Soluble E-cadherin participates in BLM-induced pulmonary fibrosis by promoting EMT and lung fibroblast migration.

Soluble E-cadherin (sE-cad) is an 80 kDa fragment derived from E-cadherin that is shed from the cell surface through proteolytic cleavage and is a biomarker in various cancers that promotes invasion and migration. Alveolar epithelial destruction, aberrant lung fibroblast migration and inflammation contribute to pulmonary fibrosis. Here, we hypothesized that E-cadherin plays an important role in lung fibrosis. In this study, we found that E-cadherin was markedly increased in the bronchoalveolar lavage fluid (BALF) and serum of mice with pulmonary fibrosis and that blocking sE-cad with HECD-1, a neutralizing antibody targeting the ectodomain of E-cadherin, effectively inhibited myofibroblast accumulation and collagen deposition in the lungs after bleomycin (BLM) exposure. Moreover, transforming growth factor-ß (TGF-ß1) induced the shedding of sE-cad from A549 cells, and treatment with HECD-1 inhibited epithelial-mesenchymal transition (EMT) stimulated by TGF-ß1. Fc-E-cadherin (Fc-Ecad), which is an exogenous form of sE-cad, robustly promoted lung fibroblast migration. E-cadherin participates in bleomycin (BLM)-induced lung fibrosis by promoting EMT in the alveolar epithelium and fibroblast activation. E-cadherin may be a novel therapeutic target for lung fibrosis.

Spider Silk Protein Forms Amyloid-Like Nanofibrils through a Non-Nucleation-Dependent Polymerization Mechanism.

Amyloid fibrils-nanoscale fibrillar aggregates with high levels of order-are pathogenic in some today incurable human diseases; however, there are also many physiologically functioning amyloids in nature. The process of amyloid formation is typically nucleation-elongation-dependent, as exemplified by the pathogenic amyloid-ß peptide (Aß) that is associated with Alzheimer's disease. Spider silk, one of the toughest biomaterials, shares characteristics with amyloid. In this study, it is shown that forming amyloid-like nanofibrils is an inherent property preserved by various spider silk proteins (spidroins). Both spidroins and Aß capped by spidroin N- and C-terminal domains, can assemble into macroscopic spider silk-like fibers that consist of straight nanofibrils parallel to the fiber axis as observed in native spider silk. While Aß forms amyloid nanofibrils through a nucleation-dependent pathway and exhibits strong cytotoxicity and seeding effects, spidroins spontaneously and rapidly form amyloid-like nanofibrils via a non-nucleation-dependent polymerization pathway that involves lateral packing of fibrils. Spidroin nanofibrils share amyloid-like properties but lack strong cytotoxicity and the ability to self-seed or cross-seed human amyloidogenic peptides. These results suggest that spidroins´ unique primary structures have evolved to allow functional properties of amyloid, and at the same time direct their fibrillization pathways to avoid formation of cytotoxic intermediates.

Label-free Single-Molecule Quantification of Rapamycin-induced FKBP-FRB Dimerization for Direct Control of Cellular Mechanotransduction.

Chemically induced dimerization (CID) has been applied to study numerous biological processes and has important pharmacological applications. However, the complex multistep interactions under various physical constraints involved in CID impose a great challenge for the quantification of the interactions. Furthermore, the mechanical stability of the ternary complexes has not been characterized; hence, their potential application in mechanotransduction studies remains unclear. Here, we report a single-molecule detector that can accurately quantify almost all key interactions involved in CID and the mechanical stability of the ternary complex, in a label-free manner. Its application is demonstrated using rapamycin-induced heterodimerization of FRB and FKBP as an example. We revealed the sufficient mechanical stability of the FKBP/rapamycin/FRB ternary complex and demonstrated its utility in the precise switching of talin-mediated force transmission in integrin-based cell adhesions.

Vaginoplasty With Mesh Autologous Buccal Mucosa in Vaginal Agenesis: A Multidisciplinary Approach and Literature Review.

