METTL5 deficiency impairs osteogenesis through OSER1-dependent antioxidant regulation
Kexin Lei, Qi Yin, Qiwen Li, Qian Wang, Zhong Zhang, Fei Xue, Ruoshi Xu, Xinyi Zhou, Lin Peng, Shoichiro Kokabu, Shuibin Lin, Quan Yuan
Kexin Lei, Qi Yin, Qiwen Li, Qian Wang, Zhong Zhang, Fei Xue, Ruoshi Xu, Xinyi Zhou, Lin Peng, Shoichiro Kokabu, Shuibin Lin, Quan Yuan
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Research Article Bone biology Cell biology

METTL5 deficiency impairs osteogenesis through OSER1-dependent antioxidant regulation

Abstract

Methyltransferase-like 5 (METTL5) is a methyltransferase responsible for rRNA N6-methyladenosine (m6A) modification, mutations in which are associated with skeletal abnormalities and cognitive deficits. Despite METTL5’s clinical relevance, the molecular mechanisms underlying METTL5-related genetic disorders remain poorly understood. In this study, we demonstrated that Mettl5 KO led to reduced bone mass and smaller body size in mice and impaired the osteogenic differentiation of mesenchymal stem cells. Mechanistically, Mettl5 deficiency decreased the translation efficiency of oxidative stress–responsive serine-rich protein 1 mRNA, downregulated the expression of key antioxidant genes, and diminished antioxidant capacity. Importantly, administration of the antioxidant N-acetylcysteine (NAC) partially rescued skeletal defects in Mettl5-KO mice. These findings reveal a critical role for METTL5 in antioxidant defense and suggest that NAC supplementation may represent a promising therapeutic strategy for METTL5-related disorders.

Authors

Kexin Lei, Qi Yin, Qiwen Li, Qian Wang, Zhong Zhang, Fei Xue, Ruoshi Xu, Xinyi Zhou, Lin Peng, Shoichiro Kokabu, Shuibin Lin, Quan Yuan

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Figure 4

OSER1 is involved in osteogenic differentiation.

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OSER1 is involved in osteogenic differentiation. (A) Violin plot showing...
(A) Violin plot showing Oser1 expression levels in different cell types within skeletal cell populations of embryonic mouse limbs. (B) Pseudo-time analysis showing normalized expression of Oser1 and osteogenic marker genes in perichondrial cells and osteoblasts along differentiation trajectory. (C) Representative images of IHC staining showing OSER1 expression in P1 mouse femurs. Scale bar: 100 μm. n = 3. (D) qRT-PCR analysis of Oser1 mRNA levels at 0, 3, 5, and 7 days during osteogenic induction. n = 3. (E) qRT-PCR analysis of Oser1 knockdown efficiency using siRNA in MC3T3-E1 cells. n = 3. (F) Representative images of ALP and ARS staining in si-Control and si-Oser1–treated MC3T3-E1 cells after osteogenic induction. n = 5. (G and H) Quantitative analyses of ALP activity (n = 3) and ARS staining (n = 5) in si-Control and si-Oser1–treated MC3T3-E1 cells after osteogenic induction. (I) qRT-PCR analysis showing expression of osteogenesis-related markers in MC3T3-E1 cells after osteogenic induction with si-Control or si-Oser1 treatment. n = 3. (J) Representative Western blot images and quantifications showing protein levels of osteogenic markers in si-Control and si-Oser1 MC3T3-E1 cells after osteogenic induction. n = 3. (K) Representative Western blot images and quantifications showing OSER1 protein levels in WT and Mettl5-KO MSCs transduced with OSER1-overexpressing or control adenovirus. n = 3. (L) Representative images of ALP and ARS staining in MSCs after osteogenic induction with OSER1-overexpressing adenovirus or control adenovirus. n = 3. (M) Quantitative analyses of ALP activity in MSCs after osteogenic induction with OSER1-overexpressing adenovirus or control adenovirus. n = 3. (N) Quantitative analyses of ARS staining in MSCs after osteogenic induction with OSER1-overexpressing adenovirus or control adenovirus. n = 3. Data shown as mean ± SD; P values determined by 1-way ANOVA (D), 2-tailed Student’s t test (E and G–J), and 2-way ANOVA (K, M, and N).