Biochemistry (Moscow) (v.79, #10)
New data on programmed aging — slow phenoptosis by M. V. Skulachev; V. P. Skulachev (977-993).
This review summarizes the latest data on biochemistry and physiology of living organisms. These data suggest that aging, i.e. coordinated age-dependent weakening of many vital functions leading to gradual increase in the probability of dying, is not common to all organisms. Some species have been described whose probability of death does not depend on age or even decreases with age, this being accompanied by constant or increasing fertility. In the case of the naked mole rat (a non-aging mammal), a mechanism has been identified that protects this animal from cancer and the most common age-related diseases. The high molecular weight polysaccharide hyaluronan, a linear polymer composed of multiple repeated disaccharide of glucuronic acid and glucosamine, plays the key role in this mechanism. Hyaluronan is accumulated in the intercellular spaces in the organs and tissues of the naked mole rat. This polysaccharide provides early contact inhibition of cell division (anti-cancer effect). In addition, hyaluronan prevents the development of certain types of apoptosis, in particular, those induced by reactive oxygen species (ROS) (geroprotective effect preventing ROS-induced decrease in cellularity in the organs and tissues of aging organisms). Extraordinary longevity of the naked mole rat (over 30 years, which is long for a rodent the size of a mouse) is connected to its eusocial lifestyle, when only the “queen” and its few “husbands” breed, while the huge army of non-breeding “subordinates” provide the “royal family” with protection from predators, food, and construction and maintenance of an underground labyrinth size of a football field. This way of life removes the pressure of natural selection from the “family” and makes aging — the program that is counterproductive for the individual but increases “evolvability” of its offspring — unnecessary. The example of the naked mole rat demonstrates the optional character of the aging program for the organism. Many facts indicating that aging can be regulated by an organism provide another argument in favor of optionality of aging. Cases have been described when aging as a program useful for the evolution of offspring but counterproductive for the parental individual slows under conditions that threaten the very existence of the individual. These conditions include food restriction (the threat of death from starvation), heavy muscular work, decrease or increase in the environmental temperature, small amounts of poisons (including ROS; here we speak about the paradoxical geroprotective effect of the low doses of prooxidants that inhibit apoptosis). On the other hand, aging can be inhibited (and maybe even cancelled) artificially. This can be done by turning off the genes encoding the proteins participating in the aging program, such as FAT10, p66shc, and some others. In addition, the gene of the antioxidant enzyme catalase can be addressed into mitochondria, where it will split mitochondrial hydrogen peroxide, the level of which increases with age. However, today the simplest way to slow down the aging program is the use of mitochondria-targeted low molecular weight antioxidant compounds of plastoquinonyl decyltriphenylphosphonium-type (SkQ1), which prolong the life of animals, plants, and fungi and inhibit the development of many age-related diseases and symptoms.
Keywords: phenoptosis; aging program; geroprotectors; antioxidants; mitochondria; evolution
Receptor regulation of senile phenoptosis by M. V. Skulachev; F. F. Severin; V. P. Skulachev (994-1003).
Here we present a concept that considers organism aging as an additional facultative function promoting evolution, but counterproductive for an individual. We hypothesize that aging can be inhibited or even arrested when full mobilization of all resources is needed for the survival of an individual. We believe that the organism makes such a decision based on the analysis of signals of special receptors that monitor a number of parameters of the internal and external environment. The amount of available food is one of these parameters. Food restriction is perceived by the organism as a signal of coming starvation; in response to it, the organism inhibits its counterproductive programs, in particular, aging. We hypothesize that the level of protein obtained with food is estimated based on blood concentration of one of the essential amino acids (methionine), of carbohydrates — via glucose level, and fats — based on the level of one of the free fatty acids. When the amount of available food is sufficient, these receptors transmit the signal allowing aging. In case of lack of food, this signal is cancelled, and as a result aging is inhibited, i.e. age-related weakening of physiological functions is inhibited, and lifespan increases (the well-known geroprotective effect of partial food restriction). In Caenorhabditis elegans, lowering of the ambient temperature has a similar effect. This geroprotective effect is removed by the knockout of one of the cold receptors, and replacement of the C. elegans receptor by a similar human receptor restores the ability of low temperature to increase the lifespan of the nematode. A chain of events linking the receptor with the aging mechanism has been discovered in mice — for one of the pain receptors in neurons, the nerve endings of which entwine pancreas β-cells. Age-related activation of these receptors inhibits the work of insulin genes in β-cells. Problems with insulin secretion lead to oxidative stress, chronic inflammation, and type II diabetes, which can be regarded as one of the forms of senile phenoptosis. In conclusion, we consider the role of some psychological factors in the regulation of the aging program.
