Age-dependent declines in proteasome activity in the heart

Adaptive homeostasis and the free radical theory of ageing

The Free Radical Theory of Ageing, was first proposed by Denham Harman in the mid-1950's, based largely on work conducted by Rebeca Gerschman and Daniel Gilbert. At its core, the Free Radical Theory of Ageing posits that free radical and related oxidants, from the environment and internal metabolism, cause damage to cellular constituents that, over time, result in an accumulation of structural and functional problems. Several variations on the original concept have been advanced over the past six decades, including the suggestion of a central role for mitochondria-derived reactive species, and the proposal of an age-related decline in the effectiveness of protein, lipid, and DNA repair systems. Such innovations have helped the Free Radical Theory of Aging to achieve widespread popularity. Nevertheless, an ever-growing number of apparent 'exceptions' to the Theory have seriously undermined its acceptance. In part, we suggest, this has resulted from a rather simplistic experimental approach of knocking-out, knocking-down, knocking-in, or overexpressing antioxidant-related genes to determine effects on lifespan. In some cases such experiments have yielded results that appear to support the Free Radical Theory of Aging, but there are just as many published papers that appear to contradict the Theory. We suggest that free radicals and related oxidants are but one subset of stressors with which all life forms must cope over their lifespans. Adaptive Homeostasis is the mechanism by which organisms dynamically expand or contract the homeostatic range of stress defense and repair systems, employing a veritable armory of signal transduction pathways (such as the Keap1-Nrf2 system) to generate a complex profile of inducible and enzymatic protection that best fits the particular need. Viewed as a component of Adaptive Homeostasis, the Free Radical Theory of Aging appears both viable and robust.

Unexpected metabolic disorders induced by endocrine disruptors in Xenopus tropicalis provide new lead for understanding amphibian decline

Despite numerous studies suggesting that amphibians are highly sensitive to endocrine disruptors (EDs), both their role in the decline of populations and the underlying mechanisms remain unclear. This study showed that frogs exposed throughout their life cycle to ED concentrations low enough to be considered safe for drinking water, developed a prediabetes phenotype and, more commonly, a metabolic syndrome. Female Xenopus tropicalis exposed from tadpole stage to benzo(a)pyrene or triclosan at concentrations of 50 ng⋅L-1 displayed glucose intolerance syndrome, liver steatosis, liver mitochondrial dysfunction, liver transcriptomic signature, and pancreatic insulin hypersecretion, all typical of a prediabetes state. This metabolic syndrome led to progeny whose metamorphosis was delayed and occurred while the individuals were both smaller and lighter, all factors that have been linked to reduced adult recruitment and likelihood of reproduction. We found that F1 animals did indeed have reduced reproductive success, demonstrating a lower fitness in ED-exposed Xenopus Moreover, after 1 year of depuration, Xenopus that had been exposed to benzo(a)pyrene still displayed hepatic disorders and a marked insulin secretory defect resulting in glucose intolerance. Our results demonstrate that amphibians are highly sensitive to EDs at concentrations well below the thresholds reported to induce stress in other vertebrates. This study introduces EDs as a possible key contributing factor to amphibian population decline through metabolism disruption. Overall, our results show that EDs cause metabolic disorders, which is in agreement with epidemiological studies suggesting that environmental EDs might be one of the principal causes of metabolic disease in humans.

Protein aggregates and proteostasis in aging: Amylin and β-cell function

The ubiquitin-proteasomal-system (UPS) and the autophagy-lysosomal-system (ALS) are both highly susceptible for disturbances leading to the accumulation of cellular damage. A decline of protein degradation during aging results in the formation of oxidatively damaged and aggregated proteins finally resulting in failure of cellular functionality. Besides protein aggregation in response to oxidative damage, amyloids are a different type of protein aggregates able to distract proteostasis and interfere with cellular functionality. Amyloids are clearly linked to the pathogenesis of age-related degenerative diseases such as Alzheimer's disease. Human amylin is one of the peptides forming fibrils in β-sheet conformation finally leading to amyloid formation. In contrast to rodent amylin, human amylin is prone to form amyloidogenic aggregates, proposed to play a role in the pathogenesis of Type 2 Diabetes by impairing β-cell functionality. Since aggregates such as lipofuscin and β-amyloid are known to impair proteostasis, it is likely to assume similar effects for human amylin. In this review, we focus on the effects of IAPP on UPS and ALS and their role in amylin degradation, since both systems play a crucial role in maintaining proteome balance thereby influencing, at least in part, cellular fate and aging.

Axonal Degeneration during Aging and Its Functional Role in Neurodegenerative Disorders

Aging constitutes the main risk factor for the development of neurodegenerative diseases. This represents a major health issue worldwide that is only expected to escalate due to the ever-increasing life expectancy of the population. Interestingly, axonal degeneration, which occurs at early stages of neurodegenerative disorders (ND) such as Alzheimer's disease, Amyotrophic lateral sclerosis, and Parkinson's disease, also takes place as a consequence of normal aging. Moreover, the alteration of several cellular processes such as proteostasis, response to cellular stress and mitochondrial homeostasis, which have been described to occur in the aging brain, can also contribute to axonal pathology. Compelling evidence indicate that the degeneration of axons precedes clinical symptoms in NDs and occurs before cell body loss, constituting an early event in the pathological process and providing a potential therapeutic target to treat neurodegeneration before neuronal cell death. Although, normal aging and the development of neurodegeneration are two processes that are closely linked, the molecular basis of the switch that triggers the transition from healthy aging to neurodegeneration remains unrevealed. In this review we discuss the potential role of axonal degeneration in this transition and provide a detailed overview of the literature and current advances in the molecular understanding of the cellular changes that occur during aging that promote axonal degeneration and then discuss this in the context of ND.

Insulin-like growth factor-1 signaling in cardiac aging

Cardiovascular disease (CVD) is the leading cause of death in most developed countries. Aging is associated with enhanced risk of CVD. Insulin-like growth factor-1 (IGF-1) binds to its cognate receptor, IGF-1 receptor (IGF-1R), and exerts pleiotropic effects on cell growth, differentiation, development, and tissue repair. Importantly, IGF-1/IGF-1R signaling is implicated in cardiac aging and longevity. Cardiac aging is an intrinsic process that results in cardiac dysfunction, accompanied by molecular and cellular changes. In this review, we summarize the current state of knowledge regarding the link between the IGF-1/IGF-1R system and cardiac aging. The biological effects of IGF-1R and insulin receptor will be discussed and compared. Furthermore, we describe data regarding how deletion of IGF-1R in cardiomyocytes of aged knockout mice may delay the development of senescence-associated myocardial pathologies. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.

