Molecular chaperones and Parkinson's disease

Exploring the complex interplay between Parkinson's disease and BAG proteins

Parkinsons disease (PD) is a chronic fast growing neurodegenerative disorder of Central Nervous System (CNS) characterized by progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and formation of Lewy bodies (LBs) which causes dopamine deficiency within basal ganglia leading to motor and non-motor manifestation. According to reports, many factors are responsible for pathogenesis of PD which includes environmental factors, genetic factors, and aging factors. Whereas death of dopaminergic neurons is also caused by oxidative stress, neuroinflammation, and autophagy disorder. Molecular chaperones/co-chaperones are proteins that binds to an unstable conformer of another protein and stabilizes it. Chaperones prevent incorrect interaction between non-native polypeptides which increases the yield but not the rate of reaction. The Bcl-2-associated athanogene (BAG) is a multifunctional group of proteins belonging to BAG family of co-chaperones. Recent studies demonstrates that chaperones interact with PD-related proteins. Co-chaperones like BAG family proteins regulate the function of chaperones. Molecular chaperones regulate the mitochondrial functions by interacting with the PD-related proteins associated with it. This review studies the contribution of chaperones and PD-related proteins in pathogenesis of PD aiming to provide an alternate molecular target for preventing the disease progression.

Characterization of HSP90 expression and function following CNS injury

Spinal cord injury induces significant cellular stress responses. The Heat Shock Protein 90 (HSP90) plays a pivotal role as a molecular chaperone and is crucial for protein folding, stabilization, and cellular signaling pathways. Despite its important function in stress adaptation, the specific expression patterns and functional roles of HSP90 after nerve injury remain unclear. This study aimed to elucidate the expression dynamics and functional implications of HSP90 following central nervous system (CNS) injury. Using western blotting and immunohistochemical analyses, we observed upregulation of HSP90 expression in spinal cord tissues and within injured neurons in a spinal cord contusion injury model. Additionally, HSP90 was found to enhance neurite outgrowth in primary cortical neurons cultured in vitro. Furthermore, in a glutamate-induced neuronal injury model, the expression of HSP90 was up-regulated, and overexpression of HSP90 promoted neurite re-growth in damaged neurons. Overall, our findings highlight the critical involvement of HSP90 in the neural response to injury and offer valuable insights into potential therapeutic strategies for CNS repair.

The Role and Mechanism of Ambra1-Mediated Mitophagy in TDCPP-Exposed Mouse Hippocampal Neurons

Tri(1,3-dichloro-2-propyl)phosphate (TDCPP) is one of the most widely used organophosphorus flame retardants in consumer products. TDCPP has been confirmed to be neurotoxic, but its mechanism has not been clarified and may be related to mitophagy. AMBRA1 can promote neurological autophagy, but whether AMBRA1 is involved in the mechanism of TDCPP-induced neurotoxicity has not been elucidated. In this study, the optimal neuronal damage model was established by exposing mice hippocampal neurons to TDCPP. Furthermore, on the basis of this model, siRNA was used to knock down AMBRA1. Combined with qRT-PCR and Western blot techniques, we identified AMBRA1-mediated mitophagy-induced neuronal damage in vitro mechanism. The experimental results indicated that TDCPP treatment for 24 h led to a decrease in the cell viability of mouse hippocampal neurons, causing neuronal damage. Meanwhile, TDCPP exposure increased autophagy marker proteins p62 and LC3B, and down-regulated mitochondrial DNA ND1 damage and TOMM20 protein, suggesting that TDCPP exposure promoted mitophagy. In addition, TDCPP exposure led to changes in the expression of AMBRA1 and the key factors of mitophagy, FUNDC1, PINK1, and PARKIN, whereas mitophagy was inhibited after knockdown of AMBRA1. The research results indicated that exposure to TDCPP induced neuronal damage and promoted mitophagy. The mechanism may be that AMBRA1 promoted mitophagy in neuronal cells through the PARKIN-dependent/non-dependent pathway. This study revealed the toxic effects of TDCPP on the nervous system and its potential molecular mechanisms, which provided important clues for further understanding the mechanism of action of AMBAR1-mediated mitophagy.

Global profiling of functional histidines in live cells using small-molecule photosensitizer and chemical probe relay labelling

Recent advances in chemical proteomics have focused on developing chemical probes that react with nucleophilic amino acid residues. Although histidine is an attractive candidate due to its importance in enzymatic catalysis, metal binding and protein-protein interaction, its moderate nucleophilicity poses challenges. Its modification is frequently influenced by cysteine and lysine, which results in poor selectivity and narrow proteome coverage. Here we report a singlet oxygen and chemical probe relay labelling method that achieves high selectivity towards histidine. Libraries of small-molecule photosensitizers and chemical probes were screened to optimize histidine labelling, enabling histidine profiling in live cells with around 7,200 unique sites. Using NMR spectroscopy and X-ray crystallography, we characterized the reaction mechanism and the structures of the resulting products. We then applied this method to discover unannotated histidine sites key to enzymatic activity and metal binding in select metalloproteins. This method also revealed the accessibility change of histidine mediated by protein-protein interaction that influences select protein subcellular localization, underscoring its capability in discovering functional histidines.

