Structural basis for the dual catalytic activity of the Legionella pneumophila ovarian tumor (OTU) domain deubiquitinase LotA.

Legionella pneumophila, a bacterial pathogen that causes a severe pneumonia known as Legionnaires' disease, extensively exploits the ubiquitin (Ub) pathway in the infected host cells through certain virulence effectors excreted by the Dot/Icm system. To date, several Dot/Icm effectors have been found to act as Ub ligases, and four effectors, including LotA, LotB, LotC, and Ceg7, have been identified as deubiquitinases (DUBs) from the ovarian tumor (OTU) domain family. LotA is unique among other OTU DUBs because it possesses two distinct DUB domains and exclusively exhibits catalytic activity against K6-linked diUb and polyUb chains. However, the structure of LotA and the molecular mechanism for the dual DUB activity remains elusive. In this study, we solved the structure of LotA in complex with proximally bound Ub and distal covalently bound Ub. Both Ub molecules are bound to the DUB1 domain and mimic a K6-linked diUb. Structural analysis reveals that the DUB1 domain utilizes a distinct mechanism for recognition of the K6-linked diUb within a large S1' binding site that is uncommon to OTU DUBs. Structural fold of the LotA DUB2 domain closely resembles LotB and LotC, similarly containing an extra α-helix lobe that has been demonstrated to play an important role in Ub binding. Collectively, our study uncovers the structural basis for the dual catalytic activity of the unique OTU family DUB LotA.

Han family with essential tremor caused by the P421L variant of the TENM4 gene in China.

BACKGROUND: Essential tremor (ET) is an autosomal dominant inheritance disorder. Mutations in fusion sarcoma (FUS), mitochondrial serine peptidase 2 (HTRA2), teneurin transmembrane protein 4 (TENM4), sortilin1 (SORT1), SCN11A, and notch2N-terminal-like (NOTCH2NLC) genes are associated with familial ET. METHODS: A proband with ET was tested using whole-exome sequencing and repeat-primed polymerase chain reaction. Subsequently, the family members were screened for the suspected mutation, and the results were verified using Sanger sequencing. The relationship between pedigree and phenotype was also analyzed, and structural and functional changes in the variants were predicted using bioinformatics analysis. RESULTS: In a family with ET, the proband (III4) and the proband's father (II1), grandfather (I1), uncle (II2), and cousin (III5) all presented with involuntary tremors of both upper limbs. The responsible mutation was identified as TENM4 c.1262C > T (p.P421L), which showed genetic co-segregation in the family survey. AlphaFold predicted a change in the spatial position of TENM4 after the P421L mutation, which may have affected its stability. AlphaFold also predicted P421L to be a deleterious variation, which would lead to lower degrees of freedom of the TENM4 protein, thereby affecting the protein's structure and stability. According to the bioinformatics analysis, TENM4 (p.P421L) may reduce the signal reaching the nucleus by affecting the expression of TENM4 messenger RNA (mRNA), thereby impairing the normal oligodendrocyte differentiation process and leading to impaired myelination. CONCLUSION: This study revealed that the TENM4 (p.P421L) pathogenic missense variation was responsible for ET in the proband.

Yishen Jiangzhuo decoction attenuates cisplatin­induced acute kidney injury by inhibiting inflammation, oxidative stress and apoptosis through the TNF signal pathway.

The present study aimed to investigate the therapeutic effects and mechanisms of Yishen Jiangzhuo decoction (YSJZD) in a mouse model of cisplatin-induced acute kidney injury (AKI). The mice were divided into the NC, cisplatin and cisplatin + YSJZD groups. A concentration-dependent effect of YSJZD on cisplatin-induced AKI was observed and the optimal concentration for intervention was calculated. Changes in blood urea nitrogen and serum creatinine levels combined with hematoxylin and eosin and periodic acid-Schiff staining and transmission electron microscopy observations indicated that YSJZD enhanced renal function, reduced pathological injury and protected renal tubular epithelial cells in cisplatin-induced AKI mice. The results of the transcriptomic and enrichment analyses showed that the mechanisms of YSJZD may be associated with inflammation, oxidation, apoptosis and the TNF signal pathway. Immunofluorescence, oxidative stress index, terminal deoxynucleotidyl transferase dUTP nick end labeling assay and western blotting revealed that YSJZD downregulated apoptosis in the renal tissues of AKI mice and further decreased the expression levels of p-p65, p-p38 MAPK, TNF-α, cleaved-caspase-3 and malondialdehyde, while increasing the levels of NAD-dependent protein deacetylase sirtuin-3, glutathione and superoxide dismutase. Overall, the results showed that YSJZD could effectively abrogate cisplatin-induced AKI in mice through mechanisms primarily related to its anti-inflammatory, antioxidative and antiapoptotic effects by inhibited the TNF signal pathway. YSJZD warrants further investigation as a clinical empirical prescription.

