Labor patterns of spontaneous first-stage labor in Chinese women with normal neonatal outcomes.

BACKGROUND: Friedman's standards, developed almost 50 years ago, may no longer align with the needs of today's obstetric population and current pregnancy management practices. This study aims to analyze contemporary labor patterns and estimate labor duration in China, focusing on first-stage labor data from Chinese parturients with a spontaneous onset of labor. METHODS: This retrospective observational study utilized data from electronic medical records of a tertiary hospital in Changsha, Hunan. Out of a total of 2,689 parturients, exclusions were made for multiple gestations, preterm, post-term, or stillbirth, cesarean delivery, non-vertex presentation, and neonatal intensive care unit admission. Average labor curves were constructed by parity using repeated-measure analysis, and labor duration was estimated through interval-censored regression, stratified by cervical dilation at admission. We performed an analysis to assess the impact of oxytocin augmentation and amniotomy on labor progression and conducted a sensitivity analysis using women with complicated outcomes. RESULTS: Nulliparous women take over 180 minutes for cervical dilation from 3 to 4 cm, and the duration from 5 to 6 cm exceeds 145 minutes. Multiparous women experience shorter labor durations than nulliparous. Labor acceleration is observed after 5 cm in nulliparous, but no distinct inflection point is evident in the average labor curve. In the second stage of labor, the 95th percentile for nulliparous, with and without epidural analgesia, is 142 minutes and 127 minutes, respectively. CONCLUSIONS: These findings provide valuable insights for the reassessment of labor and delivery processes in contemporary obstetric populations, including current Chinese obstetric practice.

Polydopamine modified colloidal gold nanotag-based lateral flow immunoassay platform for highly sensitive detection of pathogenic bacteria and fast evaluation of antibacterial agents.

Bacterial infection is a great threat to human health. Lateral flow immunoassays (LFIAs) with the merits of low cost, quick screening, and on-site detection are competitive technologies for bacteria detection, but their detection limits depend on the optical performance of the adopted nanotags. Herein, we presented a LFIA platform for bacteria detection using polydopamine (PDA) functionalized Au nanoparticles (denoted as Au@PDA) as the nanotag. The introduction of PDA could provide enhanced light absorption of Au, as well as numerous functional groups for conjugation. Small recognition molecules i.e. vancomycin (Van) and p-mercaptophenylboronic acid (PMBA) were covalently anchored to Au@PDA, and selected as the specific probes towards Gram-positive (G+) and Gram-negative (G-) bacteria, respectively. Taken Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as the representative targets of G+ and G- bacteria, two LFA strips were successfully constructed based on the immuno-sandwich principle. They could quantitatively detect S. aureus and E. coli both down to 102 cfu/mL, a very competitive detection limit in comparison with other colorimetric or luminescent probes-based LFIAs. Furthermore, the proposed two strips were applied for the quantitative, accurate, and rapid detection of S. aureus and E. coli in food and human urine samples with good analytical results obtained. In addition, they were integrated as a screening platform for quick evaluation of diverse antibacterial agents within 3 h, which is remarkably shortened compared with that of the two traditional methods i.e. bacterial culture and plate-counting.

UCHL5 is a putative prognostic marker in renal cell carcinoma: a study of UCHL family.

A macroscopic perspective is indispensable for understanding the intricate relationship between deubiquitinases and tumorigenesis. Proteomics has been proposed as a viable approach for elucidating the complex role of deubiquitylation in cellular progression. Instead of studying the function of a single ubiquitinase, research on a deubiquitinase family with similar catalytic core(s) may provide a new perspective for the pathological understanding of cancer. The Ubiquitin C-terminal hydrolase L (UCHL) family consists of four members: UCHL1, UCHL3, UCHL5, and BRAC1 associated protein-1 (BAP1), and they have been implicated in tumorigenesis and metastasis. Some members are considered hallmarks of intracranial lesions, colon cancer, chromatin remodeling, and histone stability. The present study uncovered an unknown correlation between the UCHL family and renal cancer. We discovered that UCHLs exhibit diverse regulatory effects in renal cancer, establishing connections between the renal cancer and truncated gene mutations, mitochondrial energetic metastasis, immune cell infiltration, and chromosomal stability of UCHLs family. Notably, we found that the increase of UCHL5 expression in renal cancer cells decreases the antigen processing and presentation of RCC tumor-infiltrating B cells. Further research identified that the expression of UCHL5 in RCC tumors is correlated with transport proteins, which led us to find that the abundance of UCHL5 in the blood of late-stage renal cell cancer patients is upregulated from 18 ng/L to 500 ng/L. Therefore, we propose that the abundance of UCHL5 in patients' blood can be a possible indicator of poor prognosis for renal cell cancer.

