Heparin-fibronectin interactions in the development of extracellular matrix insolubility.

TitleHeparin-fibronectin interactions in the development of extracellular matrix insolubility.
Publication TypeJournal Article
Year of Publication2018
AuthorsRaitman, I, Huang, ML, Williams, SA, Friedman, B, Godula, K, Schwarzbauer, JE
JournalMatrix Biol
Date Published2018 Apr
KeywordsAnimals, Binding Sites, CHO Cells, Cricetulus, Extracellular Matrix, Fibronectins, Heparin, Mice, NIH 3T3 Cells, Protein Binding, Proteolysis, Solubility

<p>During extracellular matrix (ECM) assembly, fibronectin (FN) fibrils are irreversibly converted into a detergent-insoluble form which, through FN's multi-domain structure, can interact with collagens, matricellular proteins, and growth factors to build a definitive matrix. FN also has heparin/heparan sulfate (HS) binding sites. Using HS-deficient CHO cells, we show that the addition of soluble heparin significantly increased the amount of FN matrix that these cells assemble. Sulfated HS glycosaminoglycan (GAG) mimetics similarly increased FN assembly and demonstrated a dependence on GAG sulfation. The length of the heparin chains also plays a role in assembly. Chains of sufficient length to bind to two FN molecules gave maximal stimulation of assembly whereas shorter heparin had less of an effect. Using a decellularized fibroblast matrix for proteolysis, detergent fractionation, and mass spectrometry, we found that the predominant domain within insoluble fibril fragments is FN's major heparin-binding domain HepII (modules III). Multiple HepII domains bind simultaneously to a single heparin chain in size exclusion chromatography analyses. We propose a model in which heparin/HS binding to the HepII domain connects multiple FNs together to facilitate the formation of protein interactions for insoluble fibril assembly.</p>

Alternate JournalMatrix Biol
PubMed ID29223498
PubMed Central IDPMC5910196
Grant ListDP2 HD087954 / HD / NICHD NIH HHS / United States
P01 HL107150 / HL / NHLBI NIH HHS / United States
R01 CA160611 / CA / NCI NIH HHS / United States
F32 GM077891 / GM / NIGMS NIH HHS / United States
T32 GM007388 / GM / NIGMS NIH HHS / United States
R00 EB013446 / EB / NIBIB NIH HHS / United States