Development of Inhibitors, Probes, and PROTAC Provides a Complete Toolbox to Study PARK7 in the Living Cell

The integration of diverse chemical tools like small-molecule inhibitors, activity-based probes (ABPs), and proteolysis targeting chimeras (PROTACs) advances clinical drug discovery and facilitates the exploration of various biological facets of targeted proteins. Here, we report the development of such a chemical toolbox for the human Parkinson disease protein 7 (PARK7/DJ-1) implicated in Parkinson's disease and cancers. By combining structure-guided design, miniaturized library synthesis, and high-throughput screening, we identified two potent compounds, JYQ-164 and JYQ-173, inhibiting PARK7 in vitro and in cells by covalently and selectively targeting its critical residue, Cys106. Leveraging JYQ-173, we further developed a cell-permeable Bodipy probe, JYQ-196, for covalent labeling of PARK7 in living cells and a first-in-class PARK7 degrader JYQ-194 that selectively induces its proteasomal degradation in human cells. Our study provides a valuable toolbox to enhance the understanding of PARK7 biology in cellular contexts and opens new opportunities for therapeutic interventions.

PRKN-linked familial Parkinson's disease: cellular and molecular mechanisms of disease-linked variants

Parkinson's disease (PD) is a common and incurable neurodegenerative disorder that arises from the loss of dopaminergic neurons in the substantia nigra and is mainly characterized by progressive loss of motor function. Monogenic familial PD is associated with highly penetrant variants in specific genes, notably the PRKN gene, where homozygous or compound heterozygous loss-of-function variants predominate. PRKN encodes Parkin, an E3 ubiquitin-protein ligase important for protein ubiquitination and mitophagy of damaged mitochondria. Accordingly, Parkin plays a central role in mitochondrial quality control but is itself also subject to a strict protein quality control system that rapidly eliminates certain disease-linked Parkin variants. Here, we summarize the cellular and molecular functions of Parkin, highlighting the various mechanisms by which PRKN gene variants result in loss-of-function. We emphasize the importance of high-throughput assays and computational tools for the clinical classification of PRKN gene variants and how detailed insights into the pathogenic mechanisms of PRKN gene variants may impact the development of personalized therapeutics.

A reduced proteomic signature in critically ill Covid-19 patients determined with plasma antibody micro-array and machine learning

BACKGROUND

COVID-19 is a complex, multi-system disease with varying severity and symptoms. Identifying changes in critically ill COVID-19 patients' proteomes enables a better understanding of markers associated with susceptibility, symptoms, and treatment. We performed plasma antibody microarray and machine learning analyses to identify novel proteins of COVID-19.

METHODS

A case-control study comparing the concentration of 2000 plasma proteins in age- and sex-matched COVID-19 inpatients, non-COVID-19 sepsis controls, and healthy control subjects. Machine learning was used to identify a unique proteome signature in COVID-19 patients. Protein expression was correlated with clinically relevant variables and analyzed for temporal changes over hospitalization days 1, 3, 7, and 10. Expert-curated protein expression information was analyzed with Natural language processing (NLP) to determine organ- and cell-specific expression.

RESULTS

Machine learning identified a 28-protein model that accurately differentiated COVID-19 patients from ICU non-COVID-19 patients (accuracy = 0.89, AUC = 1.00, F1 = 0.89) and healthy controls (accuracy = 0.89, AUC = 1.00, F1 = 0.88). An optimal nine-protein model (PF4V1, NUCB1, CrkL, SerpinD1, Fen1, GATA-4, ProSAAS, PARK7, and NET1) maintained high classification ability. Specific proteins correlated with hemoglobin, coagulation factors, hypertension, and high-flow nasal cannula intervention (P < 0.01). Time-course analysis of the 28 leading proteins demonstrated no significant temporal changes within the COVID-19 cohort. NLP analysis identified multi-system expression of the key proteins, with the digestive and nervous systems being the leading systems.

CONCLUSIONS

The plasma proteome of critically ill COVID-19 patients was distinguishable from that of non-COVID-19 sepsis controls and healthy control subjects. The leading 28 proteins and their subset of 9 proteins yielded accurate classification models and are expressed in multiple organ systems. The identified COVID-19 proteomic signature helps elucidate COVID-19 pathophysiology and may guide future COVID-19 treatment development.

6-Hydroxy-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline Demonstrates Neuroprotective Properties in Experimental Parkinson's Disease by Enhancing the Antioxidant System, Normalising Chaperone Activity and Suppressing Apoptosis

Parkinson's disease (PD) is a neurodegenerative disease, whereby disturbances within the antioxidant defence system, increased aggregation of proteins, and activation of neuronal apoptosis all have a crucial role in the pathogenesis. In this context, exploring the neuroprotective capabilities of compounds that sustain the effectiveness of cellular defence systems in neurodegenerative disorders is worthwhile. During this study, we assessed how 6-hydroxy-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline (HTHQ), which has antioxidant properties, affects the functioning of the antioxidant system, the activity of NADPH-generating enzymes and chaperones, and the level of apoptotic processes in rats with rotenone-induced PD. Six groups of animals were formed for our experiment, each with 12 animals. These were: a control group, animals with rotenone-induced PD, rats with PD given HTHQ at a dose of 50 mg/kg, rats with PD given HTHQ at a dose of 25 mg/kg, animals with pathology who were administered a comparison drug rasagiline, and control animals who were administered HTHQ at a dose of 50 mg/kg. The study results indicate that administering HTHQ led to a significant decrease in oxidative stress in PD rats. The enhanced redox status in animal tissues was linked with the recovery of antioxidant enzyme activities and NADPH-generating enzyme function, as well as an upsurge in the mRNA expression levels of antioxidant genes and factors Nrf2 and Foxo1. Administering HTHQ to rats with PD normalized the chaperone-like activity and mRNA levels of heat shock protein 70. Rats treated with the compound displayed lower apoptosis intensity when compared to animals with pathology. Therefore, owing to its antioxidant properties, HTHQ demonstrated a beneficial impact on the antioxidant system, resulting in decreased requirements for chaperone activation and the inhibition of apoptosis processes triggered in PD. HTHQ at a dose of 50 mg/kg had a greater impact on the majority of the examined variables compared to rasagiline.

