J Biol Chem. 2004 Dec 10;279(50):51897-907. Epub 2004 Sep 28.

PAN1/NALP2/PYPAF2, an inducible inflammatory mediator that regulates NF-kappaB and caspase-1 activation in macrophages.External

Bruey, J. M., Bruey-Sedano, N., Newman, R., Chandler, S., Stehlik, C., Reed, J. C.,
--- - Burnham Institute, La Jolla, California 92037, USA.
Genes encoding proteins with PYRIN/PAAD/DAPIN domains, a nucleotide binding fold (NACHT), and leucine rich repeats have recently been recognized as important mediators in autoimmune inflammatory disorders. Here we characterize the expression and function of a member of the PYRIN and NACHT domain (PAN) family, PAN1 (also known as NALP2 and PYPAF2). PAN1 protein expression is regulated by lipopolysaccharide (LPS) and interferons (IFNbeta and IFNgamma) in THP-1 macrophage cells. In gene transfection studies PAN1 manifests an inhibitory influence on NF-kappaB activation induced by various pro-inflammatory stimuli, including tumor necrosis factor TNFalpha and interleukin-1beta (IL-1beta). Gene transfer-mediated elevations in PAN1 protein also suppressed activation of IkappaB kinases induced by inflammatory cytokines. Conversely, reducing endogenous levels of PAN1 using small interfering RNA enhanced LPS-induced production of ICAM-1 (intercellular adhesion molecule 1), an NF-kappaB-dependent gene. We also show here that PAN1 binds via its PYRIN domain to ASC, an adapter protein involved in caspase-1 activation. This binding is disrupted by mutation of the alpha1 helix of ASC. In gene transfer experiments PAN1 enhances caspase-1 activation and IL-1beta secretion in collaboration with ASC. Conversely, reducing endogenous levels of PAN1 using small interfering RNA significantly reduced LPS-induced secretion of IL-1beta in monocytes. We propose that PAN1 functions as a modulator of the activation of NF-kappaB and pro-caspase-1 in macrophages.
PMID: 15456791External
Arrow2 In vitro interaction Arrow2 In vivo interaction Arrow2 Characterization Arrow2 Functional role Arrow2 top
In vivo interaction
  Endogenous
expression
Overexpression DD1 DD2 Reference
Family DD1 DD2 Method Species Region Species Region
PYD ASC Link NLRP2 Co-immunoprecipitation HEK293 Not specified Full length Not specified Full length 15456791
PYD ASC Link NLRP2 Co-immunoprecipitation HEK293 Not specified Not specified Not specified Full length 15456791
PYD NLRP1 Link NLRP2 Co-immunoprecipitation HEK293 Not specified Not specified Not specified Full length 15456791
(Link: click this icon to show interactions only between the two corresponding DDs)
Arrow2 In vitro interaction Arrow2 In vivo interaction Arrow2 Characterization Arrow2 Functional role Arrow2 top
Characterization
  Stoichiometry Affinity Protein-Protein interface Reference
Family DD1 DD2 Method Mutation Complex structure
PYD ASC Link NLRP2 Co-immunoprecipitation E13W (ASC) 15456791
(Link: click this icon to show interactions only between the two corresponding DDs)
Arrow2 In vitro interaction Arrow2 In vivo interaction Arrow2 Characterization Arrow2 Functional role Arrow2 top
Functional Role
Family DD1 DD2 Method Death-related Death-unrelated Reference
PYD ASC Link NLRP2 ELISA IL-1b secretion (Inflammasome) 15456791
(Link: click this icon to show interactions only between the two corresponding DDs)