Biology subjects

Snelson, M.

Publications and source records attributed to Snelson, M..

3 recordsLinked to original sources

bioRxiv2023

Deep multi-omic profiling reveals extensive mitochondrial remodeling driven by glycemia in early diabetic kidney disease

Changes in mitochondrial energy metabolism are thought to be central to the development of diabetic kidney disease (DKD); however, whether this response is explicitly driven by systemic glucose concentrations remains unknown. Here, we show that titrating blood glucose concentrations in vivo directly impacts mitochondrial morphology and bioenergetics and remodels the mitochondrial proteome in the kidney in early DKD. Mitoproteomic analysis revealed profound metabolic disturbances induced by severe hyperglycemia, including upregulation of enzymes involved in the TCA cycle and fatty acid metabolism, enhanced ketogenesis as well as dysregulation of the mitochondrial SLC25 carrier family. Untargeted metabolomics and lipidomics confirmed the enrichment of TCA cycle metabolites, an increase in triglyceride concentrations, and extensive and specific cardiolipin remodeling. Lowering blood glucose to moderate hyperglycemia stabilized all three omic landscapes, partially prevented changes in mitochondrial morphology and bioenergetics, and improved kidney injury. This study demonstrates altered substrate utilization and energy generation in the kidney early in diabetes, during moderate and severe hyperglycemia and provides new insights into kidney metabolism, which has implications for therapeutic strategies aiming at the reinvigoration of mitochondrial function and signaling in diabetes.

cell biology↗

bioRxiv2023

Experimental Factors Influence Diversity Metrics of the Gut Microbiome in Laboratory Mice

IntroductionAnimal models are regularly used to test the role of the gut microbiome in hypertension. Small-scale pre-clinical studies have investigated changes to the gut microbiome in the angiotensin II hypertensive model. However, the gut microbiome is influenced by internal and external factors not regularly considered in the study design. Once these factors are accounted for, it is unclear if microbiome signatures are reproduceable. We aimed to determine the influence of angiotensin II treatment on the gut microbiome using a large and diverse cohort of mice and to quantify the magnitude by which other factors contribute to microbiome variations. Methods and ResultsWe conducted a retrospective study to establish a diverse mouse cohort resembling large human studies. We sequenced the V4 region of the 16S rRNA gene from 538 samples across the gastrointestinal tract of 303 male and female C57BL/6J mice randomised into sham or angiotensin II treatment from different genotypes, diets, animal facilities, and age groups. Analysing over 17 million sequencing reads, we observed that angiotensin II treatment influenced -diversity (P=0.0137) and {beta}-diversity (i.e., composition of the microbiome, P<0.001). Bacterial abundance analysis revealed patterns consistent with a reduction in short-chain fatty acid-producers, microbial metabolites that lower blood pressure. Furthermore, animal facility, genotype, diet, age, sex, intestinal sampling site, and sequencing batch had significant effects on both - and {beta}-diversity (all P<0.001). Sampling site (6.8%) and diet (6%) had the largest impact on the microbiome, while angiotensin II and sex had the smallest effect (each 0.4%). ConclusionsOur large-scale data confirmed findings from small-scale studies that angiotensin II impacted the gut microbiome. However, this effect was modest relative to most of the other factors studied. Accounting for these factors in future pre-clinical hypertensive studies will increase the likelihood that microbiome findings are replicable and translatable.

microbiology↗

bioRxiv2019

Resistant starch does not protect against nephropathy or alter intestinal permeability in an STZ-induced diabetic mouse model

Alterations in gut homeostasis may contribute to the progression of diabetic nephropathy. There has been recent attention on the renoprotective effects of metabolite-sensing receptors in chronic renal injury, including the G-protein-coupled-receptor (GPR)109a, which ligates the short chain fatty acid butyrate. However, the role of GPR109a in the development of diabetic nephropathy, a milieu of diminished microbiome-derived metabolites, has not yet been determined. This study aimed to assess the effects of insufficient GPR109a signalling via genetic deletion of GPR109a on the development of renal injury in diabetic nephropathy. Gpr109a-/- mice or their wildtype littermates (Gpr109a+/+) were rendered diabetic with streptozotocin (STZ). Mice received a control diet or an isocaloric high fiber diet (12.5% resistant starch) for 24 weeks and gastrointestinal permeability and renal injury were determined. Diabetes was associated with increased albuminuria, glomerulosclerosis and inflammation. In comparison, Gpr109a-/- mice with diabetes did not show an altered renal phenotype. Resistant starch supplementation did not afford protection from renal injury in diabetic nephropathy. Whilst diabetes was associated with alterations in intestinal morphology, intestinal permeability assessed in vivo using the FITC-dextran test was unaltered. GPR109a deletion did not worsen gastrointestinal permeability. Further, 12.5% resistant starch supplementation, at physiological concentrations, had no effect on intestinal permeability or morphology. These studies indicate that GPR109a does not play a critical role in intestinal homeostasis in a model of type 1 diabetes or in the development of diabetic nephropathy.

molecular biology↗