Delineating the Molecular Basis of the Inactivity of Tissue Inhibitor of Metalloproteinase-2 against Tumor Necrosis Factor-α-converting Enzyme

Engineering metalloproteinase inhibitors: tissue inhibitors of metalloproteinases or antibodies, that is the question

Targeting metalloproteinases (MPs) has been the center of attention for developing therapeutics due to their contribution to a wide range of diseases, including cancer, cardiovascular, neurodegenerative disease, and preterm labor. Protein-based MP inhibitors offer higher stability and selectivity, which is critical for developing efficient therapeutics with low off-target effects. Tissue inhibitors of metalloproteinases (TIMPs), natural inhibitors of MPs, and antibodies provide excellent protein scaffolds for engineering selective or multispecific MP inhibitors. Advances in protein engineering and design techniques, such as rational design and directed evolution using yeast display to develop potent MP inhibitors, are discussed, including but not limited to loop grafting, swapping, and counterselective selection.

Translocating a High-Affinity Designer TIMP-1 to the Cell Membrane for Total Renal Carcinoma Inhibition: Putting the Prion Protein to Good Use

Membrane type 1-matrix metalloproteinase (MT1-MMP) and tumor necrosis factor α (TNF-α)-converting enzyme (TACE) are prominent membrane-anchored metalloproteinases that regulate the turnover of extracellular matrix (ECM) components and bioactive molecules required for cancer proliferation. In this study, we describe a novel approach that would allow tissue inhibitor of metalloproteinase 1 (TIMP-1), the endogenous inhibitor of the matrix metalloproteinases (MMPs), to be translocated to the cell membrane for simultaneous MT1-MMP/TACE inhibition. We achieve this by fusing T1^TACE, a designer TIMP-1 with superb affinities for MT1-MMP and TACE, to the glycosyl-phosphatidyl inositol anchor of prions to create a membrane-tethered, broad-spectrum inhibitor, named T1^{Pr αTACE}, that colocalizes with MT1-MMP and TACE on the cell surface. Transduction of T1^{Pr αTACE} in human fibrosarcoma cells results not only in a substantial reduction in gelatinolytic and TNF-α/heparin binding epithelial growth factor shedding activities but also in a loss of tubulogenic capability in three-dimensional matrices. In renal carcinoma, T1^{Pr αTACE} triggers cellular senescence and disrupts MMP-mediated proteolysis of ECM components such as fibronectin and collagen I, leading to an impairment in cell motility and survival under both in vitro and in vivo conditions. Taken together, our findings may provide a new perspective in TIMP targeting that could be exploited to halt metastatic renal carcinoma progression.

Reflections on the evolution of the vertebrate tissue inhibitors of metalloproteinases

Jawed vertebrates (Gnathostomes) have 4 tissue inhibitors of metalloproteinases (TIMPs), multifunctional proteins that all inhibit members of the large matrix metalloproteinase (MMP) family but differ in their other roles, including the regulation of pro-MMP activation, cell growth, apoptosis and angiogenesis, and the structure of extracellular matrices (ECMs). Molecular phylogeny analyses indicate that vertebrate TIMP genes arose from an invertebrate ancestor through 3 successive duplications, possibly including 2 whole genome duplications, during early vertebrate phylogeny. TIMPs from invertebrates also inhibit metalloproteinases, bind to pro-MMPs, and contribute to ECM structures but are not orthologs of any particular vertebrate TIMP. The most ancient vertebrate superclass, the Agnatha (jawless fish), seems to provide a snapshot of a stage in TIMP evolution preceding the third gene duplication. This review examines the structures of TIMPs from different vertebrate orders using information relating to the structural basis of their various functions. Provisional conclusions are that during their evolutionary divergence, various TIMPs lost inhibitory activity toward some metalloproteinases, specialized in effects on different pro-MMPs, and developed new interactions with discrete targets (including integrins and receptors), while recapitulating a role in ECM structure. The analysis is limited by the sparse information available regarding the functional properties of nonmammalian TIMPs.-Brew, K. Reflections on the evolution of the vertebrate tissue inhibitors of metalloproteinases.