Practical Three-Component Regioselective Synthesis of Drug-Like 3-Aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines as Potential Non-Covalent Multi-Targeting Inhibitors To Combat Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are one of the prominent health challenges facing contemporary society, and many efforts have been made to overcome and (or) control it. In this research paper, we described a practical one-pot two-step three-component reaction between 3,4-dihydronaphthalen-1(2H)-one (1), aryl(or heteroaryl)glyoxal monohydrates (2a-h), and hydrazine monohydrate (NH2NH2•H2O) for the regioselective preparation of some 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnoline derivatives (3a-h). After synthesis and characterization of the mentioned cinnolines (3a-h), the in silico multi-targeting inhibitory properties of these heterocyclic scaffolds have been investigated upon various Homo sapiens-type enzymes, including hMAO-A, hMAO-B, hAChE, hBChE, hBACE-1, hBACE-2, hNQO-1, hNQO-2, hnNOS, hiNOS, hPARP-1, hPARP-2, hLRRK-2(G2019S), hGSK-3β, hp38α MAPK, hJNK-3, hOGA, hNMDA receptor, hnSMase-2, hIDO-1, hCOMT, hLIMK-1, hLIMK-2, hRIPK-1, hUCH-L1, hPARK-7, and hDHODH, which have confirmed their functions and roles in the neurodegenerative diseases (NDs), based on molecular docking studies, and the obtained results were compared with a wide range of approved drugs and well-known (with IC50, EC50, etc.) compounds. In addition, in silico ADMET prediction analysis was performed to examine the prospective drug properties of the synthesized heterocyclic compounds (3a-h). The obtained results from the molecular docking studies and ADMET-related data demonstrated that these series of 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines (3a-h), especially hit ones, can really be turned into the potent core of new drugs for the treatment of neurodegenerative diseases (NDs), and/or due to the having some reactionable locations, they are able to have further organic reactions (such as cross-coupling reactions), and expansion of these compounds (for example, with using other types of aryl(or heteroaryl)glyoxal monohydrates) makes a new avenue for designing novel and efficient drugs for this purpose.

Triaging between post-translational modification of cell cycle regulators and their therapeutics in neurodegenerative diseases

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, present challenges in healthcare because of their complicated etiologies and absence of healing remedies. Lately, the emerging role of post-translational modifications (PTMs), in the context of cell cycle regulators, has garnered big interest as a potential avenue for therapeutic intervention. The review explores the problematic panorama of PTMs on cell cycle regulators and their implications in neurodegenerative diseases. We delve into the dynamic phosphorylation, acetylation, ubiquitination, SUMOylation, Glycation, and Neddylation that modulate the key cell cycle regulators, consisting of cyclins, cyclin-dependent kinases (CDKs), and their inhibitors. The dysregulation of these PTMs is related to aberrant cell cycle in neurons, which is one of the factors involved in neurodegenerative pathologies. Moreover, the effect of exogenous activation of CDKs and CDK inhibitors through PTMs on the signaling cascade was studied in postmitotic conditions of NDDs. Furthermore, the therapeutic implications of CDK inhibitors and associated alteration in PTMs were discussed. Lastly, we explored the putative mechanism of PTMs to restore normal neuronal function that might reverse NDDs.

Heat Shock Protein 90 in Parkinson's Disease: Profile of a Serial Killer

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by abnormal α-synuclein misfolding and aggregation, mitochondrial dysfunction, oxidative stress, as well as progressive death of dopaminergic neurons in the substantia nigra. Molecular chaperones play a role in stabilizing proteins and helping them achieve their proper structure. Previous studies have shown that overexpression of heat shock protein 90 (HSP90) can lead to the death of dopaminergic neurons associated with PD. Inhibiting HSP90 is considered a potential treatment approach for neurodegenerative disorders, as it may reduce protein aggregation and related toxicity, as well as suppress various forms of regulated cell death (RCD). This review provides an overview of HSP90 and its role in PD, focusing on its modulation of proteostasis and quality control of LRRK2. The review also explores the effects of HSP90 on different types of RCD, such as apoptosis, chaperone-mediated autophagy (CMA), necroptosis, and ferroptosis. Additionally, it discusses HSP90 inhibitors that have been tested in PD models. We will highlight the under-investigated neuroprotective effects of HSP90 inhibition, including modulation of oxidative stress, mitochondrial dysfunction, PINK/PARKIN, heat shock factor 1 (HSF1), histone deacetylase 6 (HDAC6), and the PHD2-HSP90 complex-mediated mitochondrial stress pathway. By examining previous literature, this review uncovers overlooked neuroprotective mechanisms and emphasizes the need for further research on HSP90 inhibitors as potential therapeutic strategies for PD. Finally, the review discusses the potential limitations and possibilities of using HSP90 inhibitors in PD therapy.

