ABSTRACT
As a dioxygenase, Ten-Eleven Translocation 2 (TET2) catalyzes subsequent steps of 5-methylcytosine (5mC) oxidation. TET2 plays a critical role in the self-renewal, proliferation, and differentiation of hematopoietic stem cells, but its impact on mature hematopoietic cells is not well-characterized. Here we show that Tet2 plays an essential role in osteoclastogenesis. Deletion of Tet2 impairs the differentiation of osteoclast precursor cells (macrophages) and their maturation into bone-resorbing osteoclasts in vitro. Furthermore, Tet2 mice exhibit mild osteopetrosis, accompanied by decreased number of osteoclasts in vivo. Tet2 loss in macrophages results in the altered expression of a set of genes implicated in osteoclast differentiation, such as Cebpa, Mafb, and Nfkbiz. Tet2 deletion also leads to a genome-wide alteration in the level of 5-hydroxymethylcytosine (5hmC) and altered expression of a specific subset of macrophage genes associated with osteoclast differentiation. Furthermore, Tet2 interacts with Runx1 and negatively modulates its transcriptional activity. Our studies demonstrate a novel molecular mechanism controlling osteoclast differentiation and function by Tet2, that is, through interactions with Runx1 and the maintenance of genomic 5hmC. Targeting Tet2 and its pathway could be a potential therapeutic strategy for the prevention and treatment of abnormal bone mass caused by the deregulation of osteoclast activities.
Subject(s)
Animals , Mice , 5-Methylcytosine , Chemistry , Metabolism , Cell Differentiation , Cells, Cultured , Core Binding Factor Alpha 2 Subunit , Genetics , Metabolism , DNA-Binding Proteins , Physiology , Genome , Genomics , Mice, Knockout , Osteoclasts , Cell Biology , Metabolism , Proto-Oncogene Proteins , PhysiologyABSTRACT
Objective:To develop a convenient,economical and stable model of acute lung inflammation in mice.Methods:BALB/c mice were inhaled intranasally with 50 ?L of LPS(1 g/L) or sterile PBS,and sacrificed at different time points after being anaesthetized.The bronchoalveolar lavage fluid(BALF) was collected,and the lungs were separated and homogenated or embedded and sliced to 5 ?m sections,which were then stained by HE to determine the severity of inflammation.The inflammatory cell infiltration in bronchoalveolar lavage was counted and IL-1?,the pro-inflammatory cytokine,measured by ELISA in lung homogenate and BALF.Results:The data showed that administration with 50 ?g of LPS(1 g/L) for 2 h resulted in significant inflammation in the lung.LPS mainly stimulated the recruitment of neutrophils within 24 h.And LPS was a quick revulsant of IL-1? production in BALF and in lung tissue between 4 and 24 h.Macrophages and lymphocytes recruited after 1 day,and sustained for at least 3 days.Conclusion:The results indicate that intranasal administration of LPS can induce a rapid and stable acute inflammatory model in mice.