Platelet-derived Growth Factor Receptor Regulates Salivary Gland Morphogenesis via Fibroblast Growth Factor Expression*

A coordinated reciprocal interaction between epithelium and mesenchyme is involved in salivary gland morphogenesis. The submandibular glands (SMGs) of Wnt1-Cre/R26R mice have been shown positive for mesenchyme, whereas the epithelium is β-galactosidase-negative, indicating that most mesenchymal cells are derived from cranial neural crest cells. Platelet-derived growth factor (PDGF) receptor α is one of the markers of neural crest-derived cells. In this study, we analyzed the roles of PDGFs and their receptors in the morphogenesis of mouse SMGs. PDGF-A was shown to be expressed in SMG epithelium, whereas PDGF-B, PDGFRα, and PDGFRβ were expressed in mesenchyme. Exogenous PDGF-AA and -BB in SMG organ cultures demonstrated increased levels of branching and epithelial proliferation, although their receptors were found to be expressed in mesenchyme. In contrast, short interfering RNA for Pdgfa and -b as well as neutralizing antibodies for PDGF-AB and -BB showed decreased branching. PDGF-AA induced the expression of the fibroblast growth factor genes Fgf3 and -7, and PDGF-BB induced the expression of Fgf1, -3, -7, and -10, whereas short interfering RNA for Pdgfa and Pdgfb inhibited the expression of Fgf3, -7, and -10, indicating that PDGFs regulate Fgf gene expression in SMG mesenchyme. The PDGF receptor inhibitor AG-17 inhibited PDGF-induced branching, whereas exogenous FGF7 and -10 fully recovered. Together, these results indicate that fibroblast growth factors function downstream of PDGF signaling, which regulates Fgf expression in neural crest-derived mesenchymal cells and SMG branching morphogenesis. Thus, PDGF signaling is a possible mechanism involved in the interaction between epithelial and neural crest-derived mesenchyme.

[1]  Philippe Soriano,et al.  The two PDGF receptors maintain conserved signaling in vivo despite divergent embryological functions. , 2001, Molecular cell.

[2]  Wen-jie Dong,et al.  Matrix protein synthesis by glomerular mesangial cells in culture: Effects of transforming growth factor β (TGFβ) and platelet‐derived growth factor (PDGF) on fibronectin and collagen type IV mRNA , 1995, Journal of cellular physiology.

[3]  P. Lindahl,et al.  Not all myofibroblasts are alike: revisiting the role of PDGF‐A and PDGF‐B using PDGF‐targeted mice , 1998, Current opinion in nephrology and hypertension.

[4]  Jeffrey H. Miner,et al.  Laminin α5 is necessary for submandibular gland epithelial morphogenesis and influences FGFR expression through β1 integrin signaling , 2007 .

[5]  Melinda Larsen,et al.  Role of PI 3-kinase and PIP3 in submandibular gland branching morphogenesis. , 2003, Developmental biology.

[6]  F. Shibasaki,et al.  Spina bifida occulta in homozygous Patch mouse embryos , 1997, Developmental dynamics : an official publication of the American Association of Anatomists.

[7]  Melinda Larsen,et al.  FGFR2b signaling regulates ex vivo submandibular gland epithelial cell proliferation and branching morphogenesis , 2005, Development.

[8]  C. Betsholtz,et al.  Developmental roles of platelet‐derived growth factors , 2001, BioEssays : news and reviews in molecular, cellular and developmental biology.

[9]  Richard G. W. Anderson,et al.  LRP: Role in Vascular Wall Integrity and Protection from Atherosclerosis , 2003, Science.

[10]  S. Fukumoto,et al.  Amelogenin is a negative regulator of osteoclastogenesis via downregulation of RANKL, M-CSF and fibronectin expression in osteoblasts. , 2007, Archives of oral biology.

[11]  T. Faraggiana,et al.  The ERK-1/2 signaling pathway is involved in the stimulation of branching morphogenesis of fetal mouse submandibular glands by EGF. , 2000, Developmental biology.

[12]  Philippe Soriano,et al.  Cell autonomous requirement for PDGFRα in populations of cranial and cardiac neural crest cells , 2003, Development.

[13]  S. Kato,et al.  FGF10 acts as a major ligand for FGF receptor 2 IIIb in mouse multi-organ development. , 2000, Biochemical and biophysical research communications.

[14]  H. Kleinman,et al.  Gene expression profiles of mouse submandibular gland development: FGFR1 regulates branching morphogenesis in vitro through BMP- and FGF-dependent mechanisms , 2002, Development.

[15]  J. Milunsky,et al.  LADD syndrome is caused by FGF10 mutations , 2006, Clinical genetics.

[16]  B. Wehrle-Haller,et al.  Diminished matrix metalloproteinase 2 (MMP-2) in ectomesenchyme-derived tissues of the Patch mutant mouse: regulation of MMP-2 by PDGF and effects on mesenchymal cell migration. , 1999, Developmental biology.

[17]  K. Tryggvason,et al.  Distinctive functions of membrane type 1 matrix-metalloprotease (MT1-MMP or MMP-14) in lung and submandibular gland development are independent of its role in pro-MMP-2 activation. , 2005, Developmental biology.

