METTL3-mediated m6A RNA modification promotes corneal neovascularization by upregulating the canonical Wnt pathway during HSV-1 infection

Abstract

Background: Corneal neovascularization (CNV) is a symptom of herpes simplex keratitis (HSK), which can result in blindness. The corneal angiogenesis brought on by herpes simplex virus type 1 (HSV-1) is strongly affected by vascular endothelial growth factor A (VEGFA). The N⁶-methyladenosine (m⁶A) modification catalyzed by methyltransferase-like 3 (METTL3) is a crucial epigenetic regulatory process for angiogenic properties. However, the roles of METTL3 and m⁶A in HSK-induced CNV remain unknown. Here, we investigated these roles in vitro and in vivo.

Methods: A PCR array in HSV-1-infected human umbilical vein endothelial cells (HUVECs) was used to screen for METTL3 among the epitranscriptomic genes. Tube formation and scratch assays were conducted to investigate cell migration capacity. The global mRNA m⁶A abundance was evaluated using a dot blot assay. Gene expression was assessed by RT-qPCR, western blotting, and fluorescence immunostaining. In addition, bioinformatic analysis was conducted to identify the downstream molecules of METTL3 in HUVECs. METTL3 knockdown and STM2457 treatment clarified the specific underlying molecular mechanisms affecting HSV-1-induced angiogenesis in vitro. An acute HSK mouse model was established to examine the effects of METTL3 knockdown or inhibition using STM2457 on pathological angiogenic development in vivo.

Results: METTL3 was highly upregulated in HSV-1-infected HUVECs and led to increased m⁶A levels. METTL3 knockdown or inhibition by STM2457 further reduced m⁶A levels and VEGFA expression and impaired migration and tube formation capacity in HUVECs after HSV-1 infection. Mechanistically, METTL3 regulated LRP6 expression through post-transcriptional mRNA modification in an m⁶A-dependent manner, increasing its stability, upregulating VEGFA expression, and promoting angiogenesis in HSV-1-infected HUVECs. Furthermore, METTL3 knockdown or inhibition by STM2457 reduced CNV in vivo.

Conclusion: Our findings revealed that METTL3 promotes pathological angiogenesis through canonical Wnt and VEGF signaling in vitro and in vivo, providing potential pharmacological targets for preventing the progression of CNV in HSK.

Keywords: Corneal neovascularization; HSV-1; Herpes simplex keratitis; METTL3, m(6)A modification; VEGFA.