The effect of isoprenoid side chain length of ubiquinone on life span

Regulation of coenzyme Q biosynthesis pathway in eukaryotes

Coenzyme Q (CoQ, ubiquinone/ubiquinol) is a ubiquitous and unique molecule that drives electrons in mitochondrial respiratory chain and an obligatory step for multiple metabolic pathways in aerobic metabolism. Alteration of CoQ biosynthesis or its redox stage are causing mitochondrial dysfunctions as hallmark of heterogeneous disorders as mitochondrial/metabolic, cardiovascular, and age-associated diseases. Regulation of CoQ biosynthesis pathway is demonstrated to affect all steps of proteins production of this pathway, posttranslational modifications and protein-protein-lipid interactions inside mitochondria. There is a bi-directional relationship between CoQ and the epigenome in which not only the CoQ status determines the epigenetic regulation of many genes, but CoQ biosynthesis is also a target for epigenetic regulation, which adds another layer of complexity to the many pathways by which CoQ levels are regulated by environmental and developmental signals to fulfill its functions in eukaryotic aerobic metabolism.

The effect of different ubiquinones on lifespan in Caenorhabditis elegans

Ubiquinone (UQ, Coenzyme Q, CoQ) transfers electrons from complexes I and II to complex III in the mitochondrial electron transport chain. Depending on the degree of reduction, UQ can act as either a pro- or an antioxidant. Mutations disrupting ubiquinone synthesis increase lifespan in both the nematode (clk-1) and the mouse (mclk-1). The mutated nematodes survive using exogenous ubiquinone from bacteria, which has a shorter isoprenyl tail length (UQ(8)) than the endogenous nematode ubiquinone (UQ(9)). The mechanism underlying clk-1s increased longevity is not clear. Here we directly measure the effect of different exogenous ubiquinones on clk-1 lifespan and mitochondrial function. We fed clk-1 engineered bacteria that produced UQ(6), UQ(7), UQ(8), UQ(9) or UQ(10), and measured clk-1s lifespan, mitochondrial respiration, ROS production, and accumulated ROS damage to mitochondrial protein. Regardless of dietary UQ, clk-1 animals have increased lifespan, decreased mitochondrial respiration, and decreased ROS damage to mitochondrial protein than N2. However, clk-1 mitochondria did not produce less ROS than N2. The simplest explanation of our results is that clk-1 mitochondria scavenge ROS more effectively than wildtype due to the presence of DMQ(9). Moreover, when compared to other dietary quinones, UQ(10) further decreased mitochondrial oxidative damage and extended adult lifespan in clk-1.

Analysis of ubiquinones, dolichols, and dolichol diphosphate-oligosaccharides by liquid chromatography-electrospray ionization-mass spectrometry

Prenols, a class of lipids formed by the condensation of five carbon isoprenoids, have important roles in numerous metabolic pathways of the eukaryotic cell. Prenols are found in the cell as free alcohols, such as dolichol, or can be attached to vitamins, as with the fat soluble vitamins. In addition, prenols such as farnesyl- and geranylgeranyl-diphosphate are substrates for the transfer of farnesyl and geranylgeranyl units to proteins with important implications for signal transduction within the cell. Dolichol phosphate- and dolichol diphosphate-linked sugars are central to the formation of the lipid-linked branched oligosaccharide, Dol-PP-(GlcNAc)2(Man)9(Glc)3, used for co-translational en bloc protein N-glycosylation in the lumen of the endoplasmic reticulum. Toward furthering our understanding of the role of prenol lipids in the cell, we have developed a method for the detection and quantification of dolichol and coenzyme Q by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). These methods, developed using the mouse macrophage RAW 264.7 tumor cells, are broadly applicable to other cell lines, tissues, bacteria, and yeast. We also present a new MS-based method for the detection and structural characterization of the intact dolichol diphosphate oligosaccharide Dol-PP-(GlcNAc)2 (Man)9(Glc)3 from porcine pancreas.

Mitochondrial respiration and reactive oxygen species in C. elegans

A powerful approach to understanding complex processes such as aging is to study longevity in organisms that are amenable to genetic dissection. The nematode Caenorhabditis elegans represents a superb model system in which to study the effects of mitochondrial function on longevity. Several mutant strains have been identified that indicate that mitochondrial function is a major factor affecting the organism's lifespan. Taken as a group, these mutant strains indicate that metabolic rate, per se, only affects longevity indirectly. Mutations causing lowered metabolic rate potential are capable of decreasing or increasing longevity.