[18]  M. Krasnow,et al.  Genetic control of branching morphogenesis. , 1999, Science.

[19]  D. Danilenko,et al.  Fgf-10 is required for both limb and lung development and exhibits striking functional similarity to Drosophila branchless. , 1998, Genes & development.

[20]  Y. Chai,et al.  Embryonic Submandibular Gland Morphogenesis: Stage-Specific Protein Localization of FGFs, BMPs, Pax6 and Pax9 in Normal Mice and Abnormal SMG Phenotypes in FgfR2-IIIc+/Δ, BMP7–/– and Pax6–/–Mice , 2001, Cells Tissues Organs.

[21]  Nobuyuki Itoh,et al.  Fgf10 is essential for limb and lung formation , 1999, Nature Genetics.

[22]  Philippe Soriano.  Generalized lacZ expression with the ROSA26 Cre reporter strain , 1999, Nature Genetics.

[23]  M. Melnick,et al.  Mouse submandibular gland morphogenesis: a paradigm for embryonic signal processing. , 2000, Critical reviews in oral biology and medicine : an official publication of the American Association of Oral Biologists.

[24]  Andrew P. McMahon,et al.  The Wnt-1 (int-1) proto-oncogene is required for development of a large region of the mouse brain , 1990, Cell.

[25]  M. Kashimata,et al.  Epidermal growth factor system is a physiological regulator of development of the mouse fetal submandibular gland and regulates expression of the α6‐integrin subunit , 1997 .

[26]  M. Hoffman,et al.  Salivary gland branching morphogenesis. , 2006, Differentiation; research in biological diversity.

[27]  Philippe Soriano,et al.  PDGFR‐α signaling is critical for tooth cusp and palate morphogenesis , 2005 .

[28]  G. Hoyle,et al.  Overexpression of PDGF-A in the lung epithelium of transgenic mice produces a lethal phenotype associated with hyperplasia of mesenchymal cells. , 2001, Developmental biology.

[29]  S. Aaronson,et al.  Characterization of Recombinant Human Fibroblast Growth Factor (FGF)-10 Reveals Functional Similarities with Keratinocyte Growth Factor (FGF-7)* , 1998, The Journal of Biological Chemistry.

[30]  T. Saku,et al.  GD3 synthase gene found expressed in dental epithelium and shown to regulate cell proliferation. , 2005, Archives of oral biology.

[31]  D M Noden,et al.  The role of the neural crest in patterning of avian cranial skeletal, connective, and muscle tissues. , 1983, Developmental biology.

[32]  G. Plopper,et al.  PDGF-BB enhances expression of, and reduces adhesion to, laminin-5 in vascular smooth muscle cells. , 2002, Biochemical and biophysical research communications.

[33]  H. Miyazaki,et al.  Laminin α5 Is Required for Dental Epithelium Growth and Polarity and the Development of Tooth Bud and Shape* , 2006, Journal of Biological Chemistry.

[34]  A. Kulkarni,et al.  Ameloblastin is a cell adhesion molecule required for maintaining the differentiation state of ameloblasts , 2004, The Journal of cell biology.

[35]  T. Yagi,et al.  Cadherin-related Neuronal Receptors in Incisor Development , 2003, Journal of dental research.

[36]  J. Miner,et al.  Defective glomerulogenesis in the absence of laminin alpha5 demonstrates a developmental role for the kidney glomerular basement membrane. , 2000, Developmental biology.

[37]  M. Mohammadi,et al.  Structural basis by which alternative splicing confers specificity in fibroblast growth factor receptors , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[38]  R. Jonsson,et al.  Mutations in the gene encoding fibroblast growth factor 10 are associated with aplasia of lacrimal and salivary glands , 2005, Nature Genetics.

[39]  C. Heldin,et al.  Mechanism of action and in vivo role of platelet-derived growth factor. , 1999, Physiological reviews.

[40]  Melinda Larsen,et al.  Fibronectin requirement in branching morphogenesis , 2003, Nature.

[41]  S. Mackem,et al.  Soluble dominant‐negative receptor uncovers essential roles for fibroblast growth factors in multi‐organ induction and patterning , 1998, The EMBO journal.

[42]  C. Cremers,et al.  Mutations in different components of FGF signaling in LADD syndrome , 2006, Nature Genetics.

[43]  G. Morriss-Kay,et al.  Analysis of cranial neural crest cell migration and early fates in postimplantation rat chimaeras. , 1986, Journal of embryology and experimental morphology.

[44]  H Nogawa,et al.  EGF‐dependent lobule formation and FGF7‐dependent stalk elongation in branching morphogenesis of mouse salivary epithelium in vitro , 1999, Developmental dynamics : an official publication of the American Association of Anatomists.

[45]  Akihiko Nakasima,et al.  Neurotrophic Factor Neurotrophin-4 Regulates Ameloblastin Expression via Full-length TrkB* , 2008, Journal of Biological Chemistry.

[46]  A. McMahon,et al.  Expression of the proto-oncogene int-1 is restricted to specific neural cells in the developing mouse embryo , 1987, Cell.

[47]  R. Lang,et al.  Endogenous and ectopic gland induction by FGF-10. , 2000, Developmental biology.