2-Methoxyestradiol and Hydrogen Peroxide as Promising Biomarkers in Parkinson's Disease

Estrogens function in numerous physiological processes including controlling brain cell growth and differentiation. 2-Methoxestradiol (2-ME2), a 17β-estradiol (E2) metabolite, is known for its anticancer effects as observed both in vivo and in vitro. 2-ME2 affects all actively dividing cells, including neurons. The study aimed to determine whether 2-ME2 is a potentially cancer-protective or rather neurodegenerative agent in a specific tissue culture model as well as a clinical setup. In this study, 2-ME2 activity was determined in a Parkinson's disease (PD) in vitro model based on the neuroblastoma SH-SY5Y cell line. The obtained results suggest that 2-ME2 generates nitro-oxidative stress and controls heat shock proteins (HSP), resulting in DNA strand breakage and apoptosis. On the one hand, it may affect intensely dividing cells preventing cancer development; however, on the other hand, this kind of activity within the central nervous system may promote neurodegenerative diseases like PD. Thus, the translational value of 2-ME2's neurotoxic activity in a PD in vitro model was also investigated. LC-MS/MS technique was used to evaluate estrogens and their derivatives, namely, hydroxy and methoxyestrogens, in PD patients' blood, whereas the stopped-flow method was used to assess hydrogen peroxide (H2O2) levels. Methoxyestrogens and H2O2 levels were increased in patients' blood as compared to control subjects, but hydoxyestrogens were simultaneously decreased. From the above, we suggest that the determination of plasma levels of methoxyestrogens and H2O2 may be a novel PD biomarker. The presented research is the subject of the pending patent application "The use of hydrogen peroxide and 17β-estradiol and its metabolites as biomarkers in the diagnosis of neurodegenerative diseases," no. P.441360.

Investigating the neuroprotective potential of rAAV2-PCBP1-EGFP gene therapy against a 6-OHDA-induced model of Parkinson's disease

OBJECTIVES

Previous studies have suggested a potential link between poly(rC)-binding protein 1 (PCBP1) and neurodegenerative diseases, including Parkinson's disease (PD). However, the precise role of PCBP1 in the pathogenesis of PD remains unclear. Therefore, the main objective of this study was to investigate the neuroprotective effects of PCBP1 in a PD model.

METHODS

To evaluate the neuroprotective potential of PCBP1, we conducted cell count assays and observed the expression of heat shock protein 70 (HSP70) in SH-SY5Y cells exposed to 6-OHDA-induced neurotoxicity. Additionally, we utilized recombinant adeno-associated virus (rAAV2) vectors encoding PCBP1 or EGFP, which were injected into the rat striatum. After 2 weeks of vector or saline injection, 6-OHDA was administered to the rat striatum. Behavioral assessments using the open field test (OFT) were performed weekly for 7 weeks. At the seventh week after 6-OHDA injection, immunohistochemistry and protein expression analyses were conducted in the three groups.

RESULTS

The results indicated that PCBP1 treatment significantly reduced the proliferation of 6-OHDA-induced SH-SY5Y cells. Additionally, in surviving cells, overexpression of PCBP1 enhanced the expression of HSP70. Similarly, rAAV2 vectors effectively delivered PCBP1 into the brain, resulting in sustained expression of rAAV2-PCBP1-EGFP. In the OFT, PCBP1 exhibited significant improvements in behavioral abnormalities and reduced anxiety in the PD model rats (p < .01). Moreover, PCBP1 effectively prevented the decrease of tyrosine hydroxylase and HSP70 expression in the lesioned side induced by 6-OHDA (p < .01). Consistent with expectations, PCBP1 efficiently protected against cell death caused by 6-OHDA (p < .01).

CONCLUSIONS

In conclusion, our findings provide compelling evidence for the beneficial effects of PCBP1 in the PD model, suggesting that PCBP1 could be a potential therapeutic target for PD.

Linking Heat Shock Protein 70 and Parkin in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease that affects millions of elderly people worldwide and is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The precise mechanisms underlying the pathogenesis of PD are still not fully understood, but it is well accepted that the misfolding, aggregation, and abnormal degradation of proteins are the key causative factors of PD. Heat shock protein 70 (Hsp70) is a molecular chaperone that participates in the degradation of misfolded and aggregated proteins in living cells and organisms. Parkin, an E3 ubiquitin ligase, participates in the degradation of proteins via the proteasome pathway. Recent studies have indicated that both Hsp70 and Parkin play pivotal roles in PD pathogenesis. In this review, we focus on discussing how dysregulation of Hsp70 and Parkin leads to PD pathogenesis, the interaction between Hsp70 and Parkin in the context of PD and their therapeutic applications in PD.

Modulating Stress Proteins in Response to Therapeutic Interventions for Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative illness characterized by the degeneration of dopaminergic neurons in the substantia nigra, resulting in motor symptoms and without debilitating motors. A hallmark of this condition is the accumulation of misfolded proteins, a phenomenon that drives disease progression. In this regard, heat shock proteins (HSPs) play a central role in the cellular response to stress, shielding cells from damage induced by protein aggregates and oxidative stress. As a result, researchers have become increasingly interested in modulating these proteins through pharmacological and non-pharmacological therapeutic interventions. This review aims to provide an overview of the preclinical experiments performed over the last decade in this research field. Specifically, it focuses on preclinical studies that center on the modulation of stress proteins for the treatment potential of PD. The findings display promise in targeting HSPs to ameliorate PD outcomes. Despite the complexity of HSPs and their co-chaperones, proteins such as HSP70, HSP27, HSP90, and glucose-regulated protein-78 (GRP78) may be efficacious in slowing or preventing disease progression. Nevertheless, clinical validation is essential to confirm the safety and effectiveness of these preclinical approaches.

