Collagen XII Interacts with Avian Tenascin-X through Its NC3 Domain

Abstract

Large oligomeric proteins often contain several binding sites for different molecules and can therefore induce formation of larger protein complexes. Collagen XII, a multidomain protein with a small collagenous region, interacts with fibrillar collagens through its C-terminal region. However, no interactions to other extracellular proteins have been identified involving the non-collagenous N-terminal NC3 domain. To further elucidate the components of protein complexes present close to collagen fibrils, different extracellular matrix proteins were tested for interaction in a solid phase assay. Binding to the NC3 domain of collagen XII was found for the avian homologue of tenascin-X that in humans is linked to Ehlers-Danlos disease. The binding was further characterized by surface plasmon resonance spectroscopy and supported by immunohistochemical co-localization in chick and mouse tissue. On the ultrastructural level, detection of collagen XII and tenascin-X by immunogold labeling confirmed this finding.The integrity of extracellular matrix is maintained by supramolecular networks assembled by a large variety of matrix macromolecules. Among those is the group of 28 different collagen types so far described in the literature. Collagens are further subdivided into several families reflecting their assemblyforming properties (1). As a common feature, fibril-associated collagens with interrupted triple helices (FACITs) 2 comprise at least two collagenous domains interrupted by non-collagenous domains. Collagen XII is a member of the FACIT subfamily, and its three chains are encoded by a single gene. The two collagenous domains (Col1 and Col2) are interrupted and flanked by three non-collagenous domains (NC1-NC3), of which the large trimeric NC3 domain contains up to 90% of the molecular mass of collagen XII. The N-terminal NC3 part of each polypeptide chain consists of two to four von Willebrand factor type A domains, several fibronectin type III repeats, and a thrombospondin N-terminal domain (2, 3). The size of the protein is variable due to two alternative splice sites located at the 5Ј-and 3Ј-ends of the collagen XII mRNA. Especially remarkable is the splicing mechanism that produces mRNA encoding for NC3 domains that differ ϳ100 kDa in mass, denoted as XIIA for the large form and as XIIB for the small form (4, 5). The other alternative splicing generates two NC1 domains of similar size, termed -1 or -2, which results in the nomenclature of the four different collagen XII isoforms: XIIA-1, XIIA-2, XIIB-1 and XIIB-2 (for overview of the domain structure please refer to Fig. 2A) (6). The isoforms differ in their histological and developmental distribution: the large forms XIIA-1 and XIIA-2 are preferably expressed during embryonic stages, whereas the expression of the small forms persists in adult tissues (7). Furthermore, the small isoform XIIB-1 predominantly occurs in ligaments and tendons, whereas the XIIB-2 shows a more widespread expression (6). The isoforms also differ in their biochemical properties. The ...

Tenascin-X Induces Cell Detachment through p38 Mitogen-Activated Protein Kinase Activation

“…12) TNX haploinsufficiency is associated with joint hypermobility type of EDS. 14) Previous studies have indicated several functional properties of TNX, including collagen fibrillogenesis, 15,16) collagen deposition, 17) and development and maintenance of elastic fibers. 18) As for the adhesive properties of bovine TNX in which the 10th FNIII repeat possesses an Arg-Gly-Asp (RGD) putative cell attachment sequence, Elefteriou et al 9,19) demonstrated that osteosarcoma (MG63) and bladder carcinoma (ECV304) cells adhere to bovine TNX weakly and that do not spread and do not assemble actin stress fibers.…”

Increased Expression of Tenascin-X in Thoracic and Abdominal Aortic Aneurysm Tissues

“…TNX-deficient mice partly mimic this phenotype. 3) Several observations suggest that TNX is involved in collagen fibrillogenesis, 4,5) collagen deposition, 6) modulation of collagen stiffness, 7) and development and maintenance of elastic fibers. 8) The serum form of TNX has also been identified in humans and mice.…”

Serum Tenascin-X Strongly Binds to Vascular Endothelial Growth Factor

“…16) As a biological feature of TNX, it has been shown that TNX interacts with types I, III and V fibrillar collagen and fibril-associated types XII and XIV collagen 15,17) and with proteoglycan decorin.…”

“…Furthermore, recent genetic studies have revealed a strong association between the TNX locus and other diseases such as schizophrenia, 10) arterial tortuosity syndrome (ATS), 11) and systemic lupus erythematosus. 12) Recent evidence has suggested that TNX is involved in collagen fibrillogenesis, 13,14) collagen deposition, 15) and development and maintenance of elastic fibers. 16) As a biological feature of TNX, it has been shown that TNX interacts with types I, III and V fibrillar collagen and fibril-associated types XII and XIV collagen 15,17) and with proteoglycan decorin.…”

“…12) Recent evidence has suggested that TNX is involved in collagen fibrillogenesis, 13,14) collagen deposition, 15) and development and maintenance of elastic fibers. 16) As a biological feature of TNX, it has been shown that TNX interacts with types I, III and V fibrillar collagen and fibril-associated types XII and XIV collagen 15,17) and with proteoglycan decorin.…”