Proteolysis dysfunction in the process of aging and age-related diseases

Oxidative stress, defective proteostasis and immunometabolic complications in critically ill patients

Oxidative stress (OS) develops in critically ill patients as a metabolic consequence of the immunoinflammatory and degenerative processes of the tissues. These induce increased and/or dysregulated fluxes of reactive species enhancing their pro-oxidant activity and toxicity. At the same time, OS sustains its own inflammatory and immunometabolic pathogenesis, leading to a pervasive and vitious cycle of events that contribute to defective immunity, organ dysfunction and poor prognosis. Protein damage is a key player of these OS effects; it generates increased levels of protein oxidation products and misfolded proteins in both the cellular and extracellular environment, and contributes to forms DAMPs and other proteinaceous material to be removed by endocytosis and proteostasis processes of different cell types, as endothelial cells, tissue resident monocytes-macrophages and peripheral immune cells. An excess of OS and protein damage in critical illness can overwhelm such cellular processes ultimately interfering with systemic proteostasis, and consequently with innate immunity and cell death pathways of the tissues thus sustaining organ dysfunction mechanisms. Extracorporeal therapies based on biocompatible/bioactive membranes and new adsorption techniques may hold some potential in reducing the impact of OS on the defective proteostasis of patients with critical illness. These can help neutralizing reactive and toxic species, also removing solutes in a wide spectrum of molecular weights thus improving proteostasis and its immunometabolic corelates. Pharmacological therapy is also moving steps forward which could help to enhance the efficacy of extracorporeal treatments. This narrative review article explores the aspects behind the origin and pathogenic role of OS in intensive care and critically ill patients, with a focus on protein damage as a cause of impaired systemic proteostasis and immune dysfunction in critical illness.

Kallikrein-related peptidase's significance in Alzheimer's disease pathogenesis: A comprehensive survey

Alzheimer's disease (AD) and related dementias constitute an important global health challenge. Detailed understanding of the multiple molecular mechanisms underlying their pathogenesis constitutes a clue for the management of the disease. Kallikrein-related peptidases (KLKs), a lead family of serine proteases, have emerged as potential biomarkers and therapeutic targets in the context of AD and associated cognitive decline. Hence, KLKs were proposed to display multifaceted impacts influencing various aspects of neurodegeneration, including amyloid-beta aggregation, tau pathology, neuroinflammation, and synaptic dysfunction. We propose here a comprehensive survey to summarize recent findings, providing an overview of the main kallikreins implicated in AD pathophysiology namely KLK8, KLK6 and KLK7. We explore the interplay between KLKs and key AD molecular pathways, shedding light on their significance as potential biomarkers for early disease detection. We also discuss their pertinence as therapeutic targets for disease-modifying interventions to develop innovative therapeutic strategies aimed at halting or ameliorating the progression of AD and associated dementias.

Non-coding RNAs in Regulation of Protein Aggregation and Clearance Pathways: Current Perspectives Towards Alzheimer's Research and Therapy

Alzheimer's disease (AD) is the leading cause of dementia, affecting approximately 45.0 million people worldwide and ranking as the fifth leading cause of mortality. AD is identified by neurofibrillary tangles (NFTs), which include abnormally phosphorylated tau-protein and amyloid protein (amyloid plaques). Peptide dysregulation is caused by an imbalance between the production and clearance of the amyloid-beta (Aβ) and NFT. AD begins to develop when these peptides are not cleared from the body. As a result, understanding the processes that control both normal and pathological protein recycling in neuronal cells is critical. Insufficient Aβ and NFT clearance are important factors in the development of AD. Autophagy, lysosomal dysfunction, and ubiquitin-proteasome dysfunction have potential roles in the pathogenesis of many neurodegenerative disorders, particularly in AD. Modulation of these pathways may provide a novel treatment strategy for AD. Non-coding RNAs (ncRNAs) have recently emerged as important biological regulators, with particular relevance to the emergence and development of neurodegenerative disorders such as AD. ncRNAs can be used as potential therapeutic targets and diagnostic biomarkers due to their critical regulatory functions in several biological processes involved in disease development, such as the aggregation and accumulation of Aβ and NFT. It is evident that ncRNAs play a role in the pathophysiology of AD. In this communication, we explored the link between ncRNAs and AD and their regulatory mechanisms that may help in finding new therapeutic targets and AD medications.

