SIRT1 inhibits Smad3 acetylation by reducing Lnc CRNDE transcription and inhibits BV2 cell overactivation to promote SCI neurological repair

Abstract

Methods We established a BV2 cell activation model by in vitro lipopolysaccharide (LPS) treatment and a rat SCI model according to physical injury. We used HE staining, Luxol solid blue staining and Nissl staining to observe the spinal cord structure, RT‒qPCR to detect SIRT1 mRNA and Lnc CRNDE expression, western blotting to detect SIRT1 protein, BV2 cell activation protein marker (Iba-1) and autophagy-related protein (LC3; Beclin-1; P62) expression, immunoprecipitation reaction to detect the relationship between Smad3 and SIRT1 binding, RNA binding protein immunoprecipitation (RIP) to detect the relationship between Smad3 and CRNDE, dual luciferase reporter gene to verify the transcriptional regulation of CRNDE by Smad3, and immunofluorescence staining to detect the coexpression of BV2 cell activation marker (Iba-1) and autophagy marker (P62). Results SIRT1 was expressed at low levels in SCI and LPS-treated BV2 cells from SCI rats. Overexpression of SIRT1 promoted BV2 cell autophagy, inhibited BV2 cell overactivation, alleviated the pathological conditions of spinal cord congestion, edema and structural damage after SCI, improved BBB scores, increased neuronal numbers and promoted myelin regeneration. SIRT1 could inhibit Lnc CRNDE transcription by reducing Smad3. SIRT1 inhibits Lnc CRNDE transcription by reducing Smad3 acetylation and inhibiting its nuclear localization. Overexpression of CRNDE reversed the protective effect on SCI exhibited by SIRT1, and knockdown of CRNDE inhibited BV2 cell overactivation and promoted SCI repair. Conclusion SIRT1 promotes SCI repair by reducing Smad3 acetylation and inhibiting its nuclear localization to suppress Lnc CRNDE transcription and inhibit BV2 cell overactivation.