Molecular Structure and Tissue Distribution of Matrilin-3, a Filament-forming Extracellular Matrix Protein Expressed during Skeletal Development

Abstract

Matrilin-3 is a recently identified member of the superfamily of proteins containing von Willebrand factor A-like domains and is able to form hetero-oligomers with matrilin-1 (cartilage matrix protein) via a C-terminal coiled-coil domain. Full-length matrilin-3 and a fragment lacking the assembly domain were expressed in 293-EBNA cells, purified, and subjected to biochemical characterization. Recombinantly expressed full-length matrilin-3 occurs as monomers, dimers, trimers, and tetramers, as detected by electron microscopy and SDSpolyacrylamide gel electrophoresis, whereas matrilin-3, purified from fetal calf cartilage, forms homotetramers as well as hetero-oligomers of variable stoichiometry with matrilin-1. In the matrix formed by cultured chondrosarcoma cells, matrilin-3 is found in a filamentous, collagen-dependent network connecting cells and in a collagen-independent pericellular network. Affinity-purified antibodies detect matrilin-3 expression in a variety of mouse cartilaginous tissues, such as sternum, articular, and epiphyseal cartilage, and in the cartilage anlage of developing bones. It is found both inside the lacunae and in the interterritorial matrix of the resting, proliferating, hypertrophic, and calcified cartilage zones, whereas the expression is lower in the superficial articular cartilage. In trachea and in costal cartilage of adult mice, an expression was seen in the perichondrium. Furthermore, matrilin-3 is found in bone, and its expression is, therefore, not restricted to chondroblasts and chondrocytes.The matrilins constitute a recently discovered family of noncollagenous proteins (1) belonging to the von Willebrand factor A (vWFA) 1 -like domain superfamily. To date, there are four matrilins known. Matrilin-2 (2, 3) and matrilin-4 (4, 5) have a broad tissue distribution, whereas the expression of matrilin-1 (also known as cartilage matrix protein) (6 -8) and matrilin-3 (9 -11) is more restricted to skeletal tissues. The division of the family into two subgroups can also be concluded from evolutionary studies (1). The descent from a common ancestor and the divergence through duplication of whole domains indicates the possibility of the different family members providing similar functions in different tissues. The at least partially coordinated expression of matrilin-1 and -3 gains further functional significance through the recent discovery of hetero-oligomers formed by matrilin-1 and -3 in epiphyseal cartilage of fetal calf femur (12).Matrilin-3 has most features of the modular structure typical for matrilins and consists of an N-terminal vWFA-like domain, four EGF-like domains, and a C-terminal ␣-helical coiled-coil oligomerization domain (9 -11), but it lacks the second vWFAlike domain that is present in all the other matrilins. Similarly, a unique mouse matrilin-4 splice variant lacking the N-terminal vWFA-like domain was recently identified (4). In addition, matrilin-3 possesses a domain with a high content of positively charged amino acids between the N-terminal vWFA-like domain ...

Complexes of Matrilin-1 and Biglycan or Decorin Connect Collagen VI Microfibrils to Both Collagen II and Aggrecan

“…2). Since the two matrilins showed extensive co-localization with each other and may well occur in hybrid molecules and hybrid filaments (21,26), only matrilin-3 was studied in further double immunofluorescence experiments (Fig. 2).…”

“…All matrilins form homo-oligomers through assembly of coiled-coil structures from a common C-terminal stretch of heptad repeats. In addition, matrilin-1 and -3 form hetero-oligomers in bovine epiphyseal cartilage (21,26). Matrilin-1 has been shown to interact with fibrillar collagens (27) and aggrecan (28,29).…”

“…18). Matrilin-1 (also known as cartilage matrix protein, CMP), and matrilin-3 are abundant in cartilage (19,20,21) while matrilin-2 and matrilin-4 show a broader tissue distribution (22)(23)(24)(25). All matrilins form homo-oligomers through assembly of coiled-coil structures from a common C-terminal stretch of heptad repeats.…”

Increased expression of matrilin‐3 not only in osteoarthritic articular cartilage but also in cartilage‐forming tumors, and down‐regulation of SOX9 via epidermal growth factor domain 1–dependent signaling

“…Detailed characterization of MATN3 remains elusive, however. On the one hand, MATN3 is known to interact directly with the pericellular matrix, in which it is believed to play a role in interconnecting macromolecular networks (12)(13)(14)(15). On the other hand, coated MATN3 was demonstrated to promote settling of primary human chondrocytes (PHCs) (16), suggesting that MATN3 interacts physically with cells.…”

Cartilage Extracellular Matrix Integrity and OA

“…MATN1 and MATN3 are cartilage specific while MATN2 and MATN4 are found in many connective tissue types (van der Weyden et al 2006;Wu et al, 1998;Piecha et al, 2002). It has been demonstrated that matrilins form a filamentous network pericellularly in the cartilage ECM (Klatt et al, 2000). Structurally, MATN1 consists of two Von Willebrand Factor A (vWFA) domains, one epidermal growth factor-like (EGF) domain, so named because they share a forty amino-acid long residue commonly found in epidermal growth factor protein, and one alpha helical coil-coiled oligomerization domain.…”