Vascular endothelial cell growth-activated XBP1 splicing in endothelial cells is crucial for angiogenesis

Endoplasmic reticulum stress is attenuated by glycolysis in lymphatic malformations

BACKGROUND

This study aims to investigate the role of endoplasmic reticulum stress (ER stress) in human dermal lymphatic endothelial cells (HDLECs) and lymphatic malformations (LMs) and its relationship with aerobic glycolysis and inflammation.

METHODS

The proliferation and apoptosis of HDLECs were examined with lipopolysaccharide (LPS) treatment. ER stress-associated proteins and glycolysis-related markers were detected by western blot. Glycolysis indexes were detected by seahorse analysis and lactic acid production assay kits. Immunohistochemistry was used to reveal the ER stress state of lymphatic endothelial cells (LECs) in LMs.

RESULTS

LPS induced ER stress in HDLECs but did not trigger detectable apoptosis. Intriguingly, LPS-treated HDLECs also showed increased glycolysis flux. Knockdown of Hexokinase 2, a key enzyme for aerobic glycolysis, significantly inhibited the ability of HDLECs to resist ER stress-induced apoptosis. Moreover, compared to normal skin, glucose-regulated protein 78 (GRP78/BIP), and phosphorylation protein kinase R-like kinase (p-PERK), two key ER stress-associated markers, were upregulated in LECs of LMs, which was correlated with the inflected state. In addition, excessively activated ER stress inhibited the progression of LMs in rat models.

CONCLUSIONS

These data indicate that glycolysis could rescue activated ER stress in HDLECs, which is required for the accelerated development of LMs.

IMPACT

Inflammation enhances both ER stress and glycolysis in LECs while glycolysis is required to attenuate the pro-apoptotic effect of ER stress. Endoplasmic reticulum (ER) stress is activated in lymphatic endothelial cells (LECs) of LMs, especially in inflammatory condition. The expression of ER stress-related proteins is increased in LMs and correlated with Hexokinase 2 expression. Pharmacological activation of ER stress suppresses the formation of LM lesions in the rat model. ER stress may be a promising and effective therapeutic target for the treatment of LMs.

Progression of unfolded protein response and ferroptosis in angiogenesis

Angiogenesis is the growth of new blood vessels on preexisting ones. It is the outcome of a multifactorial effect involving several cells, which can be brought on by different stress reactions.The accumulation of unfolded proteins in the endoplasmic reticulum occurs when cells are stressed due to environmental changes, where physical or chemical stimuli induce endoplasmic reticulum stress, thereby activating the unfolded protein response (UPR), a homeostasis response designed to re-establish protein balance. Ferroptosis is a planned death of lipid peroxidation and anomalies in metabolism that is dependent on iron. Large concentrations of iron ions accumulate there, along with high concentrations of lipid peroxides and reactive oxygen species, all of which can contribute to the development of several diseases. Through the production of growth factors, adhesion factors, and inflammatory factors that trigger the start of angiogenesis, both UPR and Ferroptosis can be implicated in angiogenesis.To set the stage for further research on angiogenesis, this work concentrated on the effects of Ferroptosis and UPR on angiogenesis, respectively.

HSP47 Increases the Expression of Type I Collagen in Fibroblasts through IRE1α Activation, XBP1 Splicing, and Nuclear Translocation of β-Catenin

Heat shock protein 47 (HSP47), also known as SERPINH1, functions as a collagen-specific molecular chaperone protein essential for the formation and stabilization of the collagen triple helix. Here, we delved into the regulatory pathways governed by HSP47, shedding light on collagen homeostasis. Our investigation revealed a significant reduction in HSP47 mRNA levels in the skin tissue of older mice as compared to their younger counterparts. The augmented expression of HSP47 employing lentivirus infection in fibroblasts resulted in an increased secretion of type I collagen. Intriguingly, the elevated expression of HSP47 in fibroblasts correlated with increased protein and mRNA levels of type I collagen. The exposure of fibroblasts to IRE1α RNase inhibitors resulted in the reduced manifestation of HSP47-induced type I collagen secretion and expression. Notably, HSP47-overexpressing fibroblasts exhibited increased XBP1 mRNA splicing. The overexpression of HSP47 or spliced XBP1 facilitated the nuclear translocation of β-catenin and transactivated a reporter harboring TCF binding sites on the promoter. Furthermore, the overexpression of HSP47 or spliced XBP1 or the augmentation of nuclear β-catenin through Wnt3a induced the expression of type I collagen. Our findings substantiate that HSP47 enhances type I collagen expression and secretion in fibroblasts by orchestrating a mechanism that involves an increase in nuclear β-catenin through IRE1α activation and XBP1 splicing. This study therefore presents potential avenues for an anti-skin-aging strategy targeting HSP47-mediated processes.