A Prospective Cohort Study Evaluating Impact of Sarcopenia on Hospitalization in Patients on Continuous Ambulatory Peritoneal Dialysis.

Data regarding the association of sarcopenia with hospitalization has led to inconclusive results in patients undergoing dialysis. The main goal of this research was to investigate the association between sarcopenia and hospitalization in Chinese individuals on continuous ambulatory peritoneal dialysis (CAPD). Eligible patients on CAPD were prospectively included, and followed up for 48 weeks in our PD center. Sarcopenia was identified utilizing the criteria set by the Asian Working Group on Sarcopenia in 2019 (AWGS 2019). Participants were categorized into sarcopenia (non-severe sarcopenia + severe sarcopenia) and non-sarcopenia groups. The primary outcome was all-cause hospitalization during the 48-week follow-up period. Association of sarcopenia with all-cause hospitalization was examined by employing multivariate logistic regression models. The risk of cumulative incidence of hospitalization in the 48-week follow-up was estimated using relative risk (RR and 95% CI). The cumulative hospitalization time and frequency at the end of 48-week follow-up were described as categorical variables, and compared by χ2 test or fisher's exact test as appropriate. Subgroup and sensitivity analyses were also conducted to examine whether the potential association between sarcopenia and hospitalization was modified. A total of 220 patients on CAPD (5 of whom were lost in follow-up) were included. Prevalences of total sarcopenia and severe sarcopenia were 54.1% (119/220) and 28.2% (62/220) according to AWGS 2019, respectively. A total of 113 (51.4%) participants were hospitalized during the 48-week follow-up period, of which, the sarcopenia group was 65.5% (78/119) and the non-sarcopenia group was 34.7% (35/101), with an estimated RR of 1.90 (95%CI 1.43-2.52). The cumulative hospitalization time and frequency between sarcopenia and non-sarcopenia groups were significantly different (both P < 0.001). Participants with sarcopenia (OR = 3.21, 95%CI 1.75-5.87, P < 0.001), non-severe sarcopenia (OR = 2.84, 95%CI 1.39-5.82, P = 0.004), and severe sarcopenia (OR = 3.66, 95%CI 1.68-8.00, P = 0.001) demonstrated a significant association with all-cause hospitalization compared to individuals in non-sarcopenia group in the 48-week follow-up. Moreover, participants in subgroups (male or female; < 60 or ≥ 60 years) diagnosed with sarcopenia, as per AWGS 2019, were at considerably high risk for hospitalization compared to those with non-sarcopenia. In sensitivity analyses, excluding participants lost in the follow-up, the relationships between sarcopenia and hospitalization (sarcopenia vs. non-sarcopenia; severe sarcopenia/non-severe sarcopenia vs. non-sarcopenia) were consistent. This research involving Chinese patients on CAPD demonstrated a significant association between sarcopenia and incident hospitalization, thereby emphasizing the importance of monitoring sarcopenia health in this population.

An alternative 3' splice site of PeuHKT1;3 improves the response to salt stress through enhancing affinity to K+ in Populus.

Alternative splicing (AS) serves as a crucial post-transcriptional regulator in plants that contributes to the resistance to salt stress. However, the underlying mechanism is largely unknown. In this research, we identified an important AS transcript in Populus euphratica, PeuHKT1:3a, generated by alternative 3' splice site splicing mode that resulted in the removal of 252 bases at the 5' end of the first exon in PeuHKT1:3. Protein sequence comparison showed that the site of AS occurred in PeuHKT1:3 is located at a crucial Ser residue within the first pore-loop domain, which leads to inefficient K+ transport in HKT I-type transporters. Expressing PeuHKT1;3a in an axt3 mutant yeast strain can effectively compensate for the lack of intracellular K+, whereas the expression of PeuHKT1;3 cannot yield the effect. Furthermore, in transgenic Arabidopsis and poplar plants, it was observed that lines expressing PeuHKT1;3a exhibited greater salt tolerance compared to those expressing the PeuHKT1;3 strain. Analysis of ion content and flux demonstrated that the transgenic PeuHKT1;3a line exhibited significantly higher K+ content compared to the PeuHKT1;3 line, while there was no significant difference in Na+ content. In conclusion, our findings revealed that AS can give rise to novel variants of HKT I-type proteins in P. euphratica with modified K+ selectivity to keep a higher K+/Na+ ratio to enhanced salt tolerance.