ADAMTS13 and 15 are not regulated by the full length and N-terminal domain forms of TIMP-1, -2, -3 and -4

A disintegrin and metalloproteinase with thombospondin motifs (ADAMTS) 13 and 15 are secreted zinc proteinases involved in the turnover of von Willebrand factor and cancer suppression. In the present study, ADAMTS13 and 15 were subjected to inhibition studies with the full-length and N-terminal domain forms of tissue inhibitor of metalloproteinases (TIMPs)-1 to -4. TIMPs have no ability to inhibit the ADAMTS proteinases in the full-length or N-terminal domain form. While ADAMTS13 is also not sensitive to the hydroxamate inhibitors, batimastat and ilomastat, ADAMTS15 can be effectively inhibited by batimastat (K_i^app 299 nM). In conclusion, the present results indicate that TIMPs are not the regulators of these two ADAMTS proteinases.

Respiratory protease/antiprotease balance determines susceptibility to viral infection and can be modified by nutritional antioxidants

The respiratory epithelium functions as a central orchestrator to initiate and organize responses to inhaled stimuli. Proteases and antiproteases are secreted from the respiratory epithelium and are involved in respiratory homeostasis. Modifications to the protease/antiprotease balance can lead to the development of lung diseases such as emphysema or chronic obstructive pulmonary disease. Furthermore, altered protease/antiprotease balance, in favor for increased protease activity, is associated with increased susceptibility to respiratory viral infections such as influenza virus. However, nutritional antioxidants induce antiprotease expression/secretion and decrease protease expression/activity, to protect against viral infection. As such, this review will elucidate the impact of this balance in the context of respiratory viral infection and lung disease, to further highlight the role epithelial cell-derived proteases and antiproteases contribute to respiratory immune function. Furthermore, this review will offer the use of nutritional antioxidants as possible therapeutics to boost respiratory mucosal responses and/or protect against infection.

ADAM12 is expressed in the tumour vasculature and mediates ectodomain shedding of several membrane-anchored endothelial proteins

ADAM (a disintegrin and metalloproteinase) 12 is a metalloprotease implicated in cancer progression. ADAM12 can activate membrane-anchored proteins, such as sonic hedgehog, Delta-like 1 and certain epidermal growth factor receptor ligands, through a process called ectodomain shedding. We screened several membrane-anchored proteins to further dissect the substrate profile of ADAM12-mediated ectodomain shedding, and found shedding of five previously unreported substrates [Kitl1, VE-cadherin (vascular endothelial cadherin), Flk-1 (fetal liver kinase 1), Tie-2, and VCAM-1 (vascular cell adhesion molecule 1)], of which the latter four are specifically expressed by endothelial cells. We also observed that ADAM12 expression was increased in the tumour vasculature of infiltrating ductal carcinoma of the human breast as compared with little to no expression in normal breast tissue vasculature, suggesting a role for ADAM12 in tumour vessels. These results prompted us to further evaluate ADAM12-mediated shedding of two endothelial cell proteins, VE-cadherin and Tie-2. Endogenous ADAM12 expression was very low in cultured endothelial cells, but was significantly increased by cytokine stimulation. In parallel, the shed form of VE-cadherin was elevated in such cytokine-stimulated endothelial cells, and ADAM12 siRNA (small interfering RNA) knockdown reduced cytokine-induced shedding of VE-cadherin. In conclusion, the results of the present study demonstrate a role for ADAM12 in ectodomain shedding of several membrane-anchored endothelial proteins. We speculate that this process may have importance in tumour neovascularization or/and tumour cell extravasation.

