title: TAZ activation drives fibroblast spheroid growth, expression of profibrotic paracrine signals, and context-dependent ECM gene expression.
abstract: Recent studies have implicated the Hippo pathway and its transcriptional effectors YAP and TAZ as necessary for fibroblast activation and tissue fibrosis. To test the specific and sufficient roles for TAZ in driving autonomous fibroblast activation, we cultured NIH3T3 fibroblasts expressing a doxycycline-inducible nuclear-localized mutant of TAZ (TAZ4SA) in scaffold-free 3D hanging drop spheroids, or on matrices of specified mechanical rigidity. Control NIH3T3 fibroblasts formed spheroids in hanging drop culture that remained stable and neither increased nor decreased in size significantly over 15 days. In contrast, TAZ4SA-transduced fibroblasts grew robustly in spheroid culture, and expressed enhanced levels of genes encoding profibrotic soluble factors connective tissue growth factor (CTGF), endothelin-1 (Et-1), and plasminogen activator inhibitor 1 (PAI-1). However, TAZ4SA expression was unable to enhance expression of extracellular matrix (ECM)-encoding genesCol1a1, Col1a2, Col3a1, orFn1in spheroid culture. Micromechanical testing indicated that spheroids composed of either control or TAZ4SA-expressing cells were highly compliant and indistinguishable in mechanical properties. In fibroblasts cultured on 2D matrices of compliance similar to spheroids, TAZ4SA expression was able to enhance contractile force generation, but was unable to enhance ECM gene expression. In contrast, culture on stiff hydrogels potentiated TAZ4SA enhancement of ECM expression. TAZ4SA enhancement ofCol1a1expression on soft matrices was potentiated by TGF-β1, while on stiff matrices it was abrogated by inhibition of myocardin-related transcription factor, demonstrating context-dependent crosstalk of TAZ with these pathways. These findings demonstrate sufficiency of TAZ activation for driving fibroblast proliferation, contraction, and soluble profibrotic factor expression, and mechanical context-dependent crosstalk of TAZ with other pathways in regulatingCol1a1expression.
authors.affiliation: Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Jorgenson
authors.affiliation: Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Kyoung Moo
authors.initials: KM
authors.lastname: Choi
authors.affiliation: Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Delphine
authors.initials: D
authors.lastname: Sicard
authors.affiliation: Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Karry M J
authors.initials: KM
authors.lastname: Smith
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts.
authors.forename: Samantha E
authors.initials: SE
authors.lastname: Hiemer
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts.
authors.forename: Xaralabos
authors.initials: X
authors.lastname: Varelas
authors.affiliation: Department of Physiology and Biomedical Engineering, College of Medicine, Mayo Clinic, Rochester, Minnesota; and tschumperlin.daniel@mayo.edu.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Tschumperlin
mesh_terms: D000217:Acyltransferases; D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D005355:Fibrosis; D051379:Mice; D041681:NIH 3T3 Cells; D019899:Paracrine Communication; D018874:Spheroids, Cellular / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D016326:Extracellular Matrix Proteins; D014157:Transcription Factors; D000217:Acyltransferases; C108675:TAFAZZIN protein, human
keywords: Hippo; collagen; extracellular matrix; fibrosis; stiffness