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 1

Mettl5 deficiency leads to reduced bone mass and impaired osteogenic differentiation.

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Mettl5 deficiency leads to reduced bone mass and impaired osteogenic di...
(A) Gross appearance and femoral morphology of 6-week-old male WT and Mettl5-KO mice. n = 8. (B) Von Kossa staining of femurs at P1, with quantification of femur length and mineralized area. Scale bar: 400 μm. n = 5. (C) ALP activity staining of P1 femurs from WT and Mettl5-KO mice. GP, growth plate; TB, trabecular bone. Scale bar: 200 μm. n = 3. (D) Representative immunofluorescence images and quantification of SP7 staining in femurs from P14 WT and Mettl5-KO mice, with magnified views of the boxed regions. Scale bar: 100 μm. n = 3. (E) MicroCT analysis of trabecular bone and cortical bone in femurs from 6-week-old male WT and Mettl5-KO mice. Scale bar: 400 μm. n = 8. (F) Representative Von Kossa staining of femurs from 6-week-old male WT and Mettl5-KO mice. Scale bar: 400 μm. n = 5. (G) Representative Calcein labeling images and quantification showing the mineral apposition rate (MAR). Scale bar: 50 μm. n = 6. (H) Representative TRAP staining of femurs from 6-week-old male WT and Mettl5-KO mice, with quantification of osteoclast number per bone perimeter (N.Oc/B.Pm). Scale bar: 50 μm. n = 6. (I) Representative images of ALP and ARS staining in MSCs derived from WT and Mettl5-KO mice after osteogenic induction. n = 5. (J and K) Quantification of ALP activity (n = 3) and ARS staining (n = 5) in MSCs derived from WT and Mettl5-KO mice. (L) qRT-PCR analysis of Sp7 and Runx2 in MSCs from WT and Mettl5-KO mice after 3 days of osteogenic induction. n = 3. (M) qRT-PCR analysis of osteogenic markers in MSCs from WT and Mettl5-KO mice after 5 days of osteogenic induction. n = 3. (N) Representative Western blot images and quantifications showing the protein levels of osteogenic markers in MSCs from WT and Mettl5-KO mice after osteogenic induction. n = 3. Data are expressed as mean ± SD; P values were determined by 2-tailed Student’s t test.