Producing highly effective extracellular vesicles using IBAR and talin F3 domain fusion.

Extracellular vesicles (EVs), transporting diverse cellular components, play a crucial role in intercellular communication in numerous physiological and pathological processes. EVs have also been recognized as a drug delivery platform for therapeutic purposes and cell-free regenerative medicine. While various approaches have focused on increasing EV production for efficient use therapeutic use of EVs, enhancing the quality of EVs, such as ensuring efficient uptake by their target cells, has not been widely explored. In this study, we linked a negative membrane curvature-forming inverse BAR (IBAR) domain with an integrin ß tail-binding talin F3 domain to create the IBAR-F3 fusion protein. We observed that IBAR-F3 can trigger filopodia-like membrane protrusions and attract integrins to those protrusion-rich regions, when expressed in Chinese hamster ovary cells expressing integrin αIIbß3. Surprisingly, the expression of IBAR-F3 also induced a robust production of EVs, which were then efficiently taken up by nearby cells in an integrin-dependent manner. Moreover, IBAR triggered integrin activation, presumably by inducing negative membrane curvature that likely disrupts the interaction between the integrin α and ß transmembrane domain. Therefore, we suggest that IBAR-F3 should be utilized to promote both EV production and efficient uptake mediated by integrins. Furthermore, the negative curvature-inducing integrin activation suggests that integrins on EVs can be activated by the nanoscale change in the curvature of the EV without the need for conventional machinery to activate integrin inside the EVs.

α-Hemolysin promotes uropathogenic E. coli persistence in bladder epithelial cells via abrogating bacteria-harboring lysosome acidification.

There is a growing consensus that a significant proportion of recurrent urinary tract infections are linked to the persistence of uropathogens within the urinary tract and their re-emergence upon the conclusion of antibiotic treatment. Studies in mice and human have revealed that uropathogenic Escherichia coli (UPEC) can persist in bladder epithelial cells (BECs) even after the apparent resolution of the infection. Here, we found that, following the entry of UPEC into RAB27b+ fusiform vesicles in BECs, some bacteria escaped into the cytoplasmic compartment via a mechanism involving hemolysin A (HlyA). However, these UPEC were immediately recaptured within LC3A/B+ autophagosomes that matured into LAMP1+ autolysosomes. Thereafter, HlyA+ UPEC-containing lysosomes failed to acidify, which is an essential step for bacterial elimination. This lack of acidification was related to the inability of bacteria-harboring compartments to recruit V-ATPase proton pumps, which was attributed to the defragmentation of cytosolic microtubules by HlyA. The persistence of UPEC within LAMP1+ compartments in BECs appears to be directly linked to HlyA. Thus, through intravesicular instillation of microtubule stabilizer, this host defense response can be co-opted to reduce intracellular bacterial burden following UTIs in the bladder potentially preventing recurrence.

Incidence and Risk Factors for Pregnancy-Related de Quervain's Tenosynovitis in South Korea: A Population-Based Epidemiologic Study.

Background: Although pregnant or lactating women have been recognized to be predisposed to de Quervain's tenosynovitis (DQT), there is a lack of epidemiologic evidence. The purpose of this study was to estimate the nationwide incidence of pregnancy-related DQT (PRDQT) and to analyze risk factors using the Korean National Health Insurance (NHI) database. Methods: A retrospective epidemiologic study of pregnant women in South Korea from 2013 to 2017 was conducted using the NHI claims database. Using corresponding diagnostic codes, we identified women diagnosed with DQT during pregnancy or the postpartum period. We calculated the cumulative incidence and analyzed risk factors such as demographics, pregnancy type, delivery method, gestational complications, and comorbidities using multivariate logistic regression analysis. Results: Between 2013 and 2017, 34,342 patients with PRDQT were identified among 1,601,501 pregnant women, representing a cumulative incidence of approximately 2.1%. Age ≥ 30 years, multiple gestation, cesarean delivery, hypertensive disorders in pregnancy, and underlying rheumatoid arthritis were all identified as significant risk factors for the occurrence of PRDQT, whereas diabetic disorders in pregnancy and underlying diabetes mellitus were not. Conclusions: In South Korea, PRDQT was found to affect approximately 2.1 out of 100 pregnant women between 2013 and 2017. The incidence and risk factors identified in this study can be used for clinical consultations and prediction, as well as for development of national health policies.

Mortality rates of hip fracture patients with non-operative treatment.