FOXO Transcriptional Factors and Long-Term Living

Several pathologies such as neurodegeneration and cancer are associated with aging, which is affected by many genetic and environmental factors. Healthy aging conceives human longevity, possibly due to carrying the defensive genes. For instance, FOXO (forkhead box O) genes determine human longevity. FOXO transcription factors are involved in the regulation of longevity phenomenon via insulin and insulin-like growth factor signaling. Only one FOXO gene (FOXO DAF-16) exists in invertebrates, while four FOXO genes, that is, FOXO1, FOXO3, FOXO4, and FOXO6 are found in mammals. These four transcription factors are involved in the multiple cellular pathways, which regulate growth, stress resistance, metabolism, cellular differentiation, and apoptosis in mammals. However, the accurate mode of longevity by FOXO factors is unclear until now. This article describes briefly the existing knowledge that is related to the role of FOXO factors in human longevity.

SIPS as a model to study age-related changes in proteolysis and aggregate formation

Aging is accompanied by the accumulation of cellular damage over time in response to stress, lifestyle and environmental factors ultimately leading to age-related diseases and death. Additionally, the number of senescent cells increases with age. Senescence is most likely not a static endpoint, it represents a series of hallmarks including morphological changes, alterations in protein turnover and accumulation of protein aggregates. The importance of protein oxidation and aggregate accumulation in the progression of aging is not yet fully understood and research to what extent the accumulation of oxidized proteins has an effect on senescence and the aging process is still ongoing. To study the mechanisms of aging, the impact of senescence and the role of protein aggregates on the aging process, cell culture models are useful tools. Most notably stress induced premature senescence (SIPS) models have contributed to the identification of mechanisms involved in the aging process and helped unravel the age-related changes in proteolysis and the importance of protein aggregation. Here we review characteristics of replicative and premature senescence, how to induce most frequently used senescence models and gained knowledge on age-related changes in the major proteolytic systems.

Proteostasis, oxidative stress and aging

The production of reactive species is an inevitable by-product of metabolism and thus, life itself. Since reactive species are able to damage cellular structures, especially proteins, as the most abundant macromolecule of mammalian cells, systems are necessary which regulate and preserve a functional cellular protein pool, in a process termed “proteostasis”. Not only the mammalian protein pool is subject of a constant turnover, organelles are also degraded and rebuild. The most important systems for these removal processes are the “ubiquitin-proteasomal system” (UPS), the central proteolytic machinery of mammalian cells, mainly responsible for proteostasis, as well as the “autophagy-lysosomal system”, which mediates the turnover of organelles and large aggregates.

Many age-related pathologies and the aging process itself are accompanied by a dysregulation of UPS, autophagy and the cross-talk between both systems. This review will describe the sources and effects of oxidative stress, preservation of cellular protein- and organelle-homeostasis and the effects of aging on proteostasis in mammalian cells.

Vascular ageing: Underlying mechanisms and clinical implications

Epidemiological studies have shown that ageing is a major non-reversible risk factor for cardiovascular disease. Vascular ageing starts early in life and is characterized by a gradual change of vascular structure and function resulting in increased arterial stiffening. At the present review we discuss the role of the most important molecular pathways involved in vascular ageing, their association with arterial stiffening and possible novel therapeutic targets that may delay this otherwise irreversible degenerating process. Specifically, we discuss the role of oxidative stress, telomere shortening, and ubiquitin proteasome system in endothelial cell senescence and dysfunction in vascular inflammation and in arterial stiffening. Further, we summarize the most important molecular mechanisms regulating vascular ageing including sirtuin 1, telomerase, klotho, JunD, and amyloid beta 1-40 peptide.

The age- and sex-specific decline of the 20s proteasome and the Nrf2/CncC signal transduction pathway in adaption and resistance to oxidative stress in Drosophila melanogaster

Hallmarks of aging include loss of protein homeostasis and dysregulation of stress-adaptive pathways. Loss of adaptive homeostasis, increases accumulation of DNA, protein, and lipid damage. During acute stress, the Cnc-C (Drosophila Nrf2 orthologue) transcriptionally-regulated 20S proteasome degrades damaged proteins in an ATP-independent manner. Exposure to very low, non-toxic, signaling concentrations of the redox-signaling agent hydrogen peroxide (H2O2) cause adaptive increases in the de novo expression and proteolytic activity/capacity of the 20S proteasome in female D. melanogaster (fruit-flies). Female 20S proteasome induction was accompanied by increased tolerance to a subsequent normally toxic but sub-lethal amount of H2O2, and blocking adaptive increases in proteasome expression also prevented full adaptation. We find, however, that this adaptive response is both sex- and age-dependent. Both increased proteasome expression and activity, and increased oxidative-stress resistance, in female flies, were lost with age. In contrast, male flies exhibited no H2O2 adaptation, irrespective of age. Furthermore, aging caused a generalized increase in basal 20S proteasome expression, but proteolytic activity and adaptation were both compromised. Finally, continual knockdown of Keep1 (the cytosolic inhibitor of Cnc-C) in adults resulted in older flies with greater stress resistance than their age-matched controls, but who still exhibited an age-associated loss of adaptive homeostasis.

Proteasome dysfunction in cardiomyopathies

The ubiquitin-proteasome system (UPS) plays a critical role in removing unwanted intracellular proteins and is involved in protein quality control, signalling and cell death. Because the heart is subject to continuous metabolic and mechanical stress, the proteasome plays a particularly important role in the heart, and proteasome dysfunction has been suggested as a causative factor in cardiac dysfunction. Proteasome impairment has been detected in cardiomyopathies, heart failure, myocardial ischaemia, and hypertrophy. Proteasome inhibition is also sufficient to cause cardiac dysfunction in healthy pigs, and patients using a proteasome inhibitor for cancer therapy have a higher incidence of heart failure. In this Topical Review we discuss the experimental data which suggest UPS dysfunction is a common feature of cardiomyopathies, with an emphasis on hypertrophic cardiomyopathy caused by sarcomeric mutations. We also propose potential mechanisms by which cardiomyopathy-causing mutations may lead to proteasome impairment, such as altered calcium handling and increased oxidative stress due to mitochondrial dysfunction.

Modest overexpression of FOXO maintains cardiac proteostasis and ameliorates age-associated functional decline

Heart performance declines with age. Impaired protein quality control (PQC), due to reduced ubiquitin‐proteasome system (UPS) activity, autophagic function, and/or chaperone‐mediated protein refolding, contributes to cardiac deterioration. The transcription factor FOXO participates in regulating genes involved in PQC, senescence, and numerous other processes. Here, a comprehensive approach, involving molecular genetics, novel assays to probe insect cardiac physiology, and bioinformatics, was utilized to investigate the influence of heart‐restricted manipulation of dFOXO expression in the rapidly aging Drosophila melanogaster model. Modest dFOXO overexpression was cardioprotective, ameliorating nonpathological functional decline with age. This was accompanied by increased expression of genes associated predominantly with the UPS, relative to other PQC components, which was validated by a significant decrease in ubiquitinated proteins. RNAi knockdown of UPS candidates accordingly compromised myocardial physiology in young flies. Conversely, excessive dFOXO overexpression or suppression proved detrimental to heart function and/or organismal development. This study highlights D. melanogaster as a model of cardiac aging and FOXO as a tightly regulated mediator of proteostasis and heart performance over time.

