Melatonin MT1 receptors regulate the Sirt1/Nrf2/Ho-1/Gpx4 pathway to prevent α-synuclein-induced ferroptosis in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic (DA) neurons and aggregation of α-synuclein (α-syn). Ferroptosis, a form of cell death induced by iron accumulation and lipid peroxidation, is involved in the pathogenesis of PD. It is unknown whether melatonin receptor 1 (MT1) modulates α-syn and ferroptosis in PD. Here, we used α-syn preformed fibrils (PFFs) to induce PD models in vivo and in vitro. In PD mice, α-syn aggregation led to increased iron deposition and ferroptosis. MT1 knockout exacerbated these changes and resulted in more DA neuronal loss and severe motor impairment. MT1 knockout also suppressed the Sirt1/Nrf2/Ho1/Gpx4 pathway, reducing resistance to ferroptosis, and inhibited expression of ferritin Fth1, leading to more release of ferrous ions. In vitro experiments confirmed these findings. Knockdown of MT1 enhanced α-syn PFF-induced intracellular α-syn aggregation and suppressed expression of the Sirt1/Nrf2/Ho1/Gpx4 pathway and Fth1 protein, thereby aggravating ferroptosis. Conversely, overexpression of MT1 reversed these effects. Our findings reveal a novel mechanism by which MT1 activation prevents α-syn-induced ferroptosis in PD, highlighting the neuroprotective role of MT1 in PD.

Gut microbiota modification by diosgenin mediates antiepileptic effects in a mouse model of epilepsy.

Diosgenin, a natural steroid saponin, holds promise as a multitarget therapeutic for various diseases, including neurodegenerative conditions. Its efficacy in slowing Alzheimer's disease, Parkinson's disease, multiple sclerosis, and stroke progression has been demonstrated. However, the role of diosgenin in anti-epilepsy and its potential connection to the modulation of the intestinal microbiota remain poorly understood. In this study, exogenous diosgenin significantly mitigated pentylenetetrazole (PTZ)-induced seizures, learning and memory deficits, and hippocampal neuronal injury. 16S ribosomal RNA (16S rRNA) sequencing revealed a reversal in the decrease of Bacteroides and Parabacteroides genera in the PTZ-induced mouse epileptic model following diosgenin treatment. Fecal microbiota transplantation (FMT) experiments illustrated the involvement of diosgenin in modulating gut microbiota and providing neuroprotection against epilepsy. Our results further indicated the repression of enteric glial cells (EGCs) activation and the TLR4-MyD88 pathway, coupled with reduced production of inflammatory cytokines in the colonic lumen, and improved intestinal barrier function in epilepsy mice treated with diosgenin or FMT. This study suggests that diosgenin plays a role in modifying gut microbiota, contributing to the alleviation of intestinal inflammation and neuroinflammation, ultimately inhibiting epilepsy progression in a PTZ-induced mouse model. Diosgenin emerges as a potential therapeutic option for managing epilepsy and its associated comorbidities.

Role of α-synuclein in microglia: autophagy and phagocytosis balance neuroinflammation in Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is the second most common neurodegenerative disease, and is characterized by accumulation of α-synuclein (α-syn). Neuroinflammation driven by microglia is an important pathological manifestation of PD. α-Syn is a crucial marker of PD, and its accumulation leads to microglia M1-like phenotype polarization, activation of NLRP3 inflammasomes, and impaired autophagy and phagocytosis in microglia. Autophagy of microglia is related to degradation of α-syn and NLRP3 inflammasome blockage to relieve neuroinflammation. Microglial autophagy and phagocytosis of released α-syn or fragments from apoptotic neurons maintain homeostasis in the brain. A variety of PD-related genes such as LRRK2, GBA and DJ-1 also contribute to this stability process. OBJECTIVES: Further studies are needed to determine how α-syn works in microglia. METHODS: A keyword-based search was performed using the PubMed database for published articles. CONCLUSION: In this review, we discuss the interaction between microglia and α-syn in PD pathogenesis and the possible mechanism of microglial autophagy and phagocytosis in α-syn clearance and inhibition of neuroinflammation. This may provide a novel insight into treatment of PD.