Elucidation of the mechanism underlying the sequential catalysis of inulin by fructotransferase.

Glycoside hydrolase family 91 (GH91) inulin fructotransferase (IFTases) enables biotransformation of fructans into sugar substitutes for dietary intervention in metabolic syndrome. However, the catalytic mechanism underlying the sequential biodegradation of inulin remains unelusive during the biotranformation of fructans. Herein we present the crystal structures of IFTase from Arthrobacter aurescens SK 8.001 in apo form and in complexes with kestose, nystose, or fructosyl nystose, respectively. Two kinds of conserved noncatalytic binding regions are first identified for IFTase-inulin interactions. The conserved interactions of substrates were revealed in the catalytic center that only contained a catalytic residue E205. A switching scaffold was comprised of D194 and Q217 in the catalytic channel, which served as the catalytic transition stabilizer through side chain displacement in the cycling of substrate sliding in/out the catalytic pocket. Such features in GH91 contribute to the catalytic model for consecutive cutting of substrate chain as well as product release in IFTase, and thus might be extended to other exo-active enzymes with an enclosed bottom of catalytic pocket. The study expands the current general catalytic principle in enzyme-substrate complexes and shed light on the rational design of IFTase for fructan biotransformation.

Clinical phenotype and genetic function analysis of a family with hypomyelinating leukodystrophy-7 caused by POLR3A mutation.

Hypomyelinating leukodystrophy (HLD) is a rare genetic heterogeneous disease that can affect myelin development in the central nervous system. This study aims to analyze the clinical phenotype and genetic function of a family with HLD-7 caused by POLR3A mutation. The proband (IV6) in this family mainly showed progressive cognitive decline, dentin dysplasia, and hypogonadotropic hypogonadism. Her three old brothers (IV1, IV2, and IV4) also had different degrees of ataxia, dystonia, or dysarthria besides the aforementioned manifestations. Their brain magnetic resonance imaging showed bilateral periventricular white matter atrophy, brain atrophy, and corpus callosum atrophy and thinning. The proband and her two living brothers (IV2 and IV4) were detected to carry a homozygous mutation of the POLR3A (NM_007055.4) gene c. 2300G > T (p.Cys767Phe), and her consanguineous married parents (III1 and III2) were p.Cys767Phe heterozygous carriers. In the constructed POLR3A wild-type and p.Cys767Phe mutant cells, it was seen that overexpression of wild-type POLR3A protein significantly enhanced Pol III transcription of 5S rRNA and tRNA Leu-CAA. However, although the mutant POLR3A protein overexpression was increased compared to the wild-type protein overexpression, it did not show the expected further enhancement of Pol III function. On the contrary, Pol III transcription function was frustrated (POLR3A, BC200, and tRNA Leu-CAA expression decreased), and MBP and 18S rRNA expressions were decreased. This study indicates that the POLR3A p.Cys767Phe variant caused increased expression of mutated POLR3A protein and abnormal expression of Pol III transcripts, and the mutant POLR3A protein function was abnormal.

Research Progress on the Anti-Aging Potential of the Active Components of Ginseng.

Aging is a cellular state characterized by a permanent cessation of cell division and evasion of apoptosis. DNA damage, metabolic dysfunction, telomere damage, and mitochondrial dysfunction are the main factors associated with senescence. Aging increases ß-galactosidase activity, enhances cell spreading, and induces Lamin B1 loss, which further accelerate the aging process. It is associated with a variety of diseases, such as Alzheimer's disease, Parkinson's, type 2 diabetes, and chronic inflammation. Ginseng is a traditional Chinese medicine with anti-aging effects. The active components of ginseng, including saponins, polysaccharides, and active peptides, have antioxidant, anti-apoptotic, neuroprotective, and age-delaying effects. DNA damage is the main factor associated with aging, and the mechanism through which the active ingredients of ginseng reduce DNA damage and delay aging has not been comprehensively described. This review focuses on the anti-aging mechanisms of the active ingredients of ginseng. Furthermore, it broadens the scope of ideas for further research on natural products and aging.

