Bone Morphogenetic Protein 2 (BMP-2) Enhances BMP-3, BMP-4, and Bone Cell Differentiation Marker Gene Expression During the Induction of Mineralized Bone Matrix Formation in Culturesof Fetal Rat Calvarial Osteoblasts

Abstract

Normal bone formation is a prolonged process that is carefully regulated and involves sequential expression of growth regulatory factors by osteoblasts as they proliferate and ultimately differentiate. Since this orderly sequence of gene expression by osteoblasts suggests a cascade effect, and BMP-2 is capable of initiating and maintaining this effect, we examined the effects of BMP-2 on expression of other BMPs and compared these effects with the expression pattern of bone cell differentiation marker genes in primary cultures of fetal rat calvarial (FRC) osteoblasts. To examine the gene expression profile during bone cell differentiation and bone formation, we also examined the effects of rBMP-2 on bone formation in vivo and in vitro. rBMP-2 stimulated bone formation on the periosteal surface of mice when 500 ng/day rBMP-2 was injected subctaneously. When rBMP-2 was added to primary cultures of FRC osteoblasts, it accelerated mineralized nodule formation in a time and concentration-dependent manner (10-40 ng/ml). rBMP-2 (40 ng/ml) enhanced BMP-3 and -4 mRNA expression during the mineralization phase of primary cultures of FRC osteoblasts. Enhancement of BMP-3 and -4 mRNA expression by rBMP-2 was associated with increased expression of bone cell differentiation marker genes, alkaline phosphatase (ALP), type I collagen, osteocalcin (OC), osteopontin (OP), and bone sialoprotein (BSP). These results suggest that BMP-2 enhances expression of other BMP genes during bone cell differentiation. BMP-2 may act in a paracrine fashion in concert with other BMPs it induces to stimulate bone cell differentiation and bone formation during remodeling.

The Protein Kinase 2 Inhibitor CX-4945 Regulates Osteoclast and Osteoblast Differentiation In Vitro

“…Since several studies have reported the possible involvement of CK2 and its effect Akt in bone metabolism (Bragdon et al, 2010;Moon et al, 2012), here we evaluated and found the antiosteoclastogenic and anabolic activity of CX-4945; CX-4945 inhibited the RANKL-induced osteoclast differentiation accompanied with suppression of Akt/NFATc1 signaling axis, but it enhanced the BMP-2-induced osteoblast differentiation via the ERK1/2-Smad signaling axis. Since BMP-2 enhances the expression of other BMP genes during osteoblast differentiation (Chen et al, 1997;Kawai et al, 2006), these reports demonstrate that CX-4945 could enhance the BMP-2-induced increases in ALP and BMP-4 mRNA levels (Fig. 3C).…”

Cationic Nanogel-mediated Runx2 and Osterix siRNA Delivery Decreases Mineralization in MC3T3 Cells

“…Mid-and late-stage osteogenic markers including OPN, bone sialoprotein (BSP), and OCN are temporal successors to RUNX2 and OSX expression after rhBMP-2 stimulation [63]. The complex temporal expression profiles of OPN, BSP, and OCN have been elucidated [15,16,23,25,26,30,53,59,66]; therefore, a coordinated, temporal RNAi treatment cycle may enhance the duration and intensity of gene silencing and prevent HA deposition in vitro. Consequently, the evolution of RNAi therapeutics must match RNAi targets to their expression profiles.…”

Fibronectin Regulates Latent Transforming Growth Factor-β (TGFβ) by Controlling Matrix Assembly of Latent TGFβ-binding Protein-1

“…LTBP1 Stably Expressing Cell Lines-To generate UMR-106 cell lines stably overexpressing LTBP1, a full-length human LTBP1 construct in the PSV7d vector (kindly provided by K. Miyazono, Japanese Foundation for Cancer Research, Tokyo) was co-transfected at a 10:1 ratio with an RSVneo selection vector, using calcium phosphate precipitation as described elsewhere (33). The transfected cells were selected with 400 g/ml G418, and resistant single cell clones were screened for LTBP1 expression using an ELISA, as described previously (7).…”