Figure 6 PAT inhibitor decreased BMP2 induced osteoblast differentiation, which was likely mediated by Osx.A. 2BP diminished the ALP expression induced by BMP2. Primary osteoblasts were cultured in the presence or absence of 2BP for 1 day, and then were further cultured in the presence of 50 ng/ml of BMP2 for 4 days. The plates were then stained for ALP. B. 2BP down regulated BMP2 induced Osx expression. Primary osteoblasts were cultured in the absence or presence of different concentrations of 2BP for a day, and then further cultured in the presence of 50 ng/ml of BMP2 for 16 hrs. The cells were collected and total RNA was isolated, which was used to perform RT PCR to determine the mRNA levels of Osx and Runx2. The value of control (lane 1) was set at 1.00..
Protein Palmitoylation Regulates Osteoblast Differentiation through BMP Induced Osterix Expression
PLoS ONE. 2009 Jan 6; 4(1):e4135
Osteoporosis is one of the most common diseases and can be treated by either anti resorption drugs, anabolic drugs, or both. To search for anabolic dr.....
Osteoporosis is one of the most common diseases and can be treated by either anti resorption drugs, anabolic drugs, or both. To search for anabolic drug targets for osteoporosis therapy, it is crucial to understand the biology of bone forming cells, osteoblasts, in terms of their proliferation, differentiation, and function. Here we found that protein palmitoylation participates in signaling pathways that control osterix expression and osteoblast differentiation. Mouse calvarial osteoblasts express most of the 24 palmitoyl transferases, with some being up regulated during differentiation. Inhibition of protein palmitoylation, with a substrate analog inhibitor, diminished osteoblast differentiation and mineralization, but not proliferation or survival. The decrease in differentiation capacity is associated with a reduction in osterix, but not Runx2 or Atf4. Inhibition of palmitoyl transferases had little effect in p53 / osteoblasts that show accelerated differentiation due to overexpression of osterix, suggesting that osterix, at least partially, mediated the effect of inhibition of palmitoyl transferases on osteoblast differentiation. BMPs are the major driving force of osteoblast differentiation in the differentiation assays. We found that inhibition of palmitoyl transferases also compromised BMP2 induced osteoblast differentiation through down regulating osterix induction. However, palmitoyl transferases inhibitor did not inhibit Smad1/5/8 activation. Instead, it compromised the activation of p38 MAPK, which are known positive regulators of osterix expression and differentiation. These results indicate that protein palmitoylation plays an important role in BMP induced MAPK activation, osterix expression, and osteoblast differentiation.
Leong et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.