MCP-1-induced protein-1 (MCPIP1) is a newly identified protein that is crucial to immune regulation. Mice lacking MCPIP1 gene suffer from severe immune disorders, and most of them cannot survive longer than 12 weeks. Considerable progress has been made in revealing the mechanism underlying the immune regulatory function of MCPIP1. MCPIP1 can act as an RNase to promote the mRNA degradation of some inflammatory cytokines, such as IL-6 and IL-1. Pre-microRNAs are also confirmed to be the substrate of MCPIP1 RNase. The structure of MCPIP1 N-terminal conserved domain shows a PilT N-terminus-like RNase structure, further supporting the notion that MCPIP1 has RNase activity. MCPIP1 can also deubiquitinate TNF receptor-associated factor family proteins, which are known to mediate immune and inflammatory responses. In this review, we summarize recent progress on the immune regulatory role of MCPIP1 and discuss the mechanisms underlying its function.
Amino Acid Sequence ; Animals ; Humans ; Immunity ; Molecular Sequence Data ; Ribonucleases ; metabolism ; Transcription Factors ; chemistry ; metabolism ; Tumor Necrosis Factor Receptor-Associated Peptides and Proteins ; metabolism ; Ubiquitination

The guanine-nucleotide exchange factor (GEF) RalGPS1a activates small GTPase Ral proteins such as RalA and RalB by stimulating the exchange of Ral bound GDP to GTP, thus regulating various downstream cellular processes. RalGPS1a is composed of an Nterminal Cdc25-like catalytic domain, followed by a PXXP motif and a C-terminal pleckstrin homology (PH) domain. The Cdc25 domain of RalGPS1a, which shares about 30% sequence identity with other Cdc25-domain proteins, is thought to be directly engaged in binding and activating the substrate Ral protein. Here we report the crystal structure of the Cdc25 domain of RalGPS1a. The bowl shaped structure is homologous to the Cdc25 domains of SOS and RasGRF1. The most remarkable difference between these three Cdc25 domains lies in their active sites, referred to as the helical hairpin region. Consistent with previous enzymological studies, the helical hairpin of RalGPS1a adopts a conformation favorable for substrate binding. A modeled RalGPS1a-RalA complex structure reveals an extensive binding surface similar to that of the SOS-Ras complex. However, analysis of the electrostatic surface potential suggests an interaction mode between the RalGPS1a active site helical hairpin and the switch 1 region of substrate RalA distinct from that of the SOS-Ras complex.
Amino Acid Sequence ; Binding Sites ; Catalytic Domain ; Cloning, Molecular ; Crystallography, X-Ray ; Escherichia coli ; Guanosine Diphosphate ; metabolism ; Guanosine Triphosphate ; metabolism ; Humans ; Models, Molecular ; Molecular Conformation ; Molecular Sequence Data ; Plasmids ; metabolism ; Protein Binding ; Protein Structure, Tertiary ; genetics ; Recombinant Proteins ; chemistry ; genetics ; metabolism ; ral GTP-Binding Proteins ; chemistry ; genetics ; metabolism ; ral Guanine Nucleotide Exchange Factor ; chemistry ; genetics ; metabolism

Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6.
Amino Acid Sequence ; Catalytic Domain ; Crystallography, X-Ray ; Humans ; Malonates ; metabolism ; Models, Molecular ; Molecular Sequence Data ; Nitrophenols ; metabolism ; Organophosphorus Compounds ; metabolism ; Phosphoric Monoester Hydrolases ; chemistry ; classification ; metabolism ; Tartrates ; metabolism ; Water ; metabolism