Keywords: phenoptosis; aging; aging program regulation; food restriction; diabetes
The programmed aging paradigm: How we get old by Giacinto Libertini (1004-1016).
According to the traditional explanations (“old paradigm”), aging is due to the progressive accumulation of heterogeneous damages that are insufficiently contrasted by natural selection. An opposite interpretation (“new paradigm”) sees aging as selectively advantageous in terms of supra-individual natural selection, and this implies the indispensable existence of genetically controlled specific mechanisms that determine it. The aim of this work is to expound synthetically the progressive alterations that mark the aging by showing how these changes are clearly defined and regulated by genes. The possibility of such a description, based on sound evidence, is an essential element for the plausibility of the new paradigm, and a fundamental argument against the tenability of the old paradigm.
Keywords: aging; phenoptosis; programmed aging paradigm; non-programmed aging paradigm; cell turnover; cell senescence; Alzheimer; ARMD
Microbiota and mitobiota. Putting an equal sign between mitochondria and bacteria by D. B. Zorov; E. Y. Plotnikov; D. N. Silachev; L. D. Zorova; I. B. Pevzner; S. D. Zorov; V. A. Babenko; S. S. Jankauskas; V. A. Popkov; P. S. Savina (1017-1031).
The recent revival of old theories and setting them on modern scientific rails to a large extent are also relevant to mitochondrial science. Given the widespread belief that mitochondria are symbionts of ancient bacterial origin, the processes inherent to mitochondrial physiology can be revised based on their comparative analysis with possible involvement of bacteria. Such comparison combined with discussion of the role of microbiota in pathogenesis allows discussion of the role of “mitobiota” (we introduce this term) as the combination of different phenotypic manifestations of mitochondria in the organism reflecting pathological changes in the mitochondrial genome. When putting an equal sign between mitochondria and bacteria, we find similarity between the mitochondrial and bacterial theories of cancer. The presence of the term “bacterial infection” suggests “mitochondrial infection”, and mitochondrial (oxidative) theory of aging can in some way be transformed into a “bacterial theory of aging”. The possible existence of such processes and the data confirming their presence are discussed in this review. If such a comparison has the right to exist, the homeostasis of “mitobiota” is of not lesser physiological importance than homeostasis of microbiota, which has been so intensively discussed recently.
Keywords: mitochondria; ultrastructure; bacteria; microbiota; mitobiota; mitohormesis; diseases; inflammation; cancer; infection; aging; death; phenoptosis
Phenoptosis in arthropods and immortality of social insects by V. M. Kartsev (1032-1048).
In general, there are no drastic differences in phenoptosis patterns in plant and animal organisms. However, there are some specific features characteristic for insects and other arthropods: 1) their development includes metamorphosis with different biochemical laws at consecutive developmental stages; 2) arthropods can reduce or stop development and aging when in a state of diapause or temporal cold immobility; 3) their life cycle often correlates with seasonal changes of surroundings; 4) polymorphism is widespread — conspecifics differ by their lifespans and phenoptosis features; 5) lifespan-related sexual dimorphism is common; 6) significant situational plasticity of life cycle organization is an important feature; for example, the German wasp (Paravespula germanica) is obligatorily univoltine in the temperate zone, while in tropical regions its lifespan increases and leads to repeated reproduction; 7) life cycles of closely related species may differ significantly, for example, in contrast to German wasp, some tropical hornets (Vespa) have only one reproduction period. Surprisingly, many insect species have been shown to be subjected to gradual aging and phenoptosis, like the highest mammals. However, queens of social insects and some long-lived arachnids can apparently be considered non-aging organisms. In some species, lifespan is limited to one season, while others live much longer or shorter. Cases of one-time reproduction are rather rare. Aphagia is common in insects (over 10,000 species). Cannibalism is an important mortality factor in insects as well as in spiders. In social insects, which exist only in colonies (families), the lifetime of a colony can be virtually unlimited. However, in case of some species the developmental cycle and death of a colony after its completion are predetermined. Most likely, natural selection in insects does not lengthen individual lifespan, but favors increase in reproduction efficiency based on fast succession of generations leading to increased evolvability.
