Hsp90 Co-chaperone p23 contributes to dopaminergic mitochondrial stress via stabilization of PHD2: Implications for Parkinson's disease

Multiplex proteomics identifies inflammation-related plasma biomarkers for aging and cardio-metabolic disorders

BACKGROUND

Cardio-metabolic disorders (CMDs) are common in aging people and are pivotal risk factors for cardiovascular diseases (CVDs). Inflammation is involved in the pathogenesis of CVDs and aging, but the underlying inflammatory molecular phenotypes in CMDs and aging are still unknown.

METHOD

We utilized multiple proteomics to detect 368 inflammatory proteins in the plasma of 30 subjects, including healthy young individuals, healthy elderly individuals, and elderly individuals with CMDs, by Proximity Extension Assay technology (PEA, O-link). Protein-protein interaction (PPI) network and functional modules were constructed to explore hub proteins in differentially expressed proteins (DEPs). The correlation between proteins and clinical traits of CMDs was analyzed and diagnostic value for CMDs of proteins was evaluated by ROC curve analysis.

RESULT

Our results revealed that there were 161 DEPs (adjusted p < 0.05) in normal aging and EGF was the most differentially expressed hub protein in normal aging. Twenty-eight DEPs were found in elderly individuals with CMDs and MMP1 was the most differentially expressed hub protein in CMDs. After the intersection of DEPs in aging and CMDs, there were 10 overlapping proteins: SHMT1, MVK, EGLN1, SLC39A5, NCF2, CXCL6, IRAK4, REG4, PTPN6, and PRDX5. These proteins were significantly correlated with the level of HDL-C, TG, or FPG in plasma. They were verified to have good diagnostic value for CMDs in aging with an AUC > 0.7. Among these, EGLN1, NCF2, REG4, and SLC39A2 were prominently increased both in normal aging and aging with CMDs.

CONCLUSION

Our results could reveal molecular markers for normal aging and CMDs, which need to be further expanded the sample size and to be further investigated to predict their significance for CVDs.

Induced Pluripotent Stem Cells in Disease Biology and the Evidence for Their In Vitro Utility

Many human phenotypes are impossible to recapitulate in model organisms or immortalized human cell lines. Induced pluripotent stem cells (iPSCs) offer a way to study disease mechanisms in a variety of differentiated cell types while circumventing ethical and practical issues associated with finite tissue sources and postmortem states. Here, we discuss the broad utility of iPSCs in genetic medicine and describe how they are being used to study musculoskeletal, pulmonary, neurologic, and cardiac phenotypes. We summarize the particular challenges presented by each organ system and describe how iPSC models are being used to address them. Finally, we discuss emerging iPSC-derived organoid models and the potential value that they can bring to studies of human disease.

Uncovering the Role of Natural and Synthetic Small Molecules in Counteracting the Burden of α-Synuclein Aggregates and Related Toxicity in Different Models of Parkinson's Disease

A proteostasis network represents a sophisticated cellular system that controls the whole process which leads to properly folded functional proteins. The imbalance of proteostasis determines a quantitative increase in misfolded proteins prone to aggregation and elicits the onset of different diseases. Among these, Parkinson's Disease (PD) is a progressive brain disorder characterized by motor and non-motor signs. In PD pathogenesis, alpha-Synuclein (α-Syn) loses its native structure, triggering a polymerization cascade that leads to the formation of toxic inclusions, the PD hallmark. Because molecular chaperones represent a "cellular arsenal" to counteract protein misfolding and aggregation, the modulation of their expression represents a compelling PD therapeutic strategy. This review will discuss evidence concerning the effects of natural and synthetic small molecules in counteracting α-Syn aggregation process and related toxicity, in different in vitro and in vivo PD models. Firstly, the role of small molecules that modulate the function(s) of chaperones will be highlighted. Then, attention will be paid to small molecules that interfere with different steps of the protein-aggregation process. This overview would stimulate in-depth research on already-known small molecules or the development of new ones, with the aim of developing drugs that are able to modify the progression of the disease.

HSP90 mediates the connection of multiple programmed cell death in diseases

Heat shock protein (HSP) 90, an important component of the molecular chaperone network, is closely concerned with cellular signaling pathways and stress response by participating in the process of maturation and activation of client proteins, playing a crucial role both in the normal and abnormal operation of the organism. In functionally defective tissues, programmed cell death (PCD) is one of the regulable fundamental mechanisms mediated by HSP90, including apoptosis, autophagy, necroptosis, ferroptosis, and others. Here, we show the complex relationship between HSP90 and different types of PCD in various diseases, and discuss the possibility of HSP90 as the common regulatory nodal in multiple PCD, which would provide a new perspective for the therapeutic approaches in disease.

