Protein Quality Control System Research Articles

Multi-omics data and model integration reveal the main mechanisms associated with respiro-fermentative metabolism and ethanol stress responses in Kluyveromyces marxianus

Kluyveromyces marxianus is a yeast capable of fermenting sugars into ethanol and growing at high temperatures (>37ºC). However, it is less tolerant to ethanol than Saccharomyces cerevisiae, which limits its application in second-generation ethanol production. Since the mechanisms of ethanol stress response are still poorly described, especially compared to S. cerevisiae, we used an integrative multi-omics approach, combining transcriptomics, co-expression networks, gene regulation, and genome-scale metabolic modelling to gain insights about these mechanisms. Through metabolic modelling, we predicted the occurrence of a respiro-fermentative metabolism and its onset as the dilution rate increased. From gene co-expression networks, we detected that the protein quality control system is a main mechanism involved in the ethanol stress response. Further, we identified key regulators in the ethanol stress response, such as HAP3, MET4, and SNF2, and assessed how disturbances in their gene expression affect cellular metabolism. We also found that amino acid metabolism, membrane lipid metabolism, and ergosterol exhibit increased metabolic flux under the explored conditions, along with usage of enzymes related to these pathways. These findings provide useful cues to develop and implement genetic and metabolic engineering strategies to enhance ethanol tolerance and point for future research in stress responses of K. marxianus.

Pharmacological inhibition of USP14 delays proteostasis-associated aging in a proteasome-dependent but foxo-independent manner

ABSTRACT Aging is often accompanied by a decline in proteostasis, manifested as an increased propensity for misfolded protein aggregates, which are prevented by protein quality control systems, such as the ubiquitin-proteasome system (UPS) and macroautophagy/autophagy. Although the role of the UPS and autophagy in slowing age-induced proteostasis decline has been elucidated, limited information is available on how these pathways can be activated in a collaborative manner to delay proteostasis-associated aging. Here, we show that activation of the UPS via the pharmacological inhibition of USP14 (ubiquitin specific peptidase 14) using IU1 improves proteostasis and autophagy decline caused by aging or proteostatic stress in Drosophila and human cells. Treatment with IU1 not only alleviated the aggregation of polyubiquitinated proteins in aging Drosophila flight muscles but also extended the fly lifespan with enhanced locomotive activity via simultaneous activation of the UPS and autophagy. Interestingly, the effect of this drug disappeared when proteasomal activity was inhibited, but was evident upon proteostasis disruption by foxo mutation. Overall, our findings shed light on potential strategies to efficiently ameliorate age-associated pathologies associated with perturbed proteostasis. Abbreviations: AAAs: amino acid analogs; foxo: forkhead box, sub-group O; IFMs: indirect flight muscles; UPS: ubiquitin-proteasome system; USP14: ubiquitin specific peptidase 14

Comparative proteomic discovery of salt stress response in alfalfa roots and overexpression of MsANN2 confers salt tolerance

Soil salinity constrains growth, development and yield of alfalfa (Medicago sativa L.). To illustrate the molecular mechanisms responsible for salt tolerance, a comparative proteome analysis was explored to characterize protein profiles of alfalfa seedling roots exposed to 100 and 200 mM NaCl for three weeks. There were 52 differentially expressed proteins identified, among which the mRNA expressions of 12 were verified by Real-Time-PCR analysis. The results showed increase in abundance of ascorbate peroxidase, POD, CBS protein and PR-10 in salt-stressed alfalfa, suggesting an effectively antioxidant and defense systems. Alfalfa enhanced protein quality control system to refold or degrade abnormal proteins induced by salt stress through upregulation of unfolded protein response (UPR) marker PDIs and molecular chaperones (eg. HSP70, TCP-1, and GroES) as well as the ubiquitin‐proteasome system (UPS) including ubiquitin ligase enzyme (E3) and proteasome subunits. Upregulation of proteins responsible for calcium signal transduction including calmodulin and annexin helped alfalfa adapt to salt stress. Specifically, annexin (MsANN2), a key Ca2+-binding protein, was selected for further characterization. The heterologous of the MsANN2 in Arabidopsis conferred salt tolerance. These results provide detailed information for salt-responsive root proteins and highlight the importance of MsANN2 in adapting to salt stress in alfalfa.

