The m5C orchestrator NSUN7 drives SPARC/HMGB1 axis–mediated inflammation to exacerbate kidney injury [RNA-Seq]

Although RNA modifications have been implicated in regulating kidney inflammation, their precise roles remain largely unknown. Here, we show that kidney inflammation and injury were associated with elevated RNA 5-methylcytosine (m5C) modifications, primarily driven by the m5C “writer” NOP2/Sun RNA methyltransferase family member 7 (NSUN7).

Both global and kidney-specific deletion of Nsun7 in mice reduced m5C abundance, attenuated inflammatory responses, and decreased macrophage infiltration, underscoring its proinflammatory role in the kidney. Mechanistically, we identified secreted protein acidic and cysteine-rich (SPARC) as a major downstream effector of NSUN7. SPARC upregulation amplified inflammatory responses in renal tubular epithelial cells by interacting with high mobility group box 1 and further promoted proinflammatory macrophage infiltration via tubular-macrophage crosstalk.