Exploring the role of innate immunity in Cholangiocarcinoma: implications for prognosis, immune infiltration, and tumor metastasis.

The innate immune system serves as the body's primary physiological defense against the intrusion of pathogenic microorganisms, playing a pivotal role in restricting viral infections. However, current research on the interplay between innate immune pathways and cancer is limited, with reported effects often inconsistent. Therefore, we aimed to elucidate the relationship between innate immune pathways and tumors through an amalgamation of bioinformatics and extensive data analysis. Conducting a pan-cancer analysis encompassing expression, genomic alterations, and clinical prognosis, we identified a close association between the innate immune pathway and cholangiocarcinoma. Subsequently, our focus shifted to unraveling the role of innate immune pathway proteins in cholangiocarcinoma. TIMER database analysis showed that the innate immune pathway predominantly influences the infiltration of macrophages and B cells in cholangiocarcinoma. Additionally, gene ontology (GO) and pathway analyses were performed for significantly differentially expressed genes correlated with the innate immune pathway in cholangiocarcinoma. Single-cell transcriptome analysis in cholangiocarcinoma demonstrated that genes in the innate immune pathway are primarily expressed in malignant cells, endothelial cells, monocytes and macrophages. To further validate the expression of proteins in the innate immune pathway in the tumor tissues of patients with cholangiocarcinoma, tumor tissue slices from patients with liver intrahepatic cholangiocarcinoma and normal tissue slices from the HPA database were analyzed. These results indicated pronounced activation of the innate immune pathway in the tumor tissues of patients with cholangiocarcinoma. Finally, proteomic data from patients with or without intrahepatic cholangiocarcinoma metastasis were analyzed. The results revealed a significant correlation between the expression and phosphorylation of IKKε and the occurrence of intrahepatic cholangiocarcinoma metastasis. These findings not only demonstrate the significance of the innate immune pathway in cholangiocarcinoma but also its potential as a prospective prognostic biomarker and therapeutic target for this malignancy.

PARP1-DNA co-condensation: the driver of broken DNA repair.

DNA double-strand break (DSB) sites that prevent the disjunction of broken DNA ends are formed through poly (ADP-ribose) (PAR) polymerase 1 (PARP1)-DNA co-condensation. The co-condensates apply mechanical forces to hold the DNA ends together and generate enzymatic activity for the synthesis of PAR. PARylation can promote the release of PARP1 from DNA ends and recruit various proteins, such as Fused in sarcoma (FUS) proteins, thereby stabilizing broken DNA ends and preventing their separation.

TRIM25 predominately associates with anti-viral stress granules.

Stress granules (SGs) are induced by various environmental stressors, resulting in their compositional and functional heterogeneity. SGs play a crucial role in the antiviral process, owing to their potent translational repressive effects and ability to trigger signal transduction; however, it is poorly understood how these antiviral SGs differ from SGs induced by other environmental stressors. Here we identify that TRIM25, a known driver of the ubiquitination-dependent antiviral innate immune response, is a potent and critical marker of the antiviral SGs. TRIM25 undergoes liquid-liquid phase separation (LLPS) and co-condenses with the SG core protein G3BP1 in a dsRNA-dependent manner. The co-condensation of TRIM25 and G3BP1 results in a significant enhancement of TRIM25's ubiquitination activity towards multiple antiviral proteins, which are mainly located in SGs. This co-condensation is critical in activating the RIG-I signaling pathway, thus restraining RNA virus infection. Our studies provide a conceptual framework for better understanding the heterogeneity of stress granule components and their response to distinct environmental stressors.

Serotonin signaling: a new player and therapeutic target beyond Long-haul coronavirus disease.

During the coronavirus disease 2019 (COVID-19) pandemic, a subset of individuals continues to suffer from symptoms including fatigue, post-exertional malaise, dyspnea, bone loss, and memory and neurocognitive dysfunction for months and even years after infection. This clinical phenomenon has been labeled 'Long-haul COVID' or 'post-acute sequelae of COVID-19 (PASC)'; however, the underlying pathophysiological mechanisms remain unclear. In a recent study published in Cell, Wong et al. revealed that viral infection and type I interferon-driven reduction of peripheral serotonin impaired hippocampal responses and short-term memory through vagal neurons in patients with PASC. Therefore, the study provided novel insights into how serotonin links persistent viral inflammation with the neurocognitive symptoms of Long-haul COVID and actionable therapeutic targets for patients with PASC.