Keywords: phenoptosis; aging; arthropods; social insects; immortality
Modern evolutionary mechanics theories and resolving the programmed/non-programmed aging controversy by Theodore C. Goldsmith (1049-1055).
Modern programmed (adaptive) theories of biological aging contend that organisms including mammals have generally evolved mechanisms that purposely limit their lifespans in order to obtain an evolutionary benefit. Modern non-programmed theories contend that mammal aging generally results from natural deteriorative processes, and that lifespan differences between species are explained by differences in the degree to which they resist those processes. Originally proposed in the 19th century, programmed aging in mammals has historically been widely summarily rejected as obviously incompatible with the mechanics of the evolution process. However, relatively recent and continuing developments described here have dramatically changed this situation, and programmed mammal aging now has a better evolutionary basis than non-programmed aging. Resolution of this issue is critically important to medical research because the two theories predict that very different biological mechanisms are ultimately responsible for age-related diseases and conditions.
Keywords: aging; senescence; evolution; programmed aging
Decrease in ATP biosynthesis and dysfunction of biological membranes. Two possible key mechanisms of phenoptosis by A. V. Rzheshevsky (1056-1068).
Metabolic syndrome is extremely prevalent in the world and can be considered as one of main factors leading to accelerated aging and premature death. This syndrome may be closely linked with age-related disruptions in hypothalamic-pituitary system function, which perhaps represent a trigger mechanism of development of endocrine and cardiovascular pathologies. Age-related elevation of the sensitivity threshold of the hypothalamus to regulatory signals in association with low mobility and excessive diet trigger a cascade of biochemical reactions that might be used for activation of programmed death of the organism — phenoptosis. Accumulation of fatty acids in a cell and resulting lipotoxicity include resistance to insulin and leptin, endoplasmic reticulum stress, uncoupling of oxidation and phosphorylation, and dysfunction of biological membranes. Decrease in ATP synthesis is correlated with accumulation of calcium ions in cells, dysfunction of mitochondria, and increasing apoptotic activity. Age-related activation of mTOR (which is greatly influenced by excess energy substrates) has deleterious impact on one of the main mechanisms of cell defense by which defective mitochondria are replaced: mitophagy and biogenesis of mitochondria will be suppressed, and this will increase in greater degree mitochondrial dysfunction and oxidative stress. Fatty acid-induced inflammation will increase activity of nuclear factor NF-κB, the well-known stimulator of age-related pathologies. The final stage of phenoptosis can be represented by endothelium dysfunction related with oxidative stress, insulin resistance, and the most prevalent cardiovascular pathologies.
Keywords: fatty acids; leptin; insulin; AMP-activated protein kinase; mTOR; oxidative stress; apoptosis; phenoptosis; biomembranes dysfunction; mitochondria; endoplasmic reticulum
Pineal gland as an endocrine gravitational lunasensor: Manifestation of moon-phase dependent morphological changes in mice by A. V. Gerasimov; V. P. Kostyuchenko; A. S. Solovieva; A. M. Olovnikov (1069-1074).
