Project description:The circadian profile of the transcriptomes in murine tissues was compared between groups of young and old male mice. The oscillatory phase and absolute expression levels were evaluated as a function of biological age. Distinct differences in multiple pathways were apparent based on biological and circadian time in a tissue specific manner. A total of 18 young (5 month) and old (24 month) C57BL/6 mice were acclimated to a set 12 hr light dark cycle and fed ad lib on standard lab chow for 2 weeks in the PBRC Comparative Biology Core Facility. Five days prior to the study, the mice were converted to constant darkness (red light) regimen. On the day of the study, mice were euthanized by CO2 asphyxiation after ad lib feeding overnight in groups of 3 animals per young or old cohort at 4 hr intervals beginning at 7 AM and ending at 3 AM on a single day (July, 2009). The body weight of each animal was recorded prior to dissection of the following tissues: brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and liver. Individual tissues were weighed prior to freezing in liquid nitrogen. Samples were stored at -80oC until use.Total RNA was isolated from the BAT, eWAT, and liver tissues using TriReagent (MRC, Cincinnati OH) in accordance with the manufacturer’s recommendations. The Illumina TotalPrep RNA Amplification Kit (Applied Biosystems Inc., Foster City, CA, Catalog #AMIL1791) was used to create labeled cRNA from 750ng of input total RNA according to the manufacturer’s protocol. The labeled cRNA samples were then assessed for quality and quantity using a NanoDrop and an Agilent Bioanalyzer. The MouseWG-6 v2 Beadchip (Illumina Sentrix Beadchip Array #11278593) contains 45,200 transcripts and allows 6 samples to be interrogated in parallel. 1.5ug of each labeled cRNA was hybridized to each array according to the manufacturer's protocol. Experimental group samples were distributed randomly across all beadchips. After an 18 hour hybridization at 58°C, the beadchips were processed according to manufacturer’s protocol and scanned using an Illumina BeadArray Reader (Illumina, Inc., San Diego, CA).

Project description:Rodents are commonly housed below thermoneutrality (~20°C) 1. Under these conditions there is a substantial effect on rodent physiology including the hyperactivation of brown (BAT) and beige adipose tissue 2. Here, we raised animals from weaning, on an obesogenic diet at thermoneutrality (28°C) to closer mimic human physiology and determine the impact of a) moderate cold exposure (i.e. 20°C, a temperature reduction of ~8°C) or b) treatment with YM-178, a highly-selective, clinically used β3-adrenoreceptor agonist on classical BAT or subcutaneous inguinal (IWAT) beige depots. Under these conditions, uncoupling protein 1 mRNA was undetectable in IWAT in all groups. Maintenance at 20°C drove weight gain and a 125% increase in subcutaneous fat, an effect not seen with YM-178 administration thus suggesting a direct effect of ambient temperature in promoting weight gain and adiposity in obese rats. Using exploratory adipose tissue proteomics we reveal novel processes and pathways associated with cold-induced weight gain in BAT (i.e. histone deacetylation and glycosphingolipid biosynthesis) and IWAT (i.e. NAD+ binding and retinol metabolism). Conversely, YM-178 had minimal metabolic-related effects on BAT and drove a pro-inflammatory phenotype in IWAT. Exercise training elicits diverse effects on brown (BAT) and white adipose tissue (WAT) physiology in rodents housed below their thermoneutral zone (i.e. 28-32°C). In these conditions, BAT is chronically hyperactive and, unlike human residence, closer to thermoneutrality. Therefore, we set out to determine the effects of exercise training in obese animals at 28°C (i.e. thermoneutrality) on BAT and WAT in its basal (i.e. inactive) state. Sprague-Dawley rats (n=12) were housed at thermoneutrality from 3 weeks of age and fed a high-fat diet. At 12 weeks of age half these animals were randomised to 4-weeks of swim-training (1 hour/day, 5 days per week). Following a metabolic assessment interscapular and perivascular BAT and inguinal (I)WAT were taken for analysis of thermogenic genes and the proteome. Exercise attenuated weight gain but did not affect total fat mass or thermogenic gene expression. Proteomics revealed an impact of exercise training on2-oxoglutarate metabolic process, mitochondrial respiratory chain complex IV, carbon metabolism and oxidative phosphorylation. This was accompanied by an upregulation of multiple proteins involved in skeletal muscle physiology suggesting an adipocyte to myocyte switch in BAT. UCP1 mRNA was undetectable in IWAT with proteomics highlighting changes to DNA binding, the positive regulation of apoptosis, HIF-1 signalling and cytokine-cytokine receptor interaction.

Dataset Information

Biological Aging and Circadian Mechanisms in Murine Brown Adipose Tissue, Inguinal White Adipose Tissue, and Liver

Publications

Biological aging alters circadian mechanisms in murine adipose tissue depots.

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