Transcriptomic signatures of individual cell types in cerebral cavernous malformation

Cerebral cavernous malformation (CCM) is a hemorrhagic neurovascular disease with no currently available therapeutics. Prior evidence suggests that different cell types may play a role in CCM pathogenesis. The contribution of each cell type to the dysfunctional cellular crosstalk remains unclear. Herein, RNA-seq was performed on fluorescence-activated cell sorted endothelial cells (ECs), pericytes, and neuroglia from CCM lesions and non-lesional brain tissue controls. Differentially Expressed Gene (DEG), pathway and Ligand-Receptor (LR) analyses were performed to characterize the dysfunctional genes of respective cell types within CCMs. Common DEGs among all three cell types were related to inflammation and endothelial-to-mesenchymal transition (EndMT). DEG and pathway analyses supported a role of lesional ECs in dysregulated angiogenesis and increased permeability. VEGFA was particularly upregulated in pericytes. Further pathway and LR analyses identified vascular endothelial growth factor A/ vascular endothelial growth factor receptor 2 signaling in lesional ECs and pericytes that would result in increased angiogenesis. Moreover, lesional pericytes and neuroglia predominantly showed DEGs and pathways mediating the immune response. Further analyses of cell specific gene alterations in CCM endorsed potential contribution to EndMT, coagulation, and a hypoxic microenvironment. Taken together, these findings motivate mechanistic hypotheses regarding non-endothelial contributions to lesion pathobiology and may lead to novel therapeutic targets. Video Abstract.

Hypoxia signaling and metastatic progression

Disruption of oxygen homeostasis, resulting from an imbalance between O2 supply and demand during malignant proliferation, leads to the development of hypoxic tumor microenvironments that promote the acquisition of aggressive cancer cell phenotypes linked to metastasis and patient mortality. In this review, the mechanistic links between tumor hypoxia and metastatic progression are presented. Current status and perspectives of targeting hypoxia signaling pathways as a strategy to halt cancer cell metastatic activities are emphasized.

IRE1α/XBP-1 promotes β-catenin signaling activation of airway epithelium in lipopolysaccharide-induced acute lung injury

BACKGROUND

Acute lung injury (ALI), along with the more severe condition--acute respiratory distress syndrome (ARDS), is a major cause of respiratory failure in critically ill patients with high morbidity and mortality. Inositol-requiring protein 1α (IRE1α)/X box protein-1 (XBP1) pathway was proved to regulate lipopolysaccharide (LPS)-induced lung injury and inflammation. Yet, its role on epithelial β-catenin in LPS-induced ALI remains to be elucidated.

METHODS

LPS-induced models were generated in mice (5 mg/kg) and Beas-2B cells (200 μg/mL). Two selective antagonists of IRE1α (4μ8c and STF-083010) were respectively given to LPS-exposed mice and cultured cells.

RESULTS

Up-regulated expression of endoplasmic reticulum (ER) stress markers immunoglobulin-binding protein (BIP) and spliced X box protein-1(XBP-1s) was detected after LPS exposure. Besides, LPS also led to a down-regulated total β-catenin level in the lung and Beas-2B cells, with decreased membrane distribution as well as increased cytoplasmic and nuclear accumulation, paralleled by extensively up-regulated downstream targets of the Wnt/β-catenin signaling. Treatment with either 4μ8c or STF-083010 not only significantly attenuated LPS-induced lung injury and inflammation, but also recovered β-catenin expression in airway epithelia, preserving the adhesive function of β-catenin while blunting its signaling activity.

CONCLUSION

These results illustrated that IRE1α/XBP1 pathway promoted the activation of airway epithelial β-catenin signaling in LPS-induced ALI.

Novel hub genes and regulatory network related to ferroptosis in tetralogy of Fallot

Ferroptosis is a newly discovered type of cell death mainly triggered by uncontrolled lipid peroxidation, and it could potentially have a significant impact on the development and progression of tetralogy of Fallot (TOF). Our project aims to identify and validate potential genes related to ferroptosis in TOF. We obtained sequencing data of TOF from the GEO database and ferroptosis-related genes from the ferroptosis database. We employed bioinformatics methods to analyze the differentially expressed mRNAs (DEmRNAs) and microRNAs between the normal control group and TOF group and identify DEmRNAs related to ferroptosis. Protein-protein interaction analysis was conducted to screen hub genes. Furthermore, a miRNA-mRNA-TF co-regulatory network was constructed to utilize prediction software. The expression of hub genes was further validated through quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). After conducting the differential gene analysis, we observed that in TOF, 41 upregulated mRNAs and three downregulated mRNAs associated with ferroptosis genes were found. Further Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analysis revealed that these genes were primarily involved in molecular functions and biological processes related to chemical stress, oxidative stress, cellular response to starvation, response to nutrient levels, cellular response to external stimulus, and cellular response to extracellular stimulus. Furthermore, we constructed a miRNA-mRNA-TF co-regulatory network. qRT-PCR analysis of the right ventricular tissues from human cases showed an upregulation in the mRNA levels of KEAP1 and SQSTM1. Our bioinformatics analysis successfully identified 44 potential genes that are associated with ferroptosis in TOF. This finding significantly contributes to our understanding of the molecular mechanisms underlying the development of TOF. Moreover, these findings have the potential to open new avenues for the development of innovative therapeutic approaches for the treatment of this condition.

