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J Biol Chem. 2014 Oct 31;289(44):30481-98. doi: 10.1074/jbc.M114.568154. Epub 2014 Sep 4.

Incorporation of pentraxin 3 into hyaluronan matrices is tightly regulated and promotes matrix cross-linking.

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From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain.
the Humanitas Clinical and Research Center, 20089 Rozzano, Italy.
the Wellcome Trust Centre for Cell Matrix Research and.
the Department of Molecular Biology and Genetics, University of Aarhus, 8000 Aarhus C, Denmark.
the Department of Molecular Chemistry, University Grenoble Alpes and CNRS, 38000 Grenoble, France, and.
the Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
the Wellcome Trust Centre for Cell Matrix Research and
From the CIC biomaGUNE, 20009 Donostia-San Sebastian, Spain, the Department of Molecular Chemistry, University Grenoble Alpes and CNRS, 38000 Grenoble, France, and the Max-Planck-Institute for Intelligent Systems, 70569 Stuttgart, Germany


Mammalian oocytes are surrounded by a highly hydrated hyaluronan (HA)-rich extracellular matrix with embedded cumulus cells, forming the cumulus cell·oocyte complex (COC) matrix. The correct assembly, stability, and mechanical properties of this matrix, which are crucial for successful ovulation, transport of the COC to the oviduct, and its fertilization, depend on the interaction between HA and specific HA-organizing proteins. Although the proteins inter-α-inhibitor (IαI), pentraxin 3 (PTX3), and TNF-stimulated gene-6 (TSG-6) have been identified as being critical for COC matrix formation, its supramolecular organization and the molecular mechanism of COC matrix stabilization remain unknown. Here we used films of end-grafted HA as a model system to investigate the molecular interactions involved in the formation and stabilization of HA matrices containing TSG-6, IαI, and PTX3. We found that PTX3 binds neither to HA alone nor to HA films containing TSG-6. This long pentraxin also failed to bind to products of the interaction between IαI, TSG-6, and HA, among which are the covalent heavy chain (HC)·HA and HC·TSG-6 complexes, despite the fact that both IαI and TSG-6 are ligands of PTX3. Interestingly, prior encounter with IαI was required for effective incorporation of PTX3 into TSG-6-loaded HA films. Moreover, we demonstrated that this ternary protein mixture made of IαI, PTX3, and TSG-6 is sufficient to promote formation of a stable (i.e. cross-linked) yet highly hydrated HA matrix. We propose that this mechanism is essential for correct assembly of the COC matrix and may also have general implications in other inflammatory processes that are associated with HA cross-linking.


Analytical Chemistry; Biophysics; Carbohydrate-binding Protein; Extracellular Matrix Protein; Glycobiology; Hyaluronate; Quartz Crystal Microbalance; Reflection Interference-Contrast Microscopy; Spectroscopic Ellipsometry; Supramolecular Structure

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