title: Regulation of the innate immune response by fibronectin: synergism between the III-1 and EDA domains.
abstract: Fibronectin is a critical component of the extracellular matrix and alterations to its structure will influence cellular behavior. Matrix fibronectin is subjected to both mechanical and biochemical regulation. The Type III domains of fibronectin can be unfolded in response to increased cellular contractility, included or excluded from the molecule by alternative splicing mechanisms, or released from the matrix by proteolysis. Using Inflammatory Cytokine microarrays we found that the alternatively spliced fibronectin Type III domain, FnEDA, and the partially unfolded III-1 domain, FnIII-1c, induced the expression of a multitude of pro-inflammatory cytokines in human dermal fibroblasts, most notably CXCL1-3, IL-8 and TNF-α. FnIII-1c, a peptide representing an unfolded intermediate structure of the first Type III domain has been shown to initiate the toll-like receptor-4 (TLR4)-NFκB-dependent release of cytokines from human dermal fibroblasts (You, et al., J. Biol. Chem., 2010). Here we demonstrate that FnIII-1c and the alternatively spliced FnEDA domain induce a TLR4 dependent activation of p38 MAP kinase and its downstream effector, MAPKAP Kinase-2 (MK-2), to regulate cytokine expression in fibroblasts. RT-qPCR analysis indicated that the p38-MK-2 pathway regulates IL-8 mRNA stability. Interestingly, addition of FnIII-1c and FnEDA synergistically enhanced TLR4-dependent IL-8 release. These data indicate that Fn contains two Type III domains which can activate TLR signaling to induce an inflammatory response in fibroblasts. Furthermore, our data identifies the NF-κB and p38/MK2 signaling pathways as transducers of signals initiated in response to structural changes in fibronectin.
authors: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, United States of America.
authors: Rhiannon
authors: R
authors: Kelsh
authors: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, United States of America.
authors: Ran
authors: R
authors: You
authors: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, United States of America.
authors: Carol
authors: C
authors: Horzempa
authors: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, United States of America.
authors: Mingzhe
authors: M
authors: Zheng
authors: Center for Cell Biology & Cancer Research, Albany Medical College, Albany, New York, United States of America.
authors: Paula J
authors: PJ
authors: McKeown-Longo
mesh_terms: D017398:Alternative Splicing; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics* / Q000378:metabolism; D020405:Dermis / Q000166:cytology; D004357:Drug Synergism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005353:Fibronectins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects* / Q000235:genetics; D015151:Immunoblotting; D018836:Inflammation Mediators / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D000099190:MAP-Kinase-Activated Kinase 2
chemical_list: D016207:Cytokines; D005353:Fibronectins; D018836:Inflammation Mediators; D016209:Interleukin-8; D047908:Intracellular Signaling Peptides and Proteins; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases; D051197:Toll-Like Receptor 4; D048051:p38 Mitogen-Activated Protein Kinases; D000099190:MAP-Kinase-Activated Kinase 2; C495345:TLR4 protein, human