RESUMO
Dental enamel formation is coordinated by ameloblast differentiation, production of enamel matrix proteins, and crystal growth. The factors regulating ameloblast differentiation are not fully understood. Here we show that the high mobility group N (HMGN) nucleosomal binding proteins modulate the rate of ameloblast differentiation and enamel formation. We found that HMGN1 and HMGN2 proteins are downregulated during mouse ameloblast differentiation. Genetically altered mice lacking HMGN1 and HMGN2 proteins show faster ameloblast differentiation and a higher rate of enamel deposition in mice molars and incisors. In vitro differentiation of induced pluripotent stem cells to dental epithelium cells showed that HMGN proteins modulate the expression and chromatin accessibility of ameloblast-specific genes and affect the binding of transcription factors epiprofin and PITX2 to ameloblast-specific genes. Our results suggest that HMGN proteins regulate ameloblast differentiation and enamel mineralization by modulating lineage-specific chromatin accessibility and transcription factor binding to ameloblast regulatory sites.
Assuntos
Proteínas do Esmalte Dentário , Proteína HMGN1 , Proteína HMGN2 , Animais , Camundongos , Ameloblastos/metabolismo , Proteína HMGN2/genética , Proteína HMGN2/metabolismo , Proteína HMGN1/genética , Proteína HMGN1/metabolismo , Epigênese Genética , Diferenciação Celular/genética , Proteínas HMGN/genética , Proteínas HMGN/metabolismo , Fatores de Transcrição/metabolismo , Proteínas do Esmalte Dentário/genética , Proteínas do Esmalte Dentário/metabolismo , Cromatina/metabolismo , Amelogenina/metabolismoRESUMO
OBJECTIVE: Increased Wisp1 expression was previously reported in experimental and human osteoarthritis (OA). Moreover, adenoviral overexpression of Wisp1 in naïve mouse knee joints resulted in early OA-like cartilage lesions. Here, we determined how the matricellular protein WISP1 is involved in the pathology that occurs in the complex osteoarthritic environment with aging and experimental OA in wild type (WT) and Wisp1-/- mice. METHODS: WT and Wisp1-/- mice were aged or experimental OA was induced with intraarticular collagenase injection, destabilization of the medial meniscus (DMM) or anterior cruciate ligament transection (ACLT). Joint pathology was assessed using histology and microCT. Protease expression was evaluated with qRT-PCR and activity was determined by immunohistochemical staining of the aggrecan neoepitope NITEGE. Protease expression in human end-stage OA synovial tissue was determined with qRT-PCR after stimulation with WISP1. RESULTS: With aging, spontaneous cartilage degeneration in Wisp1-/- was not decreased compared to their WT controls. However, we observed significantly decreased cartilage degeneration in Wisp1-/- mice after induction of three independent experimental OA models. While the degree of osteophyte formation was comparable between WT and Wisp1-/- mice, increased cortical thickness and reduced trabecular spacing was observed in Wisp1-/- mice. In addition, we observed decreased MMP3/9 and ADAMTS4/5 expression in Wisp1-/- mice, which was accompanied by decreased levels of NITEGE. In line with this, stimulation of human OA synovium with WISP1 increased the expression of various proteases. CONCLUSIONS: WISP1 plays an aggravating role in the development of post-traumatic experimental OA.
Assuntos
Artrite Experimental/genética , Proteínas de Sinalização Intercelular CCN/genética , Cartilagem Articular/metabolismo , Osteoartrite do Joelho/genética , Peptídeo Hidrolases/genética , Proteínas Proto-Oncogênicas/genética , Animais , Ligamento Cruzado Anterior/cirurgia , Artrite Experimental/diagnóstico por imagem , Artrite Experimental/metabolismo , Artrite Experimental/patologia , Cartilagem Articular/diagnóstico por imagem , Cartilagem Articular/patologia , Colagenases , Modelos Animais de Doenças , Humanos , Injeções Intra-Articulares , Meniscos Tibiais/cirurgia , Camundongos , Camundongos Knockout , Osteoartrite do Joelho/diagnóstico por imagem , Osteoartrite do Joelho/metabolismo , Osteoartrite do Joelho/patologia , Osteófito , Peptídeo Hidrolases/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Membrana Sinovial/metabolismo , Via de Sinalização Wnt , Microtomografia por Raio-XRESUMO
A full understanding of the key regulators controlling periodontal development and homeostasis is necessary for the design of improved periodontal regenerative therapies. Small leucine-rich proteoglycans (SLRPs) are extracellular matrix molecules suggested to regulate collagen organization and cell signaling. Mice with double-deficiency of 2 SLRPs, fibromodulin and biglycan (dKO), acquire skeletal abnormalities, but their roles in regulating the periodontium remain undefined and were the focus of our studies. Transmission electron microscopy studies showed abnormal collagen fibrils in the periodontal ligament (PDL) and altered remodeling of alveolar bone in dKO mice. Immunohistochemistry (IHC) revealed increased staining of SLRPs (asporin, lumican, and decorin) and dentin matrix protein-1 (DMP1, a mechanosensory/osteocyte marker), while osteoblast markers, bone sialoprotein and osteopontin, remained unchanged. Disruption of homeostasis was further evidenced by increased expression of receptor-activator of nuclear factor-κB ligand (RANKL) and elevated numbers of osteoclasts, especially noted around the alveolar bone of molars (buccal side) and incisors. Polymerase chain reaction (PCR) array revealed hyperactive transforming growth factors beta/bone morphogenetic protein (TGFß/BMP) signaling in dKO PDL tissues, which was further confirmed by elevated expression of phosphorylated Smad5 (p-Smad5) by IHC in dKO PDL. These studies highlight the importance of SLRPs in maintaining periodontal homeostasis through regulation of TGFß/BMP signaling, matrix turnover, and collagen organization.
