Is myeloid-derived growth factor a ligand of the sphingosine-1-phosphate receptor 2?

Secretory myeloid-derived growth factor (MYDGF) exerts beneficial effects on organ repair, probably via a plasma membrane receptor; however, the identity of the expected receptor has remained elusive. In a recent study, MYDGF was reported as an agonist of the sphingosine-1-phosphate receptor 2 (S1PR2), an A-class G protein-coupled receptor that mediates the functions of the signaling lipid, sphingosine-1-phosphate (S1P). In the present study, we conducted living cell-based functional assays to test whether S1PR2 is a receptor for MYDGF. In the NanoLuc Binary Technology (NanoBiT)-based ß-arrestin recruitment assay and the cAMP-response element (CRE)-controlled NanoLuc reporter assay, S1P could efficiently activate human S1PR2 overexpressed in human embryonic kidney (HEK) 293T cells; however, recombinant human MYDGF, overexpressed either from Escherichia coli or HEK293 cells, had no detectable effect. Thus, the results demonstrated that human MYDGF is not a ligand of human S1PR2. Considering the high conservation of MYDGF and S1PR2 in evolution, MYDGF is also probably not a ligand of S1PR2 in other vertebrates.

Genome-wide analysis of in vivo-evolved Candida auris reveals multidrug-resistance mechanisms.

Candida auris, an emerging and multidrug-resistant fungal pathogen, has led to numerous outbreaks in China. While the resistance mechanisms against azole and amphotericin B have been studied, the development of drug resistance in this pathogen remains poorly understood, particularly in in vivo-generated drug-resistant strains. This study employed pathogen whole-genome sequencing to investigate the epidemiology and drug-resistance mutations of C. auris using 16 strains isolated from two patients. Identification was conducted through Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibilities were assessed using broth microdilution and Sensititre YeastOne YO10. Whole-genome sequencing revealed that all isolates belonged to the South Asian lineage, displaying genetic heterogeneity. Despite low genetic variability among patient isolates, notable mutations were identified, including Y132F in ERG11 and A585S in TAC1b, likely linked to increased fluconazole resistance. Strains from patient B also carried F214L in TAC1b, resulting in a consistent voriconazole minimum inhibitory concentration of 4 µg/mL across all isolates. Furthermore, a novel frameshift mutation in the SNG1 gene was observed in amphotericin B-resistant isolates compared to susceptible ones. Our findings suggest the potential transmission of C. auris and emphasize the need to explore variations related to antifungal resistance. This involves analyzing genomic mutations and karyotypes, especially in vivo, to compare sensitive and resistant strains. Further monitoring and validation efforts are crucial for a comprehensive understanding of the mechanisms of drug resistance in C. auris.

An efficient peptide ligase engineered from a bamboo asparaginyl endopeptidase.

In recent years, a few asparaginyl endopeptidases (AEPs) from certain higher plants have been identified as efficient peptide ligases with wide applications in protein labeling and cyclic peptide synthesis. Recently, we developed a NanoLuc Binary Technology (NanoBiT)-based peptide ligase activity assay to identify more AEP-type peptide ligases. Herein, we screened 61 bamboo species from 16 genera using this assay and detected AEP-type peptide ligase activity in the crude extract of all tested bamboo leaves. From a popular bamboo species, Bambusa multiplex, we identified a full-length AEP-type peptide ligase candidate (BmAEP1) via transcriptomic sequencing. After its zymogen was overexpressed in Escherichia coli and self-activated in vitro, BmAEP1 displayed high peptide ligase activity, but with considerable hydrolytic activity. After site-directed mutagenesis of its ligase activity determinants, the mutant zymogen of [G238V]BmAEP1 was normally overexpressed in E. coli, but failed to activate itself. To resolve this problem, we developed a novel protease-assisted activation approach in which trypsin was used to cleave the mutant zymogen and was then conveniently removed via ion-exchange chromatography. After the noncovalently bound cap domain was dissociated from the catalytic core domain under acidic conditions, the recombinant [G238V]BmAEP1 displayed high peptide ligase activity with much lower hydrolytic activity and could efficiently catalyze inter-molecular protein ligation and intramolecular peptide cyclization. Thus, the engineered bamboo-derived peptide ligase represents a novel tool for protein labeling and cyclic peptide synthesis.

