Principles of peptide selection by the transporter associated with antigen processing.

Our ability to fight pathogens relies on major histocompatibility complex class I (MHC-I) molecules presenting diverse antigens on the surface of diseased cells. The transporter associated with antigen processing (TAP) transports nearly the entire repertoire of antigenic peptides into the endoplasmic reticulum for MHC-I loading. How TAP transports peptides specific for MHC-I is unclear. In this study, we used cryo-EM to determine a series of structures of human TAP, both in the absence and presence of peptides with various sequences and lengths. The structures revealed that peptides of eight or nine residues in length bind in a similarly extended conformation, despite having little sequence overlap. We also identified two peptide-anchoring pockets on either side of the transmembrane cavity, each engaging one end of a peptide with primarily main chain atoms. Occupation of both pockets results in a global conformational change in TAP, bringing the two halves of the transporter closer together to prime it for isomerization and ATP hydrolysis. Shorter peptides are able to bind to each pocket separately but are not long enough to bridge the cavity to bind to both simultaneously. Mutations that disrupt hydrogen bonds with the N and C termini of peptides almost abolish MHC-I surface expression. Our findings reveal that TAP functions as a molecular caliper that selects peptides according to length rather than sequence, providing antigen diversity for MHC-I presentation.

Association between the frontoparietal network, clinical symptoms and treatment response in individuals with untreated anorexia nervosa.

Background: Anorexia nervosa (AN) has been characterised as a psychiatric disorder associated with increased control. Currently, it remains difficult to predict treatment response in patients with AN. Their cognitive abilities are known to be resistant to treatment. It has been established that the frontoparietal control network (FPCN) is the direct counterpart of the executive control network. Therefore, the resting-state brain activity of the FPCN may serve as a biomarker to predict treatment response in AN. Aims: The study aimed to investigate the association between resting-state functional connectivity (RSFC) of the FPCN, clinical symptoms and treatment response in patients with AN. Methods: In this case-control study, 79 female patients with AN and no prior treatment from the Shanghai Mental Health Center and 40 matched healthy controls (HCs) were recruited from January 2015 to March 2022. All participants completed the Questionnaire Version of the Eating Disorder Examination (version 6.0) to assess the severity of their eating disorder symptoms. Additionally, RSFC data were obtained from all participants at baseline by functional magnetic resonance imaging. Patients with AN underwent routine outpatient treatment at the 4th and 12th week, during which time their clinical symptoms were evaluated using the same measures as at baseline. Results: Among the 79 patients, 40 completed the 4-week follow-up and 35 completed the 12-week follow-up. The RSFC from the right posterior parietal cortex (PPC) and dorsolateral prefrontal cortex (dlPFC) increased in 79 patients with AN vs 40 HCs after controlling for depression and anxiety symptoms. By multiple linear regression, the RSFC of the PPC to the inferior frontal gyrus was found to be a significant factor for self-reported eating disorder symptoms at baseline and the treatment response to cognitive preoccupations about eating and body image, after controlling for age, age of onset and body mass index. The RSFC in the dlPFC to the middle temporal gyrus and the superior frontal gyrus may be significant factors in the treatment response to binge eating and loss of control/overeating in patients with AN. Conclusions: Alterations in RSFC in the FPCN appear to affect self-reported eating disorder symptoms and treatment response in patients with AN. Our findings offer new insight into the pathogenesis of AN and could promote early prevention and treatment.

Structure-based discovery of CFTR potentiators and inhibitors.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a crucial ion channel whose loss of function leads to cystic fibrosis, whereas its hyperactivation leads to secretory diarrhea. Small molecules that improve CFTR folding (correctors) or function (potentiators) are clinically available. However, the only potentiator, ivacaftor, has suboptimal pharmacokinetics and inhibitors have yet to be clinically developed. Here, we combine molecular docking, electrophysiology, cryo-EM, and medicinal chemistry to identify CFTR modulators. We docked ∼155 million molecules into the potentiator site on CFTR, synthesized 53 test ligands, and used structure-based optimization to identify candidate modulators. This approach uncovered mid-nanomolar potentiators, as well as inhibitors, that bind to the same allosteric site. These molecules represent potential leads for the development of more effective drugs for cystic fibrosis and secretory diarrhea, demonstrating the feasibility of large-scale docking for ion channel drug discovery.

Rare-Earth Metal Complexes Supported by A Tridentate Amidinate Ligand: Synthesis, Characterization, and Catalytic Comparison in Isoprene Polymerization.