Evaluation of ferritin and TfR level in plasma neural-derived exosomes as potential markers of Parkinson's disease.

Introduction: Early diagnosis of Parkinson's disease (PD) remains challenging. It has been suggested that abnormal brain iron metabolism leads to excessive iron accumulation in PD, although the mechanism of iron deposition is not yet fully understood. Ferritin and transferrin receptor (TfR) are involved in iron metabolism, and the exosome pathway is one mechanism by which ferritin is transported and regulated. While the blood of healthy animals contains a plentiful supply of TfR-positive exosomes, no studies have examined ferritin and TfR in plasma neural-derived exosomes. Methods: Plasma exosomes were obtained from 43 patients with PD and 34 healthy controls. Neural-derived exosomes were isolated with anti-human L1CAM antibody immunoabsorption. Transmission electron microscopy and western blotting were used to identify the exosomes. ELISAs were used to quantify ferritin and TfR levels in plasma neural-derived exosomes of patients with PD and controls. Receivers operating characteristic (ROC) curves were applied to map the diagnostic accuracy of ferritin and TfR. Independent predictors of the disease were identified using logistic regression models. Results: Neural-derived exosomes exhibited the typical exosomal morphology and expressed the specific exosome marker CD63. Ferritin and TfR levels in plasma neural-derived exosomes were significantly higher in patients with PD than controls (406.46 ± 241.86 vs. 245.62 ± 165.47 ng/µg, P = 0.001 and 1728.94 ± 766.71 vs. 1153.92 ± 539.30 ng/µg, P < 0.001, respectively). There were significant positive correlations between ferritin and TfR levels in plasma neural-derived exosomes in control group, PD group and all the individuals (rs = 0.744, 0.700, and 0.752, respectively). The level of TfR was independently associated with the disease (adjusted odds ratio 1.002; 95% CI 1.000-1.003). ROC performances of ferritin, TfR, and their combination were moderate (0.730, 0.812, and 0.808, respectively). However, no relationship was found between the biomarkers and disease progression. Conclusion: It is hypothesized that ferritin and TfR in plasma neural-derived exosomes may be potential biomarkers for PD, and that they may participate in the mechanism of excessive iron deposition in PD.

Corrigendum: Evaluation of ferritin and TfR level in plasma neural-derived exosomes as potential markers of Parkinson's disease.

[This corrects the article DOI: 10.3389/fnagi.2023.1216905.].

ACSS2-dependent histone acetylation improves cognition in mouse model of Alzheimer's disease.

BACKGROUND: Nuclear acetyl-CoA pools govern histone acetylation that controls synaptic plasticity and contributes to cognitive deterioration in patients with Alzheimer's disease (AD). Nuclear acetyl-CoA pools are generated partially from local acetate that is metabolized by acetyl-CoA synthetase 2 (ACSS2). However, the underlying mechanism of histone acetylation dysregulation in AD remains poorly understood. METHODS: We detected ACSS2 expression and histone acetylation levels in the brains of AD patients and 5 × FAD mice. When we altered ACSS2 expression by injecting adeno-associated virus into the dorsal hippocampus of 5 × FAD mice and replenished ACSS2 substrate (acetate), we observed changes in cognitive function by Morris water maze. We next performed RNA-seq, ChIP-qPCR, and electrophysiology to study molecular mechanism underlying ACSS2-mediated spatial learning and memory in 5 × FAD mice. RESULTS: We reported that ACSS2 expression and histone acetylation (H3K9, H4K12) were reduced in the hippocampus and prefrontal cortex of 5 × FAD mice. Reduced ACSS2 levels were also observed in the temporal cortex of AD patients. 5 × FAD mice exhibited a low enrichment of acetylated histones on the promoters of NMDARs and AMPARs, together with impaired basal and activity-dependent synaptic plasticity, all of which were rescued by ACSS2 upregulation. Moreover, acetate replenishment enhanced ac-H3K9 and ac-H4K12 in 5 × FAD mice, leading to an increase of NMDARs and AMPARs and a restoration of synaptic plasticity and cognitive function in an ACSS2-dependent manner. CONCLUSION: ACSS2 is a key molecular switch of cognitive impairment and that targeting ACSS2 or acetate administration may serve as a novel therapeutic strategy for the treatment of intermediate or advanced AD. Nuclear acetyl-CoA pools are generated partly from local acetate that is metabolized by acetyl-CoA synthetase 2 (ACSS2). Model depicts that ACSS2 expression is downregulated in the brains of 5×FAD model mice and AD patients. Of note, ACSS2 downregulation mediates a reduction in ionotropic glutamate receptor expression through histone acetylation, which exacerbates synaptic plasticity impairment in AD. These deficits can be rescued by ACSS2 upregulation or acetate supplementation (GTA, an FDA-approved food additive), which may serve as a promising therapeutic strategy for AD treatment.