Pramipexole inhibits astrocytic NLRP3 inflammasome activation via Drd3-dependent autophagy in a mouse model of Parkinson's disease.

Inflammation is one of the pathogenic processes in Parkinson's disease (PD). Dopamine receptor agonist pramipexole (PPX) is extensively used for PD treatment in clinics. A number of studies show that PPX exerts neuroprotection on dopaminergic (DA) neurons, but the molecular mechanisms underlying the protective effects of PPX on DA neurons are not fully elucidated. In the present study, we investigated whether PPX modulated PD-related neuroinflammation and underlying mechanisms. PD model was established in mice by bilateral striatum injection of lipopolyssaccharide (LPS). The mice were administered PPX (0.5 mg·kg-1·d-1, i.p.) 3 days before LPS injection, and for 3 or 21 days after surgery, respectively, for biochemical and histological analyses. We showed that PPX administration significantly alleviated the loss of DA neurons, and suppressed the astrocyte activation and levels of proinflammatory cytokine IL-1ß in the substantia nigra of LPS-injected mice. Furthermore, PPX administration significantly decreased the expression of NLRP3 inflammasome-associated proteins, i.e., cleaved forms of caspase-1, IL-1ß, and apoptosis-associated speck-like protein containing a caspase recruit domain (ASC) in the striatum. These results were validated in LPS+ATP-stimulated primary mouse astrocytes in vitro. Remarkably, we showed that PPX (100-400 µM) dose-dependently enhanced the autophagy activity in the astrocytes evidenced by the elevations in LC3-II and BECN1 protein expression, as well as the increase of GFP-LC3 puncta formation. The opposite effects of PPX on astrocytic NLRP3 inflammasome and autophagy were eliminated by Drd3 depletion. Moreover, we demonstrated that both pretreatment of astrocytes with autophagy inhibitor chloroquine (40 µM) in vitro and astrocyte-specific Atg5 knockdown in vivo blocked PPX-caused inhibition on NLRP3 inflammasome and protection against DA neuron damage. Altogether, this study demonstrates an anti-neuroinflammatory activity of PPX via a Drd3-dependent enhancement of autophagy activity in astrocytes, and reveals a new mechanism for the beneficial effect of PPX in PD therapy.

mTORC2 regulates hierarchical micro/nano topography-induced osteogenic differentiation via promoting cell adhesion and cytoskeletal polymerization.

Surface topography acts as an irreplaceable role in the long-term success of intraosseous implants. In this study, we prepared the hierarchical micro/nano topography using selective laser melting combined with alkali heat treatment (SLM-AHT) and explored the underlying mechanism of SLM-AHT surface-elicited osteogenesis. Our results show that cells cultured on SLM-AHT surface possess the largest number of mature FAs and exhibit a cytoskeleton reorganization compared with control groups. SLM-AHT surface could also significantly upregulate the expression of the cell adhesion-related molecule p-FAK, the osteogenic differentiation-related molecules RUNX2 and OCN as well as the mTORC2 signalling pathway key molecule Rictor. Notably, after the knocked-down of Rictor, there were no longer significant differences in the gene expression levels of the cell adhesion-related molecules and osteogenic differentiation-related molecules among the three titanium surfaces, and the cells on SLM-AHT surface failed to trigger cytoskeleton reorganization. In conclusion, the results suggest that mTORC2 can regulate the hierarchical micro/nano topography-mediated osteogenesis via cell adhesion and cytoskeletal reorganization.

Mechanistic understanding of N-glycosylation in Ebola virus glycoprotein maturation and function.