Guanylate-binding protein 1 modulates proteasomal machinery in ovarian cancer

Guanylate-binding protein 1 (GBP1) is known as an interferon-γ-induced GTPase. Here, we used genetically modified ovarian cancer (OC) cells to study the role of GBP1. The data generated show that GBP1 inhibition constrains the clonogenic potential of cancer cells. In vivo studies revealed that GBP1 overexpression in tumors promotes tumor progression and reduces median survival, whereas GBP1 inhibition delayed tumor progression with longer median survival. We employed proteomics-based thermal stability assay (CETSA) on GBP1 knockdown and overexpressed OC cells to study its molecular functions. CETSA results show that GBP1 interacts with many members of the proteasome. Furthermore, GBP1 inhibition sensitizes OC cells to paclitaxel treatment via accumulated ubiquitinylated proteins where GBP1 inhibition decreases the overall proteasomal activity. In contrast, GBP1-overexpressing cells acquired paclitaxel resistance via boosted cellular proteasomal activity. Overall, these studies expand the role of GBP1 in the activation of proteasomal machinery to acquire chemoresistance.

Proteostasis in T cell aging

Aging leads to a decline in immune cell function, which leaves the organism vulnerable to infections and age-related multimorbidities. One major player of the adaptive immune response are T cells, and recent studies argue for a major role of disturbed proteostasis contributing to reduced function of these cells upon aging. Proteostasis refers to the state of a healthy, balanced proteome in the cell and is influenced by synthesis (translation), maintenance and quality control of proteins, as well as degradation of damaged or unwanted proteins by the proteasome, autophagy, lysosome and cytoplasmic enzymes. This review focuses on molecular processes impacting on proteostasis in T cells, and specifically functional or quantitative changes of each of these upon aging. Importantly, we describe the biological consequences of compromised proteostasis in T cells, which range from impaired T cell activation and function to enhancement of inflamm-aging by aged T cells. Finally, approaches to improve proteostasis and thus rejuvenate aged T cells through pharmacological or physical interventions are discussed.

Beyond youth: Understanding CAR T cell fitness in the context of immunological aging

Population aging, a pervasive global demographic trend, is anticipated to challenge health and social systems worldwide. This phenomenon is due to medical advancements enabling longer lifespans, with 20% of the US population soon to be over 65 years old. Consequently, there will be a surge in age-related diseases. Senescence, characterized by the loss of biological maintenance and homeostasis at molecular and cellular levels, either correlates with or directly causes age-related phenotypic changes. Decline of the immune system is a critical factor in the senescence process, with cancer being a primary cause of death in elderly populations. Chimeric antigen receptor (CAR) T cell therapy, an innovative approach, has demonstrated success mainly in pediatric and young adult hematological malignancies but remains largely ineffective for diseases affecting older populations, such as late-in-life B cell malignancies and most solid tumor indications. This limitation arises because CAR T cell efficacy heavily relies on the fitness of the patient-derived starting T cell material. Numerous studies suggest that T cell senescence may be a key driver of CAR T cell deficiency. This review examines correlates and underlying factors associated with favorable CAR T cell outcomes and explores potential experimental and clinically actionable strategies for T cell rejuvenation.

Disorganization of secondary lymphoid organs and dyscoordination of chemokine secretion as key contributors to immune aging

Aging is characterized by progressive loss of organ and tissue function, and the immune system is no exception to that inevitable principle. Of all the age-related changes in the body, reduction of the size of, and naïve T (Tn) cell output from, the thymus occurs earliest, being prominent already before or by the time of puberty. Therefore, to preserve immunity against new infections, over much of their lives, vertebrates dominantly rely on peripheral maintenance of the Tn cell pool in the secondary lymphoid organs (SLO). However, SLO structure and function subsequently also deteriorate with aging. Several recent studies have made a convincing case that this deterioration is of major importance to the erosion of protective immunity in the last third of life. Specifically, the SLO were found to accumulate multiple degenerative changes with aging. Importantly, the results from adoptive transfer and parabiosis studies teach us that the old microenvironment is the limiting factor for protective immunity in old mice. In this review, we discuss the extent, mechanisms, and potential role of stromal cell aging in the age-related alteration of T cell homeostatic maintenance and immune function decline. We use that discussion to frame the potential strategies to correct the SLO stromal aging defects - in the context of other immune rejuvenation approaches, - to improve functional immune responses and protective immunity in older adults.

