The m6A reader YTHDF1 regulates axon guidance through translational control of Robo3.1 expression

TLDR

N6‑methyladenosine (m6A) is a dynamic mRNA modification that regulates protein expression, yet the role of m6A readers in the nervous system remains poorly understood. The study shows that the m6A reader YTHDF1 binds m6A‑modified Robo3.1 mRNA, enhances its translation, and that loss of YTHDF1 or m6A sites impairs Robo3.1 protein levels and causes pre‑crossing axon guidance defects, revealing YTHDF1‑mediated translation as a key regulator of spinal commissural axon guidance.

Abstract

N 6-Methyladenosine (m6A) is a dynamic mRNA modification which regulates protein expression in various posttranscriptional levels. Functional studies of m6A in nervous system have focused on its writers and erasers so far, whether and how m6A readers mediate m6A functions through recognizing and binding their target mRNA remains poorly understood. Here, we find that the expression of axon guidance receptor Robo3.1 which plays important roles in midline crossing of spinal commissural axons is regulated precisely at translational level. The m6A reader YTHDF1 binds to and positively regulates translation of m6A-modified Robo3.1 mRNA. Either mutation of m6A sites in Robo3.1 mRNA or YTHDF1 knockdown or knockout leads to dramatic reduction of Robo3.1 protein without affecting Robo3.1 mRNA level. Specific ablation of Ythdf1 in spinal commissural neurons results in pre-crossing axon guidance defects. Our findings identify a mechanism that YTHDF1-mediated translation of m6A-modified Robo3.1 mRNA controls pre-crossing axon guidance in spinal cord.