The Ebola virus (EBOV) trimeric envelope glycoprotein (GP) precursors are cleaved into the receptor-binding GP1 and the fusion-mediating GP2 subunits and incorporated into virions to initiate infection. GP1 and GP2 form heterodimers that have 15 or two N-glycosylation sites (NGSs), respectively. Here we investigated the mechanism of how N-glycosylation contributes to GP expression, maturation, and function. As reported before, we found that, although GP1 NGSs are not critical, the two GP2 NGSs, Asn563 and Asn618, are essential for GP function. Further analysis uncovered that Asn563 and Asn618 regulate GP processing, demannosylation, oligomerization, and conformation. Consequently, these two NGSs are required for GP incorporation into EBOV-like particles and HIV type 1 (HIV-1) pseudovirions and determine viral transduction efficiency. Using CRISPR/Cas9 technology, we knocked out the two classical endoplasmic reticulum chaperones calnexin (CNX) and/or calreticulin (CRT) and found that both CNX and CRT increase GP expression. Nevertheless, NGSs are not required for the GP interaction with CNX or CRT. Together, we conclude that, although Asn563 and Asn618 are not required for EBOV GP expression, they synergistically regulate its maturation, which determines its functionality.

Associations between psychological inflexibility and mental health problems during the COVID-19 pandemic: A three-level meta-analytic review.

BACKGROUND: An increasing number of research has documented the positive associations between psychological inflexibility (PI) and mental health problems (i.e., depressive, anxiety, and stress symptoms) during the COVID-19 pandemic. However, the documented associations have been inconsistent. This review thus aimed to quantitatively summarize primary research to gain better estimates of these associations. METHODS: A systematic literature review was conducted in six databases and three-level meta-analytic models were used to statistically synthesize effect sizes and to examine moderators of the associations between PI and depressive, anxiety, and stress symptoms. RESULTS: A total of 22 studies yielded 63 effect sizes on associations between PI and depressive, anxiety, or stress symptoms. The results of three separate meta-analyses revealed a large and significant association between PI and depressive (r = 0.580, 95 % CI [0.549; 0.775]), anxiety (r = 0.548, 95 % CI [0.468; 0.761]), and stress symptoms (r = 0.548, 95 % CI [0.506; 0.725]). The association between PI and depressive symptoms is stronger for males than for females, and the association between PI and stress symptoms varies by type of measure that primary studies use to assess PI and stress symptoms. LIMITATIONS: Temporal or causal conclusions are not allowed due to cross-sectional nature of the associations included in meta-analyses. Clinical samples with high levels of stress were underrepresented. CONCLUSIONS: PI seems an important risk factor for symptoms of depression, anxiety, and stress, and should therefore be targeted in interventions addressing mental health problems during the COVID-19 pandemic and beyond.

Exosomal ncRNAs facilitate interactive 'dialogue' between tumor cells and tumor-associated macrophages.

As a biological carrier, exosomes participate in the communication between various kinds of cells, and can mediate the interactive 'dialogue' between tumor cells and tumor-associated macrophages (TAMs). TAMs are the most abundant cell population in the tumor stroma and are an important part of the tumor immune microenvironment. Various stimulating factors in the tumor microenvironment influence the polarization of TAMs into multiple phenotypes, such as M1 and M2. It plays a dual role in tumor immunity by both promoting and inhibiting tumor growth. Exosome-encapsulated non-coding RNAs (ncRNAs) participate in the interactive 'dialogue' between exosome-mediated TAMs and tumor cells. Tumor-derived exosomal ncRNAs can promote macrophage polarization, whereas exosomal ncRNAs derived from TAMs can affect tumor proliferation, metastasis, angiogenesis, and chemotherapy resistance. The present review summarizes the dual effects of exosomal ncRNAs on tumor cells and TAMs, and discusses the application of exosomal ncRNAs as a potential diagnostic or prognostic marker and drug delivery system, to provide a new perspective and potential therapeutic drugs on targeting exosomes and macrophages in the treatment of tumors.

LRRK2 G2019S promotes astrocytic inflammation induced by oligomeric α-synuclein through NF-κB pathway.

Parkinson's disease (PD) is characterized by the irreversible loss of dopaminergic neurons and the accumulation of α-synuclein in Lewy bodies. The oligomeric α-synuclein (O-αS) is the most toxic form of α-synuclein species, and it has been reported to be a robust inflammatory mediator. Mutations in Leucine-Rich Repeat Kinase 2 (LRRK2) are also genetically linked to PD and neuroinflammation. However, how O-αS and LRRK2 interact in glial cells remains unclear. Here, we reported that LRRK2 G2019S mutation, which is one of the most frequent causes of familial PD, enhanced the effects of O-αS on astrocytes both in vivo and in vitro. Meanwhile, inhibition of LRRK2 kinase activity could relieve the inflammatory effects of both LRRK2 G2019S and O-αS. We also demonstrated that nuclear factor κB (NF-κB) pathway might be involved in the neuroinflammatory responses. These findings revealed that inhibition of LRRK2 kinase activity may be a viable strategy for suppressing neuroinflammation in PD.

