Project description:We generated transcriptional profiles of TNF-stimulated primary hepatocytes co-treated with PPARα and GR ligands to mimic a condition of starvation.
Project description:Cytokines such as TNF-alpha and IL-1beta are known for their contribution to inflammatory processes in liver . In contrast, the cytokine IL-17 has not yet been assigned a role in liver diseases. IL-17 can cooperate with TNF-alpha to induce a synergistic response on several target genes in different cell lines, but no data exist for primary hepatocytes. To enhance our knowledge on the impact of IL-17 alone and combined with TNF-alpha in primary murine hepatocytes a comprehensive microarray study was designed. IL-1beta was included as this cytokine is suggested to act in a similar manner as the combination of TNF-alpha and IL-17, especially with respect to its role in mRNA stabilization. Results: The present microarray analysis demonstrates that primary murine hepatocytes responded to IL-17 stimulation by upregulation of chemokines and genes, which are functionally responsible to increase and sustain inflammation. Cxcl2, Nfkbiz and Zc3h12a were strongly induced, whereas the majority of the genes were only very moderately upregulated. Promoter analysis revealed involvement of NF-kappaB in the activation of many genes. Combined stimulation of TNF-alpha/IL-17 resulted in enhanced induction of gene expression, but significantly synergistic effects could be applied only to a few genes, such as Nfkbiz, Cxcl2, Zc3h12 and Steap4. Comparison of the gene expression profile obtained after stimulation of TNF-alpha/IL-17 versus IL-1 proposed a IL-1beta-like effect of the latter cytokine combination. Moreover, evidence was provided that modulation of mRNA stability may be a major mechanism by which IL-17 regulates gene expression in primary hepatocytes. This assumption was exemplarily proven for Nfkbiz mRNA for the first time in hepatocytes. Our studies also suggest that RNA stability can partially be correlated to the existence of AU rich elements, but further mechanisms like the RNase-activity of the upregulated Zc3h12a have to be considered. Conclusions: Our microarray analysis gives new insights in IL-17 induced gene expression in primary hepatocytes highlighting the crosstalk with the NF-kappaB signalling pathway. Gene expression profile suggests IL-17 a role in sustaining liver inflammatory processes most likely by RNA stabilization. Altogether, our results provide evidence that IL-17 alone and in concert with TNF-alpha may play a role in inflammatory liver diseases. Primary murine hepatocytes of three animals stimulated for 1 or 4h by TNF-alpha, IL-1beta, IL-17 or TNF-alpha followed by IL-17 were used for microarray analysis.
Project description:Cytokines such as TNF-alpha and IL-1beta are known for their contribution to inflammatory processes in liver . In contrast, the cytokine IL-17 has not yet been assigned a role in liver diseases. IL-17 can cooperate with TNF-alpha to induce a synergistic response on several target genes in different cell lines, but no data exist for primary hepatocytes. To enhance our knowledge on the impact of IL-17 alone and combined with TNF-alpha in primary murine hepatocytes a comprehensive microarray study was designed. IL-1beta was included as this cytokine is suggested to act in a similar manner as the combination of TNF-alpha and IL-17, especially with respect to its role in mRNA stabilization. Results: The present microarray analysis demonstrates that primary murine hepatocytes responded to IL-17 stimulation by upregulation of chemokines and genes, which are functionally responsible to increase and sustain inflammation. Cxcl2, Nfkbiz and Zc3h12a were strongly induced, whereas the majority of the genes were only very moderately upregulated. Promoter analysis revealed involvement of NF-kappaB in the activation of many genes. Combined stimulation of TNF-alpha/IL-17 resulted in enhanced induction of gene expression, but significantly synergistic effects could be applied only to a few genes, such as Nfkbiz, Cxcl2, Zc3h12 and Steap4. Comparison of the gene expression profile obtained after stimulation of TNF-alpha/IL-17 versus IL-1 proposed a IL-1beta-like effect of the latter cytokine combination. Moreover, evidence was provided that modulation of mRNA stability may be a major mechanism by which IL-17 regulates gene expression in primary hepatocytes. This assumption was exemplarily proven for Nfkbiz mRNA for the first time in hepatocytes. Our studies also suggest that RNA stability can partially be correlated to the existence of AU rich elements, but further mechanisms like the RNase-activity of the upregulated Zc3h12a have to be considered. Conclusions: Our microarray analysis gives new insights in IL-17 induced gene expression in primary hepatocytes highlighting the crosstalk with the NF-kappaB signalling pathway. Gene expression profile suggests IL-17 a role in sustaining liver inflammatory processes most likely by RNA stabilization. Altogether, our results provide evidence that IL-17 alone and in concert with TNF-alpha may play a role in inflammatory liver diseases.
Project description:The biological effects of the pesticide and complex I inhibitor tebufenpyrad (TEBU) on liver cells were investigated by proteomic approaches. Cellular contents and culture media were analyzed in dose-response experiments on primary rat hepatocytes (PRHs).
Project description:The biological effects of the pesticide and complex I inhibitor tebufenpyrad (TEBU) on liver cells were investigated by proteomic approaches. Cellular contents and culture media were analyzed in dose-response experiments on human primary hepatocytes (PHHs).
Project description:The increased secretion of pro-inflammatory cytokines, such as tumor necrosis factor-alpha, is often associated with adipose tissue dysregulation, which often accompanies obesity. High levels of TNF-alpha have been linked to development of insulin resistance in several tissues and organs, including skeletal muscle and the liver. In this study, we examined the complex regulatory roles of TNF-alpha in murine hepatocytes utilizing a combination of global proteomics and phosphoproteomics analyses. Our results show that TNF-alpha promotes extensive, dynamic changes not only of protein levels, but also the dynamics of their downstream phosphorylation signaling states. We provide evidence that TNF-alpha likely induces DNA replication, and promotes G1/S transition through the activation of the MAPK pathway. Our data also highlights several other novel proteins, many of which are regulated by phosphorylation and that play a role in the progression and development of insulin resistance in hepatocytes.