FGF21 confers neuroprotection in Parkinson's disease by activating the FGFR1-sirt1 pathway.

BACKGROUND: Parkinson's disease (PD) lacks disease-modifying therapies. Fibroblast growth factor 21 (FGF21) is implicated in PD, but its neuroprotective mechanisms via fibroblast growth factor receptor 1 (FGFR1)-sirtuin 1 (Sirt1) remain unclear. METHODS: Using 1-methyl-4-phenyl-1,2,3,6-te-trahydropyridine (MPTP)-induced PD mice and lipopolysaccharides (LPS)-stimulated BV2 microglia, this study employed recombinant adeno-associated virus (rAAV)-mediated FGF21 overexpression (OE). Multi-dimensional analyses (behavior, immunofluorescence, molecular docking, Western blot, PCR, transmission electron microscopy (TEM)) assessed FGF21's effects and mechanisms. RESULTS: FGF21(OE) significantly improved motor deficits (gait, rotarod) and non-motor symptoms (depression/anxiety) in PD mice. It repaired the blood-brain barrier (BBB) by upregulating tight junction proteins (claudin, zonula occludens (ZO-1), occludin) and reducing astrocyte activation (glail fibrillary acidicprotein, GFAP). Mechanistically, FGF21 binding to FGFR1 activated Sirt1, enhancing mitochondrial fusion (optic atrophy 1 (OPA1), mitofusin 1 (Mfn1)) and inhibiting fission (dynamin-related protein 1 (Drp1), Fission 1 (Fis1)), improving membrane potential and ultrastructure. FGF21 also activated the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, boosting PINK1/Parkin-mediated mitophagy and inhibiting Casp3/Bax-dependent apoptosis. Furthermore, FGF21 reduced neuroinflammation by suppressing nuclear factor kappa-B (NF-κB)/NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and shifting microglia from pro-inflammatory M1 to anti-inflammatory M2. Molecular docking and co-IP confirmed FGF21 enhances direct FGFR1-Sirt1 interaction, synergistically regulating these pathways. CONCLUSION: FGF21 exerts multi-faceted protection in PD via the FGFR1-Sirt1 axis, including BBB repair, mitochondrial homeostasis restoration, microglial polarization towards M2, balancing autophagy and apoptosis, and promoting neuronal survival.