Associations between self-disgust, depression, and anxiety: A three-level meta-analytic review.

Self-disgust is a negative self-conscious emotion that reflects disgust or revulsion directed toward oneself. A growing body of research has demonstrated a link between self-disgust, depression, and anxiety. However, the strength of these associations varied considerably across studies, suggesting the need to conduct a meta-analysis to produce a synthesized truer estimate. This review aimed to summarize the primary literature and improve our insight into these associations. The present study used three-level meta-analytic models to synthesize effect sizes and investigate potential moderators of the associations of self-disgust with depression and anxiety. The results revealed a significant association between self-disgust and depression (pooled r = 0.520, 95 % CI [0.485; 0.669], p < .001). The results also showed a significant and moderate association between self-disgust and anxiety (pooled r = 0.452, 95 % CI [0.419; 0.556], p < .001). These associations were held according to sex and age. In conclusion, this meta-analysis supports a moderate-to-large association between self-disgust, depression, and anxiety, suggesting that it is worthy of consideration in research and clinical practice.

Protein disulfide isomerases (PDIs) negatively regulate ebolavirus structural glycoprotein expression in the endoplasmic reticulum (ER) via the autophagy-lysosomal pathway.

Zaire ebolavirus (EBOV) causes a severe hemorrhagic fever in humans and non-human primates with high morbidity and mortality. EBOV infection is dependent on its structural glycoprotein (GP), but high levels of GP expression also trigger cell rounding, detachment, and downregulation of many surface molecules that is thought to contribute to its high pathogenicity. Thus, EBOV has evolved an RNA editing mechanism to reduce its GP expression and increase its fitness. We now report that the GP expression is also suppressed at the protein level in cells by protein disulfide isomerases (PDIs). Although PDIs promote oxidative protein folding by catalyzing correct disulfide formation in the endoplasmic reticulum (ER), PDIA3/ERp57 adversely triggered the GP misfolding by targeting GP cysteine residues and activated the unfolded protein response (UPR). Abnormally folded GP was targeted by ER-associated protein degradation (ERAD) machinery and, unexpectedly, was degraded via the macroautophagy/autophagy-lysosomal pathway, but not the proteasomal pathway. PDIA3 also decreased the GP expression from other ebolavirus species but increased the GP expression from Marburg virus (MARV), which is consistent with the observation that MARV-GP does not cause cell rounding and detachment, and MARV does not regulate its GP expression via RNA editing during infection. Furthermore, five other PDIs also had a similar inhibitory activity to EBOV-GP. Thus, PDIs negatively regulate ebolavirus glycoprotein expression, which balances the viral life cycle by maximizing their infection but minimizing their cellular effect. We suggest that ebolaviruses hijack the host protein folding and ERAD machinery to increase their fitness via reticulophagy during infection.Abbreviations: 3-MA: 3-methyladenine; 4-PBA: 4-phenylbutyrate; ACTB: ß-actin; ATF: activating transcription factor; ATG: autophagy-related; BafA1: bafilomycin A1; BDBV: Bundibugyo ebolavirus; CALR: calreticulin; CANX: calnexin; CHX: cycloheximide; CMA: chaperone-mediated autophagy; ConA: concanamycin A; CRISPR: clusters of regularly interspaced short palindromic repeats; Cas9: CRISPR-associated protein 9; dsRNA: double-stranded RNA; EBOV: Zaire ebolavirus; EDEM: ER degradation enhancing alpha-mannosidase like protein; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; Env: envelope glycoprotein; ER: endoplasmic reticulum; ERAD: ER-associated protein degradation; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; GP: glycoprotein; HA: hemagglutinin; HDAC6: histone deacetylase 6; HMM: high-molecular-mass; HIV-1: human immunodeficiency virus type 1; HSPA5/BiP: heat shock protein family A (Hsp70) member 5; IAV: influenza A virus; IP: immunoprecipitation; KIF: kifenesine; Lac: lactacystin; LAMP: lysosomal associated membrane protein; MAN1B1/ERManI: mannosidase alpha class 1B member 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MARV: Marburg virus; MLD: mucin-like domain; NHK/SERPINA1: alpha1-antitrypsin variant null (Hong Kong); NTZ: nitazoxanide; PDI: protein disulfide isomerase; RAVV: Ravn virus; RESTV: Reston ebolavirus; SARS-CoV: severe acute respiratory syndrome coronavirus; SBOV: Sudan ebolavirus; sGP: soluble GP; SQSTM1/p62: sequestosome 1; ssGP: small soluble GP; TAFV: Taï Forest ebolavirus; TIZ: tizoxanide; TGN: thapsigargin; TLD: TXN (thioredoxin)-like domain; Ub: ubiquitin; UPR: unfolded protein response; VLP: virus-like particle; VSV: vesicular stomatitis virus; WB: Western blotting; WT: wild-type; XBP1: X-box binding protein 1.