A TaSnRK1α Modulates TaPAP6L-Mediated Wheat Cold Tolerance through Regulating Endogenous Jasmonic Acid

Here, a sucrose non-fermenting-1-related protein kinase alpha subunit (TaSnRK1α-1A) is identified as associated with cold stress through integration of genome-wide association study, bulked segregant RNA sequencing, and virus-induced gene silencing. It is confirmed that TaSnRK1α positively regulates cold tolerance by transgenes and ethyl methanesulfonate (EMS) mutants. A plastid-lipid-associated protein 6, chloroplastic-like (TaPAP6L-2B) strongly interacting with TaSnRK1α-1A is screened. Molecular chaperone DJ-1 family protein (TaDJ-1-7B) possibly bridged the interaction of TaSnRK1α-1A and TaPAP6L-2B. It is further revealed that TaSnRK1α-1A phosphorylated TaPAP6L-2B. Subsequently, a superior haplotype TaPAP6L-2B30S /38S is identified and confirmed that both R30S and G38S are important phosphorylation sites that influence TaPAP6L-2B in cold tolerance. Overexpression (OE) and EMS-mutant lines verified TaPAP6L positively modulating cold tolerance. Furthermore, transcriptome sequencing revealed that TaPAP6L-2B-OE lines significantly increased jasmonic acid (JA) content, possibly by improving precursor α-linolenic acid contributing to JA synthesis and by repressing JAR1 degrading JA. Exogenous JA significantly improved the cold tolerance of wheat plants. In summary, TaSnRK1α profoundly regulated cold stress, possibly through phosphorylating TaPAP6L to increase endogenous JA content of wheat plants.

Closest horizons of Hsp70 engagement to manage neurodegeneration

Our review seeks to elucidate the current state-of-the-art in studies of 70-kilodalton-weighed heat shock proteins (Hsp70) in neurodegenerative diseases (NDs). The family has already been shown to play a crucial role in pathological aggregation for a wide spectrum of brain pathologies. However, a slender boundary between a big body of fundamental data and its implementation has only recently been crossed. Currently, we are witnessing an anticipated advancement in the domain with dozens of studies published every month. In this review, we briefly summarize scattered results regarding the role of Hsp70 in the most common NDs including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). We also bridge translational studies and clinical trials to portray the output for medical practice. Available options to regulate Hsp70 activity in NDs are outlined, too.

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.

Enhanced Inhibition of Amyloid Formation by Heat Shock Protein 90 Immobilized on Nanoparticles

As the population ages, an epidemic of neurodegenerative diseases with devastating social consequences is looming. To address the pathologies leading to amyloid-related dementia, novel therapeutic strategies must be developed for the treatment or prevention of neural protein-folding disorders. Nanotechnology will be crucial to this scenario, especially in the design of nanoscale systems carrying therapeutic compounds that can navigate the nervous system and identify amyloid to treat it in situ. In this line, we have recently designed a highly simplified and versatile nanorobot consisting of a protein coating based on the heat shock protein 90 (Hsp90) chaperone that not only propels nanoparticles using ATP but also endows them with the extraordinary ability to fold and restore the activity of heat-denatured proteins. Here, we assess the effectiveness of these nanosystems in inhibiting/reducing the aggregation of amyloidogenic proteins. Using Raman spectroscopy, we qualitatively and quantitatively analyze amyloid by identifying and semi-quantifying the Amide I band. Our findings indicate that the coupling of Hsp90 to nanoparticles results in a more potent inhibition of amyloid formation when compared to the soluble protein. We propose that this enhanced performance may be attributed to enhanced release-capture cycles of amyloid precursor oligomers by Hsp90 molecules nearby on the nanosurface. Intelligent biocompatible coatings, like the one described here, that enhance the diffusivity and self-propulsion of nanoparticles while enabling them to carry out critical functions such as environmental scanning, identification, and amyloid prevention, present an exceptional opportunity for the development of advanced nanodevices in biomedical applications. This approach, which combined active biomolecules with synthetic materials, is poised to reveal remarkable prospects in the field of nanomedicine and biotechnology.

Molecular-level interplay between intrinsically disordered clients and Hsp90

Proteostasis is maintained by a network of molecular chaperones, a prominent member of which is the 90-kilodalton heat shock protein Hsp90. The chaperone function of Hsp90 has been extensively reviewed previously, emphasizing its ATPase activity and remodeling of folded client proteins. Experimental evidence implicating Hsp90 in neurodegenerative diseases has bolstered interest in the noncanonical chaperoning of intrinsically disordered protein (IDPs), however the interplay between Hsp90 and its disordered clients remains poorly understood. In this review we describe recent advances that have contributed to our understanding of the intricate mechanisms characterizing Hsp90-mediated chaperoning of the IDPs tau and α-synuclein and survey emerging insights into the modulation of the chaperone-client interplay in the context of neurodegeneration.

All3048, a DnaJ III homolog of Anabaena sp. PCC7120 mediates heat shock response in E. coli and its N-terminus J-domain stimulates DnaK ATPase activity

Cyanobacterial DnaJ offers thermo-tolerance and effectively prevents aggregation of denatured protein in coordination with DnaK. The hypothetical protein All3048 of Anabaena sp. PCC7120 was found to be a 24 kDa DnaJ III protein with a putative J-domain at the extreme N-terminus. This paper decodes the role of All3048 in thermo-tolerance and as a co-chaperon of DnaK. Semi-quantitative and RT-PCR results showed up-accumulation of all3048 in heat, UV-B, cadmium, arsenic and salt. BL21/pET-28a-all3048, all3048(1-95) and all3048(31-128) reduced the heat stress-induced ROS generation by 40 %, 21 % and 24 % as compared to BL21/pET-28-a. Conformational properties of All3048 and its truncated variants were assessed using bis ANS, guanidine hydrochloride and acrylamide quenching. All3048(1-95), All3048 and All3048(31-128) increased DnaK ATPase activity by 8.6, 8.2, and 2.5 fold, respectively. The thermostability investigated using DSC and DSF methods affirmed the relative stability of All3048 and All3048 (31-128), whereas All3048 (1-95) was the least stable. All3048 is a novel cyanobacterial DnaJ III that imparts heat stress tolerance in E. coli; however, only the J-domain present at N-terminus was sufficient for stimulating DnaK's ATPase activity.