The Role of Protein Quantity Control in Polyglutamine Spinocerebellar Ataxias.

Polyglutamine spinocerebellar ataxias (polyQ SCAs) represent the most prevalent subtype of SCAs. The primary pathogenic mechanism is believed to be the gain-of-function neurotoxicity of polyQ proteins. Strategies such as enhancing the degradation or inhibiting the accumulation of these mutant proteins are pivotal for reducing their toxicity and slowing disease progression. The protein quality control (PQC) system, comprising primarily molecular chaperones and the ubiquitin‒proteasome system (UPS), is essential for maintaining protein homeostasis by regulating protein folding, trafficking, and degradation. Notably, polyQ proteins can disrupt the PQC system by sequestering its critical components and impairing its proteasomal functions. Therefore, restoring the PQC system through genetic or pharmacological interventions could potentially offer beneficial effects and alleviate the symptoms of the disease. Here, we will provide a review on the distribution, expression, and genetic or pharmacological intervention of protein quality control system in cellular or animal models of PolyQ SCAs.

Protein quality control systems in the endoplasmic reticulum and the cytosol coordinately prevent alachlor-induced proteotoxic stress in Saccharomyces cerevisiae

Alachlor, a widely used chloroacetanilide herbicide for controlling annual grasses in crops, has been reported to rapidly trigger protein denaturation and aggregation in the eukaryotic model organism Saccharomyces cerevisiae. Therefore, this study aimed to uncover cellular mechanisms involved in preventing alachlor-induced proteotoxicity. The findings reveal that the ubiquitin-proteasome system (UPS) plays a crucial role in eliminating alachlor-denatured proteins by tagging them with polyubiquitin for subsequent proteasomal degradation. Exposure to alachlor rapidly induced an inhibition of proteasome activity by 90 % within 30 min. The molecular docking analysis suggests that this inhibition likely results from the binding of alachlor to β subunits within the catalytic core of the proteasome. Notably, our data suggest that nascent proteins in the endoplasmic reticulum (ER) are the primary targets of alachlor. Consequently, the unfolded protein response (UPR), responsible for coping with aberrant proteins in the ER, becomes activated within 1 h of alachlor treatment, leading to the splicing of HAC1 mRNA into the active transcription activator Hac1p and the upregulation of UPR gene expression. These findings underscore the critical roles of the protein quality control systems UPS and UPR in mitigating alachlor-induced proteotoxicity by degrading alachlor-denatured proteins and enhancing the protein folding capacity of the ER.

Concentration of HSPA1A and transthyretin proteins in the blood serum of patients with bipolar disorder

IntroductionInsufficient knowledge about the pathophysiological processes in bipolar disorder (BD) leads to difficulties in differentiating this disorder from other affective disorders. Quantitative analysis of serum protein profiles in BD expands our understanding of the pathophysiology of the disease and may aid in subsequent diagnosis. As a result of a previously conducted comparative mass spectrometric study of serum proteins in patients with depression, bipolar disorder and healthy donors, increased expression of Heat Shock 70kDa Protein1A (HSPA1A) and transthyretin was identified.ObjectivesDetermination of HSPA1A and transthyretin concentrations in the blood serum of patients with mental disorders.MethodsBlood serum of 28 patients with bipolar disorder aged 49 years [33;52], 30 patients with recurrent depressive disorder aged 40 years [31; 51] and 130 patients with schizophrenia aged 38 years [31;49], as well as 20 mentally and somatically healthy individuals aged 35 years [31;40] was studied. The amount of Heat shock protein 1A (HSPA1A) and Transthyretin (thyroxine and retinol transport protein) was determined using a Enzyme-linked Immunosorbent Assay Kit from Homo sapiens (Cloud-Clone Corp). Statistical data processing was carried out in the Statistica 12.0 program.ResultsA statistically significant (p = 0.016) increase in the level of HSPA1A was found in patients with BD (0.84 [0.59; 1.09] ng/ml), compared with healthy individuals (0.61 [0.51; 0.77] ng/ml). HSPA1A plays a pivotal role in the protein quality control system, ensuring the correct folding of proteins. It is known that this protein is involved in the embryonic development of the central nervous system, as well as in neuroprotection by preventing the death of neurons due to its anti-apoptotic properties. A statistically significant (p = 0.047) increase in the level of transthyretin was found in patients with BD 21.8 рg/ml, compared with healthy individuals 19.4 pg/ml. Transthyretin plays an important role in ensuring the normal state of the central nervous system and is involved in cognitive processes.ConclusionsThus, the HSPA1A and transthyretin are probably involved in the pathogenesis of BD and can be proposed as be proposed as an additional paraclinical criterion for differential diagnosis.Support by RSF №23-75-00023.Disclosure of InterestNone Declared