To systematically investigate the dependence of the initiating group and metal size on polymerization performance, a family of rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes supported by a monoanionic tridentate amidinate ligand [(2,6-iPr2C6H3)NC(Ph)N(C6H4-2-OMe]- (HL) were synthesized and well-characterized. Treatment of rare-earth metal tris(alkyl)/tris(benzyl)/tris(amide) complexes Y(CH2C6H4NMe2-o)3 or Y(CH2SiMe3)3(THF)2 or Ln[N(SiHMe2)2]3(THF)x (Ln = Sc, x = 1; Ln = Y, La, Sm, Lu, x = 2) with 1 equiv of HL gave the corresponding mono(amidinate) rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2C6H4NMe2-o)2 (1), [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2SiMe3)2(THF) (2), and [(2,6-iPr2C6H4)NC(Ph)N(C6H4-2-OMe)]Ln[N(SiHMe2)2]2(THF)n (Ln = Y, n = 1 (3); Ln = La, n = 1 (4); Ln = Sc, n = 0 (5); Ln = Lu, n = 0 (6); Ln = Sm, n = 0 (7)) in good isolated yields. These complexes were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction. In the presence of excess AlMe3 and on treatment with 1 equiv of [Ph3C][B(C6F5)4], these complexes could serve as precatalysts for cationic polymerization of isoprene, in which the dependence of the polymerization activity and regioselectivity on the initiating group and metal size was observed.

New media facilitate adolescents' body dissatisfaction and eating disorders in Mainland China.

New media play a significant role in adolescents' body dissatisfaction and eating disorders in Mainland China, through shaping social standards, peers, and family dynamics. How to mitigate their adverse effects on adolescents, reduce body dissatisfaction, and prevent eating disorders is a significant social issue that demands serious consideration.

DNAJA1­knockout alleviates heat stroke­induced endothelial barrier disruption via improving thermal tolerance and suppressing the MLCK­MLC signaling pathway.

Endothelial barrier disruption plays a key role in the pathophysiology of heat stroke (HS). Knockout of DNAJA1 (DNAJA1­KO) is thought to be protective against HS based on a genome­wide CRISPR­Cas9 screen experiment. The present study aimed to illustrate the function of DNAJA1­KO against HS in human umbilical vein endothelial cells. DNAJA1­KO cells were infected using a lentivirus to investigate the role of DNAJA1­KO in HS­induced endothelial barrier disruption. It was shown that DNAJA1­KO could ameliorate decreased cell viability and increased cell injury, according to the results of Cell Counting Kit­8 and lactate dehydrogenase assays. Moreover, HS­induced endothelial cell apoptosis was inhibited by DNAJA1­KO, as indicated by Annexin V­FITC/PI staining and cleaved­caspase­3 expression using flow cytometry and western blotting, respectively. Furthermore, the endothelial barrier function, as measured by transepithelial electrical resistance and FITC­Dextran, was sustained during HS. DNAJA1­KO was not found to have a significant effect on the expression and distribution of cell junction proteins under normal conditions without HS. However, DNAJA1­KO could effectively protect the HS­induced decrease in the expression and distribution of cell junction proteins, including zonula occludens­1, claudin­5, junctional adhesion molecule A and occludin. A total of 4,394 proteins were identified using proteomic analysis, of which 102 differentially expressed proteins (DEPs) were activated in HS­induced wild­type cells and inhibited by DNAJA1­KO. DEPs were investigated by enrichment analysis, which demonstrated significant enrichment in the 'calcium signaling pathway' and associations with vascular­barrier regulation. Furthermore, the 'myosin light­chain kinase (MLCK)­MLC signaling pathway' was proven to be activated by HS and inhibited by DNAJA1­KO, as expected. Moreover, DNAJA1­KO mice and a HS mouse model were established to demonstrate the protective effects on endothelial barrier in vivo. In conclusion, the results of the present study suggested that DNAJA1­KO alleviates HS­induced endothelial barrier disruption by improving thermal tolerance and suppressing the MLCK­MLC signaling pathway.

QoS-driven resource allocation in fog radio access network: A VR service perspective.