Correction: Hierarchical microgroove/nanopore topography regulated cell adhesion to enhance osseointegration around intraosseous implants in vivo.

Correction for 'Hierarchical microgroove/nanopore topography regulated cell adhesion to enhance osseointegration around intraosseous implants in vivo' by Yujuan Tian et al., Biomater. Sci., 2022, 10, 560-580. DOI: 10.1039/D1BM01657A.

BAG3 promotes autophagy and suppresses NLRP3 inflammasome activation in Parkinson's disease.

Background: Neuroinflammation mediated by microglia plays a key role in the pathogenesis of Parkinson's disease (PD), and our previous studies showed this was significantly inhibited by enhanced autophagy. In the autophagy pathway, Bcl2-associated athanogene (BAG)3 is a prominent co-chaperone, and we have shown BAG3 can regulate autophagy to clear the PD pathogenic protein α-synuclein. However, the connection between BAG3 and microglia mediated neuroinflammation is not clear. Methods: In this study, we explored whether BAG3 regulated related neuroinflammation and its original mechanism in PD. An inflammatory model of PD was established by injecting adeno-associated virus (AAV)-BAG3 into the bilateral striatum of C57BL/6 male mice to induce overexpression of BAG3, followed by injection of lipopolysaccharide (LPS). The striatum was extracted at 3 days after injection of LPS for Western blotting and reverse transcription quantitative polymerase chain reaction (RT-qPCR), and immunohistochemical staining was performed at 21 days after injection. At the same time, LPS was used to induce activation of BV2 cells to verify the effect of BAG3 in vitro. Results: Overexpression of BAG3 reduced LPS-induced pyroptosis by reducing activation of caspase-1, the NOD-like receptor family, and the pyrin domain-containing 3 (NLRP3) inflammasome, and by release of interleukin (IL)-1ß and tumor necrosis factor (TNF)-α. The LPS-induced inflammatory environment inhibits autophagy, and overexpression of BAG3 can restore autophagy, which may be the mechanism by which BAG3 reduces neuronal inflammation in PD. Conclusions: Our results demonstrate BAG3 promotes autophagy and suppresses NLRP3 inflammasome formation in PD.

Hierarchical microgroove/nanopore topography regulated cell adhesion to enhance osseointegration around intraosseous implants in vivo.

