Nuclear localization of vascular endothelial growth factor-D and regulation of c-Myc-dependent transcripts in human lung fibroblasts

Am J Respir Cell Mol Biol. 2014 Jul;51(1):34-42. doi: 10.1165/rcmb.2013-0417OC.

Abstract

Lymphangiogenesis and angiogenesis are processes that are, in part, regulated by vascular endothelial growth factor (VEGF)-D. The formation of lymphatic structures has been implicated in multiple lung diseases, including pulmonary fibrosis. VEGF-D is a secreted protein produced by fibroblasts and macrophages, which induces lymphangiogenesis by signaling via VEGF receptor-3, and angiogenesis through VEGF receptor-2. VEGF-D contains a central VEGF homology domain, which is the biologically active domain, with flanking N- and C-terminal propeptides. Full-length VEGF-D (∼ 50 kD) is proteolytically processed in the extracellular space, to generate VEGF homology domain that contains the VEGF-D receptor-binding sites. Here, we report that, independent of its cell surface receptors, full-length VEGF-D accumulated in nuclei of fibroblasts, and that this process appears to increase with cell density. In nuclei, full-length VEGF-D associated with RNA polymerase II and c-Myc. In cells depleted of VEGF-D, the transcriptionally regulated genes appear to be modulated by c-Myc. These findings have potential clinical implications, as VEGF-D was found in fibroblast nuclei in idiopathic pulmonary fibrosis, a disease characterized by fibroblast proliferation. These findings are consistent with actions of full-length VEGF-D in cellular homeostasis in health and disease, independent of its receptors.

Keywords: c-Myc; fibroblast; idiopathic pulmonary fibrosis; nuclei; vascular endothelial growth factor-D.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Biomarkers / metabolism
  • Blotting, Western
  • Cell Nucleus / metabolism*
  • Cell Proliferation
  • Cells, Cultured
  • Fibroblasts / cytology
  • Fibroblasts / metabolism*
  • Gene Expression Profiling*
  • Gene Expression Regulation*
  • Humans
  • Idiopathic Pulmonary Fibrosis / genetics
  • Idiopathic Pulmonary Fibrosis / metabolism*
  • Idiopathic Pulmonary Fibrosis / pathology
  • Immunoprecipitation
  • Oligonucleotide Array Sequence Analysis
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Signal Transduction
  • Vascular Endothelial Growth Factor D / metabolism*
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism
  • Vascular Endothelial Growth Factor Receptor-3 / metabolism

Substances

  • Biomarkers
  • MYC protein, human
  • Proto-Oncogene Proteins c-myc
  • VEGFD protein, human
  • Vascular Endothelial Growth Factor D
  • Vascular Endothelial Growth Factor Receptor-2
  • Vascular Endothelial Growth Factor Receptor-3