A novel function for lysyl oxidase in pluripotent mesenchymal cell proliferation and relevance to inflammation-associated osteopenia

PLoS One. 2014 Jun 27;9(6):e100669. doi: 10.1371/journal.pone.0100669. eCollection 2014.

Abstract

Lysyl oxidase is a multifunctional enzyme required for collagen biosynthesis. Various growth factors regulate lysyl oxidase during osteoblast differentiation, subject to modulation by cytokines such as TNF-α in inflammatory osteopenic disorders including diabetic bone disease. Canonical Wnt signaling promotes osteoblast development. Here we investigated the effect of Wnt3a and TNF-α on lysyl oxidase expression in pluripotent C3H10T1/2 cells, bone marrow stromal cells, and committed osteoblasts. Lysyl oxidase was up-regulated by a transcriptional mechanism 3-fold in C3H10T1/2 cells, and 2.5-fold in bone marrow stromal cells. A putative functional TCF/LEF element was identified in the lysyl oxidase promoter. Interestingly, lysyl oxidase was not up-regulated in committed primary rat calvarial- or MC3T3-E1 osteoblasts. TNF-α down-regulated lysyl oxidase both in Wnt3a-treated and in non-treated C3H10T1/2 cells by a post-transcriptional mechanism mediated by miR203. Non-differentiated cells do not produce a collagen matrix; thus, a novel biological role for lysyl oxidase in pluripotent cells was investigated. Lysyl oxidase shRNAs effectively silenced lysyl oxidase expression, and suppressed the growth of C3H10T1/2 cells by 50%, and blocked osteoblast differentiation. We propose that interference with lysyl oxidase expression under excess inflammatory conditions such as those that occur in diabetes, osteoporosis, or rheumatoid arthritis can result in a diminished pool of pluripotent cells which ultimately contributes to osteopenia.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Base Sequence
  • Bone Diseases, Metabolic / enzymology*
  • Bone Diseases, Metabolic / epidemiology
  • Bone Diseases, Metabolic / pathology*
  • Cell Differentiation
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Culture Media, Conditioned / pharmacology
  • Down-Regulation / drug effects
  • Inflammation / pathology
  • Mesenchymal Stem Cells / cytology*
  • Mesenchymal Stem Cells / enzymology*
  • Mesenchymal Stem Cells / metabolism
  • Mice
  • Mice, Inbred C57BL
  • MicroRNAs / genetics
  • MicroRNAs / metabolism
  • Molecular Sequence Data
  • Osteoblasts / cytology
  • Osteoblasts / enzymology
  • Osteoblasts / metabolism
  • Osteogenesis
  • Protein-Lysine 6-Oxidase / antagonists & inhibitors
  • Protein-Lysine 6-Oxidase / genetics
  • Protein-Lysine 6-Oxidase / metabolism*
  • RNA, Small Interfering / metabolism
  • Rats
  • Signal Transduction / drug effects
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology
  • Up-Regulation / drug effects
  • Wnt3A Protein / genetics
  • Wnt3A Protein / metabolism
  • Wnt3A Protein / pharmacology

Substances

  • Culture Media, Conditioned
  • MicroRNAs
  • RNA, Small Interfering
  • Tumor Necrosis Factor-alpha
  • Wnt3A Protein
  • Protein-Lysine 6-Oxidase