Implant surface topography plays a crucial role in achieving successful implantation. Simple and controllable surface topographical modifications are considered a promising method to accelerate bone osseointegration for biomedical applications. Moreover, comprehension of the mechanism between surface topography and cell osteogenic differentiation is vital for the manipulation of these processes to promote bone tissue regeneration. In this study, we investigated the effects of implant surfaces with various sized hierarchical microgroove/nanopore topographies on cell adhesion, osteogenesis, and their underlying mechanism both in vitro and in vivo. Our findings reveal that a titanium surface with an appropriately sized microgroove/nanopore topography (SLM-1MAH) exhibits the more satisfactory adhesive and osteogenic efficiency than the clinically used sand-blasted, large-grit, and acid-etched (SLA) surface. The underlying molecular mechanism lies in the activation of the integrin α2-PI3K-Akt signaling pathway, where the SLM-1MAH surface increased the protein expressions of integrin α2 (Itga2), phosphatidylinositol 3-kinase (PI3K), and phosphorylated serine/threonine kinase Akt (p-Akt) to enhance osteogenesis and osseointegration. Furthermore, the SLM-1MAH surface also displays better osseointegration efficiency with stronger bonding strength than that on the SLA surface. This work provides a novel strategy for implant surface topography design to improve bone-implant osseointegration.

The Role and Activation Mechanism of TAZ in Hierarchical Microgroove/Nanopore Topography-Mediated Regulation of Stem Cell Differentiation.

PURPOSE: To investigate the role and activation mechanism of TAZ in periodontal ligament stem cells (PDLSCs) perceiving hierarchical microgroove/nanopore topography. MATERIALS AND METHODS: Titanium surface with hierarchical microgroove/nanopore topography fabricated by selective laser melting combined with alkali heat treatment (SLM-AHT) was used as experimental group, smooth titanium surface (Ti) and sandblasted, large-grit, acid-etched (SLA) titanium surface were employed as control groups. Alkaline phosphatase (ALP) activity assays, qRT-PCR, Western blotting, and immunofluorescence were carried out to evaluate the effect of SLM-AHT surface on PDLSC differentiation. Moreover, TAZ activation was investigated from the perspective of nuclear localization to transcriptional activity. TAZ knockdown PDLSCs were seeded on three titanium surfaces to detect osteogenesis- and adipogenesis-related gene expression levels. Immunofluorescence and Western blotting were employed to investigate the effect of the SLM-AHT surface on actin cytoskeletal polymerization and MAPK signaling pathway. Cytochalasin D and MAPK signaling pathway inhibitors were used to determine whether actin cytoskeletal polymerization and the MAPK signaling pathway were indispensable for TAZ activation. RESULTS: Our results showed that SLM-AHT surface had a greater potential to promote PDLSC osteogenic differentiation while inhibiting adipogenic differentiation than the other two groups. The nuclear localization and transcriptional activity of TAZ were strongly enhanced on the SLM-AHT surface. Moreover, after TAZ knockdown, the enhanced osteogenesis and decreased adipogenesis in SLM-AHT group could not be observed. In addition, SLM-AHT surface could promote actin cytoskeletal polymerization and upregulate p-ERK and p-p38 protein levels. After treatment with cytochalasin D and MAPK signaling pathway inhibitors, differences in the TAZ subcellular localization and transcriptional activity were no longer observed among the different titanium surfaces. CONCLUSION: Our results demonstrated that actin cytoskeletal polymerization and MAPK signaling pathway activation triggered by SLM-AHT surface were essential for TAZ activation, which played a dominant role in SLM-AHT surface-induced stem cell fate decision.

Pramipexole regulates depression-like behavior via dopamine D3 receptor in a mouse model of Parkinson's disease.

Depression is one of the strongest predictors of quality of life in patients with Parkinson's disease (PD). Despite the high prevalence of depression, there is no clear guidance for its treatment in PD because the evidence for the efficacy of most antidepressants remains insufficient. Pramipexole, a dopamine agonist, is one of the few drugs that has proven to be clinically useful. However, the underlying mechanisms of antidepressive effects of pramipexole are still unknown. A 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model, dopamine D2 receptor (DRD2) and D3 receptor (DRD3) knockout mice were used in our study. Compared with other dopamine D2-like receptor agonists and madopar, pramipexole improved depression-like behavior and alleviate bradykinesia in an MPTP-induced mouse model of PD. Pramipexole significantly improved depression-like behavior in DRD2-/- mice but not in DRD3-/- mice. These results demonstrate that the antidepressive effect of pramipexole is mediated by DRD3 but not DRD2. Our findings highlight the need to develop novel dopamine agonists specifically targeting DRD3 for the treatment of depression in PD in the future.