Modulation of FcgammaRI (CD64) ligand binding by blocking peptides of periplakin.
FcgammaRI requires both the intracellular domain of the alpha-chain and associated leukocyte Fc receptor (FcR) gamma-chains for its biological function. We recently found the C terminus of periplakin to selectively interact with the cytoplasmic domain of the FcgammaRI alpha-chain. It thereby enhances the capacity of FcgammaRI to bind, internalize, and present antigens on MHC class II. Here, we characterized the domains involved in FcgammaRI-periplakin interaction using truncated and alanine-substituted FcgammaRI mutants and randomly mutagenized periplakin. This allowed us to design TAT peptides that selectively interfered with endogenous FcgammaRI-periplakin interactions. The addition of these peptides to FcgammaRI-expressing cells modulated FcgammaRI ligand binding, as assessed by erythrocyte-antibody-rosetting. These data support a dominant-negative role of C-terminal periplakin for FcgammaRI biological activity and implicate periplakin as a novel regulator of FcgammaRI in immune cells.
Beekman
Jeffrey M
JM
Immunotherapy Laboratory, Department of Immunology, University Medical Center Utrecht, Lundlaan 6, 3584 EA, The Netherlands.
Bakema
Jantine E
JE
van der Linden
Joke
J
Tops
Bastiaan
B
Hinten
Marja
M
van Vugt
Martine
M
van de Winkel
Jan G J
JG
Leusen
Jeanette H W
JH
D000409:Alanine; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004912:Erythrocytes / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051179:Plakins; D016133:Polymerase Chain Reaction; D017452:Receptors, IgG / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D012397:Rosette Formation; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013329:Structure-Activity Relationship; D014162:Transfection; D020798:Two-Hybrid System Techniques
D003598:Cytoskeletal Proteins; C491674:PPL protein, human; D010446:Peptide Fragments; D051179:Plakins; C110037:Ppl protein, mouse; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D000409:Alanine