Sleep and circadian defects in a Drosophila model of mitochondrial encephalomyopathy

RNAi of Complex I and V of the electron transport chain in glutamate neurons extends life span, increases sleep, and decreases locomotor activity in Drosophila melanogaster

RNAi targeting the electron transport chain has been proven to prolong life span in many different species, and experiments specifically with Drosophila melanogaster and Caenorhabditis elegans have shown a distinct role for neurons. To determine which subset of neurons is implicated in this life span extension, we used the GAL4/UAS system to activate RNAi against genes of Complex I and Complex V. We found life span extension of 18-24% with two glutamate neuron (D42 and VGlut) GAL4 lines. We used the GAL80 system to determine if the overlapping set of glutamate neurons in these two GAL4 lines imparts the life span extension. Limiting GAL4 activity to non-VGlut glutamate neurons in the D42 background failed to extend life span, suggesting that glutamate neurons have an important role in aging. Interestingly, RNAi of the electron transport chain in D42 glutamate neurons also caused an increase in daytime and nighttime sleep and a decrease in nighttime locomotor activity. Changes to sleep patterns and prolonged life span were not accompanied by any changes in female fertility or response to starvation. Our findings demonstrate that a small subset of neurons can control life span, and further studies can look into the contributions made by glutamate neurons.

Variation in mitochondrial DNA affects locomotor activity and sleep in Drosophila melanogaster

Mitochondria are organelles that produce cellular energy in the form of ATP through oxidative phosphorylation, and this primary function is conserved among many taxa. Locomotion is a trait that is highly reliant on metabolic function and expected to be greatly affected by disruptions to mitochondrial performance. To this end, we aimed to examine how activity and sleep vary between Drosophila melanogaster strains with different geographic origins, how these patterns are affected by mitochondrial DNA (mtDNA) variation, and how breaking up co-evolved mito-nuclear gene combinations affect the studied activity traits. Our results demonstrate that Drosophila strains from different locations differ in sleep and activity, and that females are generally more active than males. By comparing activity and sleep of mtDNA variants introgressed onto a common nuclear background in cytoplasmic hybrid (cybrid) strains, we were able to quantify the among-line variance attributable to mitochondrial DNA, and we establish that mtDNA variation affects both activity and sleep, in a sex-specific manner. Altogether our study highlights the important role that mitochondrial genome variation plays on organismal physiology and behaviour.

Self-reported sleep efficiency and duration are associated with bioenergetic function in peripheral blood mononuclear cells (PBMCs) of adults

Poor sleep may impair systemic mitochondrial bioenergetics, but this relationship has not been examined in humans. This study examined associations of self-reported sleep with peripheral blood mononuclear cell (PBMC) bioenergetics in adults. Forty-three participants completed the Pittsburgh Sleep Quality Index from which sleep indices were calculated. PBMCs were analyzed for bioenergetics using extracellular flux analysis. Sleep efficiency was positively correlated with maximal respiration and spare capacity. Lower sleep efficiency and longer sleep duration were associated with lower Bioenergetic Health Index in age-, sex-, and body mass index-adjusted models. Findings indicate that sleep is related to systemic bioenergetic function in humans.

Recent Advances in Chemical Biology of Mitochondria Targeting

Mitochondria are vital subcellular organelles that generate most cellular chemical energy, regulate cell metabolism and maintain cell function. Mitochondrial dysfunction is directly linked to numerous diseases including neurodegenerative disorders, diabetes, thyroid squamous disease, cancer and septicemia. Thus, the design of specific mitochondria-targeting molecules and the realization of real-time acquisition of mitochondrial activity are powerful tools in the study and treatment of mitochondria dysfunction in related diseases. Recent advances in mitochondria-targeting agents have led to several important mitochondria chemical probes that offer the opportunity for selective targeting molecules, novel biological applications and therapeutic strategies. This review details the structural and physiological functional characteristics of mitochondria, and comprehensively summarizes and classifies mitochondria-targeting agents. In addition, their pros and cons and their related chemical biological applications are discussed. Finally, the potential biomedical applications of these agents are briefly prospected.