LTBP2 down-regulated FGF2 to repress vascular smooth muscle cell proliferation and vascular remodeling in a rat model of intracranial aneurysm

This work probed into the role of latent transforming growth factor beta binding protein 2 (LTBP2) in intracranial aneurysm (IA). The rats underwent IA modeling and then stereotactic injection of short hairpin RNA against LTBP2 (shLTBP2). Hematoxylin-eosin (HE) staining was employed to assess IA model and vascular remodeling. Rat vascular smooth muscle cells (VSMCs) were transfected with shLTBP2, LTBP2 overexpression plasmid and fibroblast growth factor 2 (FGF2) overexpression plasmid. The mRNA and protein expressions of LTBP2, FGF2 and mitochondrial apoptosis-related factors (Caspase-3, Cyt-c, Mcl-1) were tested through qRT-PCR and Western blot. Cell viability, proliferation and apoptosis were examined by cell counting kit-8, EdU assay and flow cytometry. The up-regulated LTBP2 and down-regulated FGF2 were detected in IA rats. LTBP2 knockdown promoted vascular remodeling and Mcl-1 level, and restrained cell apoptosis and expressions of Caspase-3 and Cyt-c in IA model rats. Moreover, LTBP2 knockdown potentiated cell viability, proliferation and FGF2 level, and repressed apoptosis in rat VSMCs, while overexpressed LTBP2 exerted opposite effects. FGF2 overexpression promoted proliferation and Mcl-1 level, and inhibited apoptosis and expressions of Caspase-3 and Cyt-c in rat VSMCs, which also reversed the effects of overexpressed LTBP2 on these aspects. Collectively, LTBP2 down-regulates FGF2 to repress VSMCs proliferation and vascular remodeling in an IA rat model.