AAV mediated carboxyl terminus of Hsp70 interacting protein overexpression mitigates the cognitive and pathological phenotypes of APP/PS1 mice.

JOURNAL/nrgr/04.03/01300535-202501000-00033/figure1/v/2024-05-14T021156Z/r/image-tiff The E3 ubiquitin ligase, carboxyl terminus of heat shock protein 70 (Hsp70) interacting protein (CHIP), also functions as a co-chaperone and plays a crucial role in the protein quality control system. In this study, we aimed to investigate the neuroprotective effect of overexpressed CHIP on Alzheimer's disease. We used an adeno-associated virus vector that can cross the blood-brain barrier to mediate CHIP overexpression in APP/PS1 mouse brain. CHIP overexpression significantly ameliorated the performance of APP/PS1 mice in the Morris water maze and nest building tests, reduced amyloid-β plaques, and decreased the expression of both amyloid-β and phosphorylated tau. CHIP also alleviated the concentration of microglia and astrocytes around plaques. In APP/PS1 mice of a younger age, CHIP overexpression promoted an increase in ADAM10 expression and inhibited β-site APP cleaving enzyme 1, insulin degrading enzyme, and neprilysin expression. Levels of HSP70 and HSP40, which have functional relevance to CHIP, were also increased. Single nuclei transcriptome sequencing in the hippocampus of CHIP overexpressed mice showed that the lysosomal pathway and oligodendrocyte-related biological processes were up-regulated, which may also reflect a potential mechanism for the neuroprotective effect of CHIP. Our research shows that CHIP effectively reduces the behavior and pathological manifestations of APP/PS1 mice. Indeed, overexpression of CHIP could be a beneficial approach for the treatment of Alzheimer's disease.

Identification of bacterial dissimilatory antimonate reductase AnrA: genes and proteins involved in antimonate respiration and resistance in Geobacter sp. strain SVR.