Current Treatments and New, Tentative Therapies for Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative pathology, the origin of which is associated with the death of neuronal cells involved in the production of dopamine. The prevalence of PD has increased exponentially. The aim of this review was to describe the novel treatments for PD that are currently under investigation and study and the possible therapeutic targets. The pathophysiology of this disease is based on the formation of alpha-synuclein folds that generate Lewy bodies, which are cytotoxic and reduce dopamine levels. Most pharmacological treatments for PD target alpha-synuclein to reduce the symptoms. These include treatments aimed at reducing the accumulation of alpha-synuclein (epigallocatechin), reducing its clearance via immunotherapy, inhibiting LRRK2, and upregulating cerebrosidase (ambroxol). Parkinson’s disease continues to be a pathology of unknown origin that generates a significant social cost for the patients who suffer from it. Although there is still no definitive cure for this disease at present, there are numerous treatments available aimed at reducing the symptomatology of PD in addition to other therapeutic alternatives that are still under investigation. However, the therapeutic approach to this pathology should include a combination of pharmacological and non-pharmacological strategies to maximise outcomes and improve symptomatological control in these patients. It is therefore necessary to delve deeper into the pathophysiology of the disease in order to improve these treatments and therefore the quality of life of the patients.

Proteostasis in Parkinson's disease: Recent development and possible implication in diagnosis and therapeutics

The protein dyshomeostasis is identified as the hallmark of many age-related neurodegenerative disorders including Parkinson's disease (PD). The diseased brain shows the deposition of Lewy bodies composed of α-synuclein protein aggregates. Functional proteostasis is characterized by the well-coordinated signaling network constituting unfolded protein response (UPR), the ubiquitin-proteasome system (UPS), and the autophagy-lysosome pathway (ALP). These networks ensure proper synthesis, folding, confirmation, and degradation of protein i.e., α-synuclein protein in PD. The proper functioning the of intricately woven proteostasis network is quite resilient to sustain under the influence of stressors. The synuclein protein turnover is hugely influenced by the autosomal dominant, recessive, and X-linked mutational changes of a gene involved in UPR, UPS, and ALP. The methylation, acetylation-related epigenetic modifications of DNA and histone proteins along with microRNA-mediated transcriptional changes also lead to extensive proteostasis dysregulation. The result of defective proteostasis is the deposition of many proteins which start appearing in the biofluids and can be identified as potential biomarkers for early diagnosis of PD. The therapeutic intervention targeted at different strata of proteostasis machinery holds great possibilities for delaying the age-related accumulation of pathological hallmarks.

Potential application of heat shock proteins as therapeutic targets in Parkinson's disease

Parkinson's disease (PD) is a common chronic neurodegenerative disease, and the heat shock proteins (HSPs) are proved to be of great value for PD. In addition, HSPs can maintain protein homeostasis, degrade and inhibit protein aggregation by properly folding and activating intracellular proteins in PD. This study mainly summarizes the important roles of HSPs in PD and explores their feasibility as targets. We introduced the structural and functional characteristics of HSPs and the physiological functions of HSPs in PD. HSPs can protect neurons from damage by degrading aggregates with three mechanisms, including the aggregation and removing α-Synuclein (α-Syn) aggregates, promotion the autophagy of abnormal proteins, and inhibition the apoptosis of degenerated neurons. This study underscores the importance of HSPs as targets in PD and helps to expand new mechanisms in PD treatment strategies.

PARK7 is induced to protect against endotoxic acute kidney injury by suppressing NF-κB

Sepsis is a leading cause of acute kidney injury (AKI), and the pathogenesis of septic AKI remains largely unclear. Parkinson disease protein 7 (PARK7) is a protein of multiple functions that was recently implicated in septic AKI, but the underlying mechanism is unknown. In the present study, we determined the role of PARK7 in septic AKI and further explored the underlying mechanism in lipopolysaccharide (LPS)-induced endotoxic models. PARK7 was induced both in vivo and in vitro following LPS treatment. Compared with wild-type (WT) mice, Park7-deficient mice experienced aggravated kidney tissue damage and dysfunction, and enhanced tubular apoptosis and inflammation following LPS treatment. Consistently, LPS-induced apoptosis and inflammation in renal tubular cells in vitro were exacerbated by Park7 knockdown, whereas they were alleviated by PARK7 overexpression. Mechanistically, silencing Park7 facilitated nuclear translocation and phosphorylation of p65 (a key component of the nuclear factor kappa B [NF-κB] complex) during LPS treatment, whereas PARK7 overexpression partially prevented these changes. Moreover, we detected PARK7 interaction with p65 in the cytoplasm in renal tubular cells, which was enhanced by LPS treatment. Collectively, these findings suggest that PARK7 is induced to protect against septic AKI through suppressing NF-κB signaling.

