Biology subjects

de Assis, L. V.

Publications and source records attributed to de Assis, L. V..

3 recordsLinked to original sources

bioRxiv2023

Non-alcoholic steatohepatitis disrupts diurnal liver transcriptome rhythms in mice

Background & AimsThe liver ensures organismal homeostasis through modulation of physiological functions over the course of the day. How liver diseases such as non-alcoholic steatohepatitis (NASH) affects daily transcriptome rhythms in the liver remains elusive. To start closing this gap, we evaluated the impact of NASH on the diurnal regulation of the liver transcriptome in mice. Along this, we investigated how stringent consideration of circadian rhythmicity affects the outcomes of NASH transcriptome analyses. Approach & ResultsComparative rhythm analysis of the liver transcriptome from diet-induced NASH and control mice revealed an almost 3h phase advance in global gene expression rhythms. Rhythmically expressed genes associated with DNA repair and cell cycle regulation showed increased overall expression and circadian amplitude. In contrast, lipid and glucose metabolism associated genes showed loss of circadian amplitude, reduced overall expression, and phase advances in NASH livers. Comparison of NASH-induced liver transcriptome responses between published studies revealed little overlap (12%) in differentially expressed genes (DEGs). However, by controlling for sampling time and using circadian analytical tools, a 7-fold increase in DEG detection was achieved compared to methods without time control. ConclusionsNASH had a strong effect on circadian liver transcriptome rhythms with phase- and amplitude-specific effects for key metabolic and cell repair pathways, respectively. Accounting for circadian rhythms in NASH transcriptome studies markedly improves DEGs detection and enhances reproducibility.

physiology↗

bioRxiv2022

Grape-seed proanthocyanidin extract (GSPE) modulates diurnal oscillations of key hepatic metabolic genes and metabolites alleviating hepatic lipid deposition in cafeteria-fed obese rats in a time-of-day-dependent manner

Metabolic syndrome (MS) and its related diseases, including obesity and non-alcoholic fatty liver disease (NAFLD), have become a public health issue due to their increasing prevalence. Polyphenols, such as grape seed proanthocyanidin extract (GSPE), are bioactive compounds present in fruits and vegetables that show promise for MS treatment. We have previously demonstrated that the efficacy of this phenolic extract in the modulation of liver circadian clocks was affected by the time of the day at which it was ingested. Thus, we wondered if the beneficial effects of GSPE consumption in NAFLD could be mediated by diurnal modulation of hepatic lipid and glucose metabolism and whether GSPE effects on liver metabolism are impacted by the timing of administration. Results from hepatic lipid profiling, expression rhythm analysis of metabolic genes together with liver metabolomics in rats revealed that the CAF diet impaired glucose homeostasis and enhanced lipogenesis in the liver, leading to the generation of hepatosteatosis. Chronic consumption of GSPE at the onset of the active phase was able to restore the daily oscillation of liver mass and of key lipogenic and glycogenic genes, along with the reestablishment of liver metabolite rhythms, demonstrating hepatoprotective properties by decreasing triglyceride accumulation and lipid droplet formation in the liver, thus mitigating the development of CAF-induced NAFLD. Furthermore, in vitro data suggest that catechin, one of the main phenolic compounds found in the GSPE extract, may be involved in the ameliorating effects of GSPE against NAFLD.

pharmacology and toxicology↗

bioRxiv2022

Rewiring of liver diurnal transcriptome rhythms by triiodothyronine (T3) supplementation

Diurnal (i.e., 24-hour) physiological rhythms depend on transcriptional programs controlled by a set of circadian clock genes/proteins. Systemic factors like humoral and neuronal signals, oscillations in body temperature, and food intake align physiological circadian rhythms with external time. Thyroid hormones (THs) are major regulators of circadian clock target processes such as energy metabolism, but little is known about how fluctuations in TH levels affect the circadian coordination of tissue physiology. In this study, a high triiodothyronine (T3) state was induced in mice by supplementing T3 in the drinking water, which affected body temperature, and oxygen consumption in a time-of-day dependent manner. 24-hour transcriptome profiling of liver tissue identified 37 robustly and time independently T3 associated transcripts as potential TH state markers in the liver. Such genes participated in xenobiotic transport, lipid and xenobiotic metabolism. We also identified 10 - 15 % of the liver transcriptome as rhythmic in control and T3 groups, but only 4 % of the liver transcriptome (1,033 genes) were rhythmic across both conditions - amongst these several core clock genes. In-depth rhythm analyses showed that most changes in transcript rhythms were related to mesor (50%), followed by amplitude (10%), and phase (10%). Gene set enrichment analysis revealed TH state dependent reorganization of metabolic processes such as lipid and glucose metabolism. At high T3 levels, we observed weakening or loss of rhythmicity for transcripts associated with glucose and fatty acid metabolism, suggesting increased hepatic energy turnover. In sum, we provide evidence that tonic changes in T3 levels restructure the diurnal liver metabolic transcriptome independent of local molecular circadian clocks.

physiology↗