BACKGROUND: Vaginal agenesis, a rare condition, is treated by various surgical techniques to achieve neovaginal reconstruction. The main difference between the approaches lies in the graft material used to cover the newly formed cavity. OBJECTIVES: The purpose of this retrospective study was to describe the surgical procedure and outcomes of autologous buccal mucosal grafting in neovaginal reconstruction. METHODS: Sixteen patients with vaginal agenesis admitted to our department between January 2016 and January 2019 were included in our study. A reconstruction procedure, described in detail here, involving autologous buccal mucosa as graft material was successfully conducted in all of the patients. Long-term anatomic and functional outcomes were evaluated. RESULTS: The blood loss during operation was estimated to be 15 to 20 mL in all cases. No rectal or bladder injury occurred. The buccal mucosal wound completely healed 10 to 14 days after the operation. All patients had a well-formed neovagina 8 to 10 cm in length, with a mean diameter of >3 finger-breadths. CONCLUSIONS: The application of autologous buccal mucosa in neovaginal construction is a simple procedure. Autologous buccal mucosa is an ideal material to achieve excellent cosmetic and functional results in patients with vaginal agenesis.

Reversible Condensation of Mucins into Nanoparticles.

Mucins are high molar mass glycoproteins that assume an extended conformation and can assemble into mucus hydrogels that protect our mucosal epithelium. In nature, the challenging task of generating a mucus layer, several hundreds of micrometers in thickness, from micrometer-sized cells is elegantly solved by the condensation of mucins inside vesicles and their on-demand release from the cells where they suddenly expand to form the extracellular mucus hydrogel. We aimed to recreate and control the process of compaction for mucins, the first step toward a better understanding of the process and creating biomimetic in vivo delivery strategies of macromolecules. We found that by adding glycerol to the aqueous solvent, we could induce drastic condensation of purified mucin molecules, reducing their size by an order of magnitude down to tens of nanometers in diameter. The condensation effect of glycerol was fully reversible and could be further enhanced and partially stabilized by cationic cross-linkers such as calcium and polylysine. The change of structure of mucins from extended molecules to nano-sized particles in the presence of glycerol translated into macroscopic rheological changes, as illustrated by a dampened shear-thinning effect with increasing glycerol concentration. This work provides new insight into mucin condensation, which could lead to new delivery strategies mimicking cell release of macromolecules condensed in vesicles such as mucins and heparin.

Molecular basis for different substrate-binding sites and chaperone functions of the BRICHOS domain.

Proteins can misfold into fibrillar or amorphous aggregates and molecular chaperones act as crucial guardians against these undesirable processes. The BRICHOS chaperone domain, found in several otherwise unrelated proproteins that contain amyloidogenic regions, effectively inhibits amyloid formation and toxicity but can in some cases also prevent non-fibrillar, amorphous protein aggregation. Here, we elucidate the molecular basis behind the multifaceted chaperone activities of the BRICHOS domain from the Bri2 proprotein. High-confidence AlphaFold2 and RoseTTAFold predictions suggest that the intramolecular amyloidogenic region (Bri23) is part of the hydrophobic core of the proprotein, where it occupies the proposed amyloid binding site, explaining the markedly reduced ability of the proprotein to prevent an exogenous amyloidogenic peptide from aggregating. However, the BRICHOS-Bri23 complex maintains its ability to form large polydisperse oligomers that prevent amorphous protein aggregation. A cryo-EM-derived model of the Bri2 BRICHOS oligomer is compatible with surface-exposed hydrophobic motifs that get exposed and come together during oligomerization, explaining its effects against amorphous aggregation. These findings provide a molecular basis for the BRICHOS chaperone domain function, where distinct surfaces are employed against different forms of protein aggregation.

Short hydrophobic loop motifs in BRICHOS domains determine chaperone activity against amorphous protein aggregation but not against amyloid formation.