In situ surface reduction for accessing atomically dispersed platinum on carbon sheets for acidic hydrogen evolution.

Exploring the simple yet well-controlled synthesis of atomically dispersed Pt catalysts is a crucial endeavour for harvesting clean hydrogen via the kinetics-favoured acidic electrochemical water splitting technique. Here we employed the use of defective carbon sheets by KOH etching as a substrate for the in situ surface reduction of Pt(IV) ions to prepare atomically dispersed Pt. Physical and electrochemical characterizations reveal a strong interaction between the carbon substrate and Pt species, providing the basis for the in situ surface reduction. The atomically dispersed Pt electrocatalyst exhibited high HER performance in a sulfuric acid electrolyte, with an overpotential as low as 55 mV at a current density of 100 mA cm-a, and better catalytic durability compared to the commercial Pt/C. The mechanism study revealed that the full utilization of atomically dispersed Pt and the optimized catalyst surface may enhance the recombination of adsorbed *H via the Volmer-Tafel mechanism to produce H2 at a high efficiency. In the light of high activity, durability, and low cost, the atomically dispersed Pt material is promising for acidic HER application.

Comparative Efficacy and Safety of Dopamine Agonists in Advanced Parkinson's Disease With Motor Fluctuations: A Systematic Review and Network Meta-Analysis of Double-Blind Randomized Controlled Trials.

Background: Movement fluctuations are the main complication of Parkinson's disease (PD) patients receiving long-term levodopa (L-dopa) treatment. We compared and ranked the efficacy and safety of dopamine agonists (DAs) with regard to motor fluctuations by using a Bayesian network meta-analysis (NMA) to quantify information from randomized controlled trials (RCTs). Methods and Findings: We carried out a systematic review and meta-analysis, and only RCTs comparing DAs for advanced PD were included. Electronic databases (PubMed, Embase, and Cochrane Library) were systematically searched for relevant studies published until January 2021. Two reviewers independently extracted individual study data and evaluated studies for risk of bias using the Cochrane Risk of Bias tool. Network meta-analyses using a Bayesian framework were used to calculate the related parameters. The pre-specified primary and secondary outcomes were efficacy ("ON" time without troublesome dyskinesia, "OFF" time, "ON" time, "UPDRS-III," and "UPDRS-II") and safety [treatment-emergent adverse events (TEAE) and other adverse events] of DAs. The results are presented as the surface under the cumulative ranking (SUCRA) curve. A total of 20 RCTs assessing 6,560 patients were included. The general DA effects were ranked from high to low with respect to the amount of "ON" time without troublesome dyskinesia as follows: apomorphine (SUCRA = 97.08%), pramipexole_IR (probability = 79.00%), and ropinirole_PR (SUCRA = 63.92%). The general safety of DAs was ranked from high to low with respect to TEAE as follows: placebo (SUCRA = 74.49%), pramipexole_ER (SUCRA = 63.6%), sumanirole (SUCRA = 54.07%), and rotigotine (SUCRA = 53.84%). Conclusions: This network meta-analysis shows that apomorphine increased "ON" time without troublesome dyskinesia and decreased "OF" time for advanced PD patients. The addition of pramipexole, ropinirole, or rotigotine to levodopa treatment in advanced PD patients with motor fluctuations increased "ON" time without troublesome dyskinesia, improved the UPDRS III scores, and ultimately ameliorated the UPDRS II scores, thereby maximizing its benefit. This NMA of pramipexole, ropinirole, and rotigotine represents an effective treatment option and has an acceptable safety profile in patients with advanced PD.

