Project description:To identify target genes mediating the anti-apoptotic effect of Rela, we isolated primary chondrocytes from Prrx1-Cre;Relafl/fl and Relafl/fl mice, cultured them with or without 10 ng/mL TNF-α, and compared gene expression profiles by microarray analyses.
Project description:TNF-a is increased in the synovial fluid of patients with rheumatoid arthritis and osteoarthritis. TNF-a activates MEK/ERK in chondrocytes; however the overall functional relevance of MEK/ERK to TNF-a-regulated gene expression in chondrocytes is unknown. Chondrocytes were treated with TNF-a with or without the MEK1/2 inhibitor U0126 for 24 h. Microarray analysis was used to identify genes regulated by TNF-a in a MEK1/2-dependent fashion. Experiment Overall Design: Primary chondrocytes from the femoral condyles of neonatal rats were treated with DMSO (control sample), TNF-a, U0126 (selective MEK1/2 inhibitor) or TNF-a and U0126. Two biological replicates were collected for each treatment. Total RNA was collected and analyzed by Affymetrix Microarray.
Project description:Purpose: To demonstrate Runx2's association with organizing the extracellular matrix in primary chondrocytes. Method: RNA samples were collected from primary chondrocytes of 5-day-old Col2a1-CreERT2;Runx2fl/fl and Runx2fl/fl mice, cultured with or without IL-1beta. Results: Thirty-three genes cultured without IL-1beta and 45 genes with IL-1beta were up- or down-regulated by more than 2-fold in the Runx2 knockout in primary chondrocytes. Conclusions: Genes including collagen fibers were down-regulated in Runx2 cKO primary chondrocytes.
Project description:Background: Osteoarthritis (OA) is a degenerative joint disease with high global prevalence, and YKL-40 is an important factor related to the pathological process of OA. Increased levels of YKL-40 exert a protective influence against TNF-α-induced apoptosis in chondrocytes, thereby enhancing chondrocyte survival and activation, while counteracting TNF-α-driven expression of specific inflammatory mediators such as S100A8/A9.This study aims to evaluate the role and molecular mechanism of YKL-40 on chondrocytes in OA and provide a potential therapeutic avenue requiring further validation. Materials and methods: A meta-analysis compared serum YKL-40 and TNF-α levels between OA patients and healthy controls. In vitro experiments examined the effects of YKL-40 on TNF-α-induced OA chondrocytes, assessing proliferation, differentiation, apoptosis, and inflammatory pathways. Results: Meta-analysis revealed significantly elevated serum levels of YKL-40 and TNF-α in osteoarthritis (OA) patients compared to healthy controls. In vitro, TNF-α (10 ng/mL) induced extracellular matrix (ECM) degradation in chondrocytes, significantly reducing glycosaminoglycan (GAG) and type II collagen content. This degradation was effectively rescued by YKL-40 (100 ng/mL). RNA sequencing identified differentially expressed genes in TNF-α-treated chondrocytes, enriched in pathways like IL-17 and NF-κB signaling. YKL-40 treatment reversed the expression of key genes altered by TNF-α. Crucially, these differentially expressed genes (including S100A8/A9, ISG15, CDSN, BAAT, PTPN4, NPTX1, SMARCA1) were validated in independent OA cartilage and synovium GEO datasets. Protein-protein interaction (PPI) networks highlighted central genes within treatment groups. Western blotting confirmed YKL-40 counteracted TNF-α-induced NF-κB pathway activation (reduced p65 and IκBα phosphorylation) and modulated key targets (S100A8/A9, ASB7, ZFPM2), consistent with qRT-PCR data. Conclusion: YKL-40 is a promising biomarker and therapeutic target for OA. Its interplay with TNF-α provides a molecular basis for novel therapies targeting chondrocyte dysfunction, guiding future translational research.
Project description:HEK293T cells were treated with TNF-alpha for different periods of time to study the effect of siRNA-mediated knockdown of different genes (negative control: Renilla luciferase; positive controls: TNFRSF1A, RelA; gene of interest: CASP4) on TNF-induced gene expression
Project description:This SuperSeries is composed of the following subset Series: GSE13206: Human shSIRT6 TNF-alpha timecourse GSE13207: Mouse Sirt6-/- TNF-alpha timecourse GSE13208: Mouse Sirt6-/- tissues GSE13209: Mouse Sirt6-/- RelA+/- tissues Refer to individual Series
Project description:The treatment of chronic mucocutaneous ulceration is challenging and only some patients respond selectively to inhibitors of tumor necrosis factor-alpha (TNF-a). TNF-a activates opposing pathways leading to caspase-8-mediated apoptosis as well as NF-kB-dependent cell survival. We investigated the etiology of autosomal dominant mucocutaneous ulceration in a family whose proband was dependent on anti-TNF-a therapy for sustained remission. A heterozygous mutation in RELA (NM_021975: c.559+1G>A), encoding the NF-kB subunit RelA (p65), segregated with the disease phenotype and resulted in RelA haploinsufficiency. The patients’ fibroblasts exhibited increased apoptosis in response to TNF-a, impaired NF-kB activation, and defective expression of NF-B-dependent anti-apoptotic genes. We show that Rela+/- mice have similarly impaired NF-kB activation, develop cutaneous ulceration from TNF-a exposure, and exhibit severe dextran sodium sulfate-induced colitis ameliorated by TNF-a inhibition. These findings demonstrate an essential contribution of biallelic RELA expression in protecting stromal cells from TNF-a-mediated cell death, thus delineating the mechanisms driving the effectiveness of TNF-a inhibition in this disease.
Project description:As such, TNF triggers the canonical NF-?B pathway to induce a nuclear NF-?B activity composed of the RelA:p50 dimer in WT cells. Nfkb2 encodes p100, which regulates the activity of the RelB NF-?B heterodimers during immune cell-differentiation via the noncanonical pathway. Our biochemical analyses revealed that an absence of p100 instead repositions RelB under the control of the TNF-activated canonical pathway. Indeed, chronic TNF treatment of Nfkb2-/- cells activates the RelA:p50 dimer and an additional RelB:p50 dimer. On the other hand, TNF stimulation of Relb-/-Nfkb2-/- and Rela-/-Nfkb2-/- MEFs exclusively activated the RelA:p50 dimer and the RelB:p50 dimer, respectively. We treated this panel of knockout MEFs with TNF for 6h before being subjected to microarray mRNA analysis. We also included in our analysis WT MEFs and Rela-/-Relb-/-Rel-/- MEFs, which served as a negative control. Our analyses revealed overlapping and distinct gene-expression specificities of RelA:p50 and RelB:p50 dimers activated in mutant cells in response to TNF.
