Immunoproteasome is up-regulated in rotenone-induced Parkinson's disease rat model

5-Phenyl valeric acid attenuates α-synuclein aggregation and endoplasmic reticulum stress in rotenone-induced Parkinson's disease rats: A molecular mechanistic study

The abnormal accumulation of fibrillar α-synuclein in the substantia nigra contributes to Parkinson's disease (PD). Chemical chaperones like 4-phenyl butyric acid (4PBA) show neuroprotective potential, but high doses are required. A derivative, 5-phenyl valeric acid (5PVA), has reported therapeutic potential for PD by reducing Pael-R expression. This study assessed 5PVA's efficacy in PD animals and its molecular mechanism. In vitro studies revealed 5PVA's anti-aggregation ability against alpha-synuclein and neuroprotective effects on SHSY5Y neuroblastoma cells exposed to rotenone. PD-like symptoms were induced in SD rats with rotenone, followed by 5PVA treatment at 100 mg/kg and 130 mg/kg. Behavioral analysis showed significant improvement in memory and motor activity with 5PVA administration. Histopathological studies demonstrated normal neuronal histoarchitecture in mid-brain tissue sections of 5PVA-treated animals compared to the PD group. mRNA studies revealed significant suppression in the expression of various protein folding and heat-shock protein markers in the 5PVA-treated group. In conclusion, 5PVA, with its anti-aggregation ability against alpha-synuclein, acts as a chemical chaperone, showing potential as a therapeutic candidate for PD treatment.

LncRNA PSMB8-AS1 Instigates Vascular Inflammation to Aggravate Atherosclerosis

BACKGROUND

Increasing evidence suggests that long noncoding RNAs play significant roles in vascular biology and disease development. One such long noncoding RNA, PSMB8-AS1, has been implicated in the development of tumors. Nevertheless, the precise role of PSMB8-AS1 in cardiovascular diseases, particularly atherosclerosis, has not been thoroughly elucidated. Thus, the primary aim of this investigation is to assess the influence of PSMB8-AS1 on vascular inflammation and the initiation of atherosclerosis.

METHODS

We generated PSMB8-AS1 knockin and Apoe (Apolipoprotein E) knockout mice (Apoe-/-PSMB8-AS1KI) and global Apoe and proteasome subunit-β type-9 (Psmb9) double knockout mice (Apoe-/-Psmb9-/-). To explore the roles of PSMB8-AS1 and Psmb9 in atherosclerosis, we fed the mice with a Western diet for 12 weeks.

RESULTS

Long noncoding RNA PSMB8-AS1 is significantly elevated in human atherosclerotic plaques. Strikingly, Apoe-/-PSMB8-AS1KI mice exhibited increased atherosclerosis development, plaque vulnerability, and vascular inflammation compared with Apoe-/- mice. Moreover, the levels of VCAM1 (vascular adhesion molecule 1) and ICAM1 (intracellular adhesion molecule 1) were significantly upregulated in atherosclerotic lesions and serum of Apoe-/-PSMB8-AS1KI mice. Consistently, in vitro gain- and loss-of-function studies demonstrated that PSMB8-AS1 induced monocyte/macrophage adhesion to endothelial cells and increased VCAM1 and ICAM1 levels in a PSMB9-dependent manner. Mechanistic studies revealed that PSMB8-AS1 induced PSMB9 transcription by recruiting the transcription factor NONO (non-POU domain-containing octamer-binding protein) and binding to the PSMB9 promoter. PSMB9 (proteasome subunit-β type-9) elevated VCAM1 and ICAM1 expression via the upregulation of ZEB1 (zinc finger E-box-binding homeobox 1). Psmb9 deficiency decreased atherosclerotic lesion size, plaque vulnerability, and vascular inflammation in Apoe-/- mice in vivo. Importantly, endothelial overexpression of PSMB8-AS1-increased atherosclerosis and vascular inflammation were attenuated by Psmb9 knockout.

CONCLUSIONS

PSMB8-AS1 promotes vascular inflammation and atherosclerosis via the NONO/PSMB9/ZEB1 axis. Our findings support the development of new long noncoding RNA-based strategies to counteract atherosclerotic cardiovascular disease.