Mechanistic insights into the impact of Cold Atmospheric Pressure Plasma on human epithelial cell lines

Compelling evidence suggests that Cold Atmospheric Pressure Plasma (CAPP) has potential as a new cancer therapy. However, knowledge about cellular signaling events and toxicity subsequent to plasma treatment is still poorly documented. The aim of this study was to focus on the interaction between 3 different types of plasma (He, He-O₂, He-N₂) and human epithelial cell lines to gain better insight into plasma-cell interaction. We provide evidence that reactive oxygen and nitrogen species (RONS) are inducing cell death by apoptosis and that the proteasome, a major intracellular proteolytic system which is important for tumor cell growth and survival, is a target of (He or He-N₂) CAPP. However, RONS are not the only actors involved in cell death; electric field and charged particles could play a significant role especially for He-O₂ CAPP. By differential label-free quantitative proteomic analysis we found that CAPP triggers antioxidant and cellular defense but is also affecting extracellular matrix in keratinocytes. Moreover, we found that malignant cells are more resistant to CAPP treatment than normal cells. Taken together, our findings provide insight into potential mechanisms of CAPP-induced proteasome inactivation and the cellular consequences of these events.

Happily (n)ever after: Aging in the context of oxidative stress, proteostasis loss and cellular senescence

Aging is a complex phenomenon and its impact is becoming more relevant due to the rising life expectancy and because aging itself is the basis for the development of age-related diseases such as cancer, neurodegenerative diseases and type 2 diabetes. Recent years of scientific research have brought up different theories that attempt to explain the aging process. So far, there is no single theory that fully explains all facets of aging. The damage accumulation theory is one of the most accepted theories due to the large body of evidence found over the years. Damage accumulation is thought to be driven, among others, by oxidative stress. This condition results in an excess attack of oxidants on biomolecules, which lead to damage accumulation over time and contribute to the functional involution of cells, tissues and organisms. If oxidative stress persists, cellular senescence is a likely outcome and an important hallmark of aging. Therefore, it becomes crucial to understand how senescent cells function and how they contribute to the aging process. This review will cover cellular senescence features related to the protein pool such as morphological and molecular hallmarks, how oxidative stress promotes protein modifications, how senescent cells cope with them by proteostasis mechanisms, including antioxidant enzymes and proteolytic systems. We will also highlight the nutritional status of senescent cells and aged organisms (including human clinical studies) by exploring trace elements and micronutrients and on their importance to develop strategies that might increase both, life and health span and postpone aging onset.

Response of the Nitric Oxide System to Hypobaric Hypoxia in the Aged Striatum

BACKGROUND

Nitric oxide (NO) appears to play a key role in the hypoxic injury to the brain. We have previously reported that hypoxia/reoxygenation downregulated NO synthases (NOS) in the adult striatum. Until now, no data were available concerning the influence of aging in conjunction with hypoxia/reoxygenation on the NO system in the striatum.

OBJECTIVE

The aim of this study was to assess the role of the NO pathway in the hypoxic aged striatum.

METHODS

Wistar rats 24-25 months old were submitted to hypobaric hypoxia (20 min)/reoxygenation (0 h, 24 h, 5 days). Expression (PCR, immunohistochemistry/image analysis) and activity (NADPH-diaphorase/image analysis) of NOS isoforms (neuronal NOS or nNOS, endothelial NOS or eNOS, inducible NOS or iNOS) were analyzed together with nitrated protein expression (immunohistochemistry/image analysis). NO levels were indirectly quantified as nitrates/nitrites (NOx).

RESULTS

The mRNA levels of NOS isoforms were undetectable at 0 h after hypoxia in the striatum compared to the control. At later reoxygenation times, nNOS mRNA decreased, while eNOS mRNA augmented. Protein levels of nNOS and eNOS rose at 24 h after hypoxia, and iNOS protein increased at 5 days. NOx levels remained unchanged, whereas in situ NOS activity and protein nitration diminished during reoxygenation in the aged striatum.

CONCLUSION

The aged striatum may overexpress NOS isoforms as a neuroprotective-adaptive mechanism to hypoxia. However, this mechanism may not work properly in the aged striatum, since no changes in NO levels were detected after hypoxia. This may be related to the low activity of NOS isoforms in the hypoxic striatum.

Tuning the proteasome to brighten the end of the journey

Degradation by the proteasome is the fate for a large portion of cellular proteins, and it plays a major role in maintaining protein homeostasis, as well as in regulating many cellular processes like cell cycle progression. A decrease in proteasome activity has been linked to aging and several age-related neurodegenerative pathologies and highlights the importance of the ubiquitin proteasome system regulation. While the proteasome has been traditionally viewed as a constitutive element of proteolysis, major studies have highlighted how different regulatory mechanisms can impact its activity. Importantly, alterations of proteasomal activity may have major impacts for its function and in therapeutics. On one hand, increasing proteasome activity could be beneficial to prevent the age-related downfall of protein homeostasis, whereas inhibiting or reducing its activity can prevent the proliferation of cancer cells.

Aging and SKN-1-dependent Loss of 20S Proteasome Adaptation to Oxidative Stress in C. elegans

Aging is marked by a collapse of protein homeostasis and deterioration of adaptive stress responses that often lead to disease. During aging, the induction of stress responses decline along with protein quality control. Here, we have shown that the ability to mount an adaptive response by pretreatment with minor oxidative stress is abrogated in aged Caenorhabditis elegans We have identified a defect in SKN-1 signaling sensitivity during aging and have also found an aging-related increase in basal proteasome expression and in vitro activity, however, adaptation of the 20S proteasome in response to stress is lost in old animals. Interestingly, increased activation of SKN-1 promotes stress resistance, but is unable to rescue declining adaptation during aging. Our data demonstrate that the aging-dependent decline in SKN-1 signaling negatively impacts adaptation of the 20S proteasome in response to acute oxidative stress.

