CKAP4/p63 is a receptor for the frizzled-8 protein-related antiproliferative factor from interstitial cystitis patients.
Antiproliferative factor (APF) is a low molecular weight sialoglycopeptide that is secreted by bladder cells from interstitial cystitis patients and is a potent inhibitor of both normal bladder epithelial and bladder carcinoma cell proliferation. We hypothesized that APF may produce its antiproliferative effects by binding to a transmembrane receptor. This study demonstrates that cytoskeleton-associated protein 4/p63 (CKAP4/p63), a type II transmembrane receptor, binds with high affinity to APF. The antiproliferative activity of APF is effectively inhibited by preincubation with anti-CKAP4/p63-specific antibodies, as well as by short interfering RNA knockdown of CKAP4/p63. Immunofluorescent confocal microscopy showed co-localization of anti-CKAP4/p63 and rhodamine-labeled synthetic APF binding in both cell membrane and perinuclear areas. APF also inhibits the proliferation of HeLa cervical carcinoma cells that are known to express CKAP4/p63. These data indicate that CKAP4/p63 is an important epithelial cell receptor for APF.
Conrads
Thomas P
TP
Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick, Inc., NCI, National Institutes of Health, Frederick, Maryland 21702, USA.
Tocci
Gillian M
GM
Hood
Brian L
BL
Zhang
Chen-Ou
CO
Guo
Li
L
Koch
Kristopher R
KR
Michejda
Christopher J
CJ
Veenstra
Timothy D
TD
Keay
Susan K
SK
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D002478:Cells, Cultured; D018856:Cystitis, Interstitial / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D001743:Urinary Bladder / Q000378:metabolism
D000911:Antibodies, Monoclonal; C081876:CKAP4 protein, human; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C490708:antiproliferative factor APF, human