Circadian Reprogramming In The Liver Identifies Metabolic Pathways Of Aging
Background and aims: It is known a circadian clock as an endogen regulation with variations during a 24h time of the biology cycle. This cycle could be related with the aging process in a way that the variations in the circadian genes could provoke neither a decrease or an enhancing in the life-span of the organism we are studying, depending on the presence of rhythmic or non-rhythmic circadian genes. Moreover, it has been shown thought the observation of mice genes that the age-dependent decrease in the clock can affect to the internal behaviour of the animal. Also, researchers found from genetic model mice that small quantities of ARNTL (aryl hydrocarbon receptor nuclear-translocator-like) is proportional to a reduction in the lifespan, therefore it leads to premature aging.
Researchers aim to find a correlation between the circadian genes and how it affects to the aging process and lifespan trough the comparison of experimental results using young and old mice, some of them nourishing with an ad libitum diet (also known as normal-free diet) and another group which is going through a caloric restricted diet. Then these results are studied with the analysis of the circadian transcriptome from the liver, muscular and skeletal tissues. Also, demonstrate from the comparison of stem cells coming from the liver, epidermis and skeletal muscle that the circadian clock can also affect in a tissue-specific manner of aging. Methodology: cal comentar la metodologia necessària per dur a terme el treball i fer un esquema (obligatori) amb els materials i mètodes utilitzats. During this experiment, investigators have employed a number of different methods to obtain the final results that will be counteracted and studied from other techniques and programs. First of all, we have the main resources of the experiment, mices of two different age groups. The young group had an initial age of 19-29 weeks while the old group were from 55-69 weeks. Within each group there were two other subgroups divided by the diet that were going to follow, a normal diet (control) with 18. 8%/w protein, 7. 3%/w fatty acids and 55. 1%/w carbohydrates, with 3. 6 Kcal/g; and a calorie restriction group feed with 32. 9%/w protein, 12. 7%/w fatty acids and 31. 9%/w carbohydrates, with 3. 7 Kcal/g.
To adapt the calorie-restriction group to their new diet, they were feed with a 10% reduction of calories every week during 3 weeks. Then, the project will continue with the nourish of both groups for 25 weeks, where every 4 hours of the circadian clock the livers were taken and saved into liquid nitrogen to be analysed later. Later, using the previous frozen liver, investigators obtain an expression of the multiple genes that the organ contains with the application of microarrays. The RNA was extracted with trizol. The preparation of the cDNA was from 25ng of RNA using WTA2, later purished with Invitrogen, fragmented, biotinylated and hybridised during 16h at 45ºC samples were washed and stained in the GeneAtlas Fluidics Station (Affymetrix).