Beyond UPR: cell-specific roles of ER stress sensor IRE1α in kidney ischemic injury and transplant rejection

Kidney damage due to ischemia or rejection results in the accumulation of unfolded and misfolded proteins in the endoplasmic reticulum (ER) lumen, a condition known as "ER stress." Inositol-requiring enzyme 1α (IRE1α), the first ER stress sensor found, is a type I transmembrane protein with kinase and endoribonuclease activity. On activation, IRE1α nonconventionally splices an intron from unspliced X-box-binding protein 1 (XBP1) mRNA to produce XBP1s mRNA that encodes the transcription factor, XBP1s, for the expression of genes encoding proteins that mediate the unfolded protein response. The unfolded protein response promotes the functional fidelity of ER and is required for secretory cells to sustain protein folding and secretory capability. Prolonged ER stress can lead to apoptosis, which may result in detrimental repercussions to organ health and has been implicated in the pathogenesis and progression of kidney diseases. The IRE1α-XBP1 signaling acts as a major arm of unfolded protein response and is involved in regulating autophagy, cell differentiation, and cell death. IRE1α also interacts with activator protein-1 and nuclear factor-κB pathways to regulate inflammatory responses. Studies using transgenic mouse models highlight that the roles of IRE1α differ depending on cell type and disease setting. This review covers these cell-specific roles of IRE1α signaling and the potential for therapeutic targeting of this pathway in the context of ischemia and rejection affecting the kidneys.

Endoplasmic reticulum stress: a novel targeted approach to repair bone defects by regulating osteogenesis and angiogenesis

Bone regeneration therapy is clinically important, and targeted regulation of endoplasmic reticulum (ER) stress is important in regenerative medicine. The processing of proteins in the ER controls cell fate. The accumulation of misfolded and unfolded proteins occurs in pathological states, triggering ER stress. ER stress restores homeostasis through three main mechanisms, including protein kinase-R-like ER kinase (PERK), inositol-requiring enzyme 1ɑ (IRE1ɑ) and activating transcription factor 6 (ATF6), collectively known as the unfolded protein response (UPR). However, the UPR has both adaptive and apoptotic effects. Modulation of ER stress has therapeutic potential for numerous diseases. Repair of bone defects involves both angiogenesis and bone regeneration. Here, we review the effects of ER stress on osteogenesis and angiogenesis, with emphasis on ER stress under high glucose (HG) and inflammatory conditions, and the use of ER stress inducers or inhibitors to regulate osteogenesis and angiogenesis. In addition, we highlight the ability for exosomes to regulate ER stress. Recent advances in the regulation of ER stress mediated osteogenesis and angiogenesis suggest novel therapeutic options for bone defects.

Histologic and proteomic remodeling of the pulmonary veins and arteries in a porcine model of chronic pulmonary venous hypertension

AIMS

In heart failure (HF), pulmonary venous hypertension (PVH) produces pulmonary hypertension (PH) with remodeling of pulmonary veins (PV) and arteries (PA). In a porcine PVH model, we performed proteomic-based bioinformatics to investigate unique pathophysiologic mechanisms mediating PA and PV remodeling.

METHODS AND RESULTS

Large PV were banded (PVH, n = 10) or not (Sham, n = 9) in piglets. At sacrifice, PV and PA were perfusion labelled for vessel-specific histology and proteomics. The PA and PV were separately sampled with laser-capture micro-dissection for mass spectrometry. Pulmonary vascular resistance [Wood Units; 8.6 (95% confidence interval: 6.3, 12.3) vs. 2.0 (1.7, 2.3)] and PA [19.9 (standard error of mean, 1.1) vs. 10.3 (1.1)] and PV [14.2 (1.2) vs. 7.6 (1.1)] wall thickness/external diameter (%) were increased in PVH (P < 0.05 for all). Similar numbers of proteins were identified in PA (2093) and PV (2085) with 94% overlap, but biological processes differed. There were more differentially expressed proteins (287 vs. 161), altered canonical pathways (17 vs. 3), and predicted upstream regulators (PUSR; 22 vs. 6) in PV than PA. In PA and PV, bioinformatics indicated activation of the integrated stress response and mammalian target of rapamycin signalling with dysregulated growth. In PV, there was also activation of Rho/Rho-kinase signalling with decreased actin cytoskeletal signalling and altered tight and adherens junctions, ephrin B, and caveolae-mediated endocytosis signalling; all indicating disrupted endothelial barrier function. Indeed, protein biomarkers and the top PUSR in PV (transforming growth factor-beta) suggested endothelial to mesenchymal transition in PV. Findings were similar in human autopsy specimens.

CONCLUSION

These findings provide new therapeutic targets to oppose pulmonary vascular remodeling in HF-related PH.

