N-methyladenosine profiling reveals that Xuefu Zhuyu decoction upregulates METTL14 and BDNF in a rat model of traumatic brain injury.

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese herbal formula Xuefu Zhuyu decoction (XFZYD) is a classic formula in the category of invigorating blood circulation and resolving blood stasis. It has been proven to improve the neurological and ethological prognosis of traumatic brain injury. XFZYD promotes synaptic and axonal regeneration after traumatic brain injury, which is functionally modulated by the N-methyladenosine (mA) modification of RNA. However, the epigenetic effects of XFZYD on mA modification remain unknown.

AIM OF THE STUDY

To explore how XFZYD protects against traumatic brain injury induced by controlled cortical impact (CCI) injury by altering RNA mA modification.

MATERIALS AND METHODS

The modified neurological severity scoring and Morris water maze were performed to evaluate the neuroprotective effects of XFZYD for 14 days and screen the dose. Then, dot blot, western blotting, and methylated RNA immunoprecipitation sequencing (MeRIP-Seq) were used to explore changes in RNA mA modification in the perilesional cortex. The Metascape platform was used to analyze the Gene Ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Reactome pathway of the differential mA-tagged genes. Furthermore, MeRIP-qPCR was conducted to quantify differences in the hub differential mA modification gene brain-derived neurotrophic factor (Bdnf).

RESULTS

XFZYD significantly ameliorated the neurological deficits, spatial learning, and memory impairments in rats post-CCI on day 14. XFZYD enhanced the mA level, and the expression of METTL14 and YTHDC2 in the perilesional cortex of CCI rats. In all three groups, the 3'-untranslated regions and coding sequence were primarily enriched for mA peaks. XFZYD reversed the increased proportion of 3'-untranslated regions, and the decreased proportion of coding sequence and 5'-untranslated regions post-CCI. Moreover, XFZYD markedly downregulated 41 elevated mA-tagged transcripts and upregulated 119 decreased mA-tagged transcripts following CCI. Gene ontology and KEGG pathway analysis revealed that XFZYD-regulated mA-tagged transcripts were predominantly enriched in synapse assembly, synaptic plasticity, learning or memory, and MAPK signaling pathway. Then, the hub-regulated mA-tagged gene BDNF was identified. Both the mA methylation level and the protein level of BDNF were ascended by XFZYD treatment.

CONCLUSION

XFZYD improves neurological deficits, spatial learning and memory impairments in rats post-TBI probably through increasing the expression of METTL14 and BDNF in the cortex. Our study highlights a novel post-transcriptional regulation mechanism mediated by herbal medicine for traumatic brain injury treatment.