Role of common sarcomeric gene polymorphisms in genetic susceptibility to left ventricular dysfunction

Mutations in sarcomeric genes are common genetic cause of cardiomyopathies. An intronic 25-bp deletion in cardiac myosin binding protein C (MYBPC3) at 3' region is associated with dilated and hypertrophic cardiomyopathies in Southeast Asia. However, the frequency of sarcomeric gene polymorphisms and associated clinical presentation have not been established with left ventricular dysfunction (LVD). Therefore, the aim of the present study was to explore the association of MYBPC3 25-bp deletion, titin (TTN) 18 bp I/D, troponin T type 2 (TNNT2) 5 bp I/D and myospryn K2906N polymorphisms with LVD. This study includes 988 consecutive patients with angiographically confirmed coronary artery disease (CAD) and 300 healthy controls. Among the 988 CAD patients, 253 with reduced left ventricle ejection fraction (LVEF≤45%) were categorized as LVD. MYBPC3 25-bp deletion, TTN 18 bp I/D and TNNT2 5 bp I/D polymorphisms were determined by direct polymerase chain reaction method, while myospryn K2906N polymorphism by TaqMan assay. Our results showed that MYBPC3 25-bp deletion polymorphism was significantly associated with elevated risk of LVD (LVEF <45) (healthy controls versus LVD: OR=3.85, P <0.001; and nonLVD versus LVD: OR=1.65, P = 0.035), while TTN 18 bp I/D, TNNT2 5 bp I/D and myospryn K2906N polymorphisms did not show any significant association with LVD. The results also showed that MYBPC3 25-bp deletion polymorphism was significantly associated with other parameters of LV remodelling, i.e. LV dimensions (LV end diastole dimension, LVEDD: P = 0.037 and LV end systolic dimension, LVESD: P = 0.032). Our data suggests that MYBPC3 25-bp deletion may play significant role in conferring LVD as well as CAD risk in north Indian population.

Cellular degradation activity is maintained during aging in long-living queen bees

Queen honeybees (Apis mellifera) have a much longer lifespan than worker bees. Whether cellular degradation activity is involved in the longevity of queen bees is unknown. In the present study, cellular degradation activity was evaluated in the trophocytes and oenocytes of young and old queen bees. The results indicated that (i) 20S proteasome activity and the size of autophagic vacuoles decreased with aging, and (ii) there were no significant differences between young and old queen bees with regard to 20S proteasome expression or efficiency, polyubiquitin aggregate expression, microtubule-associated protein 1 light chain 3-II (LC3-II) expression, 70 kDa heat shock cognate protein (Hsc70) expression, the density of autophagic vacuoles, p62/SQSTM1 expression, the activity or density of lysosomes, or molecular target of rapamycin expression. These results indicate that cellular degradation activity maintains a youthful status in the trophocytes and oenocytes of queen bees during aging and that cellular degradation activity is involved in maintaining the longevity of queen bees.

Macromolecular Degradation Systems and Cardiovascular Aging

Aging-related cardiovascular diseases are a rapidly increasing problem worldwide. Cardiac aging demonstrates progressive decline of diastolic dysfunction of ventricle and increase in ventricular and arterial stiffness accompanied by increased fibrosis stimulated by angiotensin II and proinflammatory cytokines. Reactive oxygen species and multiple signaling pathways on cellular senescence play major roles in the process. Aging is also associated with an alteration in steady state of macromolecular dynamics including a dysfunction of protein synthesis and degradation. Currently, impaired macromolecular degradation is considered to be closely related to enhanced inflammation and be involved in the process and mechanism of cardiac aging. Herein, we review the role and mechanisms of the degradation system of intracellular macromolecules in the process and pathophysiology of cardiovascular aging.

Long live FOXO: unraveling the role of FOXO proteins in aging and longevity

Aging constitutes the key risk factor for age‐related diseases such as cancer and cardiovascular and neurodegenerative disorders. Human longevity and healthy aging are complex phenotypes influenced by both environmental and genetic factors. The fact that genetic contribution to lifespan strongly increases with greater age provides basis for research on which “protective genes” are carried by long‐lived individuals. Studies have consistently revealed FOXO (Forkhead box O) transcription factors as important determinants in aging and longevity. FOXO proteins represent a subfamily of transcription factors conserved from Caenorhabditis elegans to mammals that act as key regulators of longevity downstream of insulin and insulin‐like growth factor signaling. Invertebrate genomes have one FOXO gene, while mammals have four FOXO genes: FOXO1, FOXO3, FOXO4, and FOXO6. In mammals, this subfamily is involved in a wide range of crucial cellular processes regulating stress resistance, metabolism, cell cycle arrest, and apoptosis. Their role in longevity determination is complex and remains to be fully elucidated. Throughout this review, the mechanisms by which FOXO factors contribute to longevity will be discussed in diverse animal models, from Hydra to mammals. Moreover, compelling evidence of FOXOs as contributors for extreme longevity and health span in humans will be addressed.

Specific protein homeostatic functions of small heat-shock proteins increase lifespan

During aging, oxidized, misfolded, and aggregated proteins accumulate in cells, while the capacity to deal with protein damage declines severely. To cope with the toxicity of damaged proteins, cells rely on protein quality control networks, in particular proteins belonging to the family of heat‐shock proteins (HSPs). As safeguards of the cellular proteome, HSPs assist in protein folding and prevent accumulation of damaged, misfolded proteins. Here, we compared the capacity of all Drosophila melanogaster small HSP family members for their ability to assist in refolding stress‐denatured substrates and/or to prevent aggregation of disease‐associated misfolded proteins. We identified CG14207 as a novel and potent small HSP member that exclusively assisted in HSP70‐dependent refolding of stress‐denatured proteins. Furthermore, we report that HSP67BC, which has no role in protein refolding, was the most effective small HSP preventing toxic protein aggregation in an HSP70‐independent manner. Importantly, overexpression of both CG14207 and HSP67BC in Drosophila leads to a mild increase in lifespan, demonstrating that increased levels of functionally diverse small HSPs can promote longevity in vivo.

Age- and Hypertension-Associated Protein Aggregates in Mouse Heart Have Similar Proteomic Profiles

Neurodegenerative diseases are largely defined by protein aggregates in affected tissues. Aggregates contain some shared components as well as proteins thought to be specific for each disease. Aggregation has not previously been reported in the normal, aging heart or the hypertensive heart. Detergent-insoluble protein aggregates were isolated from mouse heart and characterized on 2-dimensional gels. Their levels increased markedly and significantly with aging and after sustained angiotensin II-induced hypertension. Of the aggregate components identified by high-resolution proteomics, half changed in abundance with age (392/787) or with sustained hypertension (459/824), whereas 30% (273/901) changed concordantly in both, each P<0.05. One fifth of these proteins were previously associated with age-progressive neurodegenerative or cardiovascular diseases, or both (eg, ApoE, ApoJ, ApoAIV, clusterin, complement C3, and others involved in stress-response and protein-homeostasis pathways). Because fibrosis is a characteristic of both aged and hypertensive hearts, we posited that aging of fibroblasts may contribute to the aggregates observed in cardiac tissue. Indeed, as cardiac myofibroblasts "senesced" (approached their replicative limit) in vitro, they accrued aggregates with many of the same constituent proteins observed in vivo during natural aging or sustained hypertension. In summary, we have shown for the first time that compact (detergent-insoluble) protein aggregates accumulate during natural aging, chronic hypertension, and in vitro myofibroblast senescence, sharing many common proteins. Thus, aggregates that arise from disparate causes (aging, hypertension, and replicative senescence) may have common underlying mechanisms of accrual.