Geobacter sp. strain SVR uses antimonate [Sb(V)] as a terminal electron acceptor for anaerobic respiration. Here, we visualized a possible key enzyme, periplasmic Sb(V) reductase (Anr), via active staining and non-denaturing gel electrophoresis. Liquid chromatography-tandem mass spectrometry analysis revealed that a novel dimethyl sulfoxide (DMSO) reductase family protein, WP_173201954.1, is involved in Anr. This protein was closely related with AnrA, a protein suggested to be the catalytic subunit of a respiratory Sb(V) reductase in Desulfuribacillus stibiiarsenatis. The anr genes of strain SVR (anrXSRBAD) formed an operon-like structure, and their transcription was upregulated under Sb(V)-respiring conditions. The expression of anrA gene was induced by more than 1 µM of antimonite [Sb(III)]; however, arsenite [As(III)] did not induce the expression of anrA gene. Tandem mass tag-based proteomic analysis revealed that, in addition to Anr proteins, proteins in the following categories were upregulated under Sb(V)-respiring conditions: (i) Sb(III) efflux systems such as Ant and Ars; (ii) antioxidizing proteins such as ferritin, rubredoxin, and thioredoxin; (iii) protein quality control systems such as HspA, HslO, and DnaK; and (iv) DNA repair proteins such as UspA and UvrB. These results suggest that strain SVR copes with antimony stress by modulating pleiotropic processes to resist and actively metabolize antimony. To the best of our knowledge, this is the first report to demonstrate the involvement of AnrA in Sb(V) respiration at the protein level. Furthermore, this is the first example to show high expression of the Ant system proteins in the Sb(V)-respiring bacterium.IMPORTANCEAntimony (Sb) exists mainly as antimonite [Sb(III)] or antimonate [Sb(V)] in the environment, and Sb(III) is more toxic than Sb(V). Recently, microbial involvement in Sb redox reactions has received attention. Although more than 90 Sb(III)-oxidizing bacteria have been reported, information on Sb(V)-reducing bacteria is limited. Especially, the enzyme involved in dissimilatory Sb(V) reduction, or Sb(V) respiration, is unclear, despite this pathway being very important for the circulation of Sb in nature. In this study, we demonstrated that the Sb(V) reductase (Anr) of an Sb(V)-respiring bacterium (Geobacter sp. SVR) is a novel member of the dimethyl sulfoxide (DMSO) reductase family. In addition, we found that strain SVR copes with Sb stress by modulating pleiotropic processes, including the Ant and Ars systems, and upregulating the antioxidant and quality control protein levels. Considering the abundance and diversity of putative anr genes in the environment, Anr may play a significant role in global Sb cycling in both marine and terrestrial environments.

Binding site prediction between lysozyme and glucose-regulated protein 78, a hope to fight amyloidosis

Amyloidosis is an extraordinarily vigorous and heterogeneous group of disorders that causes numerous organ failures due to the precipitation of misfolded proteins. Many of these damaged proteins are discarded before causing any fatal diseases due to the contribution of the protein quality control (PQC) system and its chaperons, including glucose-regulated protein (GRP78). One of the most important enzymatic proteins inside the body is lysozyme, which is reported to have many mutated variants that may cause amyloid fibrils. This study used structural bioinformatics and molecular dynamics simulations to test and suggest binding sites for the human lysozyme protein with GRP78. Multiple sequence alignment (MSA) shows that part of the lysozyme envelope protein (C65–C81 cyclic region) has high similarities (30.77% identity) with the cyclic Pep42. Additionally, the binding between the lysozyme cyclic region (C65–C81) and GRP78 substrate binding domain (SBD) is found favorable. The number and types of interactions vary between each of the mutant isoforms of lysozyme. The more significant the conformational changes in the mutation, the greater its probability of aggregation and the formation of amyloid fibrils. Each mutation leads to different interactions and binding patterns with GRP78. The present computational study suggests a lysozyme-GRP78 binding site, thus paving the way for drug designers to construct suitable carriers that can collect misfolded lysozyme proteins and eliminate them from the body, preventing their aggregation and amyloidogenesis. Communicated by Ramaswamy H. Sarma

Role of the San1 ubiquitin ligase in the heat stress-induced degradation of nonnative Nup1 in the nuclear pore complex.

The nuclear pore complex (NPC) mediates the selective exchange of macromolecules between the nucleus and the cytoplasm. Neurodegenerative diseases such as amyotrophic lateral sclerosis are characterized by mislocalization of nucleoporins (Nups), transport receptors, and Ras-related nuclear proteins into nucleoplasmic or cytosolic aggregates, underscoring the importance of precise assembly of the NPC. The assembly state of large protein complexes is strictly monitored by the protein quality control system. The ubiquitin-proteasome system may eliminate aberrant, misfolded, and/or orphan components; however, the involvement of the ubiquitin-proteasome system in the degradation of nonnative Nups in the NPC remains unclear. Here, we show that in Saccharomyces cerevisiae, although Nup1 (the FG-Nup component of the central core of the NPC) was stable, C-terminally green fluorescent protein-tagged Nup1, which had been incorporated into the NPC, was degraded by the proteasome especially under heat stress conditions. The degradation was dependent on the San1 ubiquitin ligase and Cdc48/p97, as well as its cofactor Doa1. We also demonstrate that San1 weakly but certainly contributes to the degradation of nontagged endogenous Nup1 in cells defective in NPC biogenesis by the deletion of NUP120. In addition, the overexpression of SAN1 exacerbated the growth defect phenotype of nup120Δ cells, which may be caused by excess degradation of defective Nups due to the deletion of NUP120. These biochemical and genetic data suggest that San1 is involved in the degradation of nonnative Nups generated by genetic mutation or when NPC biogenesis is impaired.

