Covalent interaction between proform of eosinophil major basic protein (proMBP) and pregnancy-associated plasma protein-A (PAPP-A) is a cell-mediated event and required for proMBP inhibition of the catalytic activity of PAPP-A.
This study was undertaken to determine the mechanism by which proform of eosinophil major basic protein (proMBP) inhibits the IGFBP-4 proteolytic activity of pregnancy-associated plasma protein (PAPP)-A. Co-overexpression of PAPP-A with proMBP in 293T cells, or co-incubation of 293T cells, respectively, overexpressing proMBP and PAPP-A resulted in the formation of a covalent proMBP-PAPP-A complex and inhibition of IGFBP-4 proteolysis. Similar results were obtained when recombinant proMBP and PAPP-A were incubated in the presence of U2 osteosarcoma cells or when recombinant proMBP was added to the U2 cells overexpressing PAPP-A. In contrast, no formation of covalent proMBP-PAPP-A complex or inhibition of IGFBP-4 proteolysis was observed when recombinant proMBP and PAPP-A were incubated under cell-free conditions, although proMBP was able to interact with PAPP-A in a non-covalent manner. These new findings suggest that formation of covalent proMBP-PAPP-A complex is a cell-mediated event and is required for proMBP to inhibit the catalytic activity of PAPP-A.
Musculoskeletal Disease Center, J.L. Pettis Memorial Veterans' Medical Center (151), 11201 Benton Street, Loma Linda, CA 92357, USA.
Arun S
AS
Sivanandam
Subburaman
S
Mohan
Sanjay
S
Kapur
Hirohito
H
Kita
K-H William
KH
Lau
Gyorgy
G
Bagi
David J
DJ
Baylink
Xuezhong
X
Qin
D001798:Blood Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D047091:Eosinophil Granule Proteins; D015870:Gene Expression; D006801:Humans; D015151:Immunoblotting; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000378:metabolism; D011266:Pregnancy-Associated Plasma Protein-A / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011498:Protein Precursors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D001798:Blood Proteins; D004791:Enzyme Inhibitors; D047091:Eosinophil Granule Proteins; D018974:Insulin-Like Growth Factor Binding Protein 4; D011498:Protein Precursors; D011994:Recombinant Proteins; D012260:Ribonucleases; D011266:Pregnancy-Associated Plasma Protein-A