Relationship among α‑synuclein, aging and inflammation in Parkinson's disease (Review)

Parkinson's disease (PD) is a common neurodegenerative pathology whose major clinical symptoms are movement disorders. The main pathological characteristics of PD are the selective death of dopaminergic (DA) neurons in the pars compacta of the substantia nigra and the presence of Lewy bodies containing α-synuclein (α-Syn) within these neurons. PD is associated with numerous risk factors, including environmental factors, genetic mutations and aging. In many cases, the complex interplay of numerous risk factors leads to the onset of PD. The mutated α-Syn gene, which expresses pathologicalα-Syn protein, can cause PD. Another important feature of PD is neuroinflammation, which is conducive to neuronal death. α-Syn is able to interact with certain cell types in the brain, including through phagocytosis and degradation of α-Syn by glial cells, activation of inflammatory pathways by α-Syn in glial cells, transmission of α-Syn between glial cells and neurons, and interactions between peripheral immune cells and α-Syn. In addition to the aforementioned risk factors, PD may also be associated with aging, as the prevalence of PD increases with advancing age. The aging process impairs the cellular clearance mechanism, which leads to chronic inflammation and the accumulation of intracellular α-Syn, which results in DA neuronal death. In the present review, the age-associated α-Syn pathogenicity and the interactions between α-Syn and certain types of cells within the brain are discussed to facilitate understanding of the mechanisms of PD pathogenesis, which may potentially provide insight for the future clinical treatment of PD.

Upregulation of immunoproteasome PSMB8 is associated with Parkinson's disease

BACKGROUND

Immunoproteasome, a part of ubiquitin-proteasome system, is involved in immune response as well as protein degradation. However, the relationship between immunoproteasome and Parkinson's disease (PD) was not evaluated clearly. We hypothesized that the shift of immunoproteasome attributes to PD pathogenesis due to its role in inflammation and protein homeostasis.

OBJECTIVE

To determine whether immunoproteasome in peripheral blood mononuclear cells (PBMC) and brain is expressed differently between patients with PD and healthy controls (HC).

METHODS

Blood samples were collected from 19 HC to 40 patients with PD of comparable ages. Peripheral blood mononuclear cells were isolated and followed by RT-qPCR to measure the mRNA levels of three catalytic subunits of immunoproteasome, namely, PSMB8, PSMB9, and PSMB10. Then, the protein levels of each subunit were measured by western blot. Finally, we confirmed the altered immunoproteasome subunit in the post-mortem human brain of PD.

RESULTS

In PBMCs, PSMB8 mRNA expression of PD group significantly increased compared to HC (p = 0.004), whereas PSMB9 and PSMB10 mRNA were not different between the PD and HC. The ratio of PSMB10 and PSMB8 mRNA (PSMB10/8 ratio) also reflected the significant difference between the PD and HC (p = 0.002). The PSMB10/8 ratio was well correlated with the UPDRS total and Part III score in the early stage of PD (Hoehn and Yahr ≤2.5) or drug-naïve PD subgroups. In terms of the protein level of immunoproteasome subunits in PBMCs, the increase of PSMB8 protein was observed in PD compared to HC (p = 0.0009), while PSMB9 and PSMB10 were not different between groups. Finally, we confirmed that immunoproteasome PSMB8 was expressed abundantly in the postmortem PD brain compared with normal control.

CONCLUSION

Our novel findings implicate that immunoproteasome PSMB8 is engaged in PD pathomechanism.

Variants in PSMB9 and FGR differentially affect Parkinson's disease risk in GBA and LRRK2 mutation carriers

INTRODUCTION

Recent studies found an association between Parkinson's disease (PD) and alterations in the innate immune system. However, whether the involvement of this system in two of the known genetic forms of PD, GBA-PD and LRRK2-PD, and in patients who do not carry these mutations is different, is yet to be determined. We aimed to test if genetic variations in the innate immune genes are differentially associated with PD in these subgroups.

METHODS

Innate immune genes were identified and classified into sub-lists according to Reactome pathways. Whole-genome-sequencing (WGS) was performed on 201 unrelated Ashkenazi-Jewish (AJ) PD patients including 104 GBA-PD, 32 LRRK2-PD, and 65 non-carriers-PD (NC-PD). To identify genes with different burden between these subgroups of PD, gene-based Sequence kernel association optimal unified test (SKAT-O) analysis was performed on innate immune pathways. Candidate variants within the significant genes were further genotyped in a cohort of 1200 unrelated, consecutively recruited, AJ-PD patients, and to evaluate their association with PD-risk their allele frequencies were compared to AJ-non-neuro cases in gnomAD database, in a stratified and un-stratified manner.

