Circadian clock genes' overexpression in Drosophila alters diet impact on lifespan

Diet restriction is one of the most accurately confirmed interventions which extend lifespan. Genes coding circadian core clock elements are known to be the key controllers of cell metabolism especially in aging aspect. The molecular mechanisms standing behind the phenomenon of diet-restriction-mediated life extension are connected to circadian clock either. Here we investigate the effects of protein-rich and low-protein diets on lifespan observed in fruit flies overexpressing core clock genes (cry, per, Clk, cyc and tim). The majority of core clock genes being upregulated in peripheral tissues (muscles and fat body) on protein-rich diet significantly decrease the lifespan of male fruit flies from 5 to 61%. Nevertheless, positive increments of median lifespan were observed in both sexes, males overexpressing cry in fat body lived 20% longer on poor diet. Overexpression of per also on poor medium resulted in life extension in female fruit flies. Diet restriction reduces mortality caused by overexpression of core clock genes. Cox-regression model revealed that diet restriction seriously decreases mortality risks of flies which overexpress core clock genes. The hazard ratios are lower for flies overexpressing clock genes in fat body relatively to muscle-specific overexpression. The present work suggests a phenomenological view of how two peripheral circadian oscillators modify effects of rich and poor diets on lifespan and hazard ratios.

Neuron-specific overexpression of core clock genes improves stress-resistance and extends lifespan of Drosophila melanogaster

Gene expression is much altered in aging. We observed age-dependent decline of core clock genes' expression in the whole body of the fruit fly. We hypothesized that inducible overexpression of clock genes (cry, per, tim, cyc and Clk) in the nervous system can improve healthspan of D. melanogaster. We studied the lifespan of transgenic Drosophila and showed life extension for cry, per, cyc and tim genes. It was also the significant positive changes in the stress-resistance of flies overexpressing core clock genes in conditions of hyperthermia, hyperoxia, starvation and persistent lighting. The overexpression of per and cry restore circadian rhythms of locomotor activity. The results presented support the hypotheses that the compensation of circadian oscillator genes expression can improve the healthspan in Drosophila melanogaster.

Genetic mechanisms of the influence of light and phototransduction on Drosophila melanogaster lifespan

The light of the visible spectrum (with wavelengths of 380-780 nm) is one of the fundamental abiotic factors to which organisms have been adapting since the start of biological evolution on the Earth. Numerous literature sources establish a connection between the duration of exposure to daylight, carcinogenesis and longevity, convincingly showing a significant reduction in the incidence of cancer in blind people, as well as in animal models. On the other hand, the stimulating nature of the effect of continuous illumination on reproductive function was noted, in particular, the effects of increasing the fecundity of females of various species are known. Increase in motor activity and, as a result, in metabolic rate and thermogenesis during permanent exposure to light also reduces the body's energy reserves and lifespan. In principle, in the context of aging, not only the exposure time, but also the age at the onset of exposure to constant illumination matter, the reverse effects are valid for the maintenance of experimental animals in the constant darkness. Over the long period of the evolution of light signal transduction systems, many mechanisms have emerged that allow to form an adequate response of the organism to illumination, modulating the highly conservative signaling cascades, including those associated with aging and lifespan (FOXO, SIRT1, NF-kB, mTOR/S6k, PPARa, etc). In this review, we consider the relationship between lifespan, photoregimens, and also the expression of the genes encoding the phototransduction cascade and the circadian oscillator elements of animal cells. In the present paper, basic transducers of light and other signals, such as the family of TRP receptors, G proteins, phospholipase C, and others, are considered in the context of aging and longevity. A relationship between the mechanisms of thermoreception, the temperature synchronization of the circadian oscillator and the life span is established in the review. Analysis of experimental data obtained from the Drosophila melano-gaster model allowed us to formulate the hypothesis of age-dependent photoresistance - a gradual decrease in the expression of genes associated with phototransduction and circadian oscillators, leading to deterioration in the ability to adapt to the photoregimen and to the increase in the rate of aging.

Polymorphism T3111C of the Clock gene in ethnic groups of women from Russia and Buryatia

Biological rhythms of organisms depend on both changing conditions of the external environment and internal “biological clock”. Circadian rhythms are the response of the organism to the change of day and night. They are some of the most important biological rhythms of organisms. Circadian rhythms are regulated by the group of circadian genes. It is known that women suffer from sleep disorders more often than men. Up to 50 % of menopausal women complain of problems associated with sleeping. The study involved 403 menopausal women aged from 45 to 60 years: 214 Russians (the average age is 52.74±6.28 years) and 189 Buryats (the average age is 51.95±5.13 years) living in Eastern Siberia (Irkutsk region, Irkutsk and Republic of Buryatia, Ulan-Ude). The prevalence of genotypes and alleles of the polymorphism T3111C of the circadian rhythm gene Clock (rs1801260) was studied in these groups. To this end, we conducted genotyping of DNA samples by polymerase chain reaction. It was shown that the compared groups have statistically significant differences in genotypes frequency (р = 0.001). It was found that in the group of Russian women the frequency of the TC genotype (p = 0.004) was significantly higher and the frequency of the TT genotype (p = 0.0001) was significantly lower than those in the sample of women of Buryatia. It was shown that in the group of Russian women allele 3111C is found in 30.4 % of cases, which is statistically significantly more often than in the group of Buryat women, where the frequency of allele 3111C was 19.3 % (p = 0.014).