Matrix metalloproteinase-10 (MMP-10) interaction with tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2: binding studies and crystal structure

Matrix metalloproteinase 10 (MMP-10, stromelysin-2) is a secreted metalloproteinase with functions in skeletal development, wound healing, and vascular remodeling; its overexpression is also implicated in lung tumorigenesis and tumor progression. To understand the regulation of MMP-10 by tissue inhibitors of metalloproteinases (TIMPs), we have assessed equilibrium inhibition constants (K(i)) of putative physiological inhibitors TIMP-1 and TIMP-2 for the active catalytic domain of human MMP-10 (MMP-10cd) using multiple kinetic approaches. We find that TIMP-1 inhibits the MMP-10cd with a K(i) of 1.1 × 10(-9) M; this interaction is 10-fold weaker than the inhibition of the similar MMP-3 (stromelysin-1) catalytic domain (MMP-3cd) by TIMP-1. TIMP-2 inhibits the MMP-10cd with a K(i) of 5.8 × 10(-9) M, which is again 10-fold weaker than the inhibition of MMP-3cd by this inhibitor (K(i) = 5.5 × 10(-10) M). We solved the x-ray crystal structure of TIMP-1 bound to the MMP-10cd at 1.9 Å resolution; the structure was solved by molecular replacement and refined with an R-factor of 0.215 (R(free) = 0.266). Comparing our structure of MMP-10cd·TIMP-1 with the previously solved structure of MMP-3cd·TIMP-1 (Protein Data Bank entry 1UEA), we see substantial differences at the binding interface that provide insight into the differential binding of stromelysin family members to TIMP-1. This structural information may ultimately assist in the design of more selective TIMP-based inhibitors tailored for specificity toward individual members of the stromelysin family, with potential therapeutic applications.

The evaluation of inhibitive effectiveness of the tumour necrosis factor-α converting enzyme selective inhibitors by HPLC

A novel high-performance liquid chromatography (HPLC) method based on the internal standard method was established for assaying the tumour necrosis factor-α converting enzyme (TACE) activity and matrix metalloprotease-9 (MMP-9) activity, and was used to evaluate the inhibitive effectiveness of inhibitors to TACE and MMP-9. In the assay method for TACE and MMP-9, peptides labelled with the ultraviolet group-Dpa were used as substrates. Alanine-Dpa was synthesised and was used as the internal standard for quantitative analysis. After the peptide substrates were hydrolysed by TACE (MMP-9) for 15 min (25 min) at 37 °C, the amount of remaining substrates were determined by reversed-phased HPLC with UV detection at 353 nm. The relative peak area of the substrate was linearly dependent on the substrate concentration. This method was then applied to determine the 50% inhibitory concentration (IC₅₀) of GM6001 and inhibitor A for both TACE and MMP-9.

Selective inhibition of ADAM12 catalytic activity through engineering of tissue inhibitor of metalloproteinase 2 (TIMP-2)

The disintegrin and metalloprotease ADAM12 has important functions in normal physiology as well as in diseases, such as cancer. Little is known about how ADAM12 confers its pro-tumorigenic effect; however, its proteolytic capacity is probably a key component. Thus selective inhibition of ADAM12 activity may be of great value therapeutically and as an investigative tool to elucidate its mechanisms of action. We have previously reported the inhibitory profile of TIMPs (tissue inhibitor of metalloproteinases) against ADAM12, demonstrating in addition to TIMP-3, a unique ADAM-inhibitory activity of TIMP-2. These findings strongly suggest that it is feasible to design a TIMP mutant selectively inhibiting ADAM12. With this purpose, we characterized the molecular determinants of the ADAM12-TIMP complex formation as compared with known molecular requirements for TIMP-mediated inhibition of ADAM17/TACE (tumour necrosis factor alpha-converting enzyme). Kinetic analysis using a fluorescent peptide substrate demonstrated that the molecular interactions of N-TIMPs (N-terminal domains of TIMPs) with ADAM12 and TACE are for the most part comparable, yet revealed strikingly unique features of TIMP-mediated ADAM12 inhibition. Intriguingly, we found that removal of the AB-loop in N-TIMP-2, which is known to impair its interaction with TACE, resulted in increased affinity to ADAM12. Importantly, using a cell-based epidermal growth factor-shedding assay, we demonstrated for the first time an inhibitory activity of TIMPs against the transmembrane ADAM12-L (full-length ADAM12), verifying the distinctive inhibitory abilities of N-TIMP-2 and engineered N-TIMP-2 mutants in a cellular environment. Taken together, our findings support the idea that a distinctive ADAM12 inhibitor with future therapeutic potential can be designed.