Alanyl-tRNA synthetase, AARS1, is a lactate sensor and lactyltransferase that lactylates p53 and contributes to tumorigenesis.

Lysine lactylation is a post-translational modification that links cellular metabolism to protein function. Here, we find that AARS1 functions as a lactate sensor that mediates global lysine lacylation in tumor cells. AARS1 binds to lactate and catalyzes the formation of lactate-AMP, followed by transfer of lactate to the lysince acceptor residue. Proteomics studies reveal a large number of AARS1 targets, including p53 where lysine 120 and lysine 139 in the DNA binding domain are lactylated. Generation and utilization of p53 variants carrying constitutively lactylated lysine residues revealed that AARS1 lactylation of p53 hinders its liquid-liquid phase separation, DNA binding, and transcriptional activation. AARS1 expression and p53 lacylation correlate with poor prognosis among cancer patients carrying wild type p53. ß-alanine disrupts lactate binding to AARS1, reduces p53 lacylation, and mitigates tumorigenesis in animal models. We propose that AARS1 contributes to tumorigenesis by coupling tumor cell metabolism to proteome alteration.

Effect of care bundles for acute kidney injury: A systematic review and meta-analysis.

PURPOSE: Acute kidney injury (AKI) is frequent among in-hospital patients with high incidence and mortality. Implementing a series of evidence-based AKI care bundles may improve patient outcomes by reducing changeable standards of care. The aim of this meta-analysis was therefore to appraise the influences of AKI care bundles on patient outcomes. MATERIALS AND METHODS: We explored three international databases (PubMed, Embase, and Cochrane Central Register of Controlled Trials) and two Chinese databases (Wanfang Data and China National Knowledge Infrastructure) for studies from databases inception until November 30, 2022, comparing the impact of different AKI care bundles with usual standards of care in patients with or at risk for AKI. The study quality of non-randomized controlled trials and randomized controlled trials was evaluated by the NIH Study Quality Assessment Tool and the Cochrane risk of bias tool. Heterogeneity between studies was appraised by Cochran's Q test and I2 statistics. The possible origins of heterogeneity between studies were assessed adopting Meta-regression and subgroup analyses. Funnel plot asymmetry and Egger regression and Begg correlation tests were performed to discover potential publication bias. Data analysis was completed by software (RevMan 5.3 and Stata 15.0). The primary outcome was short- or long-term mortality. The secondary outcomes involved the incidence and severity of AKI. RESULTS: Sixteen studies containing 25,690 patients and 25,903 AKI episodes were included. In high-risk AKI patients determined by novel biomarkers, electronic alert or risk prediction score, the application of AKI care bundles significantly reduced the AKI incidence (OR, 0.71; 95% CI, 0.53-0.96; p = 0.02; I2 = 84%) and AKI severity (OR, 0.59; 95% CI, 0.39-0.89; p = 0.01; I2 = 65%). No strong evidence is available to prove that care bundles can significantly reduce mortality (OR, 1.16; 95% CI, 0.58-2.30; p = 0.68; I2 = 97%). CONCLUSIONS: The introduction of AKI care bundles in routine clinical practice can effectively improve the outcomes of patients with or at-risk of AKI. However, the accumulated evidence is limited and not strong enough to make definite conclusions.

Accumulation patterns of tobacco root allelopathicals across different cropping durations and their correlation with continuous cropping challenges.