Chemical Toolkit for PARK7: Potent, Selective, and High-Throughput

The multifunctional human Parkinson's disease protein 7 (PARK7/DJ1) is an attractive therapeutic target due to its link with early-onset Parkinson's disease, upregulation in various cancers, and contribution to chemoresistance. However, only a few compounds have been identified to bind PARK7 due to the lack of a dedicated chemical toolbox. We report the creation of such a toolbox and showcase the application of each of its components. The selective PARK7 submicromolar inhibitor with a cyanimide reactive group covalently modifies the active site Cys106. Installment of different dyes onto the inhibitor delivered two PARK7 probes. The Rhodamine110 probe provides a high-throughput screening compatible FP assay, showcased by screening a compound library (8000 molecules). The SulfoCy5-equipped probe is a valuable tool to assess the effect of PARK7 inhibitors in a cell lysate. Our work creates new possibilities to explore PARK7 function in a physiologically relevant setting and develop new and improved PARK7 inhibitors.

Neurotransmitters and molecular chaperones interactions in cerebral malaria: Is there a missing link?

Plasmodium falciparum is responsible for the most severe and deadliest human malaria infection. The most serious complication of this infection is cerebral malaria. Among the proposed hypotheses that seek to explain the manifestation of the neurological syndrome in cerebral malaria is the vascular occlusion/sequestration/mechanic hypothesis, the cytokine storm or inflammatory theory, or a combination of both. Unfortunately, despite the increasing volume of scientific information on cerebral malaria, our understanding of its pathophysiologic mechanism(s) is still very limited. In a bid to maintain its survival and development, P. falciparum exports a large number of proteins into the cytosol of the infected host red blood cell. Prominent among these are the P. falciparum erythrocytes membrane protein 1 (PfEMP1), P. falciparum histidine-rich protein II (PfHRP2), and P. falciparum heat shock proteins 70-x (PfHsp70-x). Functional activities and interaction of these proteins with one another and with recruited host resident proteins are critical factors in the pathology of malaria in general and cerebral malaria in particular. Furthermore, several neurological impairments, including cognitive, behavioral, and motor dysfunctions, are known to be associated with cerebral malaria. Also, the available evidence has implicated glutamate and glutamatergic pathways, coupled with a resultant alteration in serotonin, dopamine, norepinephrine, and histamine production. While seeking to improve our understanding of the pathophysiology of cerebral malaria, this article seeks to explore the possible links between host/parasite chaperones, and neurotransmitters, in relation to other molecular players in the pathology of cerebral malaria, to explore such links in antimalarial drug discovery.

LRRK2 and Proteostasis in Parkinson's Disease

Parkinson’s disease is a neurodegenerative condition initially characterized by the presence of tremor, muscle stiffness and impaired balance, with the deposition of insoluble protein aggregates in Lewy’s Bodies the histopathological hallmark of the disease. Although different gene variants are linked to Parkinson disease, mutations in the Leucine-Rich Repeat Kinase 2 (LRRK2) gene are one of the most frequent causes of Parkinson’s disease related to genetic mutations. LRRK2 toxicity has been mainly explained by an increase in kinase activity, but alternative mechanisms have emerged as underlying causes for Parkinson’s disease, such as the imbalance in LRRK2 homeostasis and the involvement of LRRK2 in aggregation and spreading of α-synuclein toxicity. In this review, we recapitulate the main LRRK2 pathological mutations that contribute to Parkinson’s disease and the different cellular and therapeutic strategies devised to correct LRRK2 homeostasis. In this review, we describe the main cellular control mechanisms that regulate LRRK2 folding and aggregation, such as the chaperone network and the protein-clearing pathways such as the ubiquitin–proteasome system and the autophagic-lysosomal pathway. We will also address the more relevant strategies to modulate neurodegeneration in Parkinson’s disease through the regulation of LRRK2, using small molecules or LRRK2 silencing.

Alpha-Synuclein Aggregation Pathway in Parkinson's Disease: Current Status and Novel Therapeutic Approaches

Following Alzheimer’s, Parkinson’s disease (PD) is the second-most common neurodegenerative disorder, sharing an unclear pathophysiology, a multifactorial profile, and massive social costs worldwide. Despite this, no disease-modifying therapy is available. PD is tightly associated with α-synuclein (α-Syn) deposits, which become organised into insoluble, amyloid fibrils. As a typical intrinsically disordered protein, α-Syn adopts a monomeric, random coil conformation in an aqueous solution, while its interaction with lipid membranes drives the transition of the molecule part into an α-helical structure. The central unstructured region of α-Syn is involved in fibril formation by converting to well-defined, β-sheet rich secondary structures. Presently, most therapeutic strategies against PD are focused on designing small molecules, peptides, and peptidomimetics that can directly target α-Syn and its aggregation pathway. Other approaches include gene silencing, cell transplantation, stimulation of intracellular clearance with autophagy promoters, and degradation pathways based on immunotherapy of amyloid fibrils. In the present review, we sum marise the current advances related to α-Syn aggregation/neurotoxicity. These findings present a valuable arsenal for the further development of efficient, nontoxic, and non-invasive therapeutic protocols for disease-modifying therapy that tackles disease onset and progression in the future.

