He Hu1, Zhehai Li2, Min Lu3, Xinyi Yun4, Wei Li5, Caiyun Liu6, Ai Guo7. 1. Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, PR China; Department of Orthopedics, The Inner Mongolia People's Hospital, Hohhot, 010017, Inner Mongolia, PR China. 2. Department of Orthopedics, Beijing Northern Hospital, China North Industries, Beijing, 100089, PR China; Inner Mongolia Medical University, Hohhot, 014010, Inner Mongolia, PR China. 3. Department of Orthopedics, The Inner Mongolia People's Hospital, Hohhot, 010017, Inner Mongolia, PR China. 4. Department of Orthopedics, The Third Affiliated Hospital, Inner Mongolia Medical University, Baotou, 014010, Inner Mongolia, PR China. 5. School of Biomedical Engineering, Capital Medical University, Beijing, 100069, PR China. 6. Hunan Youcheng Biotechnology Co. Ltd, Changsha, 410000, PR China. 7. Department of Orthopedics, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, PR China. Electronic address: guoaijj@139.com.
Abstract
BACKGROUNDS: Dexamethasone (Dex) is widely used in autoimmune diseases and inflammation treatment. A sever side effect of prolonged exposure to Dex is increased risk of osteoporosis (OP) or even femoral head necrosis, which would cause much suffer to patients. To reveal the mechanism behind this phenomenon, provide therapeutic guidance and potential target, we analyzed the inhibitory mechanism of Dex on osteogenesis of rat-BMSC. METHODS: Rat BMSC were obtained and characterized with FACS analysis. Osteogenesis and adipogenesis abilities were detected with Oil-O-Red staining, Alizarin Red staining and ALP activity analysis. These BMSC were then treated with Dex in combination with recombinant OA or not and detected for osteogenesis related gene expression with qRT-PCR. Protein interaction and expression were detected by Co-Immunoprecipitation and western blot. RESULTS: Osteoactivin (OA) could promote integrin β 1 expression and interact with this protein physically, leading to ERK activation and promoting osteogenesis related genes' expression including Runx2, Col1a and OCN in BMSC. Dex, however, could block expression of several upstream genes of OA and decrease OA mRNA and protein level, and eventually suppress integrin β1-ERK activation and lead to decreased osteogenesis, which could finally develop into OP. CONCLUSION: Recombinant OA treated BMSC exerted better osteogenesis potency even with Dex administration. This is because additional OA in medium counter-acts with Dex's influence and rescued osteoblast differentiation via up-regulating integrin β1 and activate ERK/MAPK pathway which promotes osteogenesis. Hence, OA/integrin β1 could serve as potential therapeutic target for OP.
BACKGROUNDS: Dexamethasone (Dex) is widely used in autoimmune diseases and inflammation treatment. A sever side effect of prolonged exposure to Dex is increased risk of osteoporosis (OP) or even femoral head necrosis, which would cause much suffer to patients. To reveal the mechanism behind this phenomenon, provide therapeutic guidance and potential target, we analyzed the inhibitory mechanism of Dex on osteogenesis of rat-BMSC. METHODS:Rat BMSC were obtained and characterized with FACS analysis. Osteogenesis and adipogenesis abilities were detected with Oil-O-Red staining, Alizarin Red staining and ALP activity analysis. These BMSC were then treated with Dex in combination with recombinant OA or not and detected for osteogenesis related gene expression with qRT-PCR. Protein interaction and expression were detected by Co-Immunoprecipitation and western blot. RESULTS:Osteoactivin (OA) could promote integrin β 1 expression and interact with this protein physically, leading to ERK activation and promoting osteogenesis related genes' expression including Runx2, Col1a and OCN in BMSC. Dex, however, could block expression of several upstream genes of OA and decrease OA mRNA and protein level, and eventually suppress integrin β1-ERK activation and lead to decreased osteogenesis, which could finally develop into OP. CONCLUSION: Recombinant OA treated BMSC exerted better osteogenesis potency even with Dex administration. This is because additional OA in medium counter-acts with Dex's influence and rescued osteoblast differentiation via up-regulating integrin β1 and activate ERK/MAPK pathway which promotes osteogenesis. Hence, OA/integrin β1 could serve as potential therapeutic target for OP.
Authors: M Liguori; E Digifico; A Vacchini; R Avigni; F S Colombo; E M Borroni; F M Farina; S Milanesi; A Castagna; L Mannarino; I Craparotta; S Marchini; E Erba; N Panini; M Tamborini; V Rimoldi; P Allavena; C Belgiovine Journal: Cell Mol Immunol Date: 2020-07-29 Impact factor: 11.530