While immersive media services represented by virtual reality (VR) are booming, They are facing fundamental challenges, i.e., soaring multimedia applications, large operation costs and scarce spectrum resources. It is difficult to simultaneously address these service challenges in a conventional radio access network (RAN) system. These problems motivated us to explore a quality-of-service (QoS)-driven resource allocation framework from VR service perspective based on the fog radio access network (F-RAN) architecture. We elaborated details of deployment on the caching allocation, dynamic base station (BS) clustering, statistical beamforming and cost strategy under the QoS constraints in the F-RAN architecture. The key solutions aimed to break through the bottleneck of the network design and to deep integrate the network-computing resources from different perspectives of cloud, network, edge, terminal and use of collaboration and integration. Accordingly, we provided a tailored algorithm to solve the corresponding formulation problem. This is the first design of VR services based on caching and statistical beamforming under the F-RAN. A case study provided to demonstrate the advantage of our proposed framework compared with existing schemes. Finally, we concluded the article and discussed possible open research problems.

Structural basis for CFTR inhibition by CFTRinh-172.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel that regulates electrolyte and fluid balance in epithelial tissues. While activation of CFTR is vital to treating cystic fibrosis, selective inhibition of CFTR is a potential therapeutic strategy for secretory diarrhea and autosomal dominant polycystic kidney disease. Although several CFTR inhibitors have been developed by high-throughput screening, their modes of action remain elusive. In this study, we determined the structure of CFTR in complex with the inhibitor CFTRinh-172 to an overall resolution of 2.7 Å by cryogenic electron microscopy. We observe that CFTRinh-172 binds inside the pore near transmembrane helix 8, a critical structural element that links adenosine triphosphate hydrolysis with channel gating. Binding of CFTRinh-172 stabilizes a conformation in which the chloride selectivity filter is collapsed, and the pore is blocked from the extracellular side of the membrane. Single-molecule fluorescence resonance energy transfer experiments indicate that CFTRinh-172 inhibits channel gating without compromising nucleotide-binding domain dimerization. Together, these data reconcile previous biophysical observations and provide a molecular basis for the activity of this widely used CFTR inhibitor.

Structural identification of a selectivity filter in CFTR.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that regulates transepithelial salt and fluid homeostasis. CFTR dysfunction leads to reduced chloride secretion into the mucosal lining of epithelial tissues, thereby causing the inherited disease cystic fibrosis. Although several structures of CFTR are available, our understanding of the ion-conduction pathway is incomplete. In particular, the route that connects the cytosolic vestibule with the extracellular space has not been clearly defined, and the structure of the open pore remains elusive. Furthermore, although many residues have been implicated in altering the selectivity of CFTR, the structure of the "selectivity filter" has yet to be determined. In this study, we identify a chloride-binding site at the extracellular ends of transmembrane helices 1, 6, and 8, where a dehydrated chloride is coordinated by residues G103, R334, F337, T338, and Y914. Alterations to this site, consistent with its function as a selectivity filter, affect ion selectivity, conductance, and open channel block. This selectivity filter is accessible from the cytosol through a large inner vestibule and opens to the extracellular solvent through a narrow portal. The identification of a chloride-binding site at the intra- and extracellular bridging point leads us to propose a complete conductance path that permits dehydrated chloride ions to traverse the lipid bilayer.

Structure-based discovery of CFTR potentiators and inhibitors.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a crucial ion channel whose loss of function leads to cystic fibrosis, while its hyperactivation leads to secretory diarrhea. Small molecules that improve CFTR folding (correctors) or function (potentiators) are clinically available. However, the only potentiator, ivacaftor, has suboptimal pharmacokinetics and inhibitors have yet to be clinically developed. Here we combine molecular docking, electrophysiology, cryo-EM, and medicinal chemistry to identify novel CFTR modulators. We docked ~155 million molecules into the potentiator site on CFTR, synthesized 53 test ligands, and used structure-based optimization to identify candidate modulators. This approach uncovered novel mid-nanomolar potentiators as well as inhibitors that bind to the same allosteric site. These molecules represent potential leads for the development of more effective drugs for cystic fibrosis and secretory diarrhea, demonstrating the feasibility of large-scale docking for ion channel drug discovery.

Rare Earth Amide-Catalyzed Direct Thioesterification of Aldehydes with Thiols under Mild Conditions.

Direct thioesterification of aldehydes with thiols catalyzed by readily accessible rare earth/lithium amide RE[N(SiMe3)2]3(µ-Cl)Li(THF)3 is developed, which enables the preparation of a range of thioesters (31 examples) under room temperature and solvent-free conditions, without using any additive or external oxidant. This method provides a straightforward and atom-efficient approach for the thioester synthesis.

Development of a counterselectable system for rapid and efficient CRISPR-based genome engineering in Zymomonas mobilis.