Review and Analysis of Two Gitelman Syndrome Pedigrees Complicated with Proteinuria or Hashimoto's Thyroiditis Caused by Compound Heterozygous SLC12A3 Mutations.

Gitelman syndrome (GS) is an autosomal recessive inherited salt-losing renal tubular disease, which is caused by a pathogenic mutation of SLC12A3 encoding thiazide-sensitive Na-Cl cotransporter, which leads to disturbance of sodium and chlorine reabsorption in renal distal convoluted tubules, resulting in phenotypes such as hypovolemia, renin angiotensin aldosterone system (RAAS) activation, hypokalemia, and metabolic alkalosis. In this study, two GS families with proteinuria or Hashimoto's thyroiditis were analyzed for genetic-phenotypic association. Sanger sequencing revealed that two probands carried SLC12A3 compound heterozygous mutations, and proband A carried two pathogenic mutations: missense mutation Arg83Gln, splicing mutation, or frameshift mutation NC_000016.10:g.56872655_56872667 (gcggacatttttg>accgaaaatttt) in exon 8. Proband B carries two missense mutations: novel Asp839Val and Arg904Gln. Both probands manifested hypokalemia, hypomagnesemia, hypocalcinuria, metabolic alkalosis, and RAAS activation; in addition, the proband A exhibited decreased urinary chloride, phosphorus, and increased magnesium ions excretion, complicated with Hashimoto's Thyroiditis, while the proband B exhibited enhanced urine sodium excretion and proteinuria. The older sister of proband B with GS also had Hashimoto's thyroiditis. Electron microscopy revealed swelling and vacuolar degeneration of glomerular epithelial cells, diffuse proliferation of mesangial cells and matrix, accompanied by a small amount of low-density electron-dense deposition, and segmental fusion of epithelial cell foot processes in proband B. Light microscopy showed mild mesangial hyperplasia in the focal segment of the glomerulus, hyperplasia, and hypertrophy of juxtaglomerular apparatus cells, mild renal tubulointerstitial lesions, and one glomerular sclerosis. So, long-term hypokalemia of GS can cause kidney damage and may also be susceptible to thyroid disease.

Differences in gut microbiota structure in patients with stages 4-5 chronic kidney disease.

The gut microbiota can affect human metabolism, immunity, and other biologic pathways through the complex gut-kidney axis (GKA), and in turn participate in the occurrence and development of kidney disease. In this study, 39 patients with stage 4-5 chronic kidney disease (CKD) and 40 healthy individuals were recruited and 16S rDNA sequencing was performed to analyze the V3-V4 conserved regions of their microbiota. A total of 795 operational taxonomic units (OTUs) shared between groups or specific to each group were obtained, among which 255 OTUs with significant differences between the two groups were identified (P<0.05). Adonis differential analysis showed that the diversity of gut microbiota was highly correlated with CKD stages 4-5. Additionally, 61 genera with differences in the two groups were identified (P<0.05) and 111 species with significant differences in the phyla, classes, orders, families, and genera between the two groups were identified (P<0.05). The differential bacterial genera with the greatest contribution were, in descending order: c_Bacteroidia, o_Bacteroidales, p_Bacteroidetes, c_Clostridia, o_Clostridiales, etc. Those with the greatest contribution in stages 4-5 CKD were, in descending order: p_Proteobacteria, f_Enterobacteriaceae, o_Enterobacteriales, c_Gammaproteobacteria, c_Bacilli, etc. The results suggest that the diversity of the microbiota may affect the occurrence, development, and outcome of the terminal stages of CKD.

Regulation of cGAS-Mediated Immune Responses and Immunotherapy.

Early detection of infectious nucleic acids released from invading pathogens by the innate immune system is critical for immune defense. Detection of these nucleic acids by host immune sensors and regulation of DNA sensing pathways have been significant interests in the past years. Here, current understandings of evolutionarily conserved DNA sensing cyclic GMP-AMP (cGAMP) synthase (cGAS) are highlighted. Precise activation and tight regulation of cGAS are vital in appropriate innate immune responses, senescence, tumorigenesis and immunotherapy, and autoimmunity. Hence, substantial insights into cytosolic DNA sensing and immunotherapy of indispensable cytosolic sensors have been detailed to extend limited knowledge available thus far. This Review offers a critical, in-depth understanding of cGAS regulation, cytosolic DNA sensing, and currently established therapeutic approaches of essential cytosolic immune agents for improved human health.