BACKGROUND:Existing studies have made significant progress in PIWI-interacting RNAs(piRNAs)against osteoporosis,but the specific targets and related mechanisms by which piRNAs exert their functions remain to be explored.OBJECTIVE:To investigate the effects and downstream mechanisms of piR-7472 on the differentiation of mouse osteoblasts(MC3T3-E1 cells).METHODS:(1)Twelve C57/BL6J mice were randomly divided into a sham-operated and an ovariectomized group,with six mice in each group.Changes in bone mass and the expression of piR-7472 were detected using Micro-CT and RT-qPCR,respectively,at 8 weeks after surgery.(2)MC3T3-E1 cells were divided into NC mimics group,piR-7472 mimics group,NC inhibitor group,and piR-7472 inhibitor group.The mRNA expression of piR-7472,osteopontin,type I collagen,Runt-related transcription factor 2,and potassium voltage-gated channel modifier subfamily F member 1 were detected by RT-qPCR after 7 days of osteogenic induction.The protein expression of osteopontin,Runt-related transcription factor 2,bone morphogenetic protein 2,and potassium voltage-gated channel modifier subfamily F member 1(KCNF1)was detected using western blot assay.The expression of alkaline phosphatase was detected by alkaline phosphatase staining after 14 days of osteogenic induction,and the number of mineralized nodules was detected by alizarin red staining after 21 days of induction.Whether piR-7472 could bind to KCNF1 was observed by the dual luciferase reporter gene assay.RESULTS AND CONCLUSION:(1)Bone mineral density,bone volume fraction,bone trabecular thickness,bone trabecular number were significantly decreased and bone trabecular separation was significantly increased in ovariectomized mice,and piR-7472 in bone tissue was significantly down-regulated in osteoporotic mice.(2)Compared with the NC group,the mRNA expression of osteopontin,type I collagen,and Runt-related transcription factor 2 were significantly increased,the protein expression of osteopontin,Runt-related transcription factor 2,and bone morphogenetic protein 2 were significantly elevated,and the levels of mineralized deposition and alkaline phosphatase were increased in the piR-7472 mimics group.Compared with the NC inhibitor group,the mRNA expression of osteopontin,type I collagen,and Runt-related transcription factor 2 was significantly downregulated,the protein expression of osteopontin,Runt-related transcription factor 2,and bone morphogenetic protein 2 were significantly decreased,and the levels of mineralized deposition and alkaline phosphatase were reduced in the piR-7472 inhibitor group.(3)piR-7472 was found to interact with the potassium voltage-gated channel modifier subfamily F member 1 as predicted by the miRanda database.The dual luciferase reporter gene assay revealed that piR-7472 mimics could bind to and promote the expression of KCNF1.To conclude,piR-7472 can promote osteogenic differentiation of osteogenic precursor cells MC3T3-E1,and its mechanism of action may be achieved by promoting the expression of KCNF1.

BACKGROUND:Existing studies have made significant progress in PIWI-interacting RNAs(piRNAs)against osteoporosis,but the specific targets and related mechanisms by which piRNAs exert their functions remain to be explored.OBJECTIVE:To investigate the effects and downstream mechanisms of piR-7472 on the differentiation of mouse osteoblasts(MC3T3-E1 cells).METHODS:(1)Twelve C57/BL6J mice were randomly divided into a sham-operated and an ovariectomized group,with six mice in each group.Changes in bone mass and the expression of piR-7472 were detected using Micro-CT and RT-qPCR,respectively,at 8 weeks after surgery.(2)MC3T3-E1 cells were divided into NC mimics group,piR-7472 mimics group,NC inhibitor group,and piR-7472 inhibitor group.The mRNA expression of piR-7472,osteopontin,type I collagen,Runt-related transcription factor 2,and potassium voltage-gated channel modifier subfamily F member 1 were detected by RT-qPCR after 7 days of osteogenic induction.The protein expression of osteopontin,Runt-related transcription factor 2,bone morphogenetic protein 2,and potassium voltage-gated channel modifier subfamily F member 1(KCNF1)was detected using western blot assay.The expression of alkaline phosphatase was detected by alkaline phosphatase staining after 14 days of osteogenic induction,and the number of mineralized nodules was detected by alizarin red staining after 21 days of induction.Whether piR-7472 could bind to KCNF1 was observed by the dual luciferase reporter gene assay.RESULTS AND CONCLUSION:(1)Bone mineral density,bone volume fraction,bone trabecular thickness,bone trabecular number were significantly decreased and bone trabecular separation was significantly increased in ovariectomized mice,and piR-7472 in bone tissue was significantly down-regulated in osteoporotic mice.(2)Compared with the NC group,the mRNA expression of osteopontin,type I collagen,and Runt-related transcription factor 2 were significantly increased,the protein expression of osteopontin,Runt-related transcription factor 2,and bone morphogenetic protein 2 were significantly elevated,and the levels of mineralized deposition and alkaline phosphatase were increased in the piR-7472 mimics group.Compared with the NC inhibitor group,the mRNA expression of osteopontin,type I collagen,and Runt-related transcription factor 2 was significantly downregulated,the protein expression of osteopontin,Runt-related transcription factor 2,and bone morphogenetic protein 2 were significantly decreased,and the levels of mineralized deposition and alkaline phosphatase were reduced in the piR-7472 inhibitor group.(3)piR-7472 was found to interact with the potassium voltage-gated channel modifier subfamily F member 1 as predicted by the miRanda database.The dual luciferase reporter gene assay revealed that piR-7472 mimics could bind to and promote the expression of KCNF1.To conclude,piR-7472 can promote osteogenic differentiation of osteogenic precursor cells MC3T3-E1,and its mechanism of action may be achieved by promoting the expression of KCNF1.