Inactivation of N-TIMP-1 by N-terminal acetylation when expressed in bacteria

The high-affinity binding of tissue inhibitors of metalloproteinases (TIMPs) to matrix metalloproteinases (MMPs) is essential for regulation of the turnover of the extracellular matrix during development, wound healing, and progression of inflammatory diseases, such as cancer, atherosclerosis, and arthritis. Bacterially expressed N-terminal inhibitory domains of TIMPs (N-TIMPs) have been used extensively for biochemical and biophysical study of interactions with MMPs. Titration of N-TIMP-1 expressed in E. coli indicates, however, that only about 42% of the protein is active as an MMP inhibitor. The separation of inactive from fully active N-TIMP-1 has been achieved both by MMP affinity and by high-resolution cation exchange chromatography at an appropriate pH, based on a slight difference of charge. Purification by cation exchange chromatography with a Mono S column enriches the active portion of N-TIMP-1 to >95%, with K(i) of 1.5 nM for MMP-12. Mass spectra reveal that the inactive form differs from active N-TIMP-1 in being N-terminally acetylated, underscoring the importance of the free alpha-NH(2) of Cys1 for MMP inhibition. N(alpha)-acetylation of the CTCVPP sequence broadens the N-terminal sequence motifs reported to be susceptible to alpha-amino acetylation by E. coli N-acetyl transferases.

Structural determinants of the ADAM inhibition by TIMP-3: crystal structure of the TACE-N-TIMP-3 complex

TIMP-3 (tissue inhibitor of metalloproteinases 3) is unique among the TIMP inhibitors, in that it effectively inhibits the TNF-alpha converting enzyme (TACE). In order to understand this selective capability of inhibition, we crystallized the complex formed by the catalytic domain of recombinant human TACE and the N-terminal domain of TIMP-3 (N-TIMP-3), and determined its molecular structure with X-ray data to 2.3 A resolution. The structure reveals that TIMP-3 exhibits a fold similar to those of TIMP-1 and TIMP-2, and interacts through its functional binding edge, which consists of the N-terminal segment and other loops, with the active-site cleft of TACE in a manner similar to that of matrix metalloproteinases (MMPs). Therefore, the mechanism of TIMP-3 binding toward TACE is not fundamentally different from that previously elucidated for the MMPs. The Phe34 phenyl side chain situated at the tip of the relatively short sA-sB loop of TIMP-3 extends into a unique hydrophobic groove of the TACE surface, and two Leu residues in the adjacent sC-connector and sE-sF loops are tightly packed in the interface allowing favourable interactions, in agreement with predictions obtained by systematic mutations by Gillian Murphy's group. The combination of favourable functional epitopes together with a considerable flexibility renders TIMP-3 an efficient TACE inhibitor. This structure might provide means to design more efficient TIMP inhibitors of TACE.