The human Gadd45 protein family plays critical roles in DNA repair, negative growth control, genomic stability, cell cycle checkpoints and apoptosis. Here we report the crystal structure of human Gadd45γ [corrected], revealing a unique dimer formed via a bundle of four parallel helices, involving the most conserved residues among the Gadd45 isoforms. Mutational analysis of human Gadd45γ [corrected] identified a conserved, highly acidic patch in the central region of the dimer for interaction with the proliferating cell nuclear antigen (PCNA), p21 and cdc2, suggesting that the parallel dimer is the active form for the interaction. Cellular assays indicate that: (1) dimerization of Gadd45γ [corrected] is necessary for apoptosis as well as growth inhibition, and that cell growth inhibition is caused by both cell cycle arrest and apoptosis; (2) a conserved and highly acidic patch on the dimer surface, including the important residues Glu87 and Asp89, is a putative interface for binding proteins related to the cell cycle, DNA repair and apoptosis. These results reveal the mechanism of self-association by Gadd45 proteins and the importance of this self-association for their biological function.
Amino Acid Motifs ; Animals ; Apoptosis ; radiation effects ; CDC2 Protein Kinase ; Cell Cycle ; Cell Survival ; Crystallography, X-Ray ; Cyclin B ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; metabolism ; Cyclin-Dependent Kinases ; HeLa Cells ; Humans ; Intracellular Signaling Peptides and Proteins ; chemistry ; genetics ; metabolism ; Mice ; Mutagenesis, Site-Directed ; Mutation, Missense ; Proliferating Cell Nuclear Antigen ; metabolism ; Protein Binding ; Protein Interaction Domains and Motifs ; Protein Multimerization ; Protein Structure, Quaternary ; Ultraviolet Rays

Ebola virus (EBOV) is a key member of Filoviridae family and causes severe human infectious diseases with high morbidity and mortality. As a typical negative-sense single-stranded RNA (-ssRNA) viruses, EBOV possess a nucleocapsid protein (NP) to facilitate genomic RNA encapsidation to form viral ribonucleoprotein complex (RNP) together with genome RNA and polymerase, which plays the most essential role in virus proliferation cycle. However, the mechanism of EBOV RNP formation remains unclear. In this work, we solved the high resolution structure of core domain of EBOV NP. The polypeptide of EBOV NP core domain (NP(core)) possesses an N-lobe and C-lobe to clamp a RNA binding groove, presenting similarities with the structures of the other reported viral NPs encoded by the members from Mononegavirales order. Most strikingly, a hydrophobic pocket at the surface of the C-lobe is occupied by an α-helix of EBOV NP(core) itself, which is highly conserved among filoviridae family. Combined with other biochemical and biophysical evidences, our results provides great potential for understanding the mechanism underlying EBOV RNP formation via the mobility of EBOV NP element and enables the development of antiviral therapies targeting EBOV RNP formation.
Crystallography, X-Ray ; Ebolavirus ; physiology ; Humans ; Nucleoproteins ; chemistry ; genetics ; metabolism ; Protein Structure, Tertiary ; Structure-Activity Relationship ; Virus Assembly ; physiology

Enterovirus 71 (EV71), one of the major causative agents for hand-foot-and-mouth disease (HFMD), has caused more than 100 deaths among Chinese children since March 2008. The EV71 genome encodes an RNAdependent RNA polymerase (RdRp), denoted 3D(pol), which is central for viral genome replication and is a key target for the discovery of specific antiviral therapeutics. Here we report the crystal structures of EV71 RdRp (3D(pol)) and in complex with substrate guanosine-5'-triphosphate and analog 5-bromouridine-5'-triphosphate best to 2.4 Å resolution. The structure of EV71 RdRp (3D(pol)) has a wider open thumb domain compared with the most closely related crystal structure of poliovirus RdRp. And the EV71 RdRp (3D(pol)) complex with GTP or Br-UTP bounded shows two distinct movements of the polymerase by substrate or analogue binding. The model of the complex with the template:primer derived by superimposition with foot-and-mouth disease virus (FMDV) 3D/RNA complex reveals the likely recognition and binding of template:primer RNA by the polymerase. These results together provide a molecular basis for EV71 RNA replication and reveal a potential target for anti-EV71 drug discovery.
Amino Acid Sequence ; Child ; China ; epidemiology ; Crystallography, X-Ray ; Drug Discovery ; Enterovirus A, Human ; chemistry ; enzymology ; Hand, Foot and Mouth Disease ; drug therapy ; epidemiology ; virology ; Humans ; Models, Molecular ; Molecular Sequence Data ; Molecular Targeted Therapy ; Protein Conformation ; Protein Folding ; RNA Replicase ; chemistry ; genetics ; metabolism ; Sequence Alignment ; Substrate Specificity