Analysis of 50 cases of bloodstream infection with Listeria monocytogenes / 中国热带医学

@#Abstract: Objective　To analyze the characteristics of bloodstream infection of Listeria monocytogenes and provide basis for the diagnosis and treatment of the disease. Methods　We retrospectively analyzed the cases of Listeria monomyrhosi bloodstream infection in Peking Union Medical College Hospital (PUMCH) from April 2012 to April 2022. The age, sex, onset time, underlying disease, symptoms, diagnosis, treatment and prognosis of the patients were analyzed, as well as the changes of white blood cells (WBC), neutrophils, lymphocytes, and C-reactive protein (CRP) before and after anti-infection treatment. Results　Fifty cases of Listeria monocytogenes bloodstream infection confirmed by blood culture were involved. The age of patients ranged from 0 to 82 (43.7±20.0) years old, among whom 20.0% were over 60 years old. The onset time of patients was the highest in spring (44.0%), followed by winter (24.0%), and relatively fewer in summer and autumn (14.0%-18.0%). The median diagnosis time was 3 days (1-60 days). After the etiological diagnosis, 45 patients (90.0%) had underlying diseases or pregnancy status, and 45 patients were adjusted to the target antibacterial treatment mainly with carbapenems (48.9%) and penicillins (44.4%). The level of WBC, neutrophils, lymphocytes, monocytes, and CRP after treatment were significantly lower than those pre-treatments (P<0.05). Among all patients, 36 cases (72.0%) were treated according to the Antimicrobial Treatment Guidelines for Fever Sanford, of which 26 cases (72.2%) were discharged from the hospital, two cases died, one case was transferred to other hospitals, and 7 cases had a poor prognosis. Conclusions　Autoimmune diseases, tumor diseases, pregnant patients are susceptible to Listeria monocytogenes infection. Penicillins are the first choice for effective empiric therapy. For the patients allergic to penicillins, trimethoprim/sulfamethoxazole or meropenem could be used.

Effects of High Frequency Repetitive Transcranial Magnetic Stimulation on KCC2 Expression in Rats with Spasticity Following Spinal Cord Injury / 华中科技大学学报（医学）（英德文版）

The effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) on potassium-chloride cotransporter-2 (KCC2) protein expression following spinal cord injury (SCI) and the action mechanism were investigated.SCI models were established in SD rats.Five groups were set up randomly:normal control group,SCI 7-day (7D) model group,SCI 14-day (14D) model group,SCI-7D rTMS group and SCI-14D rTMS group (n=5 each).The rats in SCI rTMS groups were treated with 10 Hz rTMS from 8th day and 15th day after SCI respectively,once every day,5 days every week,a total of 4 weeks.After the model establishment,motor recovery and spasticity alleviation were evaluated with BBB scale once a week till the end of treatment.Finally,different parts of tissues were dissected out for detection of variations of KCC2 protein using Western blotting and polymerase chain reaction (PCR) technique.The results showed that the BBS scores after treatment were significantly higher in SCI-7D rTMS group than in SCI-14D rTMS group (P＜0.05).As compared with normal control groups,The KCC2 protein in SCI model groups was down-regulated after SCI,and the decrease was much more significant in SCI-14D model group than in SCI-7D group (P＜0.05).As compared with SCI model groups,KCC2 protein in rTMS groups was up-regulated after the treatment (P＜0.05).The up-regulation of KCC2 protein content and expression was more obvious in SCI-7D rTMS group than in SCI-14D rTMS group (P＜0.05).It was concluded that 10 Hz rTMS can alleviate spasticity in rats with SCI,which might be attributed to the up-regulation of KCC2 protein.It was also suggested that the high-frequency rTMS treatment after SCI at early stage might achieve more satisfactory curative effectiveness.