ATP-independent molecular chaperones are important for maintaining cellular fitness but the molecular determinants for preventing aggregation of partly unfolded protein substrates remain unclear, particularly regarding assembly state and basis for substrate recognition. The BRICHOS domain can perform small heat shock (sHSP)-like chaperone functions to widely different degrees depending on its assembly state and sequence. Here, we observed three hydrophobic sequence motifs in chaperone-active domains, and found that they get surface-exposed when the BRICHOS domain assembles into larger oligomers. Studies of loop-swap variants and site-specific mutants further revealed that the biological hydrophobicities of the three short motifs linearly correlate with the efficiency to prevent amorphous protein aggregation. At the same time, they do not at all correlate with the ability to prevent ordered amyloid fibril formation. The linear correlations also accurately predict activities of chimeras containing short hydrophobic sequence motifs from a sHSP that is unrelated to BRICHOS. Our data indicate that short, exposed hydrophobic motifs brought together by oligomerisation are sufficient and necessary for efficient chaperone activity against amorphous protein aggregation.

Self-supervised classification of subcellular morphometric phenotypes reveals extracellular matrix-specific morphological responses.

Cell morphology is profoundly influenced by cellular interactions with microenvironmental factors such as the extracellular matrix (ECM). Upon adhesion to specific ECM, various cell types are known to exhibit different but distinctive morphologies, suggesting that ECM-dependent cell morphological responses may harbour rich information on cellular signalling states. However, the inherent morphological complexity of cellular and subcellular structures has posed an ongoing challenge for automated quantitative analysis. Since multi-channel fluorescence microscopy provides robust molecular specificity important for the biological interpretations of observed cellular architecture, here we develop a deep learning-based analysis pipeline for the classification of cell morphometric phenotypes from multi-channel fluorescence micrographs, termed SE-RNN (residual neural network with squeeze-and-excite blocks). We demonstrate SERNN-based classification of distinct morphological signatures observed when fibroblasts or epithelial cells are presented with different ECM. Our results underscore how cell shapes are non-random and established the framework for classifying cell shapes into distinct morphological signature in a cell-type and ECM-specific manner.

Molecular Chaperone BRICHOS Inhibits CADASIL-Mutated NOTCH3 Aggregation In Vitro.

CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is the most common familial form of stroke, which is caused by mutations located in the epidermal growth factor (EGF)-like repeats of the NOTCH3 gene. Mutations cause the NOTCH3 (N3) protein to misfold and aggregate. These aggregates will be a component of granular osmiophilic material, which when accumulated around the arteries and arterioles is believed to cause the degradation of vascular smooth muscle cells (VSMC). VSMC degradation affects blood flow regulation and leads to white matter and neuronal death. Currently, there is no treatment for CADASIL. The dementia-relevant BRICHOS domain is a small multitalented protein with functions that include ATP-independent chaperone-like properties. BRICHOS has been shown to prevent the aggregation of both fibrillar and non-fibrillar structures. Therefore, the objective of this study is to investigate whether BRICHOS exhibits anti-aggregating properties on a recombinant CADASIL-mutated N3 protein consisting of the first five repeats of EGF (EGF1-5), harboring a cysteine instead of an arginine in the position 133, (R133C). We found that the N3 EGF1-5 R133C mutant is more prone to aggregate, while the wildtype is more stable. Recombinant human Bri2 BRICHOS is able to interact and stabilize the R133C-mutated N3 protein in a dose-dependent manner. These results suggest an anti-aggregating impact of BRICHOS on the N3 EGF1-5 R133C protein, which could be a potential treatment for CADASIL.

Vitamin D ameliorates asthma-induced lung injury by regulating HIF-1α/Notch1 signaling during autophagy.