Proteinopathies: Deciphering Physiology and Mechanisms to Develop Effective Therapies for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a cluster of diseases marked by progressive neuronal loss, axonal transport blockage, mitochondrial dysfunction, oxidative stress, neuroinflammation, and aggregation of misfolded proteins. NDs are more prevalent beyond the age of 50, and their symptoms often include motor and cognitive impairment. Even though various proteins are involved in different NDs, the mechanisms of protein misfolding and aggregation are very similar. Recently, several studies have discovered that, like prions, these misfolded proteins have the inherent capability of translocation from one neuron to another, thus having far-reaching implications for understanding the processes involved in the onset and progression of NDs, as well as the development of innovative therapy and diagnostic options. These misfolded proteins can also influence the transcription of other proteins and form aggregates, tangles, plaques, and inclusion bodies, which then accumulate in the CNS, leading to neuronal dysfunction and neurodegeneration. This review demonstrates protein misfolding and aggregation in NDs, and similarities and differences between different protein aggregates have been discussed. Furthermore, we have also reviewed the disposal of protein aggregates, the various molecular machinery involved in the process, their regulation, and how these molecular mechanisms are targeted to build innovative therapeutic and diagnostic procedures. In addition, the landscape of various therapeutic interventions for targeting protein aggregation for the effective prevention or treatment of NDs has also been discussed.

Mutual antagonism between aryl hydrocarbon receptor and hypoxia-inducible factor-1α (AhR/HIF-1α) signaling: Impact on the aging process

The ambient oxygen level, many environmental toxins, and the rays of ultraviolet light (UV) provide a significant risk for the maintenance of organismal homeostasis. The aryl hydrocarbon receptors (AhR) represent a complex sensor system not only for environmental toxins and UV radiation but also for many endogenous ligands, e.g., L-tryptophan metabolites. The AhR signaling system is evolutionarily conserved and AhR homologs existed as many as 600 million years ago. The ancient atmosphere demanded the evolution of an oxygen-sensing system, i.e., hypoxia-inducible transcription factors (HIF) and their prolyl hydroxylase regulators (PHD). Given that both signaling systems have important roles in embryogenesis, it seems that they have been involved in the evolution of multicellular organisms. The evolutionary origin of the aging process is unknown although it is most likely associated with the evolution of multicellularity. Intriguingly, there is compelling evidence that while HIF-1α signaling extends the lifespan, that of AhR promotes many age-related degenerative processes, e.g., it increases oxidative stress, inhibits autophagy, promotes cellular senescence, and aggravates extracellular matrix degeneration. In contrast, HIF-1α signaling stimulates autophagy, inhibits cellular senescence, and enhances cell proliferation. Interestingly, there is a clear antagonism between the AhR and HIF-1α signaling pathways. For instance, (i) AhR and HIF-1α factors heterodimerize with the same factor, ARNT/HIF-1β, leading to their competition for DNA-binding, (ii) AhR and HIF-1α signaling exert antagonistic effects on autophagy, and (iii) co-chaperone p23 exhibits specific functions in the signaling of AhR and HIF-1α factors. One might speculate that it is the competition between the AhR and HIF-1α signaling pathways that is a driving force in the aging process.

Targeting Chaperone/Co-Chaperone Interactions with Small Molecules: A Novel Approach to Tackle Neurodegenerative Diseases

The dysfunction of the proteostasis network is a molecular hallmark of neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. Molecular chaperones are a major component of the proteostasis network and maintain cellular homeostasis by folding client proteins, assisting with intracellular transport, and interfering with protein aggregation or degradation. Heat shock protein 70 kDa (Hsp70) and 90 kDa (Hsp90) are two of the most important chaperones whose functions are dependent on ATP hydrolysis and collaboration with their co-chaperones. Numerous studies implicate Hsp70, Hsp90, and their co-chaperones in neurodegenerative diseases. Targeting the specific protein–protein interactions between chaperones and their particular partner co-chaperones with small molecules provides an opportunity to specifically modulate Hsp70 or Hsp90 function for neurodegenerative diseases. Here, we review the roles of co-chaperones in Hsp70 or Hsp90 chaperone cycles, the impacts of co-chaperones in neurodegenerative diseases, and the development of small molecules modulating chaperone/co-chaperone interactions. We also provide a future perspective of drug development targeting chaperone/co-chaperone interactions for neurodegenerative diseases.