The ADAM17-amphiregulin-EGFR axis in mammary development and cancer

In order to fulfill its function of producing and delivering sufficient milk to newborn mammalian offspring, the mammary gland first has to form an extensive ductal network. As in all phases of mammary development, hormonal cues elicit local intra- and inter-cellular signaling cascades that regulate ductal growth and differentiation. Among other things, ductal development requires the epidermal growth factor receptor (EGFR), its ligand amphiregulin (AREG), and the transmembrane metalloproteinase ADAM17, which can cleave and release AREG from the cell surface so that it may interact with its receptor. Tissue recombination and transplantation studies demonstrate that EGFR phosphorylation and ductal development proceed only when ADAM17 and AREG are expressed on mammary epithelial cells and EGFR is present on stromal cells, and that local administration of soluble AREG can rescue the development of ADAM17-deficient transplants. Thus proper mammary morphogenesis requires the ADAM17-mediated release of AREG from ductal epithelial cells, the subsequent activation of EGFR on stromal cells, and EGFR-dependent stromal responses that in return elicit a new set of epithelial responses, all culminating in the formation of a fully functional ductal tree. This, however, raises new issues concerning what may act upstream, downstream or in parallel with the ADAM17-AREG-EGFR axis, how it may become hijacked or corrupted during the onset and evolution of cancer, and how such ill effects may be confronted.

Progress in matrix metalloproteinase research

Matrix metalloproteinases (MMPs) are now acknowledged as key players in the regulation of both cell-cell and cell-extracellular matrix interactions. They are involved in modifying matrix structure, growth factor availability and the function of cell surface signalling systems, with consequent effects on cellular differentiation, proliferation and apoptosis. They play central roles in morphogenesis, wound healing, tissue repair and remodelling in response to injury and in the progression of diseases such as arthritis, cancer and cardiovascular disease. Because of their wide spectrum of activities and expression sites, the elucidation of their potential as drug targets in disease or as important features of the repair process will be dependent upon careful analysis of their role in different cellular locations and at different disease stages. Novel approaches to the specific regulation of individual MMPs in different contexts are also being developed.

The isolated N-terminal domains of TIMP-1 and TIMP-3 are insufficient for ADAM10 inhibition

ADAM (a disintegrin and metalloproteinase) 10 is a key member of the ADAM family of disintegrin and metalloproteinases which process membrane-associated proteins to soluble forms in a process known as 'shedding'. Among the major targets of ADAM10 are Notch, EphrinA2 and CD44. In many cell-based studies of shedding, the activity of ADAM10 appears to overlap with that of ADAM17, which has a similar active-site topology relative to the other proteolytically active ADAMs. The tissue inhibitors of metalloproteinases, TIMPs, have proved useful in the study of ADAM function, since TIMP-1 inhibits ADAM10, but not ADAM17; however, both enzymes are inhibited by TIMP-3. In the present study, we show that, in comparison with ADAM17 and the MMPs (matrix metalloproteinases), the N-terminal domains of TIMPs alone are insufficient for the inhibition of ADAM10. This knowledge could form the basis for the design of directed inhibitors against different metalloproteinases.

Structural features of the reprolysin atrolysin C and tissue inhibitors of metalloproteinases (TIMPs) interaction

Atrolysin C is a P-I snake venom metalloproteinase (SVMP) from Crotalus atrox venom, which efficiently degrades capillary basement membranes, extracellular matrix, and cell surface proteins to produce hemorrhage. The tissue inhibitors of metalloproteinases (TIMPs) are effective inhibitors of matrix metalloproteinases which share some structural similarity with the SVMPs. In this work, we evaluated the inhibitory profile of TIMP-1, TIMP-2, and the N-terminal domain of TIMP-3 (N-TIMP-3) on the proteolytic activity of atrolysin C and analyzed the structural requirements and molecular basis of inhibitor-enzyme interaction using molecular modeling. While TIMP-1 and TIMP-2 had no inhibitory activity upon atrolysin C, the N-terminal domain of TIMP-3 (N-TIMP-3) was a potent inhibitor with a K(i) value of approximately 150nM. The predicted docking structures of atrolysin C and TIMPs were submitted to molecular dynamics simulations and the complex atrolysin C/N-TIMP-3 was the only one that maintained the inhibitory conformation. This study is the first to shed light on the structural determinants required for the interaction between a SVMP and a TIMP, and suggests a structural basis for TIMP-3 inhibitory action and related proteins such as the ADAMs.