OBJECTIVES: In this study, we aimed to analyze patient mortality rate after non-operative treatment of hip fractures to determine the distribution of causes of death and to compare factors affecting mortality. PATIENTS AND METHODS: Between January 2013 and March 2019, a total of 93 patients (17 males, 76 females; mean age: 86.0±7.4 years; range, 64 to 98 years) who had hip fractures and were treated non-operatively were analyzed retrospectively. Survival, date of death, and cause of death were collected and analyzed. Baseline demographics, pre-trauma ambulation, pre- and post-trauma residence status, American Society of Anesthesiologists Physical Status (ASA PS) classification, and Parker's mobility score were compared with one-year mortality rates. RESULTS: The mean follow-up of survivors was 16.1±11.9 (range, 6.3 to 79.6) months. The mean survival of non-survivors was 4.9±6.1 (range, 0.007 to 27.3) months. The 3-, 6-, 12-, and 24-month mortality rates were 40.9%, 53.3%, 74.4%, and 87.5%, respectively. Respiratory diseases (33.3%) and cardiovascular diseases (13.6%) were the main causes of death among the patients. There was no statistically significant difference between the patients' age, sex, fracture site, pre-trauma ambulation, pre- and post-trauma residence status, ASA PS classification, Parker's mobility score, and one-year mortality. CONCLUSION: A significant number of patients are still treated non-operatively after hip fractures, and they have a high mortality rate. Efforts and research are needed to reduce mortality and improve the quality of life.

Syndecan Transmembrane Domain Specifically Regulates Downstream Signaling Events of the Transmembrane Receptor Cytoplasmic Domain.

Despite the known importance of the transmembrane domain (TMD) of syndecan receptors in cell adhesion and signaling, the molecular basis for syndecan TMD function remains unknown. Using in vivo invertebrate models, we found that mammalian syndecan-2 rescued both the guidance defects in C. elegans hermaphrodite-specific neurons and the impaired development of the midline axons of Drosophila caused by the loss of endogenous syndecan. These compensatory effects, however, were reduced significantly when syndecan-2 dimerization-defective TMD mutants were introduced. To further investigate the role of the TMD, we generated a chimera, 2eTPC, comprising the TMD of syndecan-2 linked to the cytoplasmic domain of platelet-derived growth factor receptor (PDGFR). This chimera exhibited SDS-resistant dimer formation that was lost in the corresponding dimerization-defective syndecan-2 TMD mutant, 2eT(GL)PC. Moreover, 2eTPC specifically enhanced Tyr 579 and Tyr 857 phosphorylation in the PDGFR cytoplasmic domain, while the TMD mutant failed to support such phosphorylation. Finally, 2eTPC, but not 2eT(GL)PC, induced phosphorylation of Src and PI3 kinase (known downstream effectors of Tyr 579 phosphorylation) and promoted Src-mediated migration of NIH3T3 cells. Taken together, these data suggest that the TMD of a syndecan-2 specifically regulates receptor cytoplasmic domain function and subsequent downstream signaling events controlling cell behavior.

Topological Adaptation of Transmembrane Domains to the Force-Modulated Lipid Bilayer Is a Basis of Sensing Mechanical Force.

Cells can sense and respond to various mechanical stimuli from their surrounding environment. One of the explanations for mechanosensitivity, a lipid-bilayer model, suggests that a stretch of the membrane induced by mechanical force alters the physical state of the lipid bilayer, driving mechanosensors to assume conformations better matched to the altered membrane. However, mechanosensors of this class are restricted to ion channels. Here, we reveal that integrin αIIbß3, a prototypic adhesion receptor, can be activated by various mechanical stimuli including stretch, shear stress, and osmotic pressure. The force-induced integrin activation was not dependent on its known intracellular activation signaling events and was even observed in reconstituted cell-free liposomes. Instead, these mechanical stimuli were found to alter the lipid embedding of the integrin ß3 transmembrane domain (TMD) and subsequently weaken the αIIb-ß3 TMD interaction, which results in activation of the receptor. Moreover, artificial modulation of the membrane curvature near integrin αIIbß3 can induce its activation in cells as well as in lipid nanodiscs, suggesting that physical deformation of the lipid bilayer, either by mechanical force or curvature, can induce integrin activation. Thus, our results establish the adhesion receptor as a bona fide mechanosensor that directly senses and responds to the force-modulated lipid environment. Furthermore, this study expands the lipid-bilayer model by suggesting that the force-induced topological change of TMDs and subsequent alteration in the TMD interactome is a molecular basis of sensing mechanical force transmitted via the lipid bilayer.

Characterization and cDNA cloning of a defensin-like peptide, harmoniasin, from Harmonia axyridis.

We compared the mRNA expression profile of the Harmonia axyridis larvae that were either untreated or treated with LPS. The extracted mRNAs were subjected to ACP RTPCR analysis using a combination of arbitrary primers and oligo (dT) primer. Among the 47 DEGs differentially expressed, we identified a cDNA showing homology with defensin-like antibacterial peptide. The cDNA showed a putative 32-residue signal sequence and a 50-residue mature peptide named harmoniasin. We also investigated the antibacterial activity of the harmoniasin analog, which exhibited potent antibacterial activities against Gramnegative and -positive bacteria strains and it also evidenced no hemolytic activity.