The Drp1-Mediated Mitochondrial Fission Protein Interactome as an Emerging Core Player in Mitochondrial Dynamics and Cardiovascular Disease Therapy

Mitochondria, the membrane-bound cell organelles that supply most of the energy needed for cell function, are highly regulated, dynamic organelles bearing the ability to alter both form and functionality rapidly to maintain normal physiological events and challenge stress to the cell. This amazingly vibrant movement and distribution of mitochondria within cells is controlled by the highly coordinated interplay between mitochondrial dynamic processes and fission and fusion events, as well as mitochondrial quality-control processes, mainly mitochondrial autophagy (also known as mitophagy). Fusion connects and unites neighboring depolarized mitochondria to derive a healthy and distinct mitochondrion. In contrast, fission segregates damaged mitochondria from intact and healthy counterparts and is followed by selective clearance of the damaged mitochondria via mitochondrial specific autophagy, i.e., mitophagy. Hence, the mitochondrial processes encompass all coordinated events of fusion, fission, mitophagy, and biogenesis for sustaining mitochondrial homeostasis. Accumulated evidence strongly suggests that mitochondrial impairment has already emerged as a core player in the pathogenesis, progression, and development of various human diseases, including cardiovascular ailments, the leading causes of death globally, which take an estimated 17.9 million lives each year. The crucial factor governing the fission process is the recruitment of dynamin-related protein 1 (Drp1), a GTPase that regulates mitochondrial fission, from the cytosol to the outer mitochondrial membrane in a guanosine triphosphate (GTP)-dependent manner, where it is oligomerized and self-assembles into spiral structures. In this review, we first aim to describe the structural elements, functionality, and regulatory mechanisms of the key mitochondrial fission protein, Drp1, and other mitochondrial fission adaptor proteins, including mitochondrial fission 1 (Fis1), mitochondrial fission factor (Mff), mitochondrial dynamics 49 (Mid49), and mitochondrial dynamics 51 (Mid51). The core area of the review focuses on the recent advances in understanding the role of the Drp1-mediated mitochondrial fission adaptor protein interactome to unravel the missing links of mitochondrial fission events. Lastly, we discuss the promising mitochondria-targeted therapeutic approaches that involve fission, as well as current evidence on Drp1-mediated fission protein interactions and their critical roles in the pathogeneses of cardiovascular diseases (CVDs).

E2F2 Promotes Wound Healing of Diabetic Foot Ulcer by Regulating CDCA7L Transcription

OBJECTIVE

The E2F2 transcription factor can accelerate cell proliferation and wound healing. However, its mechanism of action in a diabetic foot ulcer (DFU) remains unclear. Therefore, this study explores the influence of E2F2 on wound healing in DFU by examining cell division cycle-associated 7-like (CDCA7L) expression.

METHODS

CDCA7L and E2F2 expression in DFU tissues were analyzed with databases. CDCA7L and E2F2 expression were altered in human umbilical vein endothelial cells (HUVECs) and spontaneously transformed human keratinocyte cell culture (HaCaT) cells. Cell viability, migration, colony formation, and angiogenesis were evaluated. Binding of E2F2 to the CDCA7L promoter was examined. Subsequently, a diabetes mellitus (DM) mouse model was established and treated with full-thickness excision followed by CDCA7L overexpression. Wound healing in these mice was observed and recorded, and vascular endothelial growth factor receptor 2 (VEGFR2) and hematopoietic progenitor cell antigen CD34 (CD34) expression were determined. E2F2 and CDCA7L expression levels in cells and mice were evaluated. The expression of growth factors was tested.

RESULTS

CDCA7L expression was downregulated in DFU tissues and wound tissues from DM mice. Mechanistically, E2F2 bound to the CDCA7L promoter to upregulate CDCA7L expression. E2F2 overexpression enhanced viability, migration, and growth factor expression in HaCaT cells and HUVECs, and augmented HUVEC angiogenesis and HaCaT cell proliferation, which was nullified by silencing CDCA7L. In DM mice, CDCA7L overexpression facilitated wound healing and elevated the expression level of growth factors.

CONCLUSIONS

E2F2 facilitated cell proliferation and migration and fostered wound healing in DFU cells through binding to the CDCA7L promoter.

Unfolded protein response and angiogenesis in malignancies

Cellular stress, arising from accumulation of unfolded proteins, occurs frequently in rapidly proliferating cancer cells. This cellular stress, in turn, activates the unfolded protein response (UPR), an interconnected set of signal transduction pathways that alleviate the proteostatic stress. The UPR is implicated in cancer cell survival and proliferation through upregulation of pro-tumorigenic pathways that ultimately promote malignant metabolism and neoangiogenesis. Here, we reviewed mechanisms of signaling crosstalk between the UPR and angiogenesis pathways, as well as transmissible ER stress and the role in tumor growth and development. To characterize differences in UPR and UPR-mediated angiogenesis in malignancy, we employed a data mining approach using patient tumor data from The Cancer Genome Atlas (TCGA). The analysis of TCGA revealed differences in UPR between malignant samples versus their non-malignant counterparts.

