Xu, Y.-Y. | Search bioRxiv

bioRxiv2026

IGF2BP2 links m6A-modified HMGA1 mRNA stability to mitochondrial metabolism and cell proliferation

Chinese hamster ovary (CHO) cells serve as the primary host for industrial therapeutic protein production, yet enhancing their productivity remains a significant challenge. Epigenetic regulation, particularly RNA N6-methyladenosine modification, offers a promising strategy. Here, we show that the m6A reader protein insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) positively regulates recombinant protein yield in CHO cells. IGF2BP2 expression was elevated in high-producing clones, and its stable overexpression promoted cell proliferation, increased the S-phase cell proportion, and boosted titers and specific productivity of recombinant proteins--adalimumab, vitronectin, and donanemab--by 2.0-, 1.6-, 2.6-fold and 1.8-, 1.4-, 2.1- fold, respectively. Mechanistically, IGF2BP2 recognized m6A sites on HMGA1 mRNA, enhancing its stability and expression. Integrated analyses of oxidative stress, mitochondrial function, and metabolomics, along with inhibitor validation, revealed that IGF2BP2 also strengthens antioxidant defense, promotes mitochondrial ATP production and utilization, and reshapes cellular redox and metabolic homeostasis. These findings highlight IGF2BP2 as a critical regulator of recombinant protein expression and mitochondrial oxidative metabolism in CHO cells, illustrating how RNA methylation cooperates with mitochondrial function and proliferation to enhance protein production.

bioengineering↗

bioRxiv2023

Mycobacterial DnaQ is an Alternative Proofreader Ensuring DNA Replication Fidelity

Remove of mis-incorporated nucleotides ensures replicative fidelity. Although the {varepsilon}-exonuclease DnaQ is a well-established proofreader in the model organism Escherichia coli, proofreading in mycobacteria relies on the polymerase and histidinol phosphatase (PHP) domain of replicative polymerase despite the presence of an alternative DnaQ homolog. Here, we show that depletion of DnaQ in Mycolicibacterium smegmatis results in increased mutation rate, leading to AT-biased mutagenesis and elevated insertions/deletions in homopolymer tract. We demonstrated that mycobacterial DnaQ binds to the {beta}-clamp and functions synergistically with the PHP domain to correct replication errors. Further, we found that the mycobacterial DnaQ sustains replicative fidelity upon chromosome topological stress. Intriguingly, we showed that a naturally evolved DnaQ variant prevalent in clinical Mycobacterium tuberculosis isolates enables hypermutability and is associated with extensive drug resistance. These results collectively establish that the alternative DnaQ functions in proofreading, and thus reveal that mycobacteria deploy two proofreaders to maintain replicative fidelity.

microbiology↗