Project description:Human amylin proteotoxicity impairs protein biosynthesis, and alters major cellular signaling pathways in the heart, brain and liver of humanized diabetic rat model in vivo. The 37 amino acid hormone Amylin is cosecreted with insulin from ß cells in the pancreas. In prediabetic and obese humans, chronic amylin hypersecretion parallels the course of disease and is involved in the pathophysiology of beta cell destruction in the pancreas. Recent studies in rats with transgenic expression of beta cell amylin (HIP), we have discovered that human amylin is prone to misfolding and has proteotoxic effects in vivo, resulting in the induction of cell death paralleling the pathophysiology of neurodegenerative disease. These misfolded proteotoxic amylin proteins are found to migrate to both the brain and heart to induce both neurologic deficits and cardiac dysfunction. In the present study, we use nontargeted GCMS metabolomics analysis to investigate the metabolic consequences of amyloidogenic and cytotoxic amylin oligomers and diabetes in HIP heart, brain, liver, and plasma compared to wild type controls at 1 year of age. We identified that HIP hearts had 45 significantly altered metabolites by ttest (p<0.05) compared to wildtype control hearts (0.134.3 fold different,N=8/group). Similarly, we identified 30 metabolites significantly different in the HIP brain by ttest (p<0.05) compared to wildtype control brains (0.225.2 fold different (N=~10/group). HIP livers had 58 metabolites significantly altered by ttest (p<0.05) compared to wildtype livers (0.0199.4 fold different,N=~10/group. Pathway enrichment analysis identified a systemic alteration in protein biosynthesis in the heart and brain of HIP rats compared to wild type controls. Alterations in phenylalanine metabolism and aminoacyltRNA biosynthesis were specifically affected in heart and plasma. Tyrosine metabolism is affected across organs, including decreased tyrosine (heart), phenylalanine (heart, liver, brain), and increased fumarate (heart, liver, brain). Increased urea and urea cycle were identified in heart and liver. As protein degradation is a major upregulator of the urea cycle in human rat diabetic models, these findings suggest a broader connection between amylin, diabetes, protein catabolism, and effects on the urea cycle, which may contribute to the increased morbidity and mortality in diabetics at a multisystem level beyond the effects on glucose metabolism.

Project description:Our present study reveals significant decelerating effects on senescence processes in middle-aged SAMP1 mice supplemented for 6 or 14 months with the reduced form (QH2, 500 mg/ kg BW/ day) of coenzyme Q10 (CoQ10). To unravel molecular mechanisms of these CoQ10 effects, a genome-wide transcript profiling in liver, heart, brain and kidney of SAMP1 mice supplemented with the reduced (QH2) or oxidized form of CoQ10 (Q10) was performed. Liver seems to be the main target tissue of CoQ10 intervention, followed by kidney, heart and brain. Stringent evaluation of the resulting data revealed that QH2 has a stronger impact on gene expression than Q10, which was primarily due to differences in the bioavailability. Indeed, we found that QH2 supplementation was more effective than Q10 to increase levels of CoQ10 in the liver of SAMP1 mice (54.92-fold and 30.36-fold, respectively). To identify functional and regulatory connections of the âtop 50â (p < 0.05) up- and down-regulated QH2-sensitive transcripts in liver (fold changes ranging from 21.24 to -6.12), text mining analysis (Genomatix BiblioSphere, GFG level B3) was used. Hereby, we identified 11 QH2-sensitive genes which are regulated by PPAR-Î± and are primarily involved in cholesterol synthesis (e.g. HMGCS1, HMGCL, HMGCR), fat assimilation (FABP5), lipoprotein metabolism (PLTP) and inflammation (STAT-1). Thus, we provide evidence that QH2 is involved in the reduction of fat and cholesterol synthesis via modulation of the PPAR-Î± signalling pathway. These data may explain, at least in part, the observed effects on decelerated age-dependent degeneration processes in QH2-supplemented SAMP1 mice. Whole genome expression profiles were analysed from liver, heart, brain and kidney (each analyzed separately) of SAMP1 mice supplemented with QH2, Q10 or a control diet. From every experimental group, three mice each were sacrificed 6 or 14 months after supplementation, resulting in a total of 72 microarrays.

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Metabolomic analysis on samples from rats expressing human amylin (cardiac tissue).

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