We found that some morphological properties of the pineal gland and submandibular salivary gland of mice are significantly distinct at the new and full moon. We suppose that the differences are initiated by the displacements of the electron-dense concretions in the secretory vesicles of pinealocytes. This presumably occurs under the influence of the gravitational field, which periodically changes during different phases of the moon. It seems that the pinealocyte is both an endocrine and gravisensory cell. A periodic secretion of the pineal gland probably stimulates, in a lunaphasic mode, the neuroendocrine system that, in turn, periodically exerts influence on different organs of the body. The observed effect probably serves, within the lifelong clock of a brain, to control development and aging in time.
Keywords: pinealocytes; electron-dense concretions in secretory vesicles; lunaphasic changes of cell morphology
The problem of determination of cause of laboratory animal’s death: A critical review of definitions of “fatal” and “incidental” lesions by V. N. Manskikh (1075-1080).
The determination of the cause of a laboratory animal’s death in gerontological experiments has become extraordinarily urgent in connection with the appearance of ideas on the programmed death of organisms. Unfortunately, the past approach to diagnosis of fatal and incidental changes based only on data of autopsy and histopathology (according to the human pathology model) is not correct for laboratory rodents. Nevertheless, the exact determination of death causes is principally possible in the future under conditions of adequate experimental design (including a large set of clinical, physiological, biochemical, and morphological examinations). However, it seems that even in this case causes of some experimental animal’s death will remain unclear.
Keywords: causes of death; pathology; laboratory animals
Prevention of peroxidation of cardiolipin liposomes by quinol-based antioxidants by A. V. Lokhmatikov; N. E. Voskoboynikova; D. A. Cherepanov; N. V. Sumbatyan; G. A. Korshunova; M. V. Skulachev; H. -J. Steinhoff; V. P. Skulachev; A. Y. Mulkidjanian (1081-1100).
In mammalian mitochondria, cardiolipin molecules are the primary targets of oxidation by reactive oxygen species. The interaction of oxidized cardiolipin molecules with the constituents of the apoptotic cascade may lead to cell death. In the present study, we compared the effects of quinol-containing synthetic and natural amphiphilic antioxidants on cardiolipin peroxidation in a model system (liposomes of bovine cardiolipin). We found that both natural ubiquinol and synthetic antioxidants, even being introduced in micro- and submicromolar concentrations, fully protected the liposomal cardiolipin from peroxidation. The duration of their action, however, varied; it increased with the presence of either methoxy groups of ubiquinol or additional reduced redox groups (in the cases of rhodamine and berberine derivates). The concentration of ubiquinol in the mitochondrial membrane substantially exceeds the concentrations of antioxidants we used and would seem to fully prevent peroxidation of membrane cardiolipin. In fact, this does not happen: cardiolipin in mitochondria is oxidized, and this process can be blocked by amphiphilic cationic antioxidants (Y. N. Antonenko et al. (2008) Biochemistry (Moscow), 73, 1273–1287). We suppose that a fraction of mitochondrial cardiolipin could not be protected by natural ubiquinol; in vivo, peroxidation most likely threatens those cardiolipin molecules that, being bound within complexes of membrane proteins, are inaccessible to the bulky hydrophobic ubiquinol molecules diffusing in the lipid bilayer of the inner mitochondrial membrane. The ability to protect these occluded cardiolipin molecules from peroxidation may explain the beneficial therapeutic action of cationic antioxidants, which accumulate electrophoretically within mitochondria under the action of membrane potential.
Keywords: apoptosis; respiratory supercomplexes; reactive oxygen species; penetrating cations; plastoquinol; SkQ1
Preventive and therapeutic effects of SkQ1-containing Visomitin eye drops against light-induced retinal degeneration by Yu. P. Novikova; O. S. Gancharova; O. V. Eichler; P. P. Philippov; E. N. Grigoryan (1101-1110).
