Transcriptomic approaches to understanding ageing and metabolism in rodents

Holmes, Andrew
Transcriptomic approaches to understanding ageing and metabolism in rodents. PhD thesis, University of Liverpool.

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Ageing is a major cause of diseases in modern society and leads to many age-related diseases. In addition, rising obesity in society increases the likelihood of various diseases. The development of genetic sequencing technologies provides a novel platform to unravel the complexity of ageing and metabolism. The Naked mole-rat (Heterocephalus glaber) is a rodent that is related to mice (Mus musculus) and ages very slowly, and can live for over 30 years without developing cancer. RNAseq analysis of H. glaber and M. musculus livers identified genes that were under- or over-expressed in H. glaber. Relative qPCR analysis was performed to confirm the expression of highly expressed genes in the naked mole-rat. Adenosine-to-Inosine (A-to-I) RNA editing is a post-transcriptional modification of specific bases that can cause an alteration in amino acid and splicing events. Recent studies indicated a gene-specific decline in RNA editing with age in humans in Cyfip2. Using SOLiD RNAseq, we sequenced the transcriptomes of 6-, 12-, and 28-month old rat cerebral cortex. We identify a conserved RNA editing site in Cog3. Upon analysis of known conserved RNA editing targets, no changes in RNA editing were observed during ageing in the rat. These results highlight the biological differences between rodent model organisms and humans, and their significance in the context of RNA editing and ageing. Dietary restriction of caloric intake is known to increase the lifespan of many species. Physiologically, these animals remain lean and show a later onset of age-related diseases. Through this concept, we were interested in studying Gnasxlm+/p- knockout mice, which remain lean due to hypermetabolism, despite increased food intake. Gnasxlm+/p- mice have a deletion in Gnas, which prevents expression of Xlαs. However, it is not known exactly how the loss of Xlαs exerts this phenotype. Due to its role in homeostasis and localisation of Xlαs expression, RNA from whole hypothalami of wildtype and Gnasxlm+/p- mice were analysed by Illumina RNAseq in order to identify expression changes that may help to explain the physiological symptoms. The glial cell marker Gfap was found to be downregulated 2-fold in Gnasxlm+/p- mice, which was confirmed by qPCR. Furthermore, in analysing the localisation of GFAP within the hypothalamus, we identified a distinct loss of GFAP expression in the arcuate nucleus, and suprachiasmatic nucleus. GFAP was not found to be decreased in postnatal (P)1 and P5 mice, indicating that the decrease in GFAP is more likely to be an adaptation to chronic undernutrition as a result of hypermetabolism, than a developmental problem in the mice.

Item Type: Thesis (PhD)
Additional Information: Date: 2014-12 (completed)
Subjects: ?? QH426 ??
Depositing User: Symplectic Admin
Date Deposited: 17 Aug 2015 08:45
Last Modified: 17 Dec 2022 01:16
DOI: 10.17638/02010820