Herein, we aimed to determine the effect of vitamin D (Vit D) and underlying mechanisms on asthma-induced lung injury via regulation of HIF-1α/Notch1 (hypoxia-inducible factor 1 alpha/neurogenic locus notch homolog protein 1) signaling during autophagy. We established an asthma mouse model using respiratory syncytial virus (RSV) nasal drop combined with ovalbumin (OVA) atomization. Mice were treated with different Vit D concentrations. Pathological changes and cell apoptosis were examined using hematoxylin-eosin (HE) staining and TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling) assay, respectively. Additionally, periodic acid-Schiff (PAS) and Masson's trichrome staining solutions were used to examine changes in lung tissue. Immunofluorescence determined LC 3B (microtubule-associated protein 1 light chain 3B) expression in lung tissues, whereas western blotting and immunohistochemistry were used to evaluate other proteins, including HIF-1α and Notch1. Compared with the normal group, the asthma model group exhibited pathological lung tissue deterioration, elevated fibrosis, increased apoptosis cell numbers, and upregulated autophagy. Vitamin D supplementation ameliorated pathological changes and fibrosis in the lung tissue. Furthermore, Vit D treatment significantly suppressed apoptotic cell numbers and autophagy while enhancing the HIF-1α/Notch1 pathway. Given the HIF-1α/Notch1 agonistic activity, Vit D treatment inhibited apoptosis cell numbers, which were increased following asthma-induced upregulation of autophagy. Vitamin D improved asthma-induced lung tissue injury by suppressing autophagy via regulation of HIF-1α/Notch1 signaling in vivo.

Amyloid Fibril Formation of Arctic Amyloid-ß 1-42 Peptide is Efficiently Inhibited by the BRICHOS Domain.

Amyloid-ß peptide (Aß) aggregation is one of the hallmarks of Alzheimer's disease (AD). Mutations in Aß are associated with early onset familial AD, and the Arctic mutant E22G (Aßarc) is an extremely aggregation-prone variant. Here, we show that BRICHOS, a natural anti-amyloid chaperone domain, from Bri2 efficiently inhibits aggregation of Aßarc by mainly interfering with secondary nucleation. This is qualitatively different from the microscopic inhibition mechanism for the wild-type Aß, against which Bri2 BRICHOS has a major effect on both secondary nucleation and fibril end elongation. The monomeric Aß42arc peptide aggregates into amyloid fibrils significantly faster than wild-type Aß (Aß42wt), as monitored by thioflavin T (ThT) binding, but the final ThT intensity was strikingly lower for Aß42arc compared to Aß42wt fibrils. The Aß42arc peptide formed large aggregates, single-filament fibrils, and multiple-filament fibrils without obvious twists, while Aß42wt fibrils displayed a polymorphic pattern with typical twisted fibril architecture. Recombinant human Bri2 BRICHOS binds to the Aß42arc fibril surface and interferes with the macroscopic fibril arrangement by promoting single-filament fibril formation. This study provides mechanistic insights on how BRICHOS efficiently affects the aggressive Aß42arc aggregation, resulting in both delayed fibril formation kinetics and altered fibril structure.

ATP-independent molecular chaperone activity generated under reducing conditions.

Molecular chaperones are essential to maintain proteostasis. While the functions of intracellular molecular chaperones that oversee protein synthesis, folding and aggregation, are established, those specialized to work in the extracellular environment are less understood. Extracellular proteins reside in a considerably more oxidizing milieu than cytoplasmic proteins and are stabilized by abundant disulfide bonds. Hence, extracellular proteins are potentially destabilized and sensitive to aggregation under reducing conditions. We combine biochemical and mass spectrometry experiments and elucidate that the molecular chaperone functions of the extracellular protein domain Bri2 BRICHOS only appear under reducing conditions, through the assembly of monomers into large polydisperse oligomers by an intra- to intermolecular disulfide bond relay mechanism. Chaperone-active assemblies of the Bri2 BRICHOS domain are efficiently generated by physiological thiol-containing compounds and proteins, and appear in parallel with reduction-induced aggregation of extracellular proteins. Our results give insights into how potent chaperone activity can be generated from inactive precursors under conditions that are destabilizing to most extracellular proteins and thereby support protein stability/folding in the extracellular space. SIGNIFICANCE: Chaperones are essential to cells as they counteract toxic consequences of protein misfolding particularly under stress conditions. Our work describes a novel activation mechanism of an extracellular molecular chaperone domain, called Bri2 BRICHOS. This mechanism is based on reducing conditions that initiate small subunits to assemble into large oligomers via a disulfide relay mechanism. Activated Bri2 BRICHOS inhibits reduction-induced aggregation of extracellular proteins and could be a means to boost proteostasis in the extracellular environment upon reductive stress.