Insights Into the Role of Heat Shock Protein 27 in the Development of Neurodegeneration

Small heat shock protein 27 is a critically important chaperone, that plays a key role in several essential and varied physiological processes. These include thermotolerance, apoptosis, cytoskeletal dynamics, cell differentiation, protein folding, among others. Despite its relatively small size and intrinsically disordered termini, it forms large and polydisperse oligomers that are in equilibrium with dimers. This equilibrium is driven by transient interactions between the N-terminal region, the α-crystallin domain, and the C-terminal region. The continuous redistribution of binding partners results in a conformationally dynamic protein that allows it to adapt to different functions where substrate capture is required. However, the intrinsic disorder of the amino and carboxy terminal regions and subsequent conformational variability has made structural investigations challenging. Because heat shock protein 27 is critical for so many key cellular functions, it is not surprising that it also has been linked to human disease. Charcot-Marie-Tooth and distal hereditary motor neuropathy are examples of neurodegenerative disorders that arise from single point mutations in heat shock protein 27. The development of possible treatments, however, depends on our understanding of its normal function at the molecular level so we might be able to understand how mutations manifest as disease. This review will summarize recent reports describing investigations into the structurally elusive regions of Hsp27. Recent insights begin to provide the required context to explain the relationship between a mutation and the resulting loss or gain of function that leads to Charcot-Marie Tooth disease and distal hereditary motor neuropathy.

Hsp90 in Human Diseases: Molecular Mechanisms to Therapeutic Approaches

The maturation of hemeprotein dictates that they incorporate heme and become active, but knowledge of this essential cellular process remains incomplete. Studies on chaperon Hsp90 has revealed that it drives functional heme maturation of inducible nitric oxide synthase (iNOS), soluble guanylate cyclase (sGC) hemoglobin (Hb) and myoglobin (Mb) along with other proteins including GAPDH, while globin heme maturations also need an active sGC. In all these cases, Hsp90 interacts with the heme-free or apo-protein and then drives the heme maturation by an ATP dependent process before dissociating from the heme-replete proteins, suggesting that it is a key player in such heme-insertion processes. As the studies on globin maturation also need an active sGC, it connects the globin maturation to the NO-sGC (Nitric oxide-sGC) signal pathway, thereby constituting a novel NO-sGC-Globin axis. Since many aggressive cancer cells make Hbβ/Mb to survive, the dependence of the globin maturation of cancer cells places the NO-sGC signal pathway in a new light for therapeutic intervention. Given the ATPase function of Hsp90 in heme-maturation of client hemeproteins, Hsp90 inhibitors often cause serious side effects and this can encourage the alternate use of sGC activators/stimulators in combination with specific Hsp90 inhibitors for better therapeutic intervention.

Baicalein Induces Mitochondrial Autophagy to Prevent Parkinson's Disease in Rats via miR-30b and the SIRT1/AMPK/mTOR Pathway

Parkinson's disease (PD) is a prevailing neurodegenerative disorder. Baicalein has neuroprotective effects on PD animals, but its mechanism is not clarified. We explored baicalein effects on PD rats. PD rat models were established by injecting 6-hydroxydopamine into the striatum of substantia nigra on the left side of the rat brain and treated with baicalein. Dopamine (DA) content, neuronal apoptosis, neuronal injury, neuronal mitochondria, and autophagy were assessed. Baicalein-treated PD rats were treated with autophagy inhibitor 3-methyladenine to identify the role of autophagy in PD. PD rats were injected with AgomiR-30b-5p or sh-SIRT1 plasmids and treated with baicalein. PD rats elicited decreased neurological score and DA secretion of the striatum, increased neuronal apoptosis, and injury, and reduced number of mitochondria and autophagy, whereas baicalein alleviated neuronal injury and partly recovered mitochondrial dysfunction, 3-methyladenine inhibited the protection of baicalein. miR-30b-5p was elevated and SIRT1 was diminished in PD rats and inhibited by baicalein. miR-30b-5p targeted SIRT1. miR-30b-5p overexpression or SIRT1 silencing annulled the protection of baicalein. The phosphorylation level of AMPK in the substantia nigra of PD rats was decreased and mTOR was increased, whereas baicalein annulled these trends. Briefly, baicalein activated mitochondrial autophagy via miR-30b-5p and the SIRT1/AMPK/mTOR pathway, thus protecting PD rats.

Stress-inducible phosphoprotein 1 (HOP/STI1/STIP1) regulates the accumulation and toxicity of α-synuclein in vivo

The predominantly pre-synaptic intrinsically disordered protein α-synuclein is prone to misfolding and aggregation in synucleinopathies, such as Parkinson's disease (PD) and Dementia with Lewy bodies (DLB). Molecular chaperones play important roles in protein misfolding diseases and members of the chaperone machinery are often deposited in Lewy bodies. Here, we show that the Hsp90 co-chaperone STI1 co-immunoprecipitated α-synuclein, and co-deposited with Hsp90 and Hsp70 in insoluble protein fractions in two mouse models of α-synuclein misfolding. STI1 and Hsp90 also co-localized extensively with filamentous S129 phosphorylated α-synuclein in ubiquitin-positive inclusions. In PD human brains, STI1 transcripts were increased, and in neurologically healthy brains, STI1 and α-synuclein transcripts correlated. Nuclear Magnetic Resonance (NMR) analyses revealed direct interaction of α-synuclein with STI1 and indicated that the STI1 TPR2A, but not TPR1 or TPR2B domains, interacted with the C-terminal domain of α-synuclein. In vitro, the STI1 TPR2A domain facilitated S129 phosphorylation by Polo-like kinase 3. Moreover, mice over-expressing STI1 and Hsp90ß presented elevated α-synuclein S129 phosphorylation accompanied by inclusions when injected with α-synuclein pre-formed fibrils. In contrast, reduced STI1 function decreased protein inclusion formation, S129 α-synuclein phosphorylation, while mitigating motor and cognitive deficits as well as mesoscopic brain atrophy in α-synuclein-over-expressing mice. Our findings reveal a vicious cycle in which STI1 facilitates the generation and accumulation of toxic α-synuclein conformers, while α-synuclein-induced proteostatic stress increased insoluble STI1 and Hsp90.