HtrAs are essential for the survival of the haloarchaeon Natrinema gari J7-2 in response to heat, high salinity, and toxic substances.

Bacterial and eukaryotic HtrAs can act as an extracytoplasmic protein quality control (PQC) system to help cells survive in stress conditions, but the functions of archaeal HtrAs remain unknown. Particularly, haloarchaea route most secretory proteins to the Tat pathway, enabling them to fold properly in well-controlled cytoplasm with cytosolic PQC systems before secretion. It is unclear whether HtrAs are required for haloarchaeal survival and stress response. The haloarchaeon Natrinema gari J7-2 encodes three Tat signal peptide-bearing HtrAs (NgHtrA, NgHtrB, and NgHtrC), and the signal peptides of NgHtrA and NgHtrC contain a lipobox. Here, the in vitro analysis reveals that the three HtrAs show different profiles of temperature-, salinity-, and metal ion-dependent proteolytic activities and could exhibit chaperone-like activities to prevent the aggregation of reduced lysozyme when their proteolytic activities are inhibited at low temperatures or the active site is disrupted. The gene deletion and complementation assays reveal that NgHtrA and NgHtrC are essential for the survival of strain J7-2 at elevated temperature and/or high salinity and contribute to the resistance of this haloarchaeon to zinc and inhibitory substances generated from tryptone. Mutational analysis shows that the lipobox mediates membrane anchoring of NgHtrA or NgHtrC, and both the membrane-anchored and free extracellular forms of the two enzymes are involved in the stress resistance of strain J7-2, depending on the stress conditions. Deletion of the gene encoding NgHtrB in strain J7-2 causes no obvious growth defect, but NgHtrB can functionally substitute for NgHtrA or NgHtrC under some conditions.IMPORTANCEHtrA-mediated protein quality control plays an important role in the removal of aberrant proteins in the extracytoplasmic space of living cells, and the action mechanisms of HtrAs have been extensively studied in bacteria and eukaryotes; however, information about the function of archaeal HtrAs is scarce. Our results demonstrate that three HtrAs of the haloarchaeon Natrinema gari J7-2 possess both proteolytic and chaperone-like activities, confirming that the bifunctional nature of HtrAs is conserved across all three domains of life. Moreover, we found that NgHtrA and NgHtrC are essential for the survival of strain J7-2 under stress conditions, while NgHtrB can serve as a substitute for the other two HtrAs under certain circumstances. This study provides the first biochemical and genetic evidence of the importance of HtrAs for the survival of haloarchaea in response to stresses.

Mouse transient receptor potential melastatin 2 (TRPM2) isoform 7 attenuates full-length mouse TRPM2 activity through reductions in its expression by targeting it to ER-associated degradation.

Transient receptor potential melastatin 2 (TRPM2) assembles into tetramers to function as an oxidative stress-sensitive Ca2+ channel at the surface membrane. Limited information is currently available on the 10 protein isoforms of mouse TRPM2 (mTRPM2) identified. This study investigated whether these isoforms function as Ca2+ channels and examined their effects on full-length mTRPM2 activity using the HEK 293 cell exogenous expression system. Only full-length mTRPM2, isoform 1 localized to the surface membrane and was activated by oxidative stress. Isoform 7 was clearly recognized by protein quality control systems and degraded by endoplasmic reticulum-associated degradation after transmembrane proteolysis. In the co-expression system, the activation and expression of full-length mTRPM2 were attenuated by its co-expression with isoform 7, but not with the other isoforms. This decrease in the expression of full-length mTRPM2 was recovered by the proteasomal inhibitor. The present results suggest that isoforms other than isoform 1 did not function as oxidative stress-sensitive channels and also that only isoform 7 attenuated the activation of full-length mTRPM2 by targeting it to endoplasmic reticulum-associated degradation. The present study will provide important information on the functional nature of mTRPM2 isoforms for the elucidation of their roles in physiological and patho-physiological responses in vivo using mouse models.