Timp3 deficiency in insulin receptor-haploinsufficient mice promotes diabetes and vascular inflammation via increased TNF-alpha

Activation of inflammatory pathways may contribute to the beginning and the progression of both atherosclerosis and type 2 diabetes. Here we report a novel interaction between insulin action and control of inflammation, resulting in glucose intolerance and vascular inflammation and amenable to therapeutic modulation. In insulin receptor heterozygous (Insr+/-) mice, we identified the deficiency of tissue inhibitor of metalloproteinase 3 (Timp3, an inhibitor of both TNF-alpha-converting enzyme [TACE] and MMPs) as a common bond between glucose intolerance and vascular inflammation. Among Insr+/- mice, those that develop diabetes have reduced Timp3 and increased TACE activity. Unchecked TACE activity causes an increase in levels of soluble TNF-alpha, which subsequently promotes diabetes and vascular inflammation. Double heterozygous Insr+/-Timp3+/- mice develop mild hyperglycemia and hyperinsulinemia at 3 months and overt glucose intolerance and hyperinsulinemia at 6 months. A therapeutic role for Timp3/TACE modulation is supported by the observation that pharmacological inhibition of TACE led to marked reduction of hyperglycemia and vascular inflammation in Insr+/- diabetic mice, as well as by the observation of increased insulin sensitivity in Tace+/- mice compared with WT mice. Our results suggest that an interplay between reduced insulin action and unchecked TACE activity promotes diabetes and vascular inflammation.

A disintegrin and metalloprotease 21 (ADAM21) is associated with neurogenesis and axonal growth in developing and adult rodent CNS

We have reported that alpha6beta1 integrin regulates the directed migration of neuroblasts from the adult rodent subventricular zone (SVZ) through the rostral migratory stream (RMS). ADAM (a disintegrin and metalloprotease) proteins bind integrins. Here, we show that ADAM21, but not ADAM2, -3, -9, -10, -12, -15, or -17, is expressed in adult rats and mice by ependyma and SVZ cells with long basal processes, and in radial glia at early postnatal times. ADAM21-positive processes projected into the RMS, contacted blood vessels, and were present within the RMS intermingled with neuroblasts up to where neuroblasts start their radial migration and differentiation in the olfactory bulb. Tissue inhibitors of metalloproteases (TIMPs) 1, 2, and 3 are present in the ependymal layer but not in the SVZ and RMS. Thus, ADAM21 could regulate neurogenesis and guide neuroblast migration through cleavage-dependent activation of proteins and integrin binding. ADAM21 is also present in growing axonal tracts during postnatal development and in growing primary olfactory axons in adults. In the olfactory nerve layer, ADAM21 often, but not always, colocalizes with OMP, a marker of mature olfactory neurons, but is not colocalized with the immature marker betaIII-tubulin. This suggests that ADAM21 is involved in the final axonal outgrowth phase and/or synapse formation. TIMP3 is present in periglomerular neurons, where it could restrict ADAM21-mediated axonal growth to the glomeruli. ADAM21's unique disintegrin and metalloprotease sequences and its restricted expression suggest that it might be a good target for influencing neurogenesis and neuronal plasticity.

Mammary ductal morphogenesis requires paracrine activation of stromal EGFR via ADAM17-dependent shedding of epithelial amphiregulin

Epithelial-mesenchymal crosstalk is essential for tissue morphogenesis, but incompletely understood. Postnatal mammary gland development requires epidermal growth factor receptor (EGFR) and its ligand amphiregulin (AREG), which generally must be cleaved from its transmembrane form in order to function. As the transmembrane metalloproteinase ADAM17 can process AREG in culture and Adam17(-/-) mice tend to phenocopy Egfr(-/-) mice, we examined the role of each of these molecules in mammary development. Tissue recombination and transplantation studies revealed that EGFR phosphorylation and ductal development occur only when ADAM17 and AREG are expressed on mammary epithelial cells, whereas EGFR is required stromally, and that local AREG administration can rescue Adam17(-/-) transplants. Several EGFR agonists also stimulated Adam17(-/-) mammary organoid growth in culture, but only AREG was expressed abundantly in the developing ductal system in vivo. Thus, ADAM17 plays a crucial role in mammary morphogenesis by releasing AREG from mammary epithelial cells, thereby eliciting paracrine activation of stromal EGFR and reciprocal responses that regulate mammary epithelial development.

