Inhibition of BET Proteins and Epigenetic Signaling as a Potential Treatment for Osteoporosis

Bone. 2017 Jan;94:10-21. doi: 10.1016/j.bone.2016.09.020. Epub 2016 Sep 23.

Abstract

Histone modifications are important for maintaining the transcription program. BET proteins, an important class of "histone reading proteins", have recently been described as essential in bone biology. This study presents the therapeutic opportunity of BET protein inhibition in osteoporosis. We find that the pharmacological BET protein inhibitor JQ1 rescues pathologic bone loss in a post-ovariectomy osteoporosis model by increasing the trabecular bone volume and restoring mechanical properties. The BET protein inhibition suppresses osteoclast differentiation and activity as well as the osteoblastogenesis in vitro. Moreover, we show that treated non-resorbing osteoclasts could still activate osteoblast differentiation. In addition, specific inhibition of BRD4 using RNA interference inhibits osteoclast differentiation but strongly activates osteoblast mineralization activity. Mechanistically, JQ1 inhibits expression of the master osteoclast transcription factor NFATc1 and the transcription factor of osteoblast Runx2. These findings strongly support that targeting epigenetic chromatin regulators such as BET proteins may offer a promising alternative for the treatment of bone-related disorders such as osteoporosis.

Keywords: Bromodomain; Epigenetic; Inhibitor; Osteoblast; Osteoclast; Osteoporosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Azepines / pharmacology
  • Azepines / therapeutic use
  • Biomechanical Phenomena
  • Cell Count
  • Cell Differentiation
  • Epigenesis, Genetic* / drug effects
  • Female
  • Humans
  • Mice, Inbred C57BL
  • Nuclear Proteins / antagonists & inhibitors*
  • Nuclear Proteins / metabolism
  • Organ Size / drug effects
  • Osteoblasts / drug effects
  • Osteoblasts / pathology
  • Osteoclasts / drug effects
  • Osteoclasts / pathology
  • Osteoporosis / drug therapy*
  • Osteoporosis / genetics*
  • Osteoporosis / pathology
  • Osteoporosis / physiopathology
  • Ovariectomy
  • Signal Transduction* / drug effects
  • Triazoles / pharmacology
  • Triazoles / therapeutic use

Substances

  • (+)-JQ1 compound
  • Azepines
  • Nuclear Proteins
  • Triazoles