Review Insights on ADAMTS proteases and ADAMTS-like proteins from mammalian genetics Johanne Dubail and Suneel S. Apte⁎ Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA Correspondence to Suneel S. Apte: Department of Biomedical Engineering (ND20), Cleveland Clinic Lerner Research Institute, 9500 Euclid Avenue, Cleveland, OH 44195, USA. [email protected] http://dx.doi.org/10.1016/j.matbio.2015.03.001 Edited by R. Iozzo Abstract The mammalian ADAMTS superfamily comprises 19 secreted metalloproteinases and 7 ADAMTS-like proteins, each the product of a distinct gene. Thus far, all appear to be relevant to extracellular matrix function or to cell–matrix interactions. Most ADAMTS functions first emerged from analysis of spontaneous human and animal mutations and genetically engineered animals. The clinical manifestations of Mendelian disorders resulting from mutations in ADAMTS2, ADAMTS10, ADAMTS13, ADAMTS17, ADAMTSL2 and ADAMTSL4 identified essential roles for each gene, but also suggested potential cooperative functions of ADAMTS proteins. These observations were extended by analysis of spontaneous animal mutations, such as in bovine ADAMTS2, canine ADAMTS10, ADAMTS17 and ADAMTSL2 and mouse ADAMTS20. These human and animal disorders are recessive and their manifestations appear to result from a loss-of-function mechanism. Genome-wide analyses have determined an association of some ADAMTS loci such as ADAMTS9 and ADAMTS7, with specific traits and acquired disorders. Analysis of genetically engineered rodent mutations, now achieved for over half the superfamily, has provided novel biological insights and animal models for the respective human genetic disorders and suggested potential candidate genes for related human phenotypes. Engineered mouse mutants have been interbred to generate combinatorial mutants, uncovering cooperative functions of ADAMTS proteins in morphogenesis. Specific genetic models have provided crucial insights on mechanisms of osteoarthritis (OA), a common adult-onset degenerative condition. Engineered mutants will facilitate interpretation of exome variants identified in isolated birth defects and rare genetic conditions, as well as in genome-wide screens for trait and disease associations. Mammalian forward and reverse genetics, together with genome-wide analysis, together constitute a powerful force for revealing the functions of ADAMTS proteins in physiological pathways and health disorders. Their continuing use, together with genome-editing technology and the ability to generate stem cells from mutants, presents numerous opportunities for advancing basic knowledge, human disease pathways and therapy. © 2015 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction (ADAMTSL1-6 and papilin) in humans, mice and other mammals [6]. The gene name ADAMTS11 was The first A disintegrin-like and metalloprotease given in error to a gene already designated as (reprolysin type) with thrombospondin type 1 motif ADAMTS5 [2,7]; thus the term ADAMTS11 is no longer (ADAMTS) proteases were discovered in the late used. Phylogenetic analysis showed considerable 1990s [1–3], and the first ADAMTS-like proteins expansion of the mammalian ADAMTS family, com- (ADAMTSL) were cloned shortly after [4,5]. pared to a much smaller repertoire in Caenorhabditis ADAMTSLs resemble the non-catalytic domains of elegans, Drosophila melanogaster and Ciona intesti- ADAMTS proteases and lack a protease domain [6]. nalis [8] (see review by Kim and Nishiwaki in this They are not proteases, nor do they arise by alternative special issue). Mammalian ADAMTS gene expansion splicing of ADAMTS protease genes. There are 19 is postulated to have arisen primarily by gene ADAMTS genes and 7 ADAMTS-like proteins duplication, representing both sub-functionalization 0022-2836/© 2015 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Matrix Biol (2015) 44-46,24–37 Insights on ADAMTS proteases and ADAMTS-like proteins 25 and neo-functionalization of the duplicated genes [8]. post-translational modifications as a prerequisite for Sub-functionalization is suggested by the shared or cleavage that are absent in synthetic substitutes. For cooperative function of a subset of ADAMTS proteases example, ADAMTS5 proteolysis uses the chondroitin in cleavage of proteoglycans such as aggrecan and sulfate chains of versican as a crucial determinant for versican [9], and involvement of several ADAMTS proteolysis [17], and ADAMTS13 processing of von proteins in fibrillin microfibril biology [10].ADAMTS Willebrand factor (vWF) requires shear stress-me- neo-functionalization is exemplified by ADAMTS13, diated unfolding of the region containing the scissile whose major