Integrated analysis reveals the pivotal interactions between immune cells in the melanoma tumor microenvironment.

Melanoma is the most lethal type of skin cancer. Despite the breakthroughs in the clinical treatment of melanoma using tumor immunotherapy, many patients do not benefit from these immunotherapies because of multiple immunosuppressive mechanisms. Therefore, there is an urgent need to determine the mechanisms of tumor-immune system interactions and their molecular determinants to improve cancer immunotherapy. In this study, combined analysis of microarray data and single-cell RNA sequencing data revealed the key interactions between immune cells in the melanoma microenvironment. First, differentially expressed genes (DEGs) between normal and malignant tissues were obtained using GEO2R. The DEGs were then subjected to downstream analyses, including enrichment analysis and protein-protein interaction analysis, indicating that these genes were associated with the immune response of melanoma. Then, the GEPIA and TIMER databases were used to verify the differential expression and prognostic significance of hub genes, and the relationship between the hub genes and immune infiltration. In addition, we combined single cell analysis from GSE123139 to identify immune cell types, and validated the expression of the hub genes in these immune cells. Finally, cell-to-cell communication analysis of the proteins encoded by the hub genes and their interactions was performed using CellChat. We found that the CCL5-CCR1, SELPLG-SELL, CXCL10-CXCR3, and CXCL9-CXCR3 pathways might play important roles in the communication between the immune cells in tumor microenvironment. This discovery may reveal the communication basis of immune cells in the tumor microenvironment and provide a new idea for melanoma immunotherapy.

The surgical strategies of vaginoplasty for vaginal agenesis patients with or without functional uterus.

BACKGROUND: Vaginal agenesis is a rare condition worldwide. Most reported cases were accompanied by the absence of uterus or uterine hypoplasia; for patients with functional endometrium, hysterectomy was most likely to be conducted to lower postoperative complications. OBJECTIVE: Based on our successful experience in vaginoplasty with autologous buccal mucosal, the purpose of this article is to discuss the surgical strategies in the reconstruction of neovaginal for vaginal agenesis patients with functional uterus and cervical hypoplasia. METHODS: The uterus was preserved in our procedure, and the cervicoplasty was performed to connect the uterine cavity with the neovagina. After the vaginal cavity was formed, the cervix was confirmed and fixed. With the assistance of laparoscope, the direction and angle of the cervix and the uterine body were observed and confirmed. An incision was made in cervix to connect the uterine cavity, and a Foley's catheter was inserted. The newly formed opening of cervix and neovagina was covered by autologous buccal mucosal. RESULTS: The connection between neovagina and cervix uteri was successfully conducted in patient with functional uterus. Unimpeded and regular menstrual was achieved, and the cyclic abdominal pain was disappeared. No complications were observed. CONCLUSION: For patients without functional uterus, vaginoplasty with autologous buccal mucosal can be conducted. However, fertility-preserving surgery should be the primary choice in patients with functional endometrium. It can be concluded from our experience that the utero-vaginal connection with the assistance of laparoscope and the use of autologous buccal mucosa is a promising way to achieve ideal outcomes.

Abilities of the BRICHOS domain to prevent neurotoxicity and fibril formation are dependent on a highly conserved Asp residue.

