Runx2 downregulates Lpl expression through super-silencer formation to alter lipid metabolism in Zhu Schwann cells after nerve injury.

BACKGROUND

Phenotypic transformation of Schwann cells (SCs) plays a crucial role in nerve regeneration. Previous studies have demonstrated that Runx2 significantly influences the biological behavior of SCs. Nonetheless, the regulatory mechanisms that govern its epigenetic regulation are not yet fully elucidated.

METHODS

To facilitate this investigation, an adenovirus for the overexpression of Runx2 was constructed. Healthy adult Sprague-Dawley rats, weighing between 100 and 150 g and irrespective of sex, were randomly selected for the study. After establishing a model of sciatic nerve crush injury, tissue samples were harvested for histological analysis at both 4 and 7 days post-injury. In vitro, an Runx2-overexpressing SC line was established. Thorough analysis of transcriptome data, coupled with CUT&Tag sequencing of histones and transcription factors in SCs following Runx2 overexpression, was conducted. Additionally, single-cell RNA sequencing data from GSE216665 were incorporated to elucidate the mechanistic role of Runx2. The findings were subsequently validated through dual-luciferase assays.

RESULTS

Following nerve crush injury, Runx2-positive SCs were identified at the injury site. Through comprehensive multiomics analysis, we discovered that lipid metabolism was disrupted in Runx2-overexpressing SCs. Further investigation established a detailed super-silencer landscape in these cells, revealing that elevated Runx2 levels form a super-silencer within the transcriptional regulatory region of the Lpl gene, thereby downregulating Lpl expression.

CONCLUSIONS

Runx2 can modulate the biological behavior of SCs by forming super-silencers that interfere with the expression of lipid metabolism genes, such as Lpl, thereby altering the metabolic capacity of SCs.