Boosting UPR transcriptional activator XBP1 accelerates acute wound healing

Patients' suffering from large or deep wounds caused by traumatic and/or thermal injuries have significantly lower chances of recapitulating lost skin function through natural healing. We tested whether enhanced unfolded protein response (UPR) by expression of a UPR transcriptional activator, X-box-binding protein 1 (XBP1) can significantly promote wound repair through stimulating growth factor production and promoting angiogenesis. In mouse models of a second-degree thermal wound, a full-thickness traumatic wound, and a full-thickness diabetic wound, the topical gene transfer of the activated form of XBP1 (spliced XBP1, XBP1s) can significantly enhance re-epithelialization and increase angiogenesis, leading to rapid, nearly complete wound closure with intact regenerated epidermis and dermis. Overexpression of XBP1s stimulated the transcription of growth factors in fibroblasts critical to proliferation and remodeling during wound repair, including platelet-derived growth factor BB, basic fibroblast growth factor, and transforming growth factor beta 3. Meanwhile, the overexpression of XBP1s boosted the migration and tube formation of dermal microvascular endothelial cells in vitro. Our functional and mechanistic investigations of XBP1-mediated regulation of wound healing processes provide novel insights into the previously undermined physiological role of the UPR in skin injuries. The finding opens an avenue to developing potential XBP1-based therapeutic strategies in clinical wound care protocols.

SUMO1 regulates post-infarct cardiac repair based on cellular heterogeneity

Small ubiquitin-related modifier (SUMOylation) is a dynamic post-translational modification that maintains cardiac function and can protect against a hypertrophic response to cardiac pressure overload. However, the function of SUMOylation after myocardial infarction (MI) and the molecular details of heart cell responses to SUMO1 deficiency have not been determined. In this study, we demonstrated that SUMO1 protein was inconsistently abundant in different cell types and heart regions after MI. However, SUMO1 knockout significantly exacerbated systolic dysfunction and infarct size after myocardial injury. Single-nucleus RNA sequencing revealed the differential role of SUMO1 in regulating heart cells. Among cardiomyocytes, SUMO1 deletion increased the Nppa ⁺ Nppb ⁺ Ankrd1 ⁺ cardiomyocyte subcluster proportion after MI. In addition, the conversion of fibroblasts to myofibroblasts subclusters was inhibited in SUMO1 knockout mice. Importantly, SUMO1 loss promoted proliferation of endothelial cell subsets with the ability to reconstitute neovascularization and expressed angiogenesis-related genes. Computational analysis of ligand/receptor interactions suggested putative pathways that mediate cardiomyocytes to endothelial cell communication in the myocardium. Mice preinjected with cardiomyocyte-specific AAV-SUMO1, but not the endothelial cell-specific form, and exhibited ameliorated cardiac remodeling following MI. Collectively, our results identified the role of SUMO1 in cardiomyocytes, fibroblasts, and endothelial cells after MI. These findings provide new insights into SUMO1 involvement in the pathogenesis of MI and reveal novel therapeutic targets.

Molecular Mechanism Underlying Role of the XBP1s in Cardiovascular Diseases

Spliced X-box binding protein-1 (XBP1s) is a protein that belongs to the cAMP-response element-binding (CREB)/activating transcription factor (ATF) b-ZIP family with a basic-region leucine zipper (bZIP). There is mounting evidence to suggest that XBP1s performs a critical function in a range of different cardiovascular diseases (CVDs), indicating that it is necessary to gain a comprehensive knowledge of the processes involved in XBP1s in various disorders to make progress in research and clinical therapy. In this research, we provide a summary of the functions that XBP1s performs in the onset and advancement of CVDs such as atherosclerosis, hypertension, cardiac hypertrophy, and heart failure. Furthermore, we discuss XBP1s as a novel therapeutic target for CVDs.

X-box binding protein 1 as a key modulator in “healing endothelial cells”, a novel EC phenotype promoting angiogenesis after MCAO

Background

Endothelial cells (ECs) play an important role in angiogenesis and vascular reconstruction in the pathophysiology of ischemic stroke. Previous investigations have provided a profound cerebral vascular atlas under physiological conditions, but have failed to identify new disease-related cell subtypes. We aimed to identify new EC subtypes and determine the key modulator genes.

Methods

Two datasets GSE174574 and GSE137482 were included in the study. Seurat was utilized as the standard quality-control pipeline. UCell was used to calculate single-cell scores to validate cellular identity. Monocle3 and CytoTRACE were utilized in aid of pseudo-time differentiation analysis. CellChat was utilized to infer the intercellular communication pathways. The angiogenesis ability of ECs was validated by MTS, Transwell, tube formation, flow cytometry, and immunofluorescence assays in vitro and in vivo. A synchrotron radiation-based propagation contrast imaging was introduced to comprehensively portray cerebral vasculature.

Results

We successfully identified a novel subtype of EC named “healing EC” that highly expressed pan-EC marker and pro-angiogenic genes but lowly expressed all the arteriovenous markers identified in the vascular single-cell atlas. Further analyses showed its high stemness to differentiate into other EC subtypes and potential to modulate inflammation and angiogenesis via excretion of signal molecules. We therefore identified X-box binding protein 1 (Xbp1) as a key modulator in the healing EC phenotype. In vitro and in vivo experiments confirmed its pro-angiogenic roles under both physiological and pathological conditions. Synchrotron radiation-based propagation contrast imaging further proved that Xbp1 could promote angiogenesis and recover normal vasculature conformation, especially in the corpus striatum and prefrontal cortex under middle cerebral artery occlusion (MCAO) condition.