BACKGROUND: Zymomonas mobilis is an important industrial bacterium ideal for biorefinery and synthetic biology studies. High-throughput CRISPR-based genome editing technologies have been developed to enable targeted engineering of genes and hence metabolic pathways in the model ZM4 strain, expediting the exploitation of this biofuel-producing strain as a cell factory for sustainable chemicals, proteins and biofuels production. As these technologies mainly take plasmid-based strategies, their applications would be impeded due to the fact that curing of the extremely stable plasmids is laborious and inefficient. Whilst counterselection markers have been proven to be efficient for plasmid curing, hitherto only very few counterselection markers have been available for Z. mobilis. RESULTS: We constructed a conditional lethal mutant of the pheS gene of Z. mobilis ZM4, clmPheS, containing T263A and A318G substitutions and coding for a mutated alpha-subunit of phenylalanyl-tRNA synthetase to allow for the incorporation of a toxic analog of phenylalanine, p-chloro-phenylalanine (4-CP), into proteins, and hence leading to inhibition of cell growth. We demonstrated that expression of clmPheS driven by a strong Pgap promoter from a plasmid could render the Z. mobilis ZM4 cells sufficient sensitivity to 4-CP. The clmPheS-expressing cells were assayed to be extremely sensitive to 0.2 mM 4-CP. Subsequently, the clmPheS-assisted counterselection endowed fast curing of genome engineering plasmids immediately after obtaining the desired mutants, shortening the time of every two rounds of multiplex chromosome editing by at least 9 days, and enabled the development of a strategy for scarless modification of the native Z. mobilis ZM4 plasmids. CONCLUSIONS: This study developed a strategy, coupling an endogenous CRISPR-based genome editing toolkit with a counterselection marker created here, for rapid and efficient multi-round multiplex editing of the chromosome, as well as scarless modification of the native plasmids, providing an improved genome engineering toolkit for Z. mobilis and an important reference to develope similar genetic manipulation systems in other non-model organisms.

Microbiota-gut-brain axis drives overeating disorders.

Overeating disorders (ODs), usually stemming from dieting history and stress, remain a pervasive issue in contemporary society, with the pathological mechanisms largely unresolved. Here, we show that alterations in intestinal microbiota are responsible for the excessive intake of palatable foods in OD mice and patients with bulimia nervosa (BN). Stress combined with a history of dieting causes significant changes in the microbiota and the intestinal metabolism, which disinhibit the vagus nerve terminals in the gut and thereby lead to a subsequent hyperactivation of the gut-brain axis passing through the vagus, the solitary tract nucleus, and the paraventricular nucleus of the thalamus. The transplantation of a probiotic Faecalibacterium prausnitzii or dietary supplement of key metabolites restores the activity of the gut-to-brain pathway and thereby alleviates the OD symptoms. Thus, our study delineates how the microbiota-gut-brain axis mediates energy balance, unveils the underlying pathogenesis of the OD, and provides potential therapeutic strategies.

ChatGPT: Opportunities, risks and priorities for psychiatry.

The advancement of large language models such as ChatGPT, opens new possibilities in psychiatry but also invites scrutiny. This paper examines the potential opportunities, risks, and crucial areas of focus within this area. The active engagement of the mental health community is seen as critical to ensure ethical practice, equal access, and a patient-centric approach.

Comparison of Recurrent With First-Time In-Stent Restenosis.

Recurrent in-stent restenosis (Re-ISR) remains a therapeutic challenge. We aimed to investigate the clinical characteristics, treatment, and long-term outcomes in patients with Re-ISR compared with those with first-time ISR (First-ISR). This retrospective study consecutively enrolled patients who underwent percutaneous coronary intervention (PCI) for ISR in Fuwai Hospital between January 2017 and December 2018. Re-ISR was defined as a second event of ISR after a previous successful treatment of the ISR lesion. The primary outcome was defined as a composite of all-cause death, spontaneous myocardial infarction, and repeat revascularization. A total of 2,006 patients (2,154 lesions) with ISR underwent successful PCI were enrolled and categorized into 2 groups: the Re-ISR group (246 patients/259 lesions) and the First-ISR group (1,760 patients/1,895 lesions). During a mean follow-up of 36 months, the primary outcomes occurred in 80 patients (32.5%) in the Re-ISR group and 349 patients (19.3%) in the First-ISR group (p <0.001 by log-rank test), major driven by spontaneous myocardial infarction (4.9% vs 2.7%, p = 0.049) and repeat revascularization (30.1% vs 16.5%, p <0.001). The multivariable Cox regression analysis revealed that Re-ISR was independently associated with a higher rate of major adverse cardiovascular events (adjusted hazard ratio 1.88, 95% confidence interval 1.39 to 2.53, p <0.001) and repeated revascularization (adjusted hazard ratio 2.09, 95% confidence interval 1.53 to 2.84, p <0.001). The relation remained consistent after the propensity score analysis. In conclusion, in the present cohort of patients who underwent PCI for ISR, Re-ISR was significantly associated with a higher risk of long-term outcomes than First-ISR.

