Cellular fibronectin exacerbates α-synuclein aggregation via integrin alpha4beta1 mediated PARP1 and SCD elevation

Mitochondrial dysfunction and lipid metabolic disturbance may promote pathologic α-synuclein (α-syn) aggregation, accelerating the progression of Parkinson's disease (PD). Whether extracellular matrices are associated with those pathological mechanisms in PD remains elusive. Here, we aimed to identify if cellular fibronectin (cFn), a component of extracellular matrices, contributes to α-syn abnormality via inducing mitochondrial energy depletion or disrupting lipid homeostasis. In Our study, 1-methyl-4-phenyl-1, 2,3,6-tetrahydropyridine (MPTP)-treated PD mice and human neuronal SH-SY5Y cells were used. Astrocyte-derived cFn protein delivery and AAV-mediated cFn knockdown mouse models were established to validate the functional role of cFn. Mitochondrial dysfunction was detected by transmission electron microscopy (TEM), and the level of poly (ADP‒ribose) (PAR) polymerase-1(PARP1), pathologic α-syn and cFn-induced lipid dysmetabolism was determined. We demonstrated that excessive cFn accumulated in the SNpc of MPTP-treated mice, and cFn rather than plasma Fn (pFn) exacerbated neuronal mitochondrial dysfunction and α-syn accumulation. Mechanically, cFn induced PARP1 activation via integrin α4β1, which contributed to neuronal NAD ​+ ​depletion and pathologic α-syn aggregation. Furthermore, cFn induced an increase in free fatty acids (FAs) and triglycerides (TAG) in neurons by binding to integrin α4β1, which synergistically contributed to α-syn abnormality. We revealed that cFn induced stearoyl-CoA desaturase (SCD) activation via integrin α4β1, which was interacted with SCD. Genetically depleting cFn suppressed PARP1 activation and SCD elevation, which further rescued the mitochondrial disruption and α-syn abnormalities in MPTP-treated mice. Overall, our findings suggest that cFn exacerbates α-syn aggregation via integrin α4β1-mediated PARP1 and SCD elevation. cFn-targeting therapy may be a promising strategy for treating PD.