Protein Expression of Proteasome Subunits in Elderly Patients with Schizophrenia

The ubiquitin proteasome system (UPS) is a major regulator of protein processing, trafficking, and degradation. While protein ubiquitination is utilized for many cellular processes, one major function of this system is to target proteins to the proteasome for degradation. In schizophrenia, studies have found UPS transcript abnormalities in both blood and brain, and we have previously reported decreased protein expression of ubiquitin-associated proteins in brain. To test whether the proteasome is similarly dysregulated, we measured the protein expression of proteasome catalytic subunits as well as essential subunits from proteasome regulatory complexes in 14 pair-matched schizophrenia and comparison subjects in superior temporal cortex. We found decreased expression of Rpt1, Rpt3, and Rpt6, subunits of the 19S regulatory particle essential for ubiquitin-dependent degradation by the proteasome. Additionally, the α subunit of the 11S αβ regulatory particle, which enhances proteasomal degradation of small peptides and unfolded proteins, was also decreased. Haloperidol-treated rats did not have altered expression of these subunits, suggesting the changes we observed in schizophrenia are likely not due to chronic antipsychotic treatment. Interestingly, expression of the catalytic subunits of both the standard and immunoproteasome were unchanged, suggesting the abnormalities we observed may be specific to the complexed state of the proteasome. Aging has significant effects on the proteasome, and several subunits (20S β2, Rpn10, Rpn13, 11Sβ, and 11Sγ) were significantly correlated with subject age. These data provide further evidence of dysfunction of the ubiquitin-proteasome system in schizophrenia, and suggest that altered proteasome activity may be associated with the pathophysiology of this illness.

UPS Activation in the Battle Against Aging and Aggregation-Related Diseases: An Extended Review

Aging is a biological process accompanied by gradual increase of damage in all cellular macromolecules, i.e., nucleic acids, lipids, and proteins. When the proteostasis network (chaperones and proteolytic systems) cannot reverse the damage load due to its excess as compared to cellular repair/regeneration capacity, failure of homeostasis is established. This failure is a major hallmark of aging and/or aggregation-related diseases. Dysfunction of the major cellular proteolytic machineries, namely the proteasome and the lysosome, has been reported during the progression of aging and aggregation-prone diseases. Therefore, activation of these pathways is considered as a possible preventive or therapeutic approach against the progression of these processes. This chapter focuses on UPS activation studies in cellular and organismal models and the effects of such activation on aging, longevity and disease prevention or reversal.

Colorectal Carcinogenesis, Radiation Quality, and the Ubiquitin-Proteasome Pathway

Adult colorectal epithelium undergoes continuous renewal and maintains homeostatic balance through regulated cellular proliferation, differentiation, and migration. The canonical Wnt signaling pathway involving the transcriptional co-activator β-catenin is important for colorectal development and normal epithelial maintenance, and deregulated Wnt/β-catenin signaling has been implicated in colorectal carcinogenesis. Colorectal carcinogenesis has been linked to radiation exposure, and radiation has been demonstrated to alter Wnt/β-catenin signaling, as well as the proteasomal pathway involved in the degradation of the signaling components and thus regulation of β-catenin. The current review discusses recent progresses in our understanding of colorectal carcinogenesis in relation to different types of radiation and roles that radiation quality plays in deregulating β-catenin and ubiquitin-proteasome pathway (UPP) for colorectal cancer initiation and progression.

Protein Oxidation in Aging: Does It Play a Role in Aging Progression?

SIGNIFICANCE

A constant accumulation of oxidized proteins takes place during aging. Oxidation of proteins leads to a partial unfolding and, therefore, to aggregation. Protein aggregates impair the activity of cellular proteolytic systems (proteasomes, lysosomes), resulting in further accumulation of oxidized proteins. In addition, the accumulation of highly crosslinked protein aggregates leads to further oxidant formation, damage to macromolecules, and, finally, to apoptotic cell death. Furthermore, protein oxidation seems to play a role in the development of various age-related diseases, for example, neurodegenerative diseases.

RECENT ADVANCES

The highly oxidized lipofuscin accumulates during aging. Lipofuscin formation might cause impaired lysosomal and proteasomal degradation, metal ion accumulation, increased reactive oxygen species formation, and apoptosis.

CRITICAL ISSUES

It is still unclear to which extent protein oxidation is involved in the progression of aging and in the development of some age-related diseases.

FUTURE DIRECTIONS

An extensive knowledge of the effects of protein oxidation on the aging process and its contribution to the development of age-related diseases could enable further strategies to reduce age-related impairments. Strategies aimed at lowering aggregate formation might be a straightforward intervention to reduce age-related malfunctions of organs.

High-throughput transcriptomic analysis nominates proteasomal genes as age-specific biomarkers and therapeutic targets in prostate cancer

BACKGROUND

Although prostate cancer (PCa) is hypothesized to differ in nature between younger versus older patients, the underlying molecular distinctions are poorly understood. We hypothesized that high-throughput transcriptomic analysis would elucidate biological differences in PCas arising in younger versus older men, and would nominate potential age-specific biomarkers and therapeutic targets.

METHODS

The high-density Affymetrix GeneChip platform, encompassing >1 million genomic loci, was utilized to assess gene expression in 1090 radical prostatectomy samples from patients with long-term follow-up. We identified genes associated with metastatic progression by 10 years post-treatment in younger (age<65) versus older (age⩾65) patients, and ranked these genes by their prognostic value. We performed Gene Set Enrichment Analysis (GSEA) to nominate biological concepts that demonstrated age-specific effects, and validated a target by treating with a clinically available drug in three PCa cell lines derived from younger men.

RESULTS

Over 80% of the top 1000 prognostic genes in younger and older men were specific to that age group. GSEA nominated the proteasome pathway as the most differentially prognostic in younger versus older patients. High expression of proteasomal genes conferred worse prognosis in younger but not older men on univariate and multivariate analysis. Bortezomib, a Food and Drug Administration approved proteasome inhibitor, decreased proliferation in three PCa cell lines derived from younger patients.

CONCLUSIONS

Our data show significant global differences in prognostic genes between older versus younger men. We nominate proteasomeal gene expression as an age-specific biomarker and potential therapeutic target specifically in younger men. Limitations of our study include clinical differences between cohorts, and increased comorbidities and lower survival in older patients. These intriguing findings suggest that current models of PCa biology do not adequately represent genetic heterogeneity of PCa related to age, and future clinical trials would benefit from stratification based on age.

Age influences inflammatory responses, hemodynamics, and cardiac proteasome activation during acute lung injury

BACKGROUND

Acute lung injury (ALI) is a significant source of morbidity and mortality in critically ill patients. Age is a major determinant of clinical outcome in ALI. The increased ALI-associated mortality in the older population suggests that there are age-dependent alterations in the responses to pulmonary challenge. The objective of this observational study was to evaluate age-dependent differences in the acute (within 6 hours) immunological and physiological responses of the heart and lung, to pulmonary challenge, that could result in increased severity.