OBJECTIVE: To observe the time distribution characteristic of silica nanoparticles in rats after one-time intratracheal infusion. METHODS: Specific pathogen free male Wistar rats were randomly divided into one control group and7 experimental groups according to different time of intratracheal infusion( 1,3,5,7,14,21 and 28 days),6 rats in each group. The experiment groups were intratracheally instilled with 1. 0 mL silica nanoparticle suspension( mass concentration 50. 00 g/L). The control group was not given any treatment. Rats were sacrificed and their organ tissue samples such as serum,lung,spleen,liver and kidney were collected at different time points. The silicon levels of tissues were determined by inductively coupled plasma optical-emission spectrometry. The histology of rat's lungs was observed by optical microscope and the location of silica in lungs was observed by polarization microscope. RESULTS: After exposure to silica nanoparticles for 1-7 days,the changes of rats' lung tissue was mainly exudative inflammation. The changes of lung was proliferative inflammatory lesions after 14-28 days of exposure to silica nanoparticles. The visible nodules of cells were observed in the lung tissue in 28 days experiment group. The distribution of silica nanoparticles was observed obviously in the lung tissues of rats of 1 day experiment group under the polarizing microscopy. The tendency decreased with the increase of observation time. Silica nanoparticles were rarely seen 21 and 28 days after intratracheal infusion in rats. The silicon levels of serum,lung and spleen tissues reached the peak in 1 day after silica nanoparticles instillation,then dropped in 3-7 days( serum) or 3-14 days( lung and spleen tissues) and went back to that of the control group's. The level of silicon in the livers and kidneys of rats in the experimental groups showed no significant increase in the level of 1-5 day after the instillation( P > 0. 05),and showed significant increase in the level of 7 day( P < 0. 05). The level reached its peak on time points of 14 and 21 days after the instillation,and subsequently decreased,and didn't returned to normal till the 28 th day. The silicon levels of the lungs,spleens,livers and kidneys were all higher in rats than that of serum( P < 0. 05). The silicon levels of the lungs and spleens were higher than that of the livers and kidneys after instillation for1-5 days( P < 0. 05). The silicon levels of the lungs and spleens were both lower than that of the livers and kidneys after instillation for 14-28 days( P < 0. 05). CONCLUSION: Silica nanoparticles can cause lung injury when instilled intratracheally in rats. After instillation,silica nanoparticles were mainly distributed in the lungs and spleens after 1-5 days and distributed in the livers and kidneys after 14-28 days.

【Objective】 To investigate the effects of preoperative lipid metabolism level on the postoperative prognosis of non-muscular invasive bladder cancer (NMIBC). 【Methods】 Clinical data of NMIBC patients who underwent surgical treatment in our hospital during Mar.2014 and May 2021 were retrospectively analyzed. Based on receiver operating characteristic (ROC) curve, the optimal cutoff values of all lipid metabolism indicators were determined and patients were classified accordingly. The independent risk factors for postoperative recurrence were identified with Cox regression model. The survival was analyzed with Kaplan-Meier, and recurrence-free survival (RFS) was compared using log-rank tests. A recurrence risk prediction model was established based on the high-density lipoprotein (HDL) and other clinic pathological factors and the accuracy of prediction was evaluated with the area under the ROC curve (AUC). 【Results】 Cox multivariate analysis showed HDL, tumor number, tumor size and histological grade were independent risk factors for recurrence (P<0.05). Kaplan-Meier analysis showed that RFS was significantly longer in the high-HDL group than in the low-HDL group (P<0.001). Incorporating HDL, tumor number, tumor size, histological grade, and tumor stage into the recurrence risk model, the AUC was 0.706, and internal cross validation showed the AUC was 0.711. 【Conclusion】 Preoperative HDL is an independent risk factor affecting the RFS of patients with NMIBC, and combining it with clinic pathological factors will improve the prediction of tumor recurrence.

