Type III and V collagens modulate the expression and assembly of EDA(+) fibronectin in the extracellular matrix of defective Ehlers-Danlos syndrome fibroblasts.
BACKGROUND
Alternative splicing of EDA fibronectin (FN) region is a cell type- and development-regulated mechanism controlled by pathological processes, growth factors and extracellular matrix (ECM). Classic and vascular Ehlers-Danlos syndrome (cEDS and vEDS) are connective tissue disorders caused by COL5A1/COL5A2 and COL3A1 gene mutations, leading to an in vivo abnormal collagen fibrillogenesis and to an in vitro defective organisation in the ECM of type V (COLLV) and type III collagen (COLLIII). These defects induce the FN-ECM disarray and the decrease of COLLs and FN receptors, the α2β1 and α5β1 integrins. Purified COLLV and COLLIII restore the COLL-FN-ECMs in both EDS cell strains.


METHODS
Real-time PCR, immunofluorescence microscopy, and Western blotting were used to investigate the effects of COLLs on FN1 gene expression, EDA region alternative splicing, EDA(+)-FN-ECM assembly, α5β1 integrin and EDA(+)-FN-specific α9 integrin subunit organisation, α5β1 integrin and FAK co-regulation in EDS fibroblasts.


RESULTS
COLLV-treated cEDS and COLLIII-treated vEDS fibroblasts up-regulate the FN1 gene expression, modulate the EDA(+) mRNA maturation and increase the EDA(+)-FN levels, thus restoring a control-like FN-ECM, which elicits the EDA(+)-FN-specific α9β1 integrin organisation, recruits the α5β1 integrin and switches on the FAK binding and phosphorylation.


CONCLUSIONS
COLLs regulate the EDA(+)-FN-ECM organisation at transcriptional and post-transcriptional level and activate the α5β1-FAK complexes. COLLs also recruit the α9β1 integrin involved in the assembly of the EDA(+)-FN-ECM in EDS cells.


CONCLUSIONS
The knowledge of the COLLs-ECM role in FN isotype expression and in EDA(+)-FN-ECM-mediated signal transduction adds insights in the ECM remodelling mechanisms in EDS cells.
Division of Biology and Genetics, Department of Biomedical Sciences and Biotechnology, Medical Faculty, University of Brescia, 25123 Brescia, Italy. zoppi@med.unibs.it
Nicoletta
N
Zoppi
Marco
M
Ritelli
Marina
M
Colombi
D016022:Case-Control Studies; D002478:Cells, Cultured; D024061:Collagen Type III / Q000494:pharmacology*; D024062:Collagen Type V / Q000494:pharmacology*; D004535:Ehlers-Danlos Syndrome / Q000378:metabolism / Q000473:pathology*; D005109:Extracellular Matrix / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005353:Fibronectins / Q000235:genetics* / Q000378:metabolism*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D008297:Male; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization / Q000187:drug effects
D024061:Collagen Type III; D024062:Collagen Type V; D005353:Fibronectins; D039081:Integrin alpha5beta1; D016023:Integrins; D020033:Protein Isoforms; C574442:extra domain A fibronectin, human; C113256:integrin alpha 9 beta 1; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human