The Study Of The Function And Mechanism Of ADAMTS-18 In Bone Remodeling Using ADAMTS-18 Knockout Mice

Background:ADAMTS is a family of 19 Zn-metalloproteinases, which is a kind of integration in the extracellular matrix or free plasma matrix. It’s widely expressed in multiple tissues and organs, participated in a variety of pathological and physiological process. ADAMTS-18 is a kind of "orphan" ADAMTSs whose physiological substrates have yet to be identified.. Some studies indicated that ADAMTS-18 is involved in tumorigenesis, abnormal eye development, and thrombin cleavage. Recently, genome-wide association studies (GWASs) in humans showed that ADAMTS-18 plays an important role in bone mineral density (BMD) formation and is closely involved in hip bone fractures in major human ethnic groups. We previously reported that ADAMTS-18 is pivotally involved in thrombin cleavage and associated with platelet lyses as well as cerebral infarction in a post-ischemic stroke model. To further study the role of ADAMTS-18 in vivo, we generated Adamts-18 knockout (KO) mice. In the process of breeding Adamts-18 KO mice, we found that the Adamts-18 KO mice have small size and low body weight. In this study, we use this genetically engineered Adamts-18 KO mouse to further shed light on the role of ADAMTS-18 in skeletal growth and remolding.Purpose:In this study, we will use the Adamts-18 KO mice to investigate the role of ADAMTS-18 in vivo skeletal development and remolding as well as the molecular events involved.Methods:1、Adamts-18 KO mice and WT littermate mice were generated and genotyped as previously described. All procedures in animal experiments were approved by the Institutional Animal Care and Use Committee of East China Normal University (ECNU). All the mice used in this study are male and maintained in a specific pathogen-free facility at ECNU.2、Mouse body weight and longitudinal spine length from nose to tail end (except the tail) was measured on a weekly basis using a digital scale till age of 15 weeks. The length and weight of bone in mouse body was finally measured using a digital scale when the mice were sacrificed at 15 weeks..3、Bones were dissected out from sacrificed mice and analyzed by HE staining,electron microscopy and Micro CT to explore the potential mechanism of ADAMTS-18 in the regulation of bone development and remolding.Result:1、Adamts-18 deficiency in mice has no effect on embryonic skeletal development but causes postnatal skeletal defects2、The deficiency of Adamts-18 in mice causes the whole body skeletal dysplasias including bone length, mineral density and subsequent biomechanical parameters. Therein, femur is the most susceptible region for Adamts-18 mutation.3、Adamts-18 deficiency in mice reduces trabecular bone and impairs bone fibers.Conclusion:1、ADAMTS-18 participated in the regulation of bone remodeling.