Reactive site mutations in tissue inhibitor of metalloproteinase-3 disrupt inhibition of matrix metalloproteinases but not tumor necrosis factor-alpha-converting enzyme

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a dual inhibitor of the matrix metalloproteinases (MMPs) and some adamalysins, two families of extracellular and cell surface metalloproteinases that function in extracellular matrix turnover and the shedding of cell surface proteins. The mechanism of inhibition of MMPs by TIMPs has been well characterized, and since the catalytic domains of MMPs and adamalysins are homologous, it was assumed that the interaction of TIMP-3 with adamalysins is closely similar. Here we report that the inhibition of the extracellular region of ADAM-17 (tumor necrosis factor alpha-converting enzyme (TACE)) by the inhibitory domain of TIMP-3 (N-TIMP-3) shows positive cooperativity. Also, mutations in the core of the MMP interaction surface of N-TIMP-3 dramatically reduce the binding affinity for MMPs but have little effect on the inhibitory activity for TACE. These results suggest that the mechanism of inhibition of ADAM-17 by TIMP-3 may be distinct from that for MMPs. The mutant proteins are also effective inhibitors of tumor necrosis factor alpha (TNF-alpha) release from phorbol ester-stimulated cells, indicating that they provide a lead for engineering TACE-specific inhibitors that may reduce side effects arising from MMP inhibition and are possibly useful for treatment of diseases associated with excessive TNF-alpha levels such as rheumatoid arthritis.

Total conversion of tissue inhibitor of metalloproteinase (TIMP) for specific metalloproteinase targeting: fine-tuning TIMP-4 for optimal inhibition of tumor necrosis factor-{alpha}-converting enzyme

Tissue inhibitors of metalloproteinases (TIMPs) are the endogenous inhibitors of the matrix metalloproteinases, the ADAMs (a disintegrin and metalloproteinase) and the ADAM-TS (ADAM with thrombospondin repeats) proteinases. There are four mammalian TIMPs (TIMP-1 to -4), and each TIMP has its own profile of metalloproteinase inhibition. TIMP-4 is the latest member of the TIMPs to be cloned, and it has never been reported to be active against the tumor necrosis factor-alpha-converting enzyme (TACE, ADAM-17). Here we examined the inhibitory properties of the full-length and the N-terminal domain form of TIMP-4 (N-TIMP-4) with TACE and showed that N-TIMP-4 is a far superior inhibitor than its full-length counterpart. Although full-length TIMP-4 displayed negligible activity against TACE, N-TIMP-4 is a slow tight-binding inhibitor with low nanomolar binding affinity. Our findings suggested that the C-terminal subdomains of the TIMPs have a significant impact over their activities with the ADAMs. To elucidate further the molecular basis that underpins TIMP/TACE interactions, we sculpted N-TIMP-4 with the surface residues of TIMP-3, the only native TIMP inhibitor of the enzyme. Transplantation of only three residues, Pro-Phe-Gly, onto the AB-loop of N-TIMP-4 resulted in a 10-fold enhancement in binding affinity; the K(i) values of the resultant mutant were almost comparable with that of TIMP-3. Further mutation at the EF-loop supported our earlier findings on the preference of TACE for leucine at this locus. Drawing together our previous experience in TACE-targeted mutagenesis by using TIMP-1 and -2 scaffolds, we have finally resolved the mystery of the selective sensitivity of TACE to TIMP-3.