Non-Genomic Hallmarks of Aging-The Review

Aging is a natural, gradual, and inevitable process associated with a series of changes at the molecular, cellular, and tissue levels that can lead to an increased risk of many diseases, including cancer. The most significant changes at the genomic level (DNA damage, telomere shortening, epigenetic changes) and non-genomic changes are referred to as hallmarks of aging. The hallmarks of aging and cancer are intertwined. Many studies have focused on genomic hallmarks, but non-genomic hallmarks are also important and may additionally cause genomic damage and increase the expression of genomic hallmarks. Understanding the non-genomic hallmarks of aging and cancer, and how they are intertwined, may lead to the development of approaches that could influence these hallmarks and thus function not only to slow aging but also to prevent cancer. In this review, we focus on non-genomic changes. We discuss cell senescence, disruption of proteostasis, deregualation of nutrient sensing, dysregulation of immune system function, intercellular communication, mitochondrial dysfunction, stem cell exhaustion and dysbiosis.

Aging, NRF2, and TAU: A Perfect Match for Neurodegeneration?

Although the trigger for the neurodegenerative disease process is unknown, the relevance of aging stands out as a major risk for the development of neurodegeneration. In this review, we highlighted the relationship between the different cellular mechanisms that occur as a consequence of aging and transcription factor nuclear factor erythroid-2-related factor 2 (NRF2) and the connection with the TAU protein. We focused on the relevance of NRF2 in the main processes involved in neurodegeneration and associated with aging, such as genomic instability, protein degradation systems (proteasomes/autophagy), cellular senescence, and stem cell exhaustion, as well as inflammation. We also analyzed the effect of aging on TAU protein levels and its aggregation and spread process. Finally, we investigated the interconnection between NRF2 and TAU and the relevance of alterations in the NRF2 signaling pathway in both primary and secondary tauopathies. All these points highlight NRF2 as a possible therapeutic target for tauopathies.

Nuclear proteostasis imbalance in laminopathy-associated premature aging diseases

Laminopathies are a group of rare genetic disorders with heterogeneous clinical phenotypes such as premature aging, cardiomyopathy, lipodystrophy, muscular dystrophy, microcephaly, epilepsy, and so on. The cellular phenomena associated with laminopathy invariably show disruption of nucleoskeleton of lamina due to deregulated expression, localization, function, and interaction of mutant lamin proteins. Impaired spatial and temporal tethering of lamin proteins to the lamina or nucleoplasmic aggregation of lamins are the primary molecular events that can trigger nuclear proteotoxicity by modulating differential protein-protein interactions, sequestering quality control proteins, and initiating a cascade of abnormal post-translational modifications. Clearly, laminopathic cells exhibit moderate to high nuclear proteotoxicity, raising the question of whether an imbalance in nuclear proteostasis is involved in laminopathic diseases, particularly in diseases of early aging such as HGPS and laminopathy-associated premature aging. Here, we review nuclear proteostasis and its deregulation in the context of lamin proteins and laminopathies.

Effects of Cathepsin S Inhibition in the Age-Related Dry Eye Phenotype

Purpose

Aged C57BL/6J (B6) mice have increased levels of cathepsin S, and aged cathepsin S (Ctss-/-) knockout mice are resistant to age-related dry eye. This study investigated the effects of cathepsin S inhibition on age-related dry eye disease.

Methods

Female B6 mice aged 15.5 to 17 months were randomized to receive a medicated diet formulated by mixing the RO5461111 cathepsin S inhibitor or a standard diet for at least 12 weeks. Cornea mechanosensitivity was measured with a Cochet-Bonnet esthesiometer. Ocular draining lymph nodes and lacrimal glands (LGs) were excised and prepared for histology or assayed by flow cytometry to quantify infiltrating immune cells. The inflammatory foci (>50 cells) were counted under a 10× microscope lens and quantified using the focus score. Goblet cell density was investigated in periodic acid-Schiff stained sections. Ctss-/- mice were compared to age-matched wild-type mice.

