Next we tried to specifically

Next, we tried to specifically inhibit DDR2 function in endochondral proliferation and ossification in vivo. We used competitive inhibition with KD-Ddr2 overexpression specifically in cartilage cells, because it is generally difficult to regulate genes by miRNA in vivo. We constructed a transgenic vector using an insulator sequence to stabilize the activity of the transgene expression [30]. Body size and skeleton length of KD-Ddr2 overexpressed mice were not significantly different compared with the littermates. On the other hand, the layer of hypertrophic chondrocytes in KD-Ddr2 transgenic mice was not significantly thicker than that of normal littermates, but the layer of proliferative chondrocytes in KD-Ddr2 transgenic mice was significantly thicker than that of normal littermates. This cellular proliferation is similar to the phenotype of miDdr2-transfected ATDC5 MK-8245 australia in vitro, which indicated that DDR2 might have various molecular functions to regulate the proliferation of chondrocytes rather than the differentiation of hypertrophic chondrocytes. The phenotypes of KD-Ddr2 transgenic mice were less severe than expected from the results of miDdr2-transfected ATDC5 cells, which indicated that DDR2 might play important roles in endochondral ossification but neither critical nor essential roles in determining total body and skeleton size. The greater thickness of the proliferative chondrocyte layer in KD-Ddr2 transgenic mice could be an anomaly in the reduction of chondrocyte proliferation in DDR2-deficient mice [11]. This difference could come from regional and functional differences in DDR2 shortage; these differences indicate that DDR2 could have various roles in different conditions, either systemically or locally. To summarize, we investigated the effects of both the decrement of DDR2 in miDdr2-transfected ATDC5 cells in vitro and in DDR2 dominant-negative overexpressed transgenic mice, and the results suggested that DDR2 might regulate proliferative chondrocytes.
Acknowledgments The α2 (XI) collagen gene-based expression vector, 742lacZInt, was kindly gifted from Dr. Tsumaki (Osaka University). The research was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Education, Cultures, Sports, Science, and Technology of Japan; by the Morinaga Foundation; and by the Foundation for Growth Science.
Introduction Idiopathic pulmonary fibrosis (IPF), the most common fibrotic conditions in the lung, is a chronic and lethal human disease with unknown etiology. IPF patients have a median survival of ∼2–3 years after diagnosis because of an irreversible loss of lung function and respiratory failure. Although a variety of inflammatory insults are associated with the development of IPF, an undeniable fact is that this type fibrotic disorder is clinically recalcitrant to treatment with immunosuppressive agents, leading to the recent shift of concept for IPF treatment away from anti-inflammation toward antifibrosis. However, although there has been a huge rise in clinical trials with antifibrotic drugs during the past decade, it was until recently that two pharmacological agents were approved for the treatment of moderate IPF.