Protein Quality Control Systems and ER Stress as Key Players in SARS-CoV-2-Induced Neurodegeneration.

The COVID-19 pandemic has brought to the forefront the intricate relationship between SARS-CoV-2 and its impact on neurological complications, including potential links to neurodegenerative processes, characterized by a dysfunction of the protein quality control systems and ER stress. This review article explores the role of protein quality control systems, such as the Unfolded Protein Response (UPR), the Endoplasmic Reticulum-Associated Degradation (ERAD), the Ubiquitin-Proteasome System (UPS), autophagy and the molecular chaperones, in SARS-CoV-2 infection. Our hypothesis suggests that SARS-CoV-2 produces ER stress and exploits the protein quality control systems, leading to a disruption in proteostasis that cannot be solved by the host cell. This disruption culminates in cell death and may represent a link between SARS-CoV-2 and neurodegeneration.

Endoplasmic Reticulum Stress and Obesity.

In recent years, the world has seen an alarming increase in obesity and is closely associated with insulin resistance, which is a state of low-grade inflammation, the latter characterized by elevated levels of proinflammatory cytokines in blood and tissues. A shift in energy balance alters systemic metabolic regulation and the important role that chronic inflammation, endoplasmic reticulum (ER) dysfunction, and activation of the unfolded protein response (UPR) plays in this process.Why obesity is so closely associated with insulin resistance and inflammation is not understood well. This suggests that there are probably many causes for obesity-related insulin resistance and inflammation. One of the faulty mechanisms is protein homeostasis, protein quality control system included protein folding, chaperone activity, and ER-associated degradation leading to endoplasmic reticulum (ER) stress.The ER is a vast membranous network responsible for the trafficking of a wide range of proteins and plays a central role in integrating multiple metabolic signals critical in cellular homeostasis. Conditions that may trigger unfolded protein response activation include increased protein synthesis, the presence of mutant or misfolded proteins, inhibition of protein glycosylation, imbalance of ER calcium levels, glucose and energy deprivation, hypoxia, pathogens, or pathogen-associated components and toxins. Thus, characterizing the mechanisms contributing to obesity and identifying potential targets for its prevention and treatment will have a great impact on the control of associated conditions, particularly T2D.

The role of plant proteases in the response of plants to abiotic stress factors

The primary function of proteolytic enzymes is the hydrolysis of peptide bonds. Enzymes responsible for catalyzing this reaction are commonly referred to as proteases. The vast majority of these enzymes belong to the class of hydrolases and operate in aqueous environments. However, there is a distinct group of proteases known as intramembrane proteases, which are integral membrane proteins capable of cleaving peptide bonds in the hydrophobic environment of biological membranes. Proteolysis serves several essential functions in plant cells, ranging from the degradation of damaged and unnecessary proteins to the removal of non-functional protein aggregates. It plays a role in the quality control system for proteins and even releases transcription factors from membrane proteins. Proteolytic processes are indispensable at every stage of plant development and allow for the modification of the cell’s protein composition based on developmental needs and environmental requirements. Proteases are also enzymatic components of the cell that facilitate the efficient regeneration of many key metabolic pathways, such as photosynthesis and respiration. The response of plant cells and the entire plant organism to various biotic and abiotic stresses often requires the remodeling of metabolic pathways, the regeneration of key enzymatic complexes, or changes in the protein profile. By participating in all these processes, proteases constitute a crucial element of the cellular response to environmental stresses. The aim of this work is to review the role that individual proteases play in the response of plant cells to abiotic stress factors, such as drought, salinity, cold, temperature, and light.

Mechanisms of Endoplasmic Reticulum Protein Homeostasis in Plants.