METHODS

Male C57Bl/6 mice (young: 2-3 months, old: 18-20 months) were challenged intratracheally with cell wall components from Gram-positive bacteria (lipoteichoic acid and peptidoglycan). After 6 hours, both biochemical and physiological consequences of the challenge were assessed. Alveolar infiltration of inflammatory cells and protein, airspace and blood cytokines, cardiac function and myocardial proteasome activity were determined.

RESULTS

In young mice, there was a dose-dependent response to pulmonary challenge resulting in increased airspace neutrophil counts, lung permeability, and concentrations of cytokines in bronchoalveolar lavage fluid and plasma. A midrange dose was then selected to compare the responses in young and old animals. In comparison, the old animals displayed increased neutrophil accumulation in the airspaces, decreased arterial oxygen saturation, body temperatures, plasma cytokine concentrations, and a lack of myocardial proteasome response, following challenge.

CONCLUSIONS

Age-dependent differences in the onset of systemic response and in maintenance of vital functions, including temperature control, oxygen saturation, and myocardial proteasome activation, are evident. We believe a better understanding of these age-related consequences of ALI can lead to more appropriate treatments in the elderly patient population.

Ambient temperature reduction extends lifespan via activating cellular degradation activity in an annual fish (Nothobranchius rachovii)

Ambient temperature reduction (ATR) can extend the lifespan of organisms, but the underlying mechanism is poorly understood. In this study, cellular degradation activity was evaluated in the muscle of an annual fish (Nothobranchius rachovii) reared under high (30 °C), moderate (25 °C), and low (20 °C) ambient temperatures. The results showed the following: (i) the activity of the 20S proteasome and the expression of polyubiquitin aggregates increased with ATR, whereas 20S proteasome expression did not change; (ii) the expression of microtubule-associated protein 1 light chain 3-II (LC3-II) increased with ATR; (iii) the expression of lysosome-associated membrane protein type 2a (Lamp 2a) increased with ATR, whereas the expression of the 70-kD heat shock cognate protein (Hsc 70) decreased with ATR; (iv) lysosome activity increased with ATR, whereas the expression of lysosome-associated membrane protein type 1 (Lamp 1) did not change with ATR; and (v) the expression of molecular target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR) as well as the p-mTOR/mTOR ratio did not change with ATR. These findings indicate that ATR activates cellular degradation activity, constituting part of the mechanism underlying the longevity-promoting effects of ATR in N. rachovii.

The age factor for mitoxantrone's cardiotoxicity: multiple doses render the adult mouse heart more susceptible to injury

Age is a known susceptibility factor for the cardiotoxicity of several anticancer drugs, including mitoxantrone (MTX). The impact of anticancer drugs in young patients is underestimated, thus we aimed to evaluate the cardiotoxicity of MTX in juvenile and adult animals. Juvenile (3 week-old) and adult (8-10 week-old) male CD-1 mice were used. Each group was treated with a 9.0mg/kg cumulative dose of MTX or saline; they were maintained in a drug-free period for 3-weeks after the last administration to allow the development of late toxicity (protocol 1), or sacrificed 24h after the last MTX administration to evaluate early cardiotoxicity (protocol 2). In protocol 1, no adult mice survived, while 2 of the juveniles reached the end of the protocol. High plasma aspartate aminotransferase/alanine aminotransferase ratio and a high cardiac reduced/oxidized glutathione ratio were found in the surviving MTX-treated juvenile mice. In protocol 2, a significant decrease in plasma creatine-kinase MB in juveniles was found 24h after the last MTX-administration. Cardiac histology showed that both MTX-treated populations had significant damage, although higher in adults. However, MTX-treated juveniles had a significant increase in fibrotic tissue. The MTX-treated adults had higher values of cardiac GSSG and protein carbonylation, but lower cardiac noradrenaline levels. For the first time, mature adult animals were shown to be more susceptible to MTX as evidenced by several biomarkers, while young animals appear to better adjust to the MTX-induced cardiac injury. Even so, the higher level of fibrotic tissue and the histological damage showed that MTX also causes cardiac damage in the juvenile population.

Long-lived species have improved proteostasis compared to phylogenetically-related shorter-lived species

Our previous studies have shown that the liver from Naked Mole Rats (NMRs), a long-lived rodent, has increased proteasome activity and lower levels of protein ubiquitination compared to mice. This suggests that protein quality control might play a role in assuring species longevity. To determine whether enhanced proteostasis is a common mechanism in the evolution of other long-lived species, here we evaluated the major players in protein quality control including autophagy, proteasome activity, and heat shock proteins (HSPs), using skin fibroblasts from three phylogenetically-distinct pairs of short- and long-lived mammals: rodents, marsupials, and bats. Our results indicate that in all cases, macroautophagy was significantly enhanced in the longer-lived species, both at basal level and after induction by serum starvation. Similarly, basal levels of most HSPs were elevated in all the longer-lived species. Proteasome activity was found to be increased in the long-lived rodent and marsupial but not in bats. These observations suggest that long-lived species may have superior mechanisms to ensure protein quality, and support the idea that protein homeostasis might play an important role in promoting longevity.

A hypertrophic cardiomyopathy-associated MYBPC3 mutation common in populations of South Asian descent causes contractile dysfunction

Hypertrophic cardiomyopathy (HCM) results from mutations in genes encoding sarcomeric proteins, most often MYBPC3, which encodes cardiac myosin binding protein-C (cMyBP-C). A recently discovered HCM-associated 25-base pair deletion in MYBPC3 is inherited in millions worldwide. Although this mutation causes changes in the C10 domain of cMyBP-C (cMyBP-C(C10mut)), which binds to the light meromyosin (LMM) region of the myosin heavy chain, the underlying molecular mechanism causing HCM is unknown. In this study, adenoviral expression of cMyBP-C(C10mut) in cultured adult rat cardiomyocytes was used to investigate protein localization and evaluate contractile function and Ca(2+) transients, compared with wild-type cMyBP-C expression (cMyBP-C(WT)) and controls. Forty-eight hours after infection, 44% of cMyBP-C(WT) and 36% of cMyBP-C(C10mut) protein levels were determined in total lysates, confirming equal expression. Immunofluorescence experiments showed little or no localization of cMyBP-C(C10mut) to the C-zone, whereas cMyBP-C(WT) mostly showed C-zone staining, suggesting that cMyBP-C(C10mut) could not properly integrate in the C-zone of the sarcomere. Subcellular fractionation confirmed that most cMyBP-C(C10mut) resided in the soluble fraction, with reduced presence in the myofilament fraction. Also, cMyBP-C(C10mut) displayed significantly reduced fractional shortening, sarcomere shortening, and relaxation velocities, apparently caused by defects in sarcomere function, because Ca(2+) transients were unaffected. Co-sedimentation and protein cross-linking assays confirmed that C10(mut) causes the loss of C10 domain interaction with myosin LMM. Protein homology modeling studies showed significant structural perturbation in cMyBP-C(C10mut), providing a potential structural basis for the alteration in its mode of interaction with myosin LMM. Therefore, expression of cMyBP-C(C10mut) protein is sufficient to cause contractile dysfunction in vitro.

