Pod1 induces myofibroblast differentiation in mesenchymal progenitor cells from mouse kidney.
The class II basic helix-loop-helix (bHLH) transcription factor Pod1 is expressed in mesenchymal cells including smooth muscle progenitors during development and in interstitial cells in adult organs. To determine the role of Pod1 in mesenchymal cell smooth muscle and myofibroblast differentiation, we examined a kidney progenitor cell line (4E) that endogenously expresses Pod1 and its class I bHLH partner E2A. In vitro-translated Pod1 co-immunoprecipitated E2A and increased E2A binding to a calponin promoter E-box sequence as determined by an electrophoresis mobility shift assay (EMSA). Overexpression of Pod1 and E2A resulted in increased smooth muscle and myofibroblast gene expression including calponin, SM22alpha, alphaSMA, fibronectin, and connective tissue growth factor (CTGF) compared with overexpression of E2A alone. Suppression of Pod1 by siRNA resulted in increased cell proliferation and reduced expression of alphaSMA, fibronectin, and CTGF, and myofibroblast secreted proteins including pro-fibrotic cytokines and inhibitors of matrix metalloproteinases. Examination of the signaling pathways for myofibroblast differentiation including Rho/Rho kinase and p38 MAPK showed that inhibition of actin polymerization by Rho kinase inhibitors decreased nuclear Pod1 levels while inhibition of p38 MAPK decreased Pod1 expression. These results indicate that Pod1 increases myofibroblast differentiation in combination with E2A and promotes a myofibroblast phenotype in mesenchymal progenitor cells.
Plotkin
Matthew
M
New York Medical College Renal Research, Valhalla, New York 10595, USA. matthew_plotkin@nymc.edu
Mudunuri
Vijay
V
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000235:genetics; D002454:Cell Differentiation; D002478:Cells, Cultured / Q000166:cytology / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D019281:Dimerization; D024721:E-Box Elements; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007668:Kidney / Q000166:cytology*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D025941:Protein Interaction Mapping; D022502:Stress Fibers / Q000378:metabolism / Q000648:ultrastructure; D016212:Transforming Growth Factor beta / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology; D000096985:Calponins
D051792:Basic Helix-Loop-Helix Proteins; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D002135:Calcium-Binding Proteins; D016207:Cytokines; D008840:Microfilament Proteins; D009124:Muscle Proteins; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D048051:p38 Mitogen-Activated Protein Kinases; D000096985:Calponins; C112923:Tcf21 protein, mouse; C075668:Tcf3 protein, mouse