Inferring the Effects of Protein Variants on Protein-Protein Interactions with Interpretable Transformer Representations.

Identifying pathogenetic variants and inferring their impact on protein-protein interactions sheds light on their functional consequences on diseases. Limited by the availability of experimental data on the consequences of protein interaction, most existing methods focus on building models to predict changes in protein binding affinity. Here, we introduced MIPPI, an end-to-end, interpretable transformer-based deep learning model that learns features directly from sequences by leveraging the interaction data from IMEx. MIPPI was specifically trained to determine the types of variant impact (increasing, decreasing, disrupting, and no effect) on protein-protein interactions. We demonstrate the accuracy of MIPPI and provide interpretation through the analysis of learned attention weights, which exhibit correlations with the amino acids interacting with the variant. Moreover, we showed the practicality of MIPPI in prioritizing de novo mutations associated with complex neurodevelopmental disorders and the potential to determine the pathogenic and driving mutations. Finally, we experimentally validated the functional impact of several variants identified in patients with such disorders. Overall, MIPPI emerges as a versatile, robust, and interpretable model, capable of effectively predicting mutation impacts on protein-protein interactions and facilitating the discovery of clinically actionable variants.

The trends of psychosomatic symptoms and perceived stress among healthcare workers during the COVID-19 pandemic in China: Four cross-sectional nationwide surveys, 2020-2023.

An unseen wave of vast infection was detected in China in December 2022, and healthcare workers faced inevitable challenges and heavy stress. We aimed to present a dynamic mental health map and, most importantly, provide a timely report of the current situation in healthcare workers. The current study conducted four national cross-sectional online surveys from February and March 2020, Apr 2022, and Jan 2023. The Psychosomatic Symptom Scale (PSSS) and Perceived Stress Scale-10 (PSS-10) were used to assess psychosomatic symptoms and perceived stress. Fourteen thousand nine hundred forty-five participants (8578 healthcare workers and 6367 others) participated in the surveys. The prevalence of psychosomatic syndrome, reflected by PSSS, was 19.3% (Wave1), 22.9% (Wave2), 36.4% (Wave3), and 60.7% (Wave4) among healthcare workers, compared to 24.0% (Wave1), 35.7% (Wave2), 34.2% (Wave3) and 50.5% (Wave4) among the others. In addition, healthcare workers exhibited lower PSSS total scores at the beginning but higher in later waves. Despite their infection status, they now suffer from more severe psychosomatic symptoms than the rest of society. Our findings suggest that healthcare workers in China have now experienced severe psychosomatic symptoms and tremendous stress. Therefore, there is an urgent need to utilize social support for them.

Chinese university students showed less disordered eating during the COVID-19 campus lockdown.

OBJECTIVE: The rapid spread of the Omicron variant of COVID-19 in China had resulted in campus lockdown in many universities since February 2022, profoundly affecting students' daily lives. Campus lockdown conditions differ considerably from home quarantine, so that the eating patterns of university students may be different. Thus, the current study aimed to: (1) investigate university students' eating patterns during campus lockdown; (2) identify factors associated with their disordered eating. METHOD: An online survey about recent life changes, disordered eating, stress, depression, and anxiety was carried out from April 8th to May 16th, 2022. A total of 2541 responses from 29 provinces/cities of China were received. RESULTS: 2213 participants were included in the main analysis, and other 86 participants were analyzed separately as a subgroup due to their diagnosis of eating disorder. Participants who were undergoing campus lockdown (the lockdown group) showed less disordered eating than those who had never been in campus lockdown (the never-lockdown group), as well as those who had experienced campus lockdown before (the once-lockdown group). However, they perceived more stress and felt more depressed. Being female, higher BMI, gaining weight, increasing exercise, spending more time on social media, higher level of depression and anxiety were all related to disordered eating in the lockdown group. CONCLUSIONS: Disordered eating among Chinese university students was less prevalent during campus lockdown due to the strict and regular diet. However, there is a potential risk of "revenge eating" after campus lockdown ends. Thus, there should be further tracking and related prevention. LEVEL OF EVIDENCE: IV, uncontrolled trials without any interventions.