The identification of cell wall degrading enzymes in Globodera rostochiensis

This thesis describes the identification of cell wall degrading enzymes of the potato cyst nematode Globodera rostochiensis . A robust method using expressed sequence tags (ESTs) was applied to identify new parasitism related enzymes. One of the ESTs revealed the first pectate lyase from a metazoan origin. Another tag shared a strong identity towards a previously determined N-terminal amino acid sequence. Further analysis of corresponding cDNA sequence and the gene revealed two closely related beta-1,4-endoglucanases. Heterologous expression of the pectate lyase and both beta-1,4-endoglucanases showed that they are active enzymes towards their appropriate substrates ( e.g. polygalacturonic acid for the pectate lyase and carboxy methyl cellulose for both beta-1,4-endoglucanases respectively). The application of in situ hybridisation predict that these cell wall degrading enzymes are produced in the subventral oesophageal gland cells. Evidence is provided that nematodes use mixtures of cell wall degrading enzymes in order to penetrate and migrate in the plant root

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The identification of cell wall degrading enzymes in Globodera rostochiensis

This thesis describes the identification of cell wall degrading enzymes of the potato cyst nematode Globodera rostochiensis . A robust method using expressed sequence tags (ESTs) was applied to identify new parasitism related enzymes. One of the ESTs revealed the first pectate lyase from a metazoan origin. Another tag shared a strong identity towards a previously determined N-terminal amino acid sequence. Further analysis of corresponding cDNA sequence and the gene revealed two closely related beta-1,4-endoglucanases. Heterologous expression of the pectate lyase and both beta-1,4-endoglucanases showed that they are active enzymes towards their appropriate substrates ( e.g. polygalacturonic acid for the pectate lyase and carboxy methyl cellulose for both beta-1,4-endoglucanases respectively). The application of in situ hybridisation predict that these cell wall degrading enzymes are produced in the subventral oesophageal gland cells. Evidence is provided that nematodes use mixtures of cell wall degrading enzymes in order to penetrate and migrate in the plant root

Peroxisome proliferator-activated receptors and the metabolic syndrome.

The prevalence of the metabolic syndrome is rapidly increasing. This syndrome is characterized by metabolic disturbances, such as abnormal lipid and carbohydrate metabolism and a low-grade inflammatory state. PPARs play an important role in these metabolic processes, which makes them effective targets for treatment and prevention of the metabolic syndrome. Synthetic PPAR agonists, such as fibrates and thiazolidinediones are already used to treat hyperlipidemia and diabetes mellitus, respectively. Besides synthetic ligands, dietary fatty acids and fatty acid derivatives can also bind to an activate PPARs. As demonstrated with ligand-binding assays, PPARs have a clear preference of binding polyunsaturated fatty acids. Monounsaturated fatty acids are also very effective in binding PPARs, whereas saturated fatty acids are poor PPAR binders. However, ligand binding does not necessarily mean transcriptional activation. Therefore, it is important to investigate transactivation properties of dietary fatty acids as PPAR agonists and their role in metabolic reactions. Furthermore, human intervention studies comparing the effects of natural versus synthetic ligands side-by-side may reveal specific fatty acids that exert beneficial PPAR-mediated metabolic effects. The ability of PPARs to sense fatty acids and to mediate lipid metabolism, glucose metabolism and the inflammatory state makes them excellent targets for dietary modulation in order to prevent and treat the metabolic syndrome and associated diseases. This review discusses the role and function of PPARs and their ligands in light of the metabolic syndrome

Butyric Acid Added Apically to Intestinal Caco-2 Cells Elevates Hepatic ApoA-I Transcription and Rescues Lower ApoA-I Expression in Inflamed HepG2 Cells Co-Cultured in the Basolateral Compartment

Apolipoprotein A-I (ApoA-I) concentrations are decreased during inflammation, which may reduce high-density lipoprotein (HDL) functionality. Thus, rescuing ApoA-I concentrations during inflammation might help to prevent atherosclerosis. Recent studies have shown that butyric acid (C4) has anti-inflammatory effects and rescues ApoA-I production. However, whether intestinal short chain fatty acids (SCFAs) are able to influence hepatic processes is unknown. Therefore, we investigated C4 anti-inflammatory effects on ApoA-I transcription in the intestine-liver co-culture model. C4 dose-response experiments in the presence or absence of cytokines were performed in a co-culture system including Caco-2 cells, HepG2 cells, or both. Changes in ApoA-I transcription in Caco-2 cells and HepG2 cells were analyzed using qPCR. C4 increased ApoA-I expression in HepG2 cells that cultured alone. When both cells were cultured together, C4 decreased ApoA-I expression in Caco-2 cells and increased ApoA-I expression in HepG2 cells. However, adding C4 to apical Caco-2 cells resulted in a smaller effect in HepG2 cells compared with adding C4 directly to the hepatocytes. Moreover, C4 rescued ApoA-I expression in inflamed HepG2 cells. These findings suggests that intestinal SCFAs can affect hepatic processes. However, the smaller effect in the co-culture experiment indicates cross-talk between intestine and liver

CCAAT/Enhancer Binding Protein beta in relation to ER Stress, Inflammation, and Metabolic Disturbances

The prevalence of the metabolic syndrome and underlying metabolic disturbances increase rapidly in developed countries. Various molecular targets are currently under investigation to unravel the molecular mechanisms that cause these disturbances. This is done in attempt to counter or prevent the negative health consequences of the metabolic disturbances. Here, we reviewed the current knowledge on the role of C/EBP-β in these metabolic disturbances. C/EBP-β deletion in mice resulted in downregulation of hepatic lipogenic genes and increased expression of β-oxidation genes in brown adipose tissue. Furthermore, C/EBP-β is important in the differentiation and maturation of adipocytes and is increased during ER stress and proinflammatory conditions. So far, studies were only conducted in animals and in cell systems. The results found that C/EBP-β is an important transcription factor within the metabolic disturbances of the metabolic system. Therefore, it is interesting to examine the potential role of C/EBP-β at molecular and physiological level in humans