Maintenance of proteome integrity is essential for cell function and survival in changing cellular and environmental conditions. The endoplasmic reticulum (ER) is the major site for the synthesis of secretory and membrane proteins. However, the accumulation of unfolded or misfolded proteins can perturb ER protein homeostasis, leading to ER stress and compromising cellular function. Eukaryotic organisms have evolved sophisticated and conserved protein quality control systems to ensure protein folding fidelity via the unfolded protein response (UPR) and to eliminate potentially harmful proteins via ER-associated degradation (ERAD) and ER-phagy. In this review, we summarize recent advances in our understanding of the mechanisms of ER protein homeostasis in plants and discuss the crosstalk between different quality control systems. Finally, we will address unanswered questions in this field.

Neuroprotective role of vitamin B12 in streptozotocin-induced type 1 diabetic rats

Chronic hyperglycemia-induced neuropathological changes include neuronal apoptosis, astrogliosis, decrease in neurotrophic support, impaired synaptic plasticity, and impaired protein quality control (PQC) system. Vitamin B12 is indispensable for neuronal development and brain function. Several studies reported the neuroprotective effect of B12 supplementation in diabetic patients. However, the underlying molecular basis for the neuroprotective effect of B12 supplementation in diabetes needs to be thoroughly investigated. Two-month-old Sprague-Dawley rats were randomly assigned into three groups: Control (CN), diabetes (D; induced with streptozotocin; STZ), and diabetic rats supplemented with vitamin B12 (DBS; vitamin B12; 50 μg/kg) for four months. At the end of 4 months of experimentation, the brain was dissected to collect the cerebral cortex (CC). The morphology of CC was investigated with H&E and Nissl body staining. Neuronal apoptosis was determined with TUNEL assay. The components of neurotrophic support, astrogliosis, synaptic plasticity, and PQC processes were investigated by immunoblotting and immunostaining methods. H& E, Nissl body, and TUNEL staining revealed that diabetes-induced neuronal apoptosis and degeneration. However, B12 supplementation ameliorated the diabetes-induced neuronal apoptosis. Further, B12 supplementation restored the markers of neurotrophic support (BDNF, NGF, and GDNF), and synaptic plasticity (SYP, and PSD-95) in diabetic rats. Interestingly, B12 supplementation also attenuated astrogliosis, ER stress, and ameliorated autophagy-related proteins in diabetic rats. Overall, these findings suggest that B12 acts as a neuroprotective agent by inhibiting the neuropathological changes in STZ-induced type 1 diabetes. Thus, B12 supplementation could produce beneficial outcomes including neuroprotective effects in diabetic patients.

Clinical Manifestations.

The accumulation of toxic amyloid-ß protein in brain is a hallmark of Alzheimer's disease. The accumulation of such toxicants is prevented by a cellular protein quality control system. Molecular chaperons, which further prevent proteins from misfolding and aggregating, are produced by this system, which is mostly activated in response to acute thermal stress. This study aims to determine the therapeutic effect of frequent thermal shock on the development of Alzheimer's disease METHOD: The induction of Alzheimer's disease was caused by the intracerebroventricular (ICV) injection of the Aß (1-42) peptide into the ventricular system of the mouse brain. The animals were divided into four groups: normal control (NC), disease control (DC), sham control (SC), water immersion/no heat group (NH), and hot water immersion/high heat group (HH). The ICV-Aß injection was given to the DC, NH, and HH groups to induce dementia and AD-like symptoms. The animals in the HH treatment group were given heat shock in the form of hot water immersion for a period of 4 weeks, where each session lasted for 20 minutes. The animals in the NH group were also exposed to water immersion for 20 minutes daily for a period of 4 weeks, but the water temperature was maintained at room temperature. After the completion of the treatment period, the behavioural and biochemical parameters of the animals were assessed for learning and memory defects. The enzyme-linked immunosorbent assay (ELISA) was carried out for the Aß estimation. Behavioural assessments in the Y-maze and morris water maze showed that the animals given daily heat exposure for a period of 4 weeks resisted the detrimental memory effects of the ICV-Aß injection and had better memory than the water immersion group with no heat treatment given. Increased levels of lipid peroxidation and decreased levels of glutathione were significantly (p<0.05) antagonised by hot water immersion treatment. ELISA showed the lower level of Aß in hot water immersion/high heat group animals when compared to the disease control animals. The study concluded that frequent heat exposure from hot baths and saunas may reduce the risk of developing dementia and Alzheimer's-like symptoms in old age.