RESULTS

SKAT-O analysis showed significantly different burden for PSMB9 (GBA-PD versus NC-PD) and FGR (GBA-PD versus LRRK2-PD). Two candidate variants in PSMB9 showed an association with GBA-PD-risk and NC-PD-risk while one FGR variant showed an association with LRRK2-PD-risk.

CONCLUSION

Our data supports differential involvement of innate immunity risk alleles in PD and emphasizes the differences between the GBA- and LRRK2-PD subgroups.

DNA sensing via the cGAS/STING pathway activates the immunoproteasome and adaptive T-cell immunity

The immunoproteasome is a specialized type of proteasome involved in MHC class I antigen presentation, antiviral adaptive immunity, autoimmunity, and is also part of a broader response to stress. Whether the immunoproteasome is regulated by DNA stress, however, is not known. We here demonstrate that mitochondrial DNA stress upregulates the immunoproteasome and MHC class I antigen presentation pathway via cGAS/STING/type I interferon signaling resulting in cell autonomous activation of CD8⁺ T cells. The cGAS/STING-induced adaptive immune response is also observed in response to genomic DNA and is conserved in epithelial and mesenchymal cells of mice and men. In patients with idiopathic pulmonary fibrosis, chronic activation of the cGAS/STING-induced adaptive immune response in aberrant lung epithelial cells concurs with CD8⁺ T-cell activation in diseased lungs. Genetic depletion of the immunoproteasome and specific immunoproteasome inhibitors counteract DNA stress induced cytotoxic CD8⁺ T-cell activation. Our data thus unravel cytoplasmic DNA sensing via the cGAS/STING pathway as an activator of the immunoproteasome and CD8⁺ T cells. This represents a novel potential pathomechanism for pulmonary fibrosis that opens new therapeutic perspectives.

ABC transporters: human disease and pharmacotherapeutic potential

Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are a 48-member superfamily of membrane proteins that actively transport a variety of biological substrates across lipid membranes. Their functional diversity defines an expansive involvement in myriad aspects of human biology. At least 21 ABC transporters underlie rare monogenic disorders, with even more implicated in the predisposition to and symptomology of common and complex diseases. Such broad (patho)physiological relevance places this class of proteins at the intersection of disease causation and therapeutic potential, underlining them as promising targets for drug discovery, as exemplified by the transformative CFTR (ABCC7) modulator therapies for cystic fibrosis. This review will explore the growing relevance of ABC transporters to human disease and their potential as small-molecule drug targets.

Crosstalk between PI3K/AKT/KLF4 signaling and microglia M1/M2 polarization as a novel mechanistic approach towards flibanserin repositioning in parkinson's disease

Balancing microglia M1/M2 polarization has been shown as a prospective therapeutic strategy for Parkinson's disease (PD). Various vital signaling pathways are likely to govern the microglial phenotype. The implication of 5HT1A receptors in neurodegenerative disorders has raised interest in exploring the repositioning of flibanserin (Flib), a 5HT1A agonist, as an effective neuroprotective agent for PD. Therefore, this study was designed to assess the ability of Flib to modulate microglia phenotype switching from M1 to M2 via PI3K/AKT downstream targets in a rotenone model of PD. Rats received rotenone (1.5 mg/kg) every other day and were concurrently treated with Flib (40 mg/kg/day) with or without wortmannin (15 μg/kg/day), a PI3K inhibitor, for 21 days. Flib improved the motor perturbations induced by rotenone, as confirmed by the reversion of histopathological damage and tyrosine hydroxylase immunohistochemical alterations in both the striata and substantia nigra. The molecular signaling of Flib was elaborated by inducing striatal AKT phosphorylation and the expression of its substantial target, KLF4. Flib induced STAT6 phosphorylation to promote M2 polarization as demonstrated by the increased CD163⁺⁺ microglial count with striatal arginase activity. In parallel, it markedly inhibited M1 activation as evidenced by the reduction in CD86⁺⁺ microglia count with striatal proinflammatory mediators, IL-1β and iNOS. The pre-administration of wortmannin mostly negated Flib's neuroprotective effects. In conclusion, Flib AKT/ KLF4-dependently amended M1/M2 microglial imbalance to exert a promising neuroprotective effect, highlighting its potential as a revolutionary candidate for conquering PD.