function seems to be hemostatic [11] and bond [22]. possibly related to evolution of a closed circulatory Given these challenges, it has been fortunate that system. genetics has stepped into the breach. In contrast Compared to other metalloprotease families, such to other metalloproteinases, the ADAMTS field as matrix metalloproteinases (MMPs), which have has benefited considerably from forward genetics, been studied for over half a century [12],theADAMTS i.e., resolution of the genetic basis of spontaneous field has thus existed only for a decade and a half. It is mutants, which exist for several ADAMTS genes. important to point out that ADAMTS proteases are Reverse genetics, i.e., where genetically engineered genetically distinct from the membrane-anchored A or chemically induced mutants are generated and the disintegrin and metalloprotease (ADAMs). Whereas resulting phenotype analyzed to define gene function, membrane localization endows ADAMs with a major has advanced understanding of the same genes as role in protein ectodomain shedding from the cell well as others of previously unknown function. That surface [13], ADAMTS proteases are secreted and ADAMTS forward genetics has revealed the basis of primarily associated with proteolytic events in extra- extremely rare inherited disorders does not diminish cellular matrix (ECM). There are distinct differences in its value, since the mutations revealed previously their respective domain structures, the hallmark of unsuspected biological pathways. As a case in point, ADAMTS proteases being a C-terminal ancillary the discovery that rare mutations in the low-density domain having a characteristic modular structure lipoprotein receptor caused hypercholesterolemia that contains one or more thrombospondin type 1 paved the way for cholesterol-lowering therapy [23]. repeats (TSRs). ADAMTS genetics has contributed new knowledge of Although there are totally 26 ADAMTS proteins to extracellular matrix assembly and degradation in be considered in defining individual and collective morphogenesis, reproductive biology and many functions of the family, and for determining their organ systems and processes as reviewed here. shared operational principles in biological networks, Other reviews in this special issue have covered the genetics has already proved to be the primary source role of ADAMTS proteases in cancer (see review by of functional insights. This was inevitable because Cal and Lopez-Otin) and cancer-related processes ADAMTS proteins are not as amenable to biochem- such as angiogenesis (see review by Rodriguez-- ical and cellular analysis as MMPs and ADAMs. For Manzaneque and Iruela-Arispe), as well as fertility example, MMPs are readily expressed, refolded and (see review by D. Russell), nervous system disor- purified in quantity from eukaryotic expression ders (see review by P. Gotschall) and procollagen systems and readily cleave peptide substrates [14]. processing (see review by Bekhouche and Colige). Analysis of ADAMs was enabled by the finding that they lacked stringent substrate sequence specificity, and mediated ectodomain shedding via a ADAMTS genomics “lawn-mower” effect enabled by their membrane anchorage [15]. Thus, ADAM activities are typically In contrast to a well-defined genomic MMP cluster determined by use of transfected constructs in which on human chromosome 11q22 [24], ADAMTS genes the target substrate's ectodomain carries an are dispersed throughout the human and mouse enzymatic reporter such as alkaline phosphatase, genomes. However, three pairs of ADAMTS genes while retaining the membrane-proximal segment of are tightly linked in regions of human-mouse synteny the ectodomain [16]. In contrast, ADAMTS protease [25], and of these, two present potential challenges for biochemistry provides many challenges, e.g., these mouse genetic engineering. These two pairs include proteases are large, have numerous disulfide bonds, evolutionarily related ADAMTS proteases, namely, the majority carry heavy and specialized glycosyla- ADAMTS1/ADAMTS5 and ADAMTS8/ADAMTS15 on tion, are poorly secreted by cells, sticky and suscep- human chromosomes 21 and 11 respectively; the tible to autocatalysis, which disrupts the ancillary corresponding mouse loci are linked on mouse domain. Unlike MMPs, ADAMTS protease domains chromosomes 16 and 9 respectively. Because these expressed in isolation do not typically have specific genes have a close evolutionary relationship, there is a activity, since the ancillary domains mediate substrate possibility that they have cooperative functions. recognition [17–21]. Furthermore, unlike MMPs, most However, tight genetic linkage precludes elucidation