Targeting the ubiquitin-proteasome system in atherosclerosis: status quo, challenges, and perspectives

SIGNIFICANCE

Atherosclerosis is a vascular disease of worldwide significance with fatal complications such as myocardial infarction, stroke, and peripheral artery disease. Atherosclerosis is recognized as a chronic inflammatory disease leading to arterial plaque formation and vessel narrowing in different vascular beds. Besides the strong inflammatory nature of atherosclerosis, it is also characterized by proliferation, apoptosis, and enhanced oxidative stress. The ubiquitin-proteasome system (UPS) is the major intracellular degradation system in eukaryotic cells. Besides its essential role in the degradation of dysfunctional and oxidatively damaged proteins, it is involved in many processes that influence disease progression in atherosclerosis. Hence, it is logical to ask whether targeting the proteasome is a reasonable and feasible option for the treatment of atherosclerosis.

RECENT ADVANCES

Several lines of evidence suggest stage-specific dysfunction of the UPS in atherogenesis. Regulation of key processes by the proteasome in atherosclerosis, as well as the modulation of these processes by proteasome inhibitors in vascular cells, is outlined in this review. The treatment of atherosclerotic animal models with proteasome inhibitors yielded partly opposing results, the potentially underlying reasons of which are discussed here.

CRITICAL ISSUES AND FUTURE DIRECTIONS

Targeting UPS function in atherosclerosis is a promising but challenging option. Limitations of current proteasome inhibitors, dose dependency, and the cell specificity of effects, as well as the potential of future therapeutics are discussed. A stage-specific in-depth exploration of UPS function in atherosclerosis in the future will help identify targets and windows for beneficial intervention.

The amazing ubiquitin-proteasome system: structural components and implication in aging

Proteome quality control (PQC) is critical for the maintenance of cellular functionality and it is assured by the curating activity of the proteostasis network (PN). PN is constituted of several complex protein machines that under conditions of proteome instability aim to, firstly identify, and then, either rescue or degrade nonnative polypeptides. Central to the PN functionality is the ubiquitin-proteasome system (UPS) which is composed from the ubiquitin-conjugating enzymes and the proteasome; the latter is a sophisticated multi-subunit molecular machine that functions in a bimodal way as it degrades both short-lived ubiquitinated normal proteins and nonfunctional polypeptides. UPS is also involved in PQC of the nucleus, the endoplasmic reticulum and the mitochondria and it also interacts with the other main cellular degradation axis, namely the autophagy-lysosome system. UPS functionality is optimum in the young organism but it is gradually compromised during aging resulting in increasing proteotoxic stress; these effects correlate not only with aging but also with most age-related diseases. Herein, we present a synopsis of the UPS components and of their functional alterations during cellular senescence or in vivo aging. We propose that mild UPS activation in the young organism will, likely, promote antiaging effects and/or suppress age-related diseases.

Reprint of "accumulation of modified proteins and aggregate formation in aging"

Increasing cellular damage during the aging process is considered to be one factor limiting the lifespan of organisms. Besides the DNA and lipids, proteins are frequent targets of non-enzymatic modifications by reactive substances including oxidants and glycating agents. Non-enzymatic protein modifications may alter the protein structure often leading to impaired functionality. Although proteolytic systems ensure the removal of modified proteins, the activity of these proteases was shown to decline during the aging process. The additional age-related increase of reactive compounds as a result of impaired antioxidant systems leads to the accumulation of damaged proteins and the formation of protein aggregates. Both, non-enzymatic modified proteins and protein aggregates impair cellular functions and tissue properties by a variety of mechanisms. This is increasingly important in aging and age-related diseases. In this review, we will give an overview on oxidation and glycation of proteins and the function of modified proteins in aggregate formation. Furthermore, their effects as well as their role in aging and age-related diseases will be highlighted.

Proteasome activation delays aging in vitro and in vivo

Aging is a natural biological process that is characterized by a progressive accumulation of macromolecular damage. In the proteome, aging is accompanied by decreased protein homeostasis and function of the major cellular proteolytic systems, leading to the accumulation of unfolded, misfolded, or aggregated proteins. In particular, the proteasome is responsible for the removal of normal as well as damaged or misfolded proteins. Extensive work during the past several years has clearly demonstrated that proteasome activation by either genetic means or use of compounds significantly retards aging. Importantly, this represents a common feature across evolution, thereby suggesting proteasome activation to be an evolutionarily conserved mechanism of aging and longevity regulation. This review article reports on the means of function of these proteasome activators and how they regulate aging in various species.

Accumulation of modified proteins and aggregate formation in aging

Increasing cellular damage during the aging process is considered to be one factor limiting the lifespan of organisms. Besides the DNA and lipids, proteins are frequent targets of non-enzymatic modifications by reactive substances including oxidants and glycating agents. Non-enzymatic protein modifications may alter the protein structure often leading to impaired functionality. Although proteolytic systems ensure the removal of modified proteins, the activity of these proteases was shown to decline during the aging process. The additional age-related increase of reactive compounds as a result of impaired antioxidant systems leads to the accumulation of damaged proteins and the formation of protein aggregates. Both, non-enzymatic modified proteins and protein aggregates impair cellular functions and tissue properties by a variety of mechanisms. This is increasingly important in aging and age-related diseases. In this review, we will give an overview on oxidation and glycation of proteins and the function of modified proteins in aggregate formation. Furthermore, their effects as well as their role in aging and age-related diseases will be highlighted.

The Mechanistic Links Between Proteasome Activity, Aging and Age-related Diseases

Damaged and misfolded proteins accumulate during the aging process, impairing cell function and tissue homeostasis. These perturbations to protein homeostasis (proteostasis) are hallmarks of age-related neurodegenerative disorders such as Alzheimer’s, Parkinson’s or Huntington’s disease. Damaged proteins are degraded by cellular clearance mechanisms such as the proteasome, a key component of the proteostasis network. Proteasome activity declines during aging, and proteasomal dysfunction is associated with late-onset disorders. Modulation of proteasome activity extends lifespan and protects organisms from symptoms associated with proteostasis disorders. Here we review the links between proteasome activity, aging and neurodegeneration. Additionally, strategies to modulate proteasome activity and delay the onset of diseases associated to proteasomal dysfunction are discussed herein.

Cardiac aging and insulin resistance: could insulin/insulin-like growth factor (IGF) signaling be used as a therapeutic target?