Hypoxia Signaling in Parkinson's Disease: There Is Use in Asking "What HIF?"

Hypoxia is a condition characterized by insufficient tissue oxygenation, which results in impaired oxidative energy production. A reduction in cellular oxygen levels induces the stabilization of hypoxia inducible factor α (HIF-1α), master regulator of the molecular response to hypoxia, involved in maintaining cellular homeostasis and driving hypoxic adaptation through the control of gene expression. Due to its high energy requirement, the brain is particularly vulnerable to oxygen shortage. Thus, hypoxic injury can cause significant metabolic changes in neural cell populations, which are associated with neurodegeneration. Recent evidence suggests that regulating HIF-1α may ameliorate the cellular damage in neurodegenerative diseases. Indeed, the hypoxia/HIF-1α signaling pathway has been associated to several processes linked to Parkinson's disease (PD) including gene mutations, risk factors and molecular pathways such as mitochondrial dysfunction, oxidative stress and protein degradation impairment. This review will explore the impact of hypoxia and HIF-1α signaling on these specific molecular pathways that influence PD development and will evaluate different novel neuroprotective strategies involving HIF-1α stabilization.

Potential benefits of phytochemicals from Azadirachta indica against neurological disorders

Azadirachta indica or Neem has been extensively used in the Indian traditional medical system because of its broad range of medicinal properties. Neem contains many chemically diverse and structurally complex phytochemicals such as limonoids, flavonoids, phenols, catechins, gallic acid, polyphenols, nimbins. These phytochemicals possess vast array of therapeutic activities that include anti-feedant, anti-viral, anti-malarial, anti-bacterial, anti-cancer properties. In recent years, many phytochemicals from Neem have been shown to be beneficial against various neurological disorders like Alzheimer's and Parkinson's disease, mood disorders, ischemic-reperfusion injury. The neuroprotective effects of the phytochemicals from Neem are primarily mediated by their anti-oxidant, anti-inflammatory and anti-apoptotic activities along with their ability to modulate signaling pathways. However, extensive studies are still required to fully understand the molecular mechanisms involved in neuropotective effects of phytochemicals from Neem. This review is an attempt to cover the neuroprotective properties of various phytochemicals from Neem along with their mechanism of action so that the potential of the compounds could be realized to reduce the burden of neurodegenerative diseases.

Heat Shock Protein HSP70 in Oxidative Stress in Apnea Patients

We studied the level of heat shock protein HSP70 under conditions of oxidative stress in 47 patients with apnea. The control group included 13 healthy subjects without verified apnea. Blood serum, plasma, and erythrocyte hemolysate were used to determine LPO and anti-oxidant protection components by spectrophotometrical and spectrofluorometrical methods. HSP70 was assayed by ELISA. A direct relationship was established between the intensity of oxidative stress and HSP70 expression in patients with apnea. Quantitative determination of HSP70 can be used as a molecular marker in the early diagnosis and prognosis of the development of various pathological conditions in hypoxia.

Chaperones and Proteostasis: Role in Parkinson's Disease

Proper folding to attain a defined three-dimensional structure is a prerequisite for the functionality of a protein. Improper folding that eventually leads to formation of protein aggregates is a hallmark of several neurodegenerative disorders. Loss of protein homeostasis triggered by cellular stress conditions is a major contributing factor for the formation of these toxic aggregates. A conserved class of proteins called chaperones and co-chaperones is implicated in maintaining the cellular protein homeostasis. Expanding the body of evidence highlights the role of chaperones as central mediators in the formation, de-aggregation and degradation of the aggregates. Altered expression and function of chaperones is associated with many neurodegenerative diseases including Parkinson’s disease. Several studies indicate that chaperones are at the center of the cause and effect cycle of this disease. An overview of the various chaperones that are associated with homeostasis of Parkinson’s disease-related proteins and their role in pathogenicity will be discussed in this review.

Biological Activities of Gedunin-A Limonoid from the Meliaceae Family

Gedunin is an important limonoid present in several genera of the Meliaceae family, mainly in seeds. Several biological activities have been attributed to gedunin, including antibacterial, insecticidal, antimalarial, antiallergic, anti-inflammatory, anticancer, and neuroprotective effects. The discovery of gedunin as a heat shock protein (Hsp) inhibitor represented a very important landmark for its application as a biological therapeutic agent. The current study is a critical literature review based on the several biological activities so far described for gedunin, its therapeutic effect on some human diseases, and future directions of research for this natural compound.