Conclusions

Our study identified a novel disease-related EC subtype that showed high stemness to differentiate into other EC subtypes. The predicted molecule Xbp1 was thus confirmed as a key modulator that can promote angiogenesis and recover normal vasculature conformation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00399-5.

Music improves the therapeutic effects of bevacizumab in rats with glioblastoma: Modulation of drug distribution to the brain

Background

The development of new methods for modulation of drug distribution across to the brain is a crucial step in the effective therapies for glioblastoma (GBM). In our previous work, we discovered the phenomenon of music-induced opening of the blood-brain barrier (OBBB) in healthy rodents. In this pilot study on rats, we clearly demonstrate that music-induced BBB opening improves the therapeutic effects of bevacizumab (BZM) in rats with GBM via increasing BZM distribution to the brain along the cerebral vessels.

Methods

The experiments were performed on Wistar male rats (200–250 g, n=161) using transfected C6-TagRFP cell line and the loud rock music for OBBB. The OBBB was assessed by spectrofluorometric assay of Evans Blue (EB) extravasation and confocal imaging of fluorescent BZM (fBZM) delivery into the brain. Additionally, distribution of fBZM and Omniscan in the brain was studied using fluorescent and magnetic resonance imaging (MRI), respectively. To analyze the therapeutic effects of BZM on the GBM growth in rats without and with OBBB, the GBM volume (MRI scans), as well as immunohistochemistry assay of proliferation (Ki67 marker) and apoptosis (Bax marker) in the GBM cells were studied. The Mann–Whitney–Wilcoxon test was used for all analysis, the significance level was p < 0.05, n=7 in each group.

Results

Our finding clearly demonstrates that music-induced OBBB increases the delivery of EB into the brain tissues and the extravasation of BZM into the brain around the cerebral vessels of rats with GBM. Music significantly increases distribution of tracers (fBZM and Omniscan) in the rat brain through the pathways of brain drainage system (perivascular and lymphatic), which are an important route of drug delivery into the brain. The music-induced OBBB improves the suppressive effects of BZM on the GBM volume and the cellular mechanisms of tumor progression that was accompanied by higher survival among rats in the GBM+BZM+Music group vs. other groups.

Conclusion

We hypothesized that music improves the therapeutic effects of BZM via OBBB in the normal cerebral vessels and lymphatic drainage of the brain tissues. This contributes better distribution of BZM in the brain fluids and among the normal cerebral vessels, which are used by GBM for invasion and co-opt existing vessels as a satellite tumor form. These results open the new perspectives for an improvement of therapeutic effects of BZM via the music-induced OBBB for BZM in the normal cerebral vessels, which are used by GBM for migration and progression.

UPR Responsive Genes Manf and Xbp1 in Stroke

Stroke is a devastating medical condition with no treatment to hasten recovery. Its abrupt nature results in cataclysmic changes in the affected tissues. Resident cells fail to cope with the cellular stress resulting in massive cell death, which cannot be endogenously repaired. A potential strategy to improve stroke outcomes is to boost endogenous pro-survival pathways. The unfolded protein response (UPR), an evolutionarily conserved stress response, provides a promising opportunity to ameliorate the survival of stressed cells. Recent studies from us and others have pointed toward mesencephalic astrocyte-derived neurotrophic factor (MANF) being a UPR responsive gene with an active role in maintaining proteostasis. Its pro-survival effects have been demonstrated in several disease models such as diabetes, neurodegeneration, and stroke. MANF has an ER-signal peptide and an ER-retention signal; it is secreted by ER calcium depletion and exits cells upon cell death. Although its functions remain elusive, conducted experiments suggest that the endogenous MANF in the ER lumen and exogenously administered MANF protein have different mechanisms of action. Here, we will revisit recent and older bodies of literature aiming to delineate the expression profile of MANF. We will focus on its neuroprotective roles in regulating neurogenesis and inflammation upon post-stroke administration. At the same time, we will investigate commonalities and differences with another UPR responsive gene, X-box binding protein 1 (XBP1), which has recently been associated with MANF’s function. This will be the first systematic comparison of these two UPR responsive genes aiming at revealing previously uncovered associations between them. Overall, understanding the mode of action of these UPR responsive genes could provide novel approaches to promote cell survival.

DDX55 promotes HCC progression via interacting with BRD4 and participating in exosome-mediated cell-cell communication

The involvement of DEAD‐box helicase 55 (DDX55) in oncogenesis has been suggested, but its biological role in hepatocellular carcinoma (HCC) remains unknown. The present study verified the upregulation of DDX55 in HCC tissues compared with non‐tumor controls. DDX55 displayed the highest prognostic values among the DEAD‐box protein family for recurrence‐free survival and overall survival of HCC patients. In addition, the effects of DDX55 in the promotion of HCC cell proliferation, migration, and invasion were determined ex vivo and in vivo. Mechanistically, we revealed that DDX55 could interact with BRD4 to form a transcriptional regulatory complex that positively regulated PIK3CA transcription. Following that, β‐catenin signaling was activated in a PI3K/Akt/GSK‐3β dependent manner, thus inducing cell cycle progression and epithelial–mesenchymal transition. Intriguingly, both DDX55 mRNA and protein were identified in the exosomes derived from HCC cells. Exosomal DDX55 was implicated in intercellular communication between HCC cells with high or low DDX55 levels and between HCC cells and endothelial cells, thereby promoting the malignant phenotype of HCC cells and angiogenesis. In conclusion, DDX55 may be a valuable prognostic biomarker and therapeutic target in HCC.

