Functional screening of five PYPAF family members identifies PYPAF5 as a novel regulator of NF-kappaB and caspase-1.
PYRIN-containing Apaf-1-like proteins (PYPAFs) are a recently identified family of proteins thought to function in apoptotic and inflammatory signaling pathways. PYPAF1 and PYPAF7 proteins have been found to assemble with the PYRIN-CARD protein ASC and coordinate the activation of NF-kappaB and pro-caspase-1. To determine if other PYPAF family members function in pro-inflammatory signaling pathways, we screened five other PYPAF proteins (PYPAF2, PYPAF3, PYPAF4, PYPAF5 and PYPAF6) for their ability to activate NF-kappaB and pro-caspase-1. Co-expression of PYPAF5 with ASC results in a synergistic activation of NF-kappaB and the recruitment of PYPAF5 to punctate structures in the cytoplasm. The expression of PYPAF5 is highly restricted to granulocytes and T-cells, indicating a role for this protein in inflammatory signaling. In contrast, PYPAF2, PYPAF3, PYPAF4 and PYPAF6 failed to colocalize with ASC and activate NF-kappaB. PYPAF5 also synergistically activated caspase-1-dependent cytokine processing when co-expressed with ASC. These findings suggest that PYPAF5 functions in immune cells to coordinate the transduction of pro-inflammatory signals to the activation of NF-kappaB and pro-caspase-1.
Grenier
Jill M
JM
Millennium Pharmaceuticals Inc., 75 Sidney Street, Cambridge, MA 02139, USA. bertin@mpi.com
Wang
Lin
L
Manji
Gulam A
GA
Huang
Waan Jeng
WJ
Al-Garawi
Amal
A
Kelly
Roxanne
R
Carlson
Adam
A
Merriam
Sarah
S
Lora
Jose M
JM
Briskin
Michael
M
DiStefano
Peter S
PS
Bertin
John
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020170:Caspase 1 / Q000502:physiology*; D002460:Cell Line; D017931:DNA Primers; D004789:Enzyme Activation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007962:Leukocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000502:physiology*; D015398:Signal Transduction
D002352:Carrier Proteins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; C468563:NLRP6 protein, human; D020170:Caspase 1