antiviral drug discovery. In the present study, we observed a significant upregulation of Glycyl-tRNA synthetase (GlyRS) within 24 h post-PR8 virus infection. The inhibition of GlyRS expression in A549 cells resulted in a marked reduction in infection rates across multiple influenza virus strains, while the overexpression of GlyRS led to an increase in viral infectivity during the early stages of infection. These findings suggest that GlyRS plays a critical role in the replication of influenza virus. Accordingly, we screened for potential inhibitors targeting GlyRS and identified Lycobetaine and Scutellarein using a multifaceted approach. Through a combination of molecular dynamics simulations, we further elucidated the mechanisms of action and potential binding sites of these compounds. Both inhibitors effectively suppressed the replication of influenza viruses, and their antiviral activity was confirmed to be mediated by GlyRS targeting. Therefore, GlyRS inhibitors, such as Lycobetaine and Scutellarein, represent promising candidates for combating influenza infections and provide novel insights into the treatment of influenza and aaRS-related diseases, opening new avenues for the development of aaRS-targeted therapeutics.