Proteins can self-assemble into amyloid fibrils or amorphous aggregates and thereby cause disease. Molecular chaperones can prevent both these types of protein aggregation, but to what extent the respective mechanisms are overlapping is not fully understood. The BRICHOS domain constitutes a disease-associated chaperone family, with activities against amyloid neurotoxicity, fibril formation, and amorphous protein aggregation. Here, we show that the activities of BRICHOS against amyloid-induced neurotoxicity and fibril formation, respectively, are oppositely dependent on a conserved aspartate residue, while the ability to suppress amorphous protein aggregation is unchanged by Asp to Asn mutations. The Asp is evolutionarily highly conserved in >3000 analysed BRICHOS domains but is replaced by Asn in some BRICHOS families. The conserved Asp in its ionized state promotes structural flexibility and has a pK a value between pH 6.0 and 7.0, suggesting that chaperone effects can be differently affected by physiological pH variations.

A "spindle and thread" mechanism unblocks p53 translation by modulating N-terminal disorder.

Disordered proteins pose a major challenge to structural biology. A prominent example is the tumor suppressor p53, whose low expression levels and poor conformational stability hamper the development of cancer therapeutics. All these characteristics make it a prime example of "life on the edge of solubility." Here, we investigate whether these features can be modulated by fusing the protein to a highly soluble spider silk domain (NT∗). The chimeric protein displays highly efficient translation and is fully active in human cancer cells. Biophysical characterization reveals a compact conformation, with the disordered transactivation domain of p53 wrapped around the NT∗ domain. We conclude that interactions with NT∗ help to unblock translation of the proline-rich disordered region of p53. Expression of partially disordered cancer targets is similarly enhanced by NT∗. In summary, we demonstrate that inducing co-translational folding via a molecular "spindle and thread" mechanism unblocks protein translation in vitro.

Recombinant Bri3 BRICHOS domain is a molecular chaperone with effect against amyloid formation and non-fibrillar protein aggregation.

Molecular chaperones assist proteins in achieving a functional structure and prevent them from misfolding into aggregates, including disease-associated deposits. The BRICHOS domain from familial dementia associated protein Bri2 (or ITM2B) probably chaperones its specific proprotein region with high ß-sheet propensity during biosynthesis. Recently, Bri2 BRICHOS activity was found to extend to other amyloidogenic, fibril forming peptides, in particular, Alzheimer's disease associated amyloid-ß peptide, as well as to amorphous aggregate forming proteins. However, the biological functions of the central nervous system specific homologue Bri3 BRICHOS are still to be elucidated. Here we give a detailed characterisation of the recombinant human (rh) Bri3 BRICHOS domain and compare its structural and functional properties with rh Bri2 BRICHOS. The results show that rh Bri3 BRICHOS forms more and larger oligomers, somewhat more efficiently prevents non-fibrillar protein aggregation, and less efficiently reduces Aß42 fibril formation compared to rh Bri2 BRICHOS. This suggests that Bri2 and Bri3 BRICHOS have overlapping molecular mechanisms and that their apparently different tissue expression and processing may result in different physiological functions.

Augmentation of Bri2 molecular chaperone activity against amyloid-ß reduces neurotoxicity in mouse hippocampus in vitro.

Molecular chaperones play important roles in preventing protein misfolding and its potentially harmful consequences. Deterioration of molecular chaperone systems upon ageing are thought to underlie age-related neurodegenerative diseases, and augmenting their activities could have therapeutic potential. The dementia relevant domain BRICHOS from the Bri2 protein shows qualitatively different chaperone activities depending on quaternary structure, and assembly of monomers into high-molecular weight oligomers reduces the ability to prevent neurotoxicity induced by the Alzheimer-associated amyloid-ß peptide 1-42 (Aß42). Here we design a Bri2 BRICHOS mutant (R221E) that forms stable monomers and selectively blocks a main source of toxic species during Aß42 aggregation. Wild type Bri2 BRICHOS oligomers are partly disassembled into monomers in the presence of the R221E mutant, which leads to potentiated ability to prevent Aß42 toxicity to neuronal network activity. These results suggest that the activity of endogenous molecular chaperones may be modulated to enhance anti-Aß42 neurotoxic effects.