Results

Aged mice subjected to cathepsin S inhibition or Ctss-/- mice showed improved conjunctival goblet cell density and cornea mechanosensitivity. There was no change in total LG focus score in the diet or Ctss-/- mice, but there was a lower frequency of CD4+IFN-γ+ cell infiltration in the LGs. Furthermore, aged Ctss-/- LGs had an increase in T central memory, higher numbers of CD19+B220-, and fewer CD19+B220+ cells than wild-type LGs.

Conclusions

Our results indicate that therapies aimed at decreasing cathepsin S can ameliorate age-related dry eye disease with a highly beneficial impact on the ocular surface. Further studies are needed to investigate the role of cathepsin S during aging.

Chronic inflammation and the hallmarks of aging

BACKGROUND

Recently, the hallmarks of aging were updated to include dysbiosis, disabled macroautophagy, and chronic inflammation. In particular, the low-grade chronic inflammation during aging, without overt infection, is defined as "inflammaging," which is associated with increased morbidity and mortality in the aging population. Emerging evidence suggests a bidirectional and cyclical relationship between chronic inflammation and the development of age-related conditions, such as cardiovascular diseases, neurodegeneration, cancer, and frailty. How the crosstalk between chronic inflammation and other hallmarks of aging underlies biological mechanisms of aging and age-related disease is thus of particular interest to the current geroscience research.

SCOPE OF REVIEW

This review integrates the cellular and molecular mechanisms of age-associated chronic inflammation with the other eleven hallmarks of aging. Extra discussion is dedicated to the hallmark of "altered nutrient sensing," given the scope of Molecular Metabolism. The deregulation of hallmark processes during aging disrupts the delicate balance between pro-inflammatory and anti-inflammatory signaling, leading to a persistent inflammatory state. The resultant chronic inflammation, in turn, further aggravates the dysfunction of each hallmark, thereby driving the progression of aging and age-related diseases.

MAIN CONCLUSIONS

The crosstalk between chronic inflammation and other hallmarks of aging results in a vicious cycle that exacerbates the decline in cellular functions and promotes aging. Understanding this complex interplay will provide new insights into the mechanisms of aging and the development of potential anti-aging interventions. Given their interconnectedness and ability to accentuate the primary elements of aging, drivers of chronic inflammation may be an ideal target with high translational potential to address the pathological conditions associated with aging.

The double-hit protocol induces HFpEF and impairs myocardial ubiquitin-proteasome system performance in FVB/N mice

Heart failure with preserved ejection fraction (HFpEF) is a leading cause of death and disability, with its prevalence surpassing that of heart failure with reduced ejection fraction. Obesity and hypertension are often associated with HFpEF. HFpEF can be modeled through simultaneous metabolic and hypertensive stresses in male C57BL/6N mice provoked by a combination treatment of a high-fat diet (HFD) and constitutive nitric oxide synthase inhibition by Nω-nitro-L-arginine methyl-ester (L-NAME). Ubiquitin-proteasome system (UPS) dysfunction was detected in many forms of cardiomyopathy, but whether it occurs in HFpEF remains unknown. We report successful modeling of HFpEF in male FVB/N mice and, by taking advantage of a transgenic UPS reporter mouse, we have detected myocardial UPS functioning impairment during HFpEF, suggesting a pathogenic role for impaired protein degradation in the development and progression of HFpEF.

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Advancement of targeted protein degradation strategies as therapeutics for undruggable disease targets

Targeted protein degradation (TPD) aids in developing novel bifunctional small-molecule degraders and eliminates proteins of interest. The TPD approach shows promising results in oncological, neurogenerative, cardiovascular and gynecological drug development. We provide an overview of technology advancements in TPD, including molecular glues, proteolysis-targeting chimeras (PROTACs), lysosome-targeting chimeras, antibody-based PROTAC, GlueBody PROTAC, autophagy-targeting chimera, autophagosome-tethering compound, autophagy-targeting chimera and chaperone-mediated autophagy-based degraders. Here we discuss the development and evolution of the TPD field, the variety of proteins that PROTACs target and the biological repercussions of their degradation. We particularly highlight the recent improvements in TPD research that utilize autophagy or the endolysosomal pathway, which enables the targeting of undruggable targets.

