biostudies-literatureNiu LThe Dunhill Medical Trustziaf007https://www.ebi.ac.uk/biostudies/studies/S-EPMC11831985biostudies-literatureUnknown9(3)A wide range of specific microRNAs have been shown to have either positive or negative effects on osteoblast differentiation and function, with consequent changes in postnatal bone mass. A number of specific targets have been identified. We previously used CrispR-Cas9 to make a miR-455 null mouse, characterizing a behavioral phenotype with age. The current study identifies a bone phenotype, starting in younger animals. At 3 weeks of age, the miR-455 null mice (both male and female) display increased length of both long bones and vertebrae and, while this difference diminishes across 1 year, it remains significant. Increased bone formation in vivo is mirrored by an increase in osteogenesis from bone marrow-derived stem cells in vitro. This is accompanied by a decrease in osteoclastogenesis JBMR plusThe microRNA-455 null mouse shows dysregulated bone turnover.PMC11831985R476/0516Hayman DJYoung DAErsek ASuelzu CNiu LSwingler TEBarter MJHorwood NClark IMOrriss IRfalseThe microRNA-455 null mouse shows dysregulated bone turnover.A wide range of specific microRNAs have been shown to have either positive or negative effects on osteoblast differentiation and function, with consequent changes in postnatal bone mass. A number of specific targets have been identified. We previously used CrispR-Cas9 to make a miR-455 null mouse, characterizing a behavioral phenotype with age. The current study identifies a bone phenotype, starting in younger animals. At 3 weeks of age, the miR-455 null mice (both male and female) display increased length of both long bones and vertebrae and, while this difference diminishes across 1 year, it remains significant. Increased bone formation in vivo is mirrored by an increase in osteogenesis from bone marrow-derived stem cells in vitro. This is accompanied by a decrease in osteoclastogenesis 2025-01-01T00:00:00Z2025 Mar2025-04-18T12:53:23.853Z2025-04-04T00:51:45.677ZS-EPMC118319853996333910.1093/jbmrpl/ziaf007