Oxidative Stress-Induced Growth Inhibitor (OSGIN1), a Target of X-Box-Binding Protein 1, Protects Palmitic Acid-Induced Vascular Lipotoxicity through Maintaining Autophagy

Saturated free fatty acids (FFAs) strongly correlate with metabolic syndromes and are well-known risk factors for cardiovascular diseases (CVDs). The mechanism of palmitic acid (PA)-induced vascular lipotoxicity under endoplasmic reticulum (ER) stress is unknown. In the present paper, we investigate the roles of spliced form of X-box-binding protein 1 (XBP1s) target gene oxidative stress-induced growth inhibitor 1 (OSGIN1) in PA-induced vascular dysfunction. PA inhibited the tube formation assay of primary human umbilical vein endothelial cells (HUVECs). Simultaneously, PA treatment induced the XBP1s expression in HUVECs. Attenuate the induction of XBP1s by silencing the XBP1s retarded cell migration and diminished endothelial nitric oxide synthase (eNOS) expression. OSGIN1 is a target gene of XBP1s under PA treatment. The silencing of OSGIN1 inhibits cell migration by decreasing phospho-eNOS expression. PA activated autophagy in endothelial cells, inhibiting autophagy by 3-methyladenine (3-MA) decreased endothelial cell migration. Silencing XBP1s and OSGIN1 would reduce the induction of LC3 II; therefore, OSGIN1 could maintain autophagy to preserve endothelial cell migration. In conclusion, PA treatment induced ER stress and activated the inositol-requiring enzyme 1 alpha–spliced XBP1 (IRE1α–XBP1s) pathway. OSGIN1, a target gene of XBP1s, could protect endothelial cells from vascular lipotoxicity by regulating autophagy.

Compound Tongluo Decoction inhibits endoplasmic reticulum stress-induced ferroptosis and promoted angiogenesis by activating the Sonic Hedgehog pathway in cerebral infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebral infarction is one of the most common types of cerebrovascular diseases that threaten people's health. Compound Tongluo Decoction (CTLD), a traditional Chinese medicine formula, has various pharmacological activities, including the alleviation of cerebral infarction symptoms.

AIM OF THE STUDY

This study aims to explore the potential mechanism by which CTLD alleviates cerebral infarction.

MATERIAL AND METHODS

Middle cerebral artery occlusion (MCAO) rat model and oxygen-glucose deprivation and reperfusion (OGD/R) cell model were established for research. The expression of proteins related to endoplasmic reticulum (ER) stress, ferroptosis, Sonic Hedgehog (SHH) pathway and angiogenesis was analyzed by Western blot analysis. The expression of CD31 was detected by immunofluorescence to investigate angiogenesis. In addition, the expression of GRP78 and XBP-1 in brain tissues was investigated by immunohistochemistry. With the application of Prussian blue staining, iron deposition in brain tissue was detected. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) were detected using ELISA kits. The angiogenesis was analyzed by tube formation assay.

RESULTS

The results presented in this research showed that CTLD and 4-phenyl butyric acid (4-PBA; the inhibitor of ER stress) could alleviate cerebral infarction. Mechanistically, CTLD and 4-PBA rescued ER stress and ferroptosis, but promoted SHH signaling in rats with cerebral infarction. In addition, cerebral infarction exhibited a high level of angiogenesis, which was aggravated by CTLD but suppressed by 4-PBA. Furthermore, CTLD inhibited ER stress and ferroptosis, but promoted SHH signaling and angiogenesis in OGD/R-induced PC12 cells, which was partly abolished by SANT-1, an antagonist of SHH signaling.

CONCLUSION

In conclusion, this study revealed that CTLD might inhibit ferroptosis induced by endoplasmic reticulum stress and promote angiogenesis by activating the Sonic Hedgehog pathway in rats with cerebral infarction.