Melatonin Alleviates the Impairment of Muscle Bioenergetics and Protein Quality Control Systems in Leptin-Deficiency-Induced Obesity.

Leptin is critically compromised in the major common forms of obesity. Skeletal muscle is the main effector tissue for energy modification that occurs as a result of the effect of endocrine axes, such as leptin signaling. Our study was carried out using skeletal muscle from a leptin-deficient animal model, in order to ascertain the importance of this hormone and to identify the major skeletal muscle mechanisms affected. We also examined the therapeutic role of melatonin against leptin-induced muscle wasting. Here, we report that leptin deficiency stimulates fatty acid β-oxidation, which results in mitochondrial uncoupling and the suppression of mitochondrial oxidative damage; however, it increases cytosolic oxidative damage. Thus, different nutrient-sensing pathways are disrupted, impairing proteostasis and promoting lipid anabolism, which induces myofiber degeneration and drives oxidative type I fiber conversion. Melatonin treatment plays a significant role in reducing cellular oxidative damage and regulating energy homeostasis and fuel utilization. Melatonin is able to improve both glucose and mitochondrial metabolism and partially restore proteostasis. Taken together, our study demonstrates melatonin to be a decisive mitochondrial function-fate regulator in skeletal muscle, with implications for resembling physiological energy requirements and targeting glycolytic type II fiber recovery.

Exercise training decreases the load and changes the content of circulating SDS-resistant protein aggregates in patients with heart failure with reduced ejection fraction

BackgroundHeart failure (HF) often disrupts the protein quality control (PQC) system leading to protein aggregate accumulation. Evidence from tissue biopsies showed that exercise restores PQC system in HF; however, little is known about its effects on plasma proteostasis.AimTo determine the effects of exercise training on the load and composition of plasma SDS-resistant protein aggregates (SRA) in patients with HF with reduced ejection fraction (HFrEF).MethodsEighteen patients with HFrEF (age: 63.4 ± 6.5 years; LVEF: 33.4 ± 11.6%) participated in a 12-week combined (aerobic plus resistance) exercise program (60 min/session, twice per week). The load and content of circulating SRA were assessed using D2D SDS-PAGE and mass spectrometry. Cardiorespiratory fitness, quality of life, and circulating levels of high-sensitive C-reactive protein, N-terminal pro-B-type natriuretic peptide (NT-proBNP), haptoglobin and ficolin-3, were also evaluated at baseline and after the exercise program.ResultsThe exercise program decreased the plasma SRA load (% SRA/total protein: 38.0 ± 8.9 to 36.1 ± 9.7%, p = 0.018; % SRA/soluble fraction: 64.3 ± 27.1 to 59.8 ± 27.7%, p = 0.003). Plasma SRA of HFrEF patients comprised 31 proteins, with α-2-macroglobulin and haptoglobin as the most abundant ones. The exercise training significantly increased haptoglobin plasma levels (1.03 ± 0.40 to 1.11 ± 0.46, p = 0.031), while decreasing its abundance in SRA (1.83 ± 0.54 × 1011 to 1.51 ± 0.59 × 1011, p = 0.049). Cardiorespiratory fitness [16.4(5.9) to 19.0(5.2) ml/kg/min, p = 0.002], quality of life, and circulating NT-proBNP [720.0(850.0) to 587.0(847.3) pg/mL, p = 0.048] levels, also improved after the exercise program.ConclusionExercise training reduced the plasma SRA load and enhanced PQC, potentially via haptoglobin-mediated action, while improving cardiorespiratory fitness and quality of life of patients with HFrEF.