Progranulin does not bind tumor necrosis factor (TNF) receptors and is not a direct regulator of TNF-dependent signaling or bioactivity in immune or neuronal cells

J Neurosci. 2013 May 22;33(21):9202-13. doi: 10.1523/JNEUROSCI.5336-12.2013.

Abstract

Progranulin (PGRN) is a secreted glycoprotein expressed in neurons and glia that is implicated in neuronal survival on the basis that mutations in the GRN gene causing haploinsufficiency result in a familial form of frontotemporal dementia (FTD). Recently, a direct interaction between PGRN and tumor necrosis factor receptors (TNFR I/II) was reported and proposed to be a mechanism by which PGRN exerts anti-inflammatory activity, raising the possibility that aberrant PGRN-TNFR interactions underlie the molecular basis for neuroinflammation in frontotemporal lobar degeneration pathogenesis. Here, we report that we find no evidence for a direct physical or functional interaction between PGRN and TNFRs. Using coimmunoprecipitation and surface plasmon resonance (SPR) we replicated the interaction between PGRN and sortilin and that between TNF and TNFRI/II, but not the interaction between PGRN and TNFRs. Recombinant PGRN or transfection of a cDNA encoding PGRN did not antagonize TNF-dependent NFκB, Akt, and Erk1/2 pathway activation; inflammatory gene expression; or secretion of inflammatory factors in BV2 microglia and bone marrow-derived macrophages (BMDMs). Moreover, PGRN did not antagonize TNF-induced cytotoxicity on dopaminergic neuroblastoma cells. Last, co-addition or pre-incubation with various N- or C-terminal-tagged recombinant PGRNs did not alter lipopolysaccharide-induced inflammatory gene expression or cytokine secretion in any cell type examined, including BMDMs from Grn+/- or Grn-/- mice. Therefore, the neuroinflammatory phenotype associated with PGRN deficiency in the CNS is not a direct consequence of the loss of TNF antagonism by PGRN, but may be a secondary response by glia to disrupted interactions between PGRN and Sortilin and/or other binding partners yet to be identified.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism
  • Analysis of Variance
  • Animals
  • Cell Line
  • Cell Proliferation / drug effects
  • Culture Media, Conditioned / pharmacology
  • Cytokines / metabolism*
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / genetics
  • Gene Expression Regulation / immunology*
  • Granulins
  • Humans
  • Immunoprecipitation
  • Intercellular Signaling Peptides and Proteins / deficiency
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Isoquinolines / metabolism
  • Lipopolysaccharides / pharmacology
  • MAP Kinase Signaling System / drug effects
  • MAP Kinase Signaling System / immunology
  • Macrophages / drug effects
  • Macrophages / immunology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microglia / drug effects
  • Microglia / metabolism
  • NF-kappa B / metabolism
  • Progranulins
  • Protein Binding / genetics
  • Receptors, Tumor Necrosis Factor / genetics
  • Receptors, Tumor Necrosis Factor / metabolism*
  • Recombinant Proteins / pharmacology
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Surface Plasmon Resonance
  • Transfection

Substances

  • Adaptor Proteins, Vesicular Transport
  • Culture Media, Conditioned
  • Cytokines
  • Granulins
  • Grn protein, mouse
  • Intercellular Signaling Peptides and Proteins
  • Isoquinolines
  • Lipopolysaccharides
  • NF-kappa B
  • Progranulins
  • Receptors, Tumor Necrosis Factor
  • Recombinant Proteins
  • lucifer yellow
  • sortilin