Longevity, Centenarians and Modified Cellular Proteodynamics

We have shown before that at least one intracellular proteolytic system seems to be at least as abundant in the peripheral blood lymphocytes of centenarians as in the same cells of young individuals (with the cells of the elderly population showing a significant dip compared to both young and centenarian cohorts). Despite scarce published data, in this review, we tried to answer the question how do different types of cells of longevous people-nonagenarians to (semi)supercentenarians-maintain the quality and quantity of their structural and functional proteins? Specifically, we asked if more robust proteodynamics participate in longevity. We hypothesized that at least some factors controlling the maintenance of cellular proteomes in centenarians will remain at the "young" level (just performing better than in the average elderly). In our quest, we considered multiple aspects of cellular protein maintenance (proteodynamics), including the quality of transcribed DNA, its epigenetic changes, fidelity and quantitative features of transcription of both mRNA and noncoding RNAs, the process of translation, posttranslational modifications leading to maturation and functionalization of nascent proteins, and, finally, multiple facets of the process of elimination of misfolded, aggregated, and otherwise dysfunctional proteins (autophagy). We also included the status of mitochondria, especially production of ATP necessary for protein synthesis and maintenance. We found that with the exception of the latter and of chaperone function, practically all of the considered aspects did show better performance in centenarians than in the average elderly, and most of them approached the levels/activities seen in the cells of young individuals.

Global Proteomic Profile of Aluminum-Induced Hippocampal Impairments in Rats: Are Low Doses of Aluminum Really Safe?

Hippocampus is the brain area where aluminum (Al) accumulates in abundance and is widely associated with learning and memory. In the present study, we evaluate behavioral, tissue, and proteomic changes in the hippocampus of Wistar rats caused by exposure to doses that mimic human consumption of aluminum chloride (AlCl₃) in urban areas. For this, male Wistar rats were divided into two groups: Control (distilled water) and AlCl₃ (8.3 mg/kg/day), both groups were exposed orally for 60 days. After the Al exposure protocol, cognitive functions were assessed by the Water maze test, followed by a collection for analysis of the global proteomic profile of the hippocampus by mass spectrometry. Aside from proteomic analysis, we performed a histological analysis of the hippocampus, to the determination of cell body density by cresyl violet staining in Cornu Ammonis fields (CA) 1 and 3, and hilus regions. Our results indicated that exposure to low doses of aluminum chloride triggered a decreased cognitive performance in learning and memory, being associated with the deregulation of proteins expression, mainly those related to the regulation of the cytoskeleton, cellular metabolism, mitochondrial activity, redox regulation, nervous system regulation, and synaptic signaling, reduced cell body density in CA1, CA3, and hilus.

Polo-Like Kinase 2 Plays an Essential Role in Cytoprotection against MG132-Induced Proteasome Inhibition via Phosphorylation of Serine 19 in HSPB5

Protein homeostasis, including protein folding, refolding, and degradation, is thought to decline with aging. HSPB5 (also known as αB-crystallin) prevents target protein aggregation as a molecular chaperone and exhibits a cytoprotective function against various cell stresses. To elucidate the effect of HSPB5 on endoplasmic reticulum (ER) stress, we searched for novel binding proteins of HSPB5 using the proximity-dependent biotin labeling method. Proteins presumed to interact with HSPB5 in cells treated with the proteasome inhibitor MG132 were identified by a reversible biotin-binding capacity method combining tamavidin2-REV magnetic beads and mass spectrometry. We discovered a new binding protein for HSPB5, polo-like kinase 2 (PLK2), which is an apoptosis-related enzyme. The expression of PLK2 was upregulated by MG132 treatment, and it was co-localized with HSPB5 near the ER in L6 muscle cells. Inhibition of PLK2 decreased ER stress-induced phosphorylation of serine 19 in HSPB5 and increased apoptosis by activation of caspase 3 under ER stress. Overexpression of HSPB5 (WT) suppressed the ER stress-induced caspase 3 activity, but this was not observed with phospho-deficient HSPB5 (3A) mutants. These results clarify the role of HSPB5 phosphorylation during ER stress and suggest that the PLK2/HSPB5 pathway plays an essential role in cytoprotection against proteasome inhibition-induced ER stress.