Introduction: Continuous cropping challenges have gradually emerged as pivotal factors limiting the sustainable development of agricultural production. Allelopathicals are considered to be the primary obstacles. However, there is limited information on allelopathic accumulation across various continuous cropping years and its correlation with the associated challenges. Methods: Tobacco was subjected to varying planting durations: 1 year (CR), 5 years (CC5), 10 years (CC10), and 15 years (CC15). Results: Our findings unveiled discernible disparities in tobacco growth patterns across diverse continuous cropping periods. Notably, the most pronounced challenges were observed in the CC5 category, characterized by yield reduction, tobacco black shank outbreaks, and a decline in beneficial flora. Conversely, CC15 exhibited a substantial reduction in challenges as the continuous cropping persisted with no significant differences when compared to CR. Within the tobacco rhizosphere, we identified 14 distinct allelopathic compounds, with 10 of these compounds displaying noteworthy variations among the four treatments. Redundancy analysis (RDA) revealed that eight allelopathic compounds exhibited autotoxic effects on tobacco growth, with MA, heptadecanoic acid, and VA ranking as the most potent inhibitors. Interaction network highlighted the pivotal roles of VA and EA in promoting pathogen proliferation and impeding the enrichment of 13 beneficial bacterial genera. Furthermore, a structural equation model elucidated that MA and EA primarily exert direct toxic effects on tobacco, whereas VA fosters pathogen proliferation, inhibits the enrichment of beneficial bacteria, and synergistically exacerbates the challenges associated with continuous cropping alongside EA. Discussion: These findings suggested discernible disparities in tobacco growth patterns across the various continuous cropping periods. The most pronounced challenges were observed in CC5, whereas CC15 exhibited a substantial reduction in challenges as continuous cropping persisted. VA may play a pivotal role in this phenomenon by interacting with pathogens, beneficial bacterial genera, and EA.

TRIM28-mediated nucleocapsid protein SUMOylation enhances SARS-CoV-2 virulence.

Viruses, as opportunistic intracellular parasites, hijack the cellular machinery of host cells to support their survival and propagation. Numerous viral proteins are subjected to host-mediated post-translational modifications. Here, we demonstrate that the SARS-CoV-2 nucleocapsid protein (SARS2-NP) is SUMOylated on the lysine 65 residue, which efficiently mediates SARS2-NP's ability in homo-oligomerization, RNA association, liquid-liquid phase separation (LLPS). Thereby the innate antiviral immune response is suppressed robustly. These roles can be achieved through intermolecular association between SUMO conjugation and a newly identified SUMO-interacting motif in SARS2-NP. Importantly, the widespread SARS2-NP R203K mutation gains a novel site of SUMOylation which further increases SARS2-NP's LLPS and immunosuppression. Notably, the SUMO E3 ligase TRIM28 is responsible for catalyzing SARS2-NP SUMOylation. An interfering peptide targeting the TRIM28 and SARS2-NP interaction was screened out to block SARS2-NP SUMOylation and LLPS, and consequently inhibit SARS-CoV-2 replication and rescue innate antiviral immunity. Collectively, these data support SARS2-NP SUMOylation is critical for SARS-CoV-2 virulence, and therefore provide a strategy to antagonize SARS-CoV-2.

Oxygen glucose deprivation-pretreated astrocyte-derived exosomes attenuates intracerebral hemorrhage (ICH)-induced BBB disruption through miR-27a-3p /ARHGAP25/Wnt/ß-catenin axis.

BACKGROUND: Blood brain barrier (BBB) breakdown is one of the key mechanisms of secondary brain injury following intracerebral hemorrhage (ICH). Astrocytes interact with endothelial and regulate BBB integrity via paracrine signaling factors. More and more studies reveal astrocyte-derived extracellular vesicles (ADEVs) as an important way of intercellular communication. However, the role of ADEV in BBB integrity after ICH remains unclear. METHODS: ADEVs were obtained from astrocytes with or without oxygen and glucose deprivation (OGD) pre-stimulation and the role of ADEVs in ICH was investigated using ICH mice model and ICH cell model. The potential regulatory effect of ADEVs on endothelial barrier integrity was identified by TEER, western blot and immunofluorescence in vitro. In vivo, functional evaluation, Evans-blue leakage and tight junction proteins (TJPs) expression were analyzed. MiRNA sequencing revealed that microRNA-27a-3p (miR-27a-3p) was differentially expressed miRNA in the EVs from OGD-pretreated astrocytes compared with normal control. The regulatory mechanism of miR-27a-3p was assessed using Luciferase assay, RT-PCR, western blot and immunofluorescence. RESULTS: OGD-activated astrocytes reduced hemin-induced endothelial hyper-permeability through secreting EVs. OGD-activated ADEVs alleviated BBB dysfunction after ICH in vivo and in vitro. MicroRNA microarray analysis indicated that miR-27a-3p is a major component that was highly expressed miRNA in OGD pretreated-ADEVs. OGD-ADEVs mitigated BBB injury through transferring miR-27a-3p into bEnd.3 cells and regulating ARHGAP25/Wnt/ß-catenin pathway. CONCLUSION: Taken together, these findings firstly revealed that miR-27a-3p, as one of the main components of OGD-pretreated ADEVs, attenuated BBB destruction and improved neurological deficits following ICH by regulating endothelial ARHGAP25/Wnt/ß-catenin axis. OGD-ADEVs might be a novel strategy for the treatment of ICH. this study implicates that EVs from OGD pre-stimulated astrocytes.

