Browsing by Author "Loeser, Richard F."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Impaired Annulus Fibrosis Development and Vertebral Fusion Cause Severe Scoliosis in Mice with Deficiency of JNK1 and JNK2
    (Elsevier, 2019) Ulici, Veronica; Kelley, Kathryn L.; Longobardi, Lara; McNulty, Margaret A.; Livingston, Eric W.; Bateman, Ted A.; Séguin, Cheryle A.; Louer, Craig R.; Loeser, Richard F.; Anatomy and Cell Biology, IU School of Medicine
    MAP kinases, including JNK, play an important role in the development and function of a large variety of tissues. We analyzed the skeletal phenotype of JNK1 and JNK2 double knockout (dKO) mice (JNK1fl/flCol2-Cre/JNK2-/-) and control genotypes, including single knockouts, at different embryonic and postnatal stages. The JNK1/2 dKO mice displayed a severe scoliotic phenotype that began during development and was grossly apparent around weaning age. Alcian blue staining of embryos (E17.5) showed abnormal fusion of the posterior spinal elements. In the adult mice, fusion of vertebral bodies and of spinous and transverse processes was noted by microCT, Alcian blue/Alizarin red stain and histology. The long bones developed normally and histological sections of the growth plate and articular cartilage did not reveal significant abnormalities. Histological sections of the vertebral column at E15.5 and E17.5 revealed an abnormal organization of the annulus fibrosus in the dKOs, with chondrocyte-like cells and fusion of dorsal processes. Spinal sections in 10-week–old dKO mice showed replacement of intervertebral disc structures (annulus fibrosus and nucleus pulposus) by cartilage and bone tissues, with cells staining for markers of hypertrophic chondrocytes including collagen X and Runx2. These findings demonstrate a requirement for both JNK1 and JNK2 in the normal development of the axial skeleton with loss of JNK signaling resulting in abnormal endochondral bone formation and subsequent severe scoliosis.
  • Thumbnail Image
    Item
    Impaired Annulus Fibrosus Development and Vertebral Fusion Cause Severe Scoliosis in Mice with Deficiency of c-Jun NH2-Terminal Kinases 1 and 2
    (Elsevier, 2019-04) Ulici, Veronica; Kelley, Kathryn L.; Longobardi, Lara; McNulty, Margaret A.; Livingston, Eric W.; Bateman, Ted A.; Séguin, Cheryle A.; Louer, Craig R.; Loeser, Richard F.; Anatomy and Cell Biology, School of Medicine
    Mitogen-activated protein kinases, including c-Jun NH2-terminal kinase (JNK), play an important role in the development and function of a large variety of tissues. The skeletal phenotype of JNK1 and JNK2 double-knockout (dKO) mice (JNK1fl/flCol2-Cre/JNK2−/−) and control genotypes were analyzed at different embryonic and postnatal stages. JNK1/2 dKO mice displayed a severe scoliotic phenotype beginning during development that was grossly apparent around weaning age. Alcian blue staining at embryonic day 17.5 showed abnormal fusion of the posterior spinal elements. In adult mice, fusion of vertebral bodies and of spinous and transverse processes was noted by micro–computed tomography, Alcian blue/Alizarin red staining, and histology. The long bones developed normally, and histologic sections of growth plate and articular cartilage revealed no significant abnormalities. Histologic sections of the vertebral column at embryonic days 15.5 and 17.5 revealed an abnormal organization of the annulus fibrosus in the dKOs, with chondrocyte-like cells and fusion of dorsal processes. Spinal sections in 10-week–old dKO mice showed replacement of intervertebral disk structures (annulus fibrosus and nucleus pulposus) by cartilage and bone tissues, with cells staining for markers of hypertrophic chondrocytes, including collagen X and runt-related transcription factor 2. These findings demonstrate a requirement for both JNK1 and JNK2 in the normal development of the axial skeleton. Loss of JNK signaling results in abnormal endochondral bone formation and subsequent severe scoliosis.
  • Thumbnail Image
    Item
    Role of the Hypoxia-Inducible Factor Pathway in Normal and Osteoarthritic Meniscus and in Mice after Destabilization of the Medial Meniscus
    (Sage, 2021) Stone, Austin V.; Loeser, Richard F.; Callahan, Michael F.; McNulty, Margaret A.; Long, David L.; Yammani, Raghunatha R.; Bean, Sara; Vanderman, Kadie; Chubinskaya, Susan; Ferguson, Cristin M.; Anatomy, Cell Biology and Physiology, School of Medicine
    Objective: Meniscus injury and the hypoxia-inducible factor (HIF) pathway are independently linked to osteoarthritis pathogenesis, but the role of the meniscus HIF pathway remains unclear. We sought to identify and evaluate HIF pathway response in normal and osteoarthritic meniscus and to examine the effects of Epas1 (HIF-2α) insufficiency in mice on early osteoarthritis development. Methods: Normal and osteoarthritic human meniscus specimens were obtained and used for immunohistochemical evaluation and cell culture studies for the HIF pathway. Meniscus cells were treated with pro-inflammatory stimuli, including interleukins (IL)-1β, IL-6, transforming growth factor (TGF)-α, and fibronectin fragments (FnF). Target genes were also evaluated with HIF-1α and HIF-2α (Epas1) overexpression and knockdown. Wild-type (n = 36) and Epas1+/- (n = 30) heterozygous mice underwent destabilization of the medial meniscus (DMM) surgery and were evaluated at 2 and 4 weeks postoperatively for osteoarthritis development using histology. Results: HIF-1α and HIF-2α immunostaining and gene expression did not differ between normal and osteoarthritic meniscus. While pro-inflammatory stimulation significantly increased both catabolic and anabolic gene expression in the meniscus, HIF-1α and Epas1 expression levels were not significantly altered. Epas1 overexpression significantly increased Col2a1 expression. Both wild-type and Epas1+/- mice developed osteoarthritis following DMM surgery. There were no significant differences between genotypes at either time point. Conclusion: The HIF pathway is likely not responsible for osteoarthritic changes in the human meniscus. Additionally, Epas1 insufficiency does not protect against osteoarthritis development in the mouse at early time points after DMM surgery. The HIF pathway may be more important for protection against catabolic stress.