The human retina is constantly affected by light of varying intensity, this being especially true for photoreceptor cells and retinal pigment epithelium. Traditionally, photoinduced damages of the retina are induced by visible light of high intensity in albino rats using the LIRD (light-induced retinal degeneration) model. This model allows study of pathological processes in the retina and the search for retinoprotectors preventing retinal photodamage. In addition, the etiology and mechanisms of retina damage in the LIRD model have much in common with the mechanisms of the development of age-related retinal disorders, in particular, with age-related macular degeneration (AMD). We have studied preventive and therapeutic effects of Visomitin eye drops (based on the mitochondria-targeted antioxidant SkQ1) on albino rat retinas damaged by bright light. In the first series of experiments, rats receiving Visomitin for two weeks prior to illumination demonstrated significantly less expressed atrophic and degenerative changes in the retina compared to animals receiving similar drops with no SkQ1. In the second series, the illuminated rats were treated for two weeks with Visomitin or similar drops without SkQ1. The damaged retinas of the experimental animals were repaired much more effectively than those of the control animals. Therefore, we conclude that Visomitin SkQ1-containing eye drops have pronounced preventive and therapeutic effects on the photodamaged retina and might be recommended as a photoprotector and a pharmaceutical preparation for the treatment of AMD in combination with conventional medicines.
Keywords: retina; photoreceptors; photodamage; SkQ1; Visomitin
Mitochondria-targeted antioxidant SkQ1 accelerates maturation in Campbell dwarf hamsters (Phodopus campbelli) by K. A. Rogovin; A. M. Khrushcheva; O. N. Shekarova; M. V. Ushakova; V. N. Manskikh; N. Yu. Vasilieva (1111-1116).
We tested two hypotheses. 1) SkQ1 positively affects postnatal development of hamsters in litters born to parents receiving long-term SkQ1 treatment. 2) SkQ1 accelerates maturation of juvenile females receiving the antioxidant treatment from 10 days of age. Parental pairs were kept in an outdoor vivarium under conditions close to natural. At the age of 25 days, juvenile males in litters born to parents treated daily with SkQ1 (50 nmol/kg per os) had higher epididymis mass. Both the size of a litter and SkQ1 affected epididymis mass in young males. Both the litter size and SkQ1 affected uterus mass in 25-day-old females. Juvenile females who received SkQ1 treatment from 10 days of age demonstrated earlier opening of the vagina. This experiment was replicated with the same result. At the age of 2.5 months, virgin females treated with SkQ1 from the early age demonstrated higher ovary mass.
Keywords: SkQ1; antioxidants; mitochondria; maturation; lifespan; Campbell dwarf hamsters
Effects of mitochondria-targeted plastoquinone derivative antioxidant (SkQ1) on demography of free-breeding Campbell dwarf hamsters (Phodopus campbelli) kept in outdoor conditions. Reproduction and lifespan: Explanation in the framework of ultimate loads by K. A. Rogovin; A. M. Khrushcheva; O. N. Shekarova; M. V. Ushakova; V. N. Manskikh; O. V. Sokolova; N. Yu. Vasilieva (1117-1129).
We studied demographic effects of the mitochondria-targeted antioxidant SkQ1 on free-breeding Campbell dwarf hamsters (Phodopus campbelli, Thomas, 1905, Rodentia, Cricetidae) in an outdoor vivarium with seasonally varying day length and temperatures. The animals were kept in pairs from their young age. We removed litters from parental cages at their age of 25 days. Experimental hamsters received daily 50 nmol/kg SkQ1 with water by oral dosing, whereas control animals received water. SkQ1 had no effect on the lifespan of either males or females in reproductive pairs. Mortality among females was higher than among males irrespective of SkQ1 treatment, this being related to higher costs of reproduction in females. However, SkQ1 accelerated breeding in pairs in the first half of the reproductive period of a year. Although there were no statistical differences in body mass of males and females between experimental and control animals during most of their life, SkQ1-receiving males had higher body mass at the end of their life. The opposite tendency was characteristic for old females. One-year-old males and females of the experimental and control groups showed no difference in intensity of immune response to sheep red blood cells. The dermal hypersensitivity response to phytohemagglutinin (test for T-cell immunity) was significantly higher in SkQ1-treated 1- and 1.5-year-old males. This was not true for females. There was a tendency toward increased density of the neutrophil population in blood in 1-year-old SkQ1-treated males. However, experimental males showed no difference from control males in the activity of the “peroxidase-endogenous hydrogen peroxide system” of neutrophils. The background level of stress estimated by the concentration of cortisol in blood serum was significantly lower in the SkQ1-treated males during autumn adaptive adjustment of the organism. A similar trend was also observed during the January frosts, when the background level of stress was rather high. We observed no differences between cortisol concentration in experimental and control animals during the reproductive period in early spring and mid-summer. We tend to interpret the absence of geroprotective effect of SkQ1 on free-breeding dwarf hamsters by its ability to intensify breeding. We previously demonstrated the ability of SkQ1 to increase the lifespan of non-breeding females.
