EMILIN-3, Peculiar Member of Elastin Microfibril Interface-located Protein (EMILIN) Family, Has Distinct Expression Pattern, Forms Oligomeric Assemblies, and Serves as Transforming Growth Factor β (TGF-β) Antagonist

• Published in: The Journal of biological chemistry Vol. 287; no. 14; pp. 11498 - 11515
• Main Authors: Schiavinato, Alvise, Becker, Ann-Kathrin A., Zanetti, Miriam, Corallo, Diana, Milanetto, Martina, Bizzotto, Dario, Bressan, Giorgio, Guljelmovic, Marija, Paulsson, Mats, Wagener, Raimund, Braghetta, Paola, Bonaldo, Paolo
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30-03-2012; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Sequence; Animals; Antigens, Surface - chemistry; Antigens, Surface - genetics; Antigens, Surface - metabolism; Disulfides - chemistry; Extracellular Matrix; Extracellular Matrix Proteins - chemistry; Extracellular Matrix Proteins - genetics; Extracellular Matrix Proteins - metabolism; Gene Expression; Gene Expression Regulation, Developmental; Glycobiology and Extracellular Matrices; Glycoproteins - chemistry; Glycoproteins - genetics; Glycoproteins - metabolism; HEK293 Cells; Heparin - metabolism; Heparin-binding Protein; Humans; Membrane Glycoproteins - chemistry; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Mice; Molecular Sequence Data; Molecular Weight; Polysaccharides - metabolism; Protein Multimerization; Protein Structure; Protein Structure, Quaternary; Protein Structure, Tertiary; Protein Transport; Transforming Growth Factor beta - antagonists & inhibitors; Transforming Growth Factor β (TGFβ); Gene Expression; Protein Structure; Extracellular Matrix; Transforming Growth Factor β (TGFβ); Heparin-binding Protein
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111.303578

EMILIN-3 is a glycoprotein of the extracellular matrix belonging to a family that contains a characteristic N-terminal cysteine-rich EMI domain. Currently, EMILIN-3 is the least characterized member of the elastin microfibril interface-located protein (EMILIN)/Multimerin family. Using RNA, immunohistochemical, and protein chemistry approaches, we carried out a detailed characterization of the expression and biochemical properties of EMILIN-3 in mouse. During embryonic and postnatal development, EMILIN-3 showed a peculiar and dynamic pattern of gene expression and protein distribution. EMILIN-3 mRNA was first detected at E8.5–E9.5 in the tail bud and in the primitive gut, and at later stages it became abundant in the developing gonads and osteogenic mesenchyme. Interestingly and in contrast to other EMILIN/Multimerin genes, EMILIN-3 was not found in the cardiovascular system. Despite the absence of the globular C1q domain, immunoprecipitation and Western blot analyses demonstrated that EMILIN-3 forms disulfide-bonded homotrimers and higher order oligomers. Circular dichroism spectroscopy indicated that the most C-terminal part of EMILIN-3 has a substantial α-helical content and forms coiled coil structures involved in EMILIN-3 homo-oligomerization. Transfection experiments with recombinant constructs showed that the EMI domain contributes to the higher order self-assembly but was dispensable for homotrimer formation. EMILIN-3 was found to bind heparin with high affinity, a property mediated by the EMI domain, thus revealing a new function for this domain that may contribute to the interaction of EMILIN-3 with other extracellular matrix and/or cell surface molecules. Finally, in vitro experiments showed that EMILIN-3 is able to function as an extracellular regulator of the activity of TGF-β ligands.
Background: EMILIN-3 is the least characterized member of the EMILIN/Multimerin family.
Results: EMILIN-3 forms homotrimers and higher order oligomers, binds heparin, has a dynamic expression during development and a restricted distribution in adult tissues, and serves as a pro-TGF-β antagonist.
Conclusion: The structure and expression of EMILIN-3 are different from other EMILINs/Multimerins.
Significance: EMILIN-3, a TGF-β antagonist, is likely to be an important regulator during development of several tissues.