<p><i>N</i><sup>6</sup>-methyladenosine (m<sup>6</sup>A) RNA modification plays critical roles in physiological and pathological processes. Our prior study demonstrated that IGFBP5 expression is upregulated in the ischemic limb, whereas endothelial-specific IGFBP5 knockout (Igfbp5<sup>EKO</sup>) protects against hind limb ischemia by enhancing angiogenesis. Here, we show that IGFBP5 deficiency elevates global m<sup>6</sup>A levels and upregulates the expression of m<sup>6</sup>A methyltransferase complex components METTL3, METTL14 and WTAP in endothelial cells. We further identified a direct interaction between IGFBP5 and the MT-A70 domain of METTL14. Knockdown of METTL14, METTL3 or WTAP attenuated the pro-angiogenic effects of IGFBP5 deficiency in vitro. In vivo, endothelial knockdown of METTL14 abolished the improved hind-limb ischemia recovery in Igfbp5<sup>EKO</sup> mice. Methylated RNA immunoprecipitation sequencing revealed that IGFBP5 depletion in endothelial cells increases both m<sup>6</sup>A modification and mRNA abundance of FGF16. Notably, METTL14 or METTL3 silencing suppressed IGFBP5-dependent FGF16 upregulation. Enhanced translational efficiency of FGF16 in IGFBP5-deficient cells was reversed by METTL14 knockdown, indicating that IGFBP5 regulates FGF16 translation via m<sup>6</sup>A modification. Mechanistically, IGFBP5 modulates FGF16 m<sup>6</sup>A modification via interaction with the m<sup>6</sup>A reader protein IGF2BP2, targeting the m<sup>6</sup>A site at position 255 of FGF16 mRNA. In summary, our study establishes METTL14-mediated m<sup>6</sup>A modification of FGF16 as a key mechanism underlying IGFBP5-driven angiogenesis. Targeting the IGFBP5–METTL14–m<sup>6</sup>A–FGF16 axis may offer novel therapeutic strategies for ischemic disease.</p><p></p>

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METTL14-dependent N6-methyladenosine modification of FGF16 participates in IGFBP5 deficiency-enhanced angiogenesis

  • Fei Song,
  • Yu Hu,
  • Yi-Xiang Hong,
  • Shan-Shan Zhao,
  • Hui-Zhu Huang,
  • Yutian Wang,
  • Le Zhang,
  • Wei-Yin Wu,
  • Yan Wang,
  • Gang Li

摘要

N6-methyladenosine (m6A) RNA modification plays critical roles in physiological and pathological processes. Our prior study demonstrated that IGFBP5 expression is upregulated in the ischemic limb, whereas endothelial-specific IGFBP5 knockout (Igfbp5EKO) protects against hind limb ischemia by enhancing angiogenesis. Here, we show that IGFBP5 deficiency elevates global m6A levels and upregulates the expression of m6A methyltransferase complex components METTL3, METTL14 and WTAP in endothelial cells. We further identified a direct interaction between IGFBP5 and the MT-A70 domain of METTL14. Knockdown of METTL14, METTL3 or WTAP attenuated the pro-angiogenic effects of IGFBP5 deficiency in vitro. In vivo, endothelial knockdown of METTL14 abolished the improved hind-limb ischemia recovery in Igfbp5EKO mice. Methylated RNA immunoprecipitation sequencing revealed that IGFBP5 depletion in endothelial cells increases both m6A modification and mRNA abundance of FGF16. Notably, METTL14 or METTL3 silencing suppressed IGFBP5-dependent FGF16 upregulation. Enhanced translational efficiency of FGF16 in IGFBP5-deficient cells was reversed by METTL14 knockdown, indicating that IGFBP5 regulates FGF16 translation via m6A modification. Mechanistically, IGFBP5 modulates FGF16 m6A modification via interaction with the m6A reader protein IGF2BP2, targeting the m6A site at position 255 of FGF16 mRNA. In summary, our study establishes METTL14-mediated m6A modification of FGF16 as a key mechanism underlying IGFBP5-driven angiogenesis. Targeting the IGFBP5–METTL14–m6A–FGF16 axis may offer novel therapeutic strategies for ischemic disease.