Lack of MDA5 delays hematopoietic aging by modulating inflammaging and proteostasis in mice.

Bergo, Veronica; Bousounis, Pavlos; To Vu, Giang; Douté, Mélodie; Polyzou, Aikaterini; Lalioti, Maria-Eleni; Grigorash, Bogdan B; Tsurkan, Lyudmila et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

"Inflammaging", the chronic increase in inflammatory signaling with age, remains poorly understood in hematopoietic aging. Here, we identify the innate immune RNA sensor melanoma differentiation-associated protein 5 (MDA5) as an important factor of hematopoietic stem cell (HSC) aging. Aged Mda5<sup>-/-</sup> mice exhibit reduced HSC accumulation and myeloid bias. Importantly, aged Mda5<sup>-/-</sup> HSCs retain greater quiescence and superior repopulation capacity in noncompetitive transplants compared to wild-type counterparts. Multiomic analyses- including chromatin accessibility, transcriptomics, and metabolomics-reveal decreased inflammatory signaling, a youthful metabolic profile, and improved proteostasis in Mda5<sup>-/-</sup> HSCs, through regulation of HSF1 and phospho-EIF2A, key proteostasis regulators. Activation of HSF1 in aged wild-type HSCs partially restores youthful features, supporting a causal role for proteostasis maintenance. Collectively, our findings demonstrate that attenuating MDA5-dependent inflammation preserves HSC function during aging by maintaining metabolic fitness and proteostasis and provide insight into potential therapeutic strategies for mitigating hematopoietic aging.

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