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. Keywords: compound, signalling response
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:Cartilage originates from mesenchymal cell condensations that differentiate into chondrocytes of transient growth plate cartilage or permanent cartilage of the articular joint surface and trachea. MicroRNAs fine-tune the activation of entire signaling networks and thereby modulate complex cellular responses, but so far only limited data are available on miRNAs that regulate cartilage development. Here we characterize an miRNA which promotes the biosynthesis of a key component in the RAF/MEK/ERK pathway in cartilage. Specifically, by transcriptome profiling we identified miR-322 to be upregulated during chondrocyte differentiation. Among the various miR-322 target genes in the RAF/MEK/ERK pathway, only Mek1 was identified as a regulated target in chondrocytes. Surprisingly, an increased concentration of miR-322 stabilizes Mek1-mRNA to arise protein levels and dampen ERK1/2 phosphorylation, while cartilage-specific inactivation in mice linked the loss of miR-322 to decreased MEK1 levels and increased RAF/MEK/ERK pathway activation. Such mice died perinatally due to tracheal growth restriction and respiratory failure. Hence, a single miRNA can stimulate the production of an inhibitory component of a central signaling pathway to impair cartilage development.
Project description:Identification of MEK-ERK or p38MAPK dependent genes in human monocyte derived dendritic cells. Dendritic cells (DC) promote tolerance or immunity depending on their maturation state. Previous studies have revealed that DC maturation is enhanced or accelerated upon MEK-ERK signaling pathway inhibition. We have now determined the contribution of MEK-ERK activation to the profile of gene expression of human immature monocyte-derived dendritic cells (MDDC) and peripheral blood myeloid DC. ERK inhibition altered the expression of genes that mediate CCL19-directed migration (CCR7) and LDL binding (CD36, SCARB1, OLR1, CXCL16) by immature DC. Besides, ERK upregulated CCL2 expression while impaired the expression of DC maturation markers (RUNX3, ITGB7, IDO1). MEK-ERK-regulated genes exhibited an over-representation of cognate sequences for the Aryl Hydrocarbon Receptor (AhR) transcription factor, and we show that AhR mediates some of the ERK-dependent transcriptional effects in DC. Therefore, MEK-ERK signaling pathway regulates antigen capture, lymph node homing and the acquisition of maturation-associated genes, and its contribution to the maintenance of the immature state of MDDC and myeloid DC is partly dependent on the activity of AhR. Since pharmacological modulation of the MEK-ERK signaling pathway has been proposed as a potential therapeutic strategy for cancer, our findings indicate that ERK inhibitors might influence the generation of anti-tumor responses through regulation of critical DC effector functions.
Project description:MicroRNAs (miRNAs) regulate cartilage differentiation and contribute to the onset and progression of joint degeneration. These small RNA molecules may affect extracellular matrix organization (ECM) in cartilage, but for only a few miRNAs has this role been defined in vivo. Previously, we showed that cartilage-specific genetic ablation of the Mirc24 cluster in mice leads to impaired cartilage development due to increased RAF/MEK/ERK pathway activation. Here, we studied the expression of the cluster in cartilage by LacZ reporter gene assays and determined its role for extracellular matrix homeostasis by proteome and immunoblot analysis. The cluster is expressed in prehypertrophic/hypertrophic chondrocytes of the growth plate and we now show that the cluster is also highly expressed in articular cartilage. Cartilage-specific loss of the cluster leads to increased proteoglycan 4 and matrix matrix metallopeptidase 13 levels and decreased aggrecan and collagen X levels in epiphyseal cartilage. Interestingly, these changes are linked to a decrease in SRY-related HMG box-containing (SOX) transcription factors 6 and 9, which regulate ECM production in chondrocytes. Our data suggests that the Mirc24 cluster is important for ECM homoeostasis and the expression of transcriptional regulators of matrix production in cartilage.
Project description:Identification of MEK-ERK or p38MAPK dependent genes in human monocyte derived dendritic cells. Dendritic cells (DC) promote tolerance or immunity depending on their maturation state. Previous studies have revealed that DC maturation is enhanced or accelerated upon MEK-ERK signaling pathway inhibition. We have now determined the contribution of MEK-ERK activation to the profile of gene expression of human immature monocyte-derived dendritic cells (MDDC) and peripheral blood myeloid DC. ERK inhibition altered the expression of genes that mediate CCL19-directed migration (CCR7) and LDL binding (CD36, SCARB1, OLR1, CXCL16) by immature DC. Besides, ERK upregulated CCL2 expression while impaired the expression of DC maturation markers (RUNX3, ITGB7, IDO1). MEK-ERK-regulated genes exhibited an over-representation of cognate sequences for the Aryl Hydrocarbon Receptor (AhR) transcription factor, and we show that AhR mediates some of the ERK-dependent transcriptional effects in DC. Therefore, MEK-ERK signaling pathway regulates antigen capture, lymph node homing and the acquisition of maturation-associated genes, and its contribution to the maintenance of the immature state of MDDC and myeloid DC is partly dependent on the activity of AhR. Since pharmacological modulation of the MEK-ERK signaling pathway has been proposed as a potential therapeutic strategy for cancer, our findings indicate that ERK inhibitors might influence the generation of anti-tumor responses through regulation of critical DC effector functions. Human peripheral blood monocytes from three independent healthy donors (DC4, DC5 and DC7) were isolated by anti-CD14-labeled magnetic microbeads. CD14+ monocytes were cultured for 5 days in RPMI 10% FCS containing GM-CSF and IL-4 to generate immature monocyte-derived dendritic cells (MDDC). Immature MDDC were exposed to MEK inhibitor, U0126, or p38MAPK inhibitor, SB203580 for 1 hour and a final dose of GM-CSF and IL-4 were added to the culture. Cells were collected for analysis after 4, 10 or 24 hours.Total RNA from each condition was extracted using the All prep DNA/RNA/protein mini kit (Qiagen) and hybridized to an Agilent Human Whole Genome (4x44) Oligo Microarray. All experimental procedures were performed following manufacturer instructions.
Project description:Inflammation is a key component of pathological angiogenesis. Here we induce cornea neovascularisation using sutures placed into the cornea, and sutures are removed to induce a regression phase. We used whole transcriptome microarray to monitor gene expression profies of several genes