Primary acinic cell carcinoma of the breast: A case report and review of literature.

BACKGROUND: In the current World Health Organization classification, acinic cell carcinoma (AcCC) of the breast is considered a rare histological subtype of triple-negative breast cancer. Because of the few reports in the literature, data concerning clinical outcomes are limited. Here, we report a case of AcCC of the breast in a 48-year-old woman. CASE SUMMARY: A 48-year-old woman with a mass in her right breast came to our hospital for further diagnosis. Mammography and an ultrasound (US) scan showed a mass in the upper inner side of the right breast. She then underwent surgery to resect the mass in her right breast. Postoperative pathological examination revealed that the tumor had abundant acinar-like structures formed by tumor cells with prominent eosinophilic granules in the cytoplasm, consistent with acinar cell carcinoma. The results of immunohistochemical analysis supported the diagnosis of breast acinar cell carcinoma. Two months later, she underwent breast-conserving surgery and sentinel lymph node biopsy. The pTNM stage was T2N0M0. After surgery, the patient received 30 radiotherapy sessions. The patient was followed up for a period of one year, and no recurrence was found. CONCLUSION: AcCC of the breast is a rare type of malignant tumor. Because it is usually asymptomatic and can be detected by imaging studies, routine breast US or mammograms are important. However, there are no characteristic diagnostic imaging findings or clinical manifestations, so immunohistochemical examination is critical for an accurate diagnosis of AcCC of the breast.

iProPhos: A Web-Based Interactive Platform for Integrated Proteome and Phosphoproteome Analysis.

Large-scale omics studies have generated a wealth of mass spectrometry-based proteomics data, which provide additional insights into disease biology spanning genomic boundaries. However, there is a notable lack of web-based analysis and visualization tools that facilitate the reutilization of these data. Given this challenge, we present iProPhos, a user-friendly web server to deliver interactive and customizable functionalities. iProPhos incorporates a large number of samples, including 1444 tumor samples and 746 normal samples across 12 cancer types, sourced from the Clinical Proteomic Tumor Analysis Consortium. Additionally, users can also upload their own proteomics/phosphoproteomics data for analysis and visualization. In iProPhos, users can perform profiling plotting and differential expression, patient survival, clinical feature-related, and correlation analyses, including protein-protein, mRNA-protein, and kinase-substrate correlations. Furthermore, functional enrichment, protein-protein interaction network, and kinase-substrate enrichment analyses are accessible. iProPhos displays the analytical results in interactive figures and tables with various selectable parameters. It is freely accessible at http://longlab-zju.cn/iProPhos without login requirement. We present two case studies to demonstrate that iProPhos can identify potential drug targets and upstream kinases contributing to site-specific phosphorylation. Ultimately, iProPhos allows end-users to leverage the value of big data in cancer proteomics more effectively and accelerates the discovery of novel therapeutic targets.

Capturing Protein-Protein Interactions with Acidic Amino Acids Reactive Cross-Linkers.

Acidic residues (Asp and Glu) have a high prevalence on protein surfaces, but cross-linking reactions targeting these residues are limited. Existing methods either require high-concentration coupling reagents or have low structural compatibility. Here a previously reported "plant-and-cast" strategy is extended to develop heterobifunctional cross-linkers. These cross-linkers first react rapidly with Lys sidechains and then react with Asp and Glu sidechains, in a proximity-enhanced fashion. The cross-linking reaction proceeds at neutral pH and room temperature without coupling reagents. The efficiency and robustness of cross-linking using model proteins, ranging from small monomeric proteins to large protein complexes are demonstrated. Importantly, it is shown that this type of cross-linkers are efficient at identifying protein-protein interactions involving acidic domains. The Cross-linking mass spectrometry (XL-MS) study with p53 identified 87 putative binders of the C-terminal domain of p53. Among them, SARNP, ZRAB2, and WBP11 are shown to regulate the expression and alternative splicing of p53 target genes. Thus, these carboxylate-reactive cross-linkers will further expand the power of XL-MS in the analysis of protein structures and protein-protein interactions.