Prevention of Bone Loss after Ovariectomy in Mice with Preferential Overexpression of the Transcription Factor Paired Box-5 in Osteoblasts

Abstract

We have recently shown that the transcription factor Paired box-5 (Pax5) promotes bone formation in vivo and osteoblastogenesis in vitro. Here, we demonstrated the involvement of Pax5 in bone remodeling after ovariectomy (OVX). A significant increase was seen in vertebrae bone volume in transgenic mice preferentially overexpressing Pax5 in osteoblasts by using the mouse α1(I)Collagen promoter, whereas OVX significantly reduced vertebrae bone volume in wild-type (WT) mice without significantly affecting that in Pax5 transgenic mice. Preferential osteoblastic Pax5 overexpression invariably led to significant increases in osteoblastic and osteoclastic parameters in mice with sham operation. However, OVX significantly increased osteoclastic parameters in WT mice, without additionally increasing osteoblastic and osteoclastic parameters in Pax5 transgenic mice. These results suggest that osteoblastic Pax5 would play a role in OVX-induced bone loss through a mechanism relevant to the promotion of both osteoblastic bone formation and osteoclastic bone resorption in vivo.