IGF dependent modulation of IGF binding protein (IGFBP) proteolysis by pregnancy-associated plasma protein-A (PAPP-A): Multiple PAPP-A–IGFBP interaction sites

• Published in: Biochimica et biophysica acta Vol. 1830; no. 3; pp. 2701 - 2709
• Main Authors: Gaidamauskas, Ervinas, Gyrup, Claus, Boldt, Henning B., Schack, Vivien R., Overgaard, Michael T., Laursen, Lisbeth S., Oxvig, Claus
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2013
• Subjects: Amino Acid Sequence; Binding Sites; bioavailability; calcium; chimerism; Female; HEK293 Cells; Humans; IGF dependent modulation; IGF-binding protein (IGFBP); Insulin-Like Growth Factor Binding Protein 3 - chemistry; Insulin-Like Growth Factor Binding Protein 3 - genetics; Insulin-Like Growth Factor Binding Protein 5 - chemistry; Insulin-Like Growth Factor Binding Protein 5 - genetics; insulin-like growth factor binding proteins; ions; methionine; Models, Molecular; Molecular Sequence Data; mutation; Pappalysins; Pregnancy; Pregnancy-associated plasma protein-A (PAPP-A); Pregnancy-Associated Plasma Protein-A - chemistry; Pregnancy-Associated Plasma Protein-A - genetics; Protein Binding; Protein Interaction Domains and Motifs; proteinases; Proteolysis; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; somatomedins; Somatomedins - chemistry; Somatomedins - genetics; Substrate Specificity; surface plasmon resonance; Transfection; Ulilysin; zinc; IGFBP; LNR; CCP; Proteolysis; Ulilysin; IGF-binding protein (IGFBP); PAPP-A; IGF; Pregnancy-associated plasma protein-A (PAPP-A); IGF dependent modulation; Pappalysins
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/j.bbagen.2012.11.002

Pregnancy-associated plasma protein-A (PAPP-A) is a local regulator of insulin-like growth factor (IGF) bioavailability in physiological systems, but many structural and functional aspects of the metzincin metalloproteinase remain to be elucidated. PAPP-A cleaves IGF binding protein (IGFBP)-4 and IGFBP-5. Cleavage of IGFBP-4, but not IGFBP-5, depends on the binding of IGF before proteolysis by PAPP-A can occur. The paralogue PAPP-A2 has two substrates among the six IGFBPs: IGFBP-3 and IGFBP-5. Sets of chimeric proteins between IGFBP-4 and -5, and IGFBP-3 and -5 were constructed to investigate the structural requirements for IGF modulation. At the proteinase level, we investigated the importance of individual acidic amino acids positioned in the proteolytic domain of PAPP-A for proteolytic activity against IGFBP-4 and -5. Interaction between PAPP-A and its substrates was analyzed by surface plasmon resonance. We provide data suggesting that the C-terminal domain of the IGFBPs is responsible for IGF-dependent modulation of access to the scissile bond. Loss or reduction of IGFBP proteolysis by PAPP-A was observed upon mutation of residues positioned in the unique 63-residue stretch separating the zinc and Met-turn motifs, and in the short sequence following the Met-turn methionine. A model of the proteolytic domain of PAPP-A suggests the presence of structural calcium ions in the C-terminal subdomain, implicated in IGFBP substrate interactions. Detailed knowledge of interactions between PAPP-A and its substrates is required to understand the modulatory role of PAPP-A on IGF receptor stimulation. ► Acidic residues of PAPP-A are required for substrate cleavage. ► Structural calcium ions are suggested to be implicated in interaction with IGFBPs. ► IGF–IGFBP interaction determines protease–substrate binding. ► The central and the C-terminal domains of IGFBPs mediate IGF dependent proteolysis.