[Objective] To analyze factors influencing the postoperative progression-free survival (PFS) in patients with renal cell carcinoma (RCC), construct a nomogram model for predicting PFS, and compare it with other predictive models. [Methods] A retrospective analysis was conducted on the general and clinical data of 263 RCC patients who underwent surgery at the Department of Urology, the Second Affiliated Hospital of Xi'an Jiaotong University, during Apr.2014 and Nov.2021.Patients were divided into the progression group (n=34) and non-progression group (n=229). The data of the two groups were analyzed to identify prognostic variables associated with PFS, and a nomogram model was constructed.The performance of this model was compared with that of the University of California, Los Angeles Integrated Staging System (UISS) score, tumor staging, tumor size, tumor pathological grade, and tumor necrosis scoring system (SSIGN score), and Leibovich score by plotting receiver operating characteristic (ROC) curve and calculating the area under the curve (AUC). Calibration curve of the nomogram was used to validate the model's performance, and K-fold cross-validation was employed to assess its external validity. [Results] Multivariate Cox regression analysis revealed that age (HR=2.255, 95%CI: 1.032-4.926), T stage (HR=5.766, 95%CI: 2.351-14.142), pathological grade (HR=3.100, 95%CI: 1.445-6.651), and pathological necrosis (HR=2.656, 95%CI: 1.253-5.629) were independent risk factors of PFS (P<0.05). The nomogram model based on these four independent variables had AUCs (95%CI) of 0.750 (0.630-0.870), 0.803 (0.705-0.902), and 0.847 (0.757-0.937) for 1, 3, and 5 years, respectively, which were higher than those of UISS score, SSIGN score, and Leibovich score.The calibration curve of the nomogram showed good consistency between predicted and actual probabilities.In K-fold cross-validation, the average AUCs of the nomogram at 1, 3, and 5 years were 0.761, 0.808, and 0.842, indicating good external validity of the nomogram. [Conclusion] The nomogram based on age, T stage, pathological grade and pathological necrosis can accurately predict the risk of postoperative PFS in RCC patients at 1, 3, and 5 years, which can aid clinicians in the early identification of high-risk progression.

【Objective】 To construct an easy-to-use individual survival prognostic tool based on competing risk analyses to predict the risk of 1-, 2- and 3- year recurrence for patients with non-muscle invasive bladder cancer (NMIBC). 【Methods】 The follow-up data of 419 NMIBC patients were obtained. The patients were randomly divided into training cohort (n=293) and validation cohort (n=126). The variables included age at diagnosis, sex, history of smoking, tumor number, tumor size, histolo-gic grade, pathological stage, and bladder perfusion drug. The cumulative incidence function (CIF) of recurrence was estimated using all variables in the training cohort and potential prognostic variables were determined with Gray’s test. The Fine-Gray subdistribution proportional hazard approach was used as a multivariate competitive risk analysis to identify independent pro-gnostic variables. A competing risk nomogram was developed to predict the recurrence. The performance of the competing risk model was evaluated with the area under the receiver operating characteristic curve (AUC), calibration curve, and Brier score. 【Results】 Five independent prognostic factors including age, number of tumors, tumor size, histologic grade and pathological stage were used to construct the competing risk model. In the validation cohort, the AUC of 1-, 2- and 3- year recurrence were 0.895 (95%CI: 0.831-0.959), 0.861(95%CI: 0.774-0.948) and 0.827(95%CI: 0.721-0.934), respectively, indicating that the model had a high predictive performance. 【Conclusion】 We successfully constructed a competing risk model to predict the risk of 1-, 2- and 3-year recurrence for NMIBC patients. It may help clinicians to improve the postoperative management of patients.