Keywords: SkQ1; antioxidants; mitochondria; aging; lifespan; fecundity; Campbell dwarf hamster
Therapeutic doses of SkQ1 do not induce cytochromes P450 in rat liver by K. N. Myasoedova; D. N. Silachev (1130-1132).
The effect of SkQ1 (a mitochondria-targeted antioxidant) on the level of cytochromes P450 in rat liver was studied. It was found that administration of therapeutic dose of SkQ1 with drinking water for 5 days (250 nmol/kg of body weight per day) did not alter the level of cytochromes P450. Under the same conditions, the standard dose of phenobarbital used for the induction of cytochromes P450 caused the 2.7-fold increase in the content of these cytochromes. We conclude that therapeutic doses of SkQ1 do not induce cytochromes P450 in rats.
Keywords: cytochrome P450; mitochondria-targeted antioxidant; SkQ1
Aging is a simple deprivation syndrome driven by a quasi-programmed preventable and reversible drift of control system set points due to inappropriate organism-environment interaction by A. V. Khalyavkin; V. N. Krutko (1133-1135).
There are two well-known but opposing concepts of the reason for aging. The first supposes that senescence is programmed similarly to the genetic program of development from a zygote up to a mature organism. Genetically determined senile wasting is thought to be associated with the necessity to renovate the population to ensure its adaptation and survival. According to the concept of the stochastic aging (due to accumulation of occasional error and damage), there is no built-in program of aging. There is only a program of development up to the state of maturity, and then the organism should be able to maintain itself limitlessly. However, although the efficiency of repair systems is assumed to be rather high, it is less than 100%. Just this has to result in aging because of accumulation of various errors. We have continued and developed another approach that considers both programmed and stochastic concepts to be incorrect. Aging is a simple deprivation syndrome driven by preventable and even reversible drifts of control systems set points because of an inappropriate “organism-environment” interaction.
Keywords: plasticity of aging; environmental influences; cause of aging; retardation of senescence; self-maintenance; reversibility of aging
Effect of the mitochondria-targeted antioxidant SkQ1 on development of spontaneous tumors in BALB/c mice by V. N. Manskikh; M. S. Krasilshchikova; V. A. Vygodin; M. V. Egorov (1136-1139).
The mitochondria-targeted antioxidant SkQ1 (10-(6′-plastoquinonyldecyl)triphenylphosphonium) is a new pharmaceutical substance with a wide spectrum of effects including increase in lifespan of laboratory animals (for example, of BALB/c mice males) and inhibition of development of some experimental tumors and also of tumor cell growth. In this work, the effects of SkQ1 on development of spontaneous tumors in female and male BALB/c mice housed in an SPF-class vivarium were studied. We found that the addition of SkQ1 to drinking water at the dose of 1 and 30 nmol/kg body weight per day throughout the lifespan modified the spectrum of spontaneous tumors in the female mice, decreasing the incidence of follicular lymphomas. SkQ1 at the dose of 1 nmol/kg per day also suppressed the dissemination of these neoplasms, but it did not significantly influence the overall incidence of benign and malignant tumors (including primary multiple tumors) or the lifespan of the tumor-bearing mice (both males and females). Hence, the previously described ability of SkQ1 to increase the lifespan of laboratory BALB/c mice is not related to its anticarcinogenic activity.
Keywords: mitochondria-targeted antioxidants; SkQ1; spontaneous tumors; BALB/c mice