Oxidative stress stimulates apoptosis and activates NF-kappaB in osteoblastic cells via a PKCbeta/p66shc signaling cascade: counter regulation by estrogens or androgens

Mol Endocrinol. 2010 Oct;24(10):2030-7. doi: 10.1210/me.2010-0189. Epub 2010 Aug 4.


Aging or acute loss of estrogens or androgens increases the levels of reactive oxygen species, activates nuclear factor-κB (NF-κB), and promotes the phosphorylation of p66(shc), a redox enzyme that amplifies mitochondrial reactive oxygen species generation and stimulates apoptosis. We report that in mesenchymal progenitor and osteoblastic cell models, H(2)O(2) activated a protein kinase C (PKC)β/p66(shc)/NF-κB signaling cascade and that p66(shc) was an essential mediator of the stimulating effects of H(2)O(2) on the apoptosis of osteoblastic cells as well as their ability to activate NF-κB. 17β-Estradiol (E(2)) or the nonaromatizable androgen dihydrotestosterone abrogated the effects of H(2)O(2) on p66(shc) and NF-κB activation by attenuating the phosphorylation of the redox-sensitive cytoplasmic kinase PKCβ. Additionally, both E(2) and dihydrotestosterone prevented H(2)O(2)-induced apoptosis by a mechanism that involved attenuation of p66(shc) resulting from decreased phosphorylation of PKCβ. Consistent with a kinase-mediated mechanism of sex steroid action, the effects of E(2) were reproduced by a polymeric form of estradiol that is not capable of stimulating the nuclear-initiated actions of ERα. These results demonstrate that p66(shc) is an essential mediator of the effects of oxidative stress on osteoblastic cell apoptosis, NF-κB activation, and cytokine production. The ability of either estrogen or androgen to attenuate the effects of oxidative stress on osteoblastic cell apoptosis, NF-κB activation, and cytokine production results from their common property to suppress PKCβ-induced p66(shc) phosphorylation via a mechanism that does not require stimulation of the nuclear-initiated actions of sex steroids.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Androgens / metabolism*
  • Animals
  • Apoptosis* / drug effects
  • Cell Line
  • Enzyme Activation
  • Estrogens / metabolism*
  • Female
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • NF-kappa B / metabolism*
  • Osteoblasts / cytology
  • Osteoblasts / drug effects
  • Osteoblasts / physiology
  • Oxidants / pharmacology
  • Oxidative Stress / physiology
  • Protein Kinase C / genetics
  • Protein Kinase C / metabolism*
  • Protein Kinase C beta
  • Shc Signaling Adaptor Proteins / genetics
  • Shc Signaling Adaptor Proteins / metabolism*
  • Signal Transduction / physiology*
  • Src Homology 2 Domain-Containing, Transforming Protein 1


  • Androgens
  • Estrogens
  • NF-kappa B
  • Oxidants
  • Shc Signaling Adaptor Proteins
  • Shc1 protein, mouse
  • Src Homology 2 Domain-Containing, Transforming Protein 1
  • Hydrogen Peroxide
  • Protein Kinase C
  • Protein Kinase C beta