RING finger protein 11 (RNF11) modulates susceptibility to 6-OHDA-induced nigral degeneration and behavioral deficits through NF-[kappa]B signaling in dopaminergic cells

• Published in: Neurobiology of disease 2013-06, Vol.54, p.264-279
• Main Authors: Pranski, Elaine L, Dalal, Nirjari V, Sanford, Carson Van, Herskowitz, Jeremy H, Gearing, Marla, Lazo, Carlos, Miller, Gary W, Lah, James J, Levey, Allan I, Betarbet, Ranjita S
• Format: Article
• Language: English
• ISSN: 0969-9961

Chronic activation of the NF-[kappa]B pathway is associated with progressive neurodegeneration in Parkinson's disease (PD). Given the role of neuronal RING finger protein 11 (RNF11) as a negative regulator of the NF-[kappa]B pathway, in this report we investigated the function of RNF11 in dopaminergic cells in PD-associated neurodegeneration. We found that RNF11 knockdown in an in vitro model of PD mediated protection against 6-OHDA-induced toxicity. In converse, over-expression of RNF11 enhanced 6-OHDA-induced dopaminergic cell death. Furthermore, by directly manipulating NF-[kappa]B signaling, we showed that the observed RNF11-enhanced 6-OHDA toxicity is mediated through inhibition of NF-[kappa]B-dependent transcription of TNF-[alpha], antioxidants GSS and SOD1, and anti-apoptotic factor BCL2. Experiments in an in vivo 6-OHDA rat model of PD recapitulated the in vitro results. In vivo targeted RNF11 over-expression in nigral neurons enhanced 6-OHDA toxicity, as evident by increased amphetamine-induced rotations and loss of nigral dopaminergic neurons as compared to controls. This enhanced toxicity was coupled with the downregulation of NF-[kappa]B transcribed GSS, SOD1, BCL2, and neurotrophic factor BDNF mRNA levels, in addition to decreased TNF-[alpha] mRNA levels in ventral mesenchephalon samples. In converse, knockdown of RNF11 was associated with protective phenotypes and increased expression of above-mentioned NF-[kappa]B transcribed genes. Collectively, our in vitro and in vivo data suggest that RNF11-mediated inhibition of NF-[kappa]B in dopaminergic cells exaggerates 6-OHDA toxicity by inhibiting neuroprotective responses while loss of RNF11 inhibition on NF-[kappa]B activity promotes neuronal survival. The decreased expression of RNF11 in surviving cortical and nigral tissue detected in PD patients, thus implies a compensatory response in the diseased brain to PD-associated insults. In summary, our findings demonstrate that RNF11 in neurons can modulate susceptibility to 6-OHDA toxicity through NF-[kappa]B mediated responses. This neuron-specific role of RNF11 in the brain has important implications for targeted therapeutics aimed at preventing neurodegeneration.