Pharmacological activation of NR4A1, in turn, inhibited osteopontin expression and osteopontin-dependent migration of osteoclast precursors resulted in reduced abundance of bone-resorbing osteoclasts in vivo as well as in an ameliorated bone loss after ovariectomy in mice.
Autophagy induction create a microenvironment that modifies osteoblast metabolism by the inhibition of the deposition of organic and mineral matrix, the induction of matrix metalloproteinase (MMP)-2, osteopontin, and RANKL secretion leading to bone loss.
Our study identifies an important paracrine loop whereby elevated secretion of OPN by osteoblasts activate Nf1+/- OCLs that already have an intrinsic propensity for bone resorption leading to osteopenia and osteoporosis.