Role of the Netrin-like Domain of Procollagen C-Proteinase Enhancer-1 in the Control of Metalloproteinase Activity

Abstract

The netrin-like (NTR) domain is a feature of several extracellular proteins, most notably the N-terminal domain of tissue inhibitors of metalloproteinases (TIMPs), where it functions as a strong inhibitor of matrix metalloproteinases and some other members of the metzincin superfamily. The presence of a C-terminal NTR domain in procollagen C-proteinase enhancers (PCPEs), proteins that stimulate the activity of astacin-like tolloid proteinases, raises the possibility that this might also have inhibitory activity. Here we show that both long and short forms of the PCPE-1 NTR domain, the latter beginning at the N-terminal cysteine known to be critical for TIMP activity, show no inhibition, at micromolar concentrations, of several members of the metzincin superfamily, including matrix metalloproteinase-2, bone morphogenetic protein-1 (a tolloid proteinase), and different ADAMTS (a disintegrin and a metalloproteinase with thrombospondin motifs) proteinases from the adamalysin family. In contrast, we report that the NTR domain within PCPE-1 leads to superstimulation of bone morphogenetic protein-1 activity in the presence of heparin and heparan sulfate. These observations point to a new mechanism whereby binding to cell surface-associated or extracellular heparin-like sulfated glycosaminoglycans might provide a means to accelerate procollagen processing in specific cellular and extracellular microenvironments.

Disruption of the murine procollagen C-proteinase enhancer 2 gene causes accumulation of pro-apoA-I and increased HDL levels

“…PCPE2, like PCPE1, consists of two cubulin (CUB) domains (CUB1 and CUB2) involved in protein-protein interaction. While several studies have been published addressing the physiological role of PCPE1 ( 13,14 ), the function of PCPE2 remains unclear. PCPE2-defi cient (PCPE2 KO) mice are viable and fertile, and they do not show gross developmental abnormalities ( 15 ).…”

Metalloproteinases in Drosophila to Humans That Are Central Players in Developmental Processes

“…The CUB domains of PCPE1 bind procollagen (82) in a cooperative manner (83), and its NTR domain can bind BMP1 and mTLL1 (84,85), suggesting that PCPE1 may act as a linker that enhances procollagen-B/TP interactions. Moreover, enhancement of pCP activity by PCPE1 is potentiated by heparin or heparan sulfate, both of which bind the PCPE1 NTR domain, procollagen, and BMP1 (85,86), suggesting that heparan sulfate proteoglycans (HSPGs) may foster procollagen processing in vivo by bolstering formation of PCPE-procollagen-B/TP complexes (85,86). HSPGs may also bind PCPEs to cell surfaces (86).…”

Binding of Procollagen C-Proteinase Enhancer-1 (PCPE-1) to Heparin/Heparan Sulfate

“…Indeed we have previously shown that kinetic data of the binding of endostatin, the C-terminal domain of collagen XVIII (30) and of HepV, a fragment of collagen V (31), to heparin/heparan sulfate were well fitted by a heterogeneous ligand model. PCPE-1 binding to heparin is mediated by the NTR domain (17,18). Therefore, we have also characterized the binding of the free NTR domain of PCPE-1 to heparin and heparan sulfate.…”

“…The NTR fragment of PCPE-1 has been reported to act as a weak inhibitor of matrix metalloproteinases (21). However, no inhibitory activity was detected by other investigators against a range of metalloproteinases, including MMPs-1, -2, -3, and -9, BMP-1 and different ADAMTS proteinases (18,22). The PCPE-1 molecule has been shown to be a rod-like molecule, with a length of ϳ15 nm (23).…”

“…PCPE-1 consists of two CUB domains that bind to the procollagen C-propeptide and are required for enhancing activity (6,15) followed by a C-terminal NTR (netrin-like) domain (16) that binds to heparin (17) and as was recently demonstrated (18), also interacts with BMP-1. The NTR domain of PCPE-1 also binds to ␤2-microglobulin, which may help initiate ␤2-microglobulin amyloid fibril formation in connective tissues (19).…”