Intrinsic cardiac aging is an independent risk factor for cardiovascular disease and is associated with structural and functional changes that impede cardiac responses to stress and to cardio-protective mechanisms. Although systemic insulin resistance and the associated risk factors exacerbate cardiac aging, cardiac-specific insulin resistance without confounding systemic alterations, could prevent cardiac aging. Thus, strategies aimed to reduce insulin/insulin-like growth factor (IGF) signaling in the heart prevent cardiac aging in lower organisms and in mammals but the mechanisms underlying this protection are not fully understood. In this review, we describe the impact of aging on the cardiovascular system and discuss the mounting evidence that reduced insulin/IGF signaling in the heart could alleviate age-associated alterations and preserve cardiac performance.

FOXO transcription factors: key regulators of cellular quality control

FOXO transcription factors are conserved regulators of longevity downstream of insulin signaling. These transcription factors integrate signals emanating from nutrient deprivation and stress stimuli to coordinate programs of genes involved in cellular metabolism and resistance to oxidative stress. Here, we discuss emerging evidence for a pivotal role of FOXO factors in promoting the expression of genes involved in autophagy and the ubiquitin-proteasome system--two cell clearance processes that are essential for maintaining organelle and protein homeostasis (proteostasis). The ability of FOXO to maintain cellular quality control appears to be critical in processes and pathologies where damaged proteins and organelles accumulate, including aging and neurodegenerative diseases.

A heart that beats for 500 years: age-related changes in cardiac proteasome activity, oxidative protein damage and expression of heat shock proteins, inflammatory factors, and mitochondrial complexes in Arctica islandica, the longest-living noncolonial animal

Study of negligibly senescent animals may provide clues that lead to better understanding of the cardiac aging process. To elucidate mechanisms of successful cardiac aging, we investigated age-related changes in proteasome activity, oxidative protein damage and expression of heat shock proteins, inflammatory factors, and mitochondrial complexes in the heart of the ocean quahog Arctica islandica, the longest-lived noncolonial animal (maximum life span potential: 508 years). We found that in the heart of A. islandica the level of oxidatively damaged proteins did not change significantly up to 120 years of age. No significant aging-induced changes were observed in caspase-like and trypsin-like proteasome activity. Chymotrypsin-like proteasome activity showed a significant early-life decline, then it remained stable for up to 182 years. No significant relationship was observed between the extent of protein ubiquitination and age. In the heart of A. islandica, an early-life decline in expression of HSP90 and five mitochondrial electron transport chain complexes was observed. We found significant age-related increases in the expression of three cytokine-like mediators (interleukin-6, interleukin-1β, and tumor necrosis factor-α) in the heart of A. islandica. Collectively, in extremely long-lived molluscs, maintenance of protein homeostasis likely contributes to the preservation of cardiac function. Our data also support the concept that low-grade chronic inflammation in the cardiovascular system is a universal feature of the aging process, which is also manifest in invertebrates.

Chronic alcohol consumption disrupts myocardial protein balance and function in aged, but not adult, female F344 rats

The purpose of this study was to assess whether the deleterious effect of chronic alcohol consumption differs in adult and aged female rats. To address this aim, adult (4 mo) and aged (18 mo) F344 rats were fed a nutritionally complete liquid diet containing alcohol (36% total calories) or an isocaloric isonitrogenous control diet for 20 wk. Cardiac structure and function, assessed by echocardiography, as well as myocardial protein synthesis and proteolysis did not differ in either alcohol- versus control-fed adult rats or in adult versus aged control-fed rats. In contrast, cardiac function was impaired in alcohol-fed aged rats compared with age-matched control rats. Additionally, alcohol feeding decreased cardiac protein synthesis that was associated with decreased phosphorylation of 4E-BP1 and S6K1. This reduction in mammalian target of rapamycin (mTOR) kinase activity was associated with reduced eIF3f and binding of both Raptor and eIF4G to eIF3. Proteasome activity was increased in alcohol-fed aged rats with a coordinate elevation in the E3 ligases atrogin-1 and muscle RING-finger protein-1 (MuRF1). These changes were associated with increased regulated in development and DNA damage response 1 (REDD1) and phosphorylation of AMP-activated protein kinase (AMPK) but no increase in AKT or forkhead transcription factor (FOXO)3 phosphorylation. Finally, markers of autophagy (e.g., LC3B, Atg7, Atg12) and TNF-α were increased to a greater extent in alcohol-fed aged rats. These data demonstrate that aged female rats exhibit an enhanced sensitivity to alcohol compared with adult animals. Our data are consistent with a model whereby alcohol increases proteolysis via FOXO-independent increase in atrogin-1, which degrades eIF3f and therefore impairs formation of a functional preinitiation complex and protein synthesis.

Ventricular fibrillation after bortezomib therapy in a patient with systemic amyloidosis

A 64-year-old female was diagnosed with systemic amyloidosis associated with multiple myeloma. Bortezomib and dexamethasone-therapy was initiated; however, she developed lethal ventricular fibrillation (VF) and cardiac arrest after 84 hours of therapy. Cardiopulmonary resuscitation using direct current shocks with epinephrine and amiodarone was initiated but failed to receive cardiac function. Although her arterial pulsations recovered immediately after the injection of vasopressin, she died of heart failure 8 hours after the onset of VF. Cardiac amyloidosis was verified by autopsy. Although the direct association of bortezomib with lethal VF remained to be clarified in our patient, the current report emphasizes on bortezomib as a substantial risk factor for cardiomyocyte damage. The potential risk of lethal events associated with cardiac amyloidosis should be carefully considered during bortezomib treatment for patients with AL amyloidosis.

Oxidative stress, neurodegeneration, and the balance of protein degradation and protein synthesis

Oxidative stress occurs in a variety of disease settings and is strongly linked to the development of neuron death and neuronal dysfunction. Cells are equipped with numerous pathways to prevent the genesis, as well as the consequences, of oxidative stress in the brain. In this review we discuss the various forms and sources of oxidative stress in the brain and briefly discuss some of the complexities in detecting the presence of oxidative stress. We then focus the review on the interplay between the diverse cellular proteolytic pathways and their roles in regulating oxidative stress in the brain. Additionally, we discuss the involvement of protein synthesis in regulating the downstream effects of oxidative stress. Together, these components of the review demonstrate that the removal of damaged proteins by effective proteolysis and the synthesis of new and protective proteins are vital in the preservation of brain homeostasis during periods of increased levels of reactive oxygen species. Last, studies from our laboratory and others have demonstrated that protein synthesis is intricately linked to the rates of protein degradation, with impairment of protein degradation sufficient to decrease the rates of protein synthesis, which has important implications for successfully responding to periods of oxidative stress. Specific neurodegenerative diseases, including Alzheimer disease, Parkinson disease, amyotrophic lateral sclerosis, and stroke, are discussed in this context. Taken together, these findings add to our understanding of how oxidative stress is effectively managed in the healthy brain and help elucidate how impairments in proteolysis and/or protein synthesis contribute to the development of neurodegeneration and neuronal dysfunction in a variety of clinical settings.