title: Neuronal RING finger protein 11 (RNF11) regulates canonical NF-κB signaling.
abstract: BACKGROUND
  The RING domain-containing protein RING finger protein 11 (RNF11) is a member of the A20 ubiquitin-editing protein complex and modulates peripheral NF-κB signaling. RNF11 is robustly expressed in neurons and colocalizes with a population of α-synuclein-positive Lewy bodies and neurites in Parkinson disease patients. The NF-κB pathway has an important role in the vertebrate nervous system, where the absence of NF-κB activity during development can result in learning and memory deficits, whereas chronic NF-κB activation is associated with persistent neuroinflammation. We examined the functional role of RNF11 with respect to canonical NF-κB signaling in neurons to gain understanding of the tight association of inflammatory pathways, including NF-κB, with the pathogenesis of neurodegenerative diseases.
  
  
  RESULTS
  Luciferase assays were employed to assess NF-κB activity under targeted short hairpin RNA (shRNA) knockdown of RNF11 in human neuroblastoma cells and murine primary neurons, which suggested that RNF11 acts as a negative regulator of canonical neuronal NF-κB signaling. These results were further supported by analyses of p65 translocation to the nucleus following depletion of RNF11. Coimmunoprecipitation experiments indicated that RNF11 associates with members of the A20 ubiquitin-editing protein complex in neurons. Site-directed mutagenesis of the myristoylation domain, which is necessary for endosomal targeting of RNF11, altered the impact of RNF11 on NF-κB signaling and abrogated RNF11's association with the A20 ubiquitin-editing protein complex. A partial effect on canonical NF-κB signaling and an association with the A20 ubiquitin-editing protein complex was observed with mutagenesis of the PPxY motif, a proline-rich region involved in Nedd4-like protein interactions. Last, shRNA-mediated reduction of RNF11 in neurons and neuronal cell lines elevated levels of monocyte chemoattractant protein 1 and TNF-α mRNA and proteins, suggesting that NF-κB signaling and associated inflammatory responses are aberrantly regulated in the absence of RNF11.
  
  
  CONCLUSIONS
  Our findings support the hypothesis that, in the nervous system, RNF11 negatively regulates canonical NF-κB signaling. Reduced or functionally compromised RNF11 could influence NF-κB-associated neuronal functions, including exaggerated inflammatory responses that may have implications for neurodegenerative disease pathogenesis and progression.
authors.affiliation: Center for Neurodegenerative Disease, Department of Neurology, Emory University School of Medicine, 615 Michael St,, Suite 500, Atlanta, GA 30322, USA. epransk@emory.edu
authors.forename: Elaine L
authors.initials: EL
authors.lastname: Pranski
authors.forename: Nirjari V
authors.initials: NV
authors.lastname: Dalal
authors.forename: Jeremy H
authors.initials: JH
authors.lastname: Herskowitz
authors.forename: Adam L
authors.initials: AL
authors.lastname: Orr
authors.forename: Leah A
authors.initials: LA
authors.lastname: Roesch
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Fritz
authors.forename: Craig
authors.initials: C
authors.lastname: Heilman
authors.forename: James J
authors.initials: JJ
authors.lastname: Lah
authors.forename: Allan I
authors.initials: AI
authors.lastname: Levey
authors.forename: Ranjita S
authors.initials: RS
authors.lastname: Betarbet
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D055785:Gene Knockdown Techniques; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism* / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D016328:NF-kappa B; C404508:RNF11 protein, human