Ellagic acid improves muscle dysfunction in cuprizone-induced demyelinated mice via mitochondrial Sirt3 regulation

Sirt3 enzyme and mitochondrial abnormality can be related to excess fatigue or muscular dysfunction in multiple sclerosis (MS).Ellagic acid (EA) has a mitochondrial protector, iron chelator, antioxidant, and axon regenerator in neurons.In this study the effect of EAon muscle dysfunction, its mitochondria, and Sirt3 enzyme incuprizone-induced model of MSwas examined. Demyelination was induced by a diet containing 0.2% w/w cuprizone (Cup) for 42 days and EA administered daily (5, 50, and 100 mg/kg P.O) either with or without cuprizone in mice. Behavioral tests were assessed, and muscle tissue markers ofoxidative stress, mitochondrial parameters, mitochondrial respiratory chain activity, the Sirt3 protein level, and Sirt3 expression were also determined. Luxol fast blue staining and the behavioral tests were performed toassess the implemented model. In Cup group an increased oxidative stress in their muscle tissues was observed. Also, muscle mitochondria exhibited mitochondria dysfunction, lowered mitochondrial respiratory chain activity, Sirt3 protein level, and Sirt3 expression.EA prevented most of these anomalous alterations. Sub-chronicEA co-treatment dose-dependently ameliorated behavioral and muscular impairment in mice that received Cup.EA can effectively protect muscle tissue against cuprizone-induced demeylination via the mitochondrial protection, oxidative stress prevention and Sirt3 overexpression.

Hsp90 and Its Co-Chaperones in Neurodegenerative Diseases

Proper folding is crucial for proteins to achieve functional activity in the cell. However, it often occurs that proteins are improperly folded (misfolded) and form aggregates, which are the main hallmark of many diseases including cancers, neurodegenerative diseases and many others. Proteins that assist other proteins in proper folding into three-dimensional structures are chaperones and co-chaperones. The key role of chaperones/co-chaperones is to prevent protein aggregation, especially under stress. An imbalance between chaperone/co-chaperone levels has been documented in neurons, and suggested to contribute to protein misfolding. An essential protein and a major regulator of protein folding in all eukaryotic cells is the heat shock protein 90 (Hsp90). The function of Hsp90 is tightly regulated by many factors, including co-chaperones. In this review we summarize results regarding the role of Hsp90 and its co-chaperones in neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and prionopathies.

Induced pluripotent stem cells for neural drug discovery

Neurological diseases such as Alzheimer's disease and Parkinson's disease are growing problems, as average life expectancy is increasing globally. Drug discovery for neurological disease remains a major challenge. Poor understanding of disease pathophysiology and incomplete representation of human disease in animal models hinder therapeutic drug development. Recent advances with induced pluripotent stem cells (iPSCs) have enabled modeling of human diseases with patient-derived neural cells. Utilizing iPSC-derived neurons advances compound screening and evaluation of drug efficacy. These cells have the genetic backgrounds of patients that more precisely model disease-specific pathophysiology and phenotypes. Neural cells derived from iPSCs can be produced in a large quantity. Therefore, application of iPSC-derived human neurons is a new direction for neuronal drug discovery.

The insights into molecular pathways of hypoxia-inducible factor in the brain

The objectives of this present work were to review recent developments on the role of hypoxia-inducible factor (HIF) in the survival of cells under normoxic versus hypoxic and inflammatory brain conditions. The dual nature of HIF effects appears well established, based on the accumulated evidence of HIF playing both the role of adaptive factor and mediator of cell demise. Cellular HIF responses depend on pathophysiological conditions, developmental phase, comorbidities, and administered medications. In addition, HIF-1α and HIF-2α actions may vary in the same tissues. The multiple roles of HIF in stem cells are emerging. HIF not only regulates expression of target genes and thereby influences resultant protein levels but also contributes to epigenetic changes that may reciprocally provide feedback regulations loops. These HIF-dependent alterations in neurological diseases and its responses to treatments in vivo need to be examined alongside with a functional status of subjects involved in such studies. The knowledge of HIF pathways might be helpful in devising HIF-mimetics and modulating drugs, acting on the molecular level to improve clinical outcomes, as exemplified here by clinical and experimental data of selected brain diseases, occasionally corroborated by the data from disorders of other organs. Because of complex role of HIF in brain injuries, prospective therapeutic interventions need to differentially target HIF responses depending on their roles in the molecular mechanisms of neurologic diseases.