Proteomic analysis reveals that Xbp1s promotes hypoxic pulmonary hypertension through the p-JNK MAPK pathway

Hypoxic pulmonary hypertension (HPH) is characterized by elevated pulmonary artery resistance and vascular remodeling. Endoplasmic reticulum stress (ERS) is reported to be involved in HPH, but the underlying mechanisms remain uncertain. We found that Xbp1s, a potent transcription factor during ERS, was elevated in hypoxic-cultured rat PASMCs and lung tissues from HPH rats. Our in vitro experiments demonstrated that overexpressing Xbp1s can promote proliferation, cell viability, and migration and inhibit the apoptosis of PASMCs, while silencing Xbp1s led to the opposite. Through data-independent acquisition (DIA) mass spectrometry, we identified extensive proteomic alterations regulated by hypoxia and Xbp1s. Further validation revealed that p-JNK, rather than p-ERK or p-p38, was the downstream effector of Xbp1s. p-JNK inhibition reversed the biological effects of Xbp1s overexpression in vitro. In the animal HPH model, rats were randomly assigned to five groups: normoxia, hypoxia, hypoxia+AAV-CTL (control), hypoxia+AAV-Xbp1s (prevention), and hypoxia+AAV-Xbp1s (therapy). Adeno-associated virus (AAV) serotype 1-mediated Xbp1s knockdown in the prevention and therapy groups significantly reduced right ventricular systolic pressure, total pulmonary resistance, right ventricular hypertrophy, and the medial wall thickness of muscularized distal pulmonary arterioles; AAV-Xbp1s also decreased proliferating cell nuclear antigen expression and increased apoptosis in pulmonary arterioles. Collectively, our findings demonstrated that the Xbp1s-p-JNK pathway is important in hypoxic vascular remodeling and that targeting this pathway could be an effective strategy to prevent and alleviate HPH development.

Inflammation and convergent placenta gene co-option contributed to a novel reproductive tissue

The evolution of pregnancy exposes parental tissues to new, potentially stressful conditions, which can trigger inflammation.¹ Inflammation is costly^2,3 and can induce embryo rejection, which constrains the evolution of pregnancy.¹ In contrast, inflammation can also promote morphological innovation at the maternal-embryonic interface as exemplified by co-option of pro-inflammatory signaling for eutherian embryo implantation.^1,4,5 Given its dual function, inflammation could be a key process explaining how innovations such as pregnancy and placentation evolved many times convergently. Pelvic brooding ricefishes evolved a novel “plug” tissue,^6,7 which forms inside the female gonoduct after spawning, anchors egg-attaching filaments, and enables pelvic brooders to carry eggs externally until hatching.^6,8 Compared to pregnancy, i.e., internal bearing of embryos, external bearing should alleviate constraints on inflammation in the reproductive tract. We thus hypothesized that an ancestral inflammation triggered by the retention of attaching filaments gave rise to pathways orchestrating plug formation. In line with our hypothesis, histological sections of the developing plug revealed signs of gonoduct injuries by egg-attaching filaments in the pelvic brooding ricefish Oryzias eversi. Tissue-specific transcriptomes showed that inflammatory signaling dominates the plug transcriptome and inflammation-induced genes controlling vital processes for plug development such as tissue growth and angiogenesis were overexpressed in the plug. Finally, mammalian placenta genes were enriched in the plug transcriptome, indicating convergent gene co-option for building, attaching, and sustaining a transient tissue in the female reproductive tract. This study highlights the role of gene co-option and suggests that recruiting inflammatory signaling into physiological processes provides a fast-track to evolutionary innovation.

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Pelvic brooding induces tissue-specific changes in gene expression

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Inflammatory signaling characterizes transcriptome of the egg-anchoring plug

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Similar to embryo implantation, the plug likely evolved from an inflammatory response

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Mammalian placenta genes were independently co-opted into the plug

Unspliced XBP1 Counteracts β-catenin to Inhibit Vascular Calcification

Background: Vascular calcification is a prevalent complication in chronic kidney disease and contributes to increased cardiovascular morbidity and mortality. XBP1 (X-box binding protein 1), existing as the unspliced (XBP1u) and spliced (XBP1s) forms, is a key component of the endoplasmic reticulum stress involved in vascular diseases. However, whether XBP1u participates in the development of vascular calcification remains unclear. Methods: We aim to investigate the role of XBP1u in vascular calcification.XBP1u protein levels were reduced in high phosphate (Pi)-induced calcified vascular smooth muscle cells (VSMCs), calcified aortas from mice with adenine diet-induced chronic renal failure (CRF) and calcified radial arteries from CRF patients. Results: Inhibition of XBP1u rather than XBP1s upregulated in the expression of the osteogenic markers runt-related transcription factor 2 (Runx2) and msh homeobox2 (Msx2), and exacerbated high Pi-induced VSMC calcification, as verified by calcium deposition and Alizarin red S staining. In contrast, XBP1u overexpression in high Pi-induced VSMCs significantly inhibited osteogenic differentiation and calcification. Consistently, SMC-specific XBP1 deficiency in mice markedly aggravated the adenine diet- and 5/6 nephrectomy-induced vascular calcification compared with that in the control littermates. Further interactome analysis revealed that XBP1u bound directly to β-catenin, a key regulator of vascular calcification, via aa 205-230 in its C-terminal degradation domain. XBP1u interacted with β-catenin to promote its ubiquitin-proteasomal degradation and thus inhibited β-catenin/T-cell factor (TCF)-mediated Runx2 and Msx2 transcription. Knockdown of β-catenin abolished the effect of XBP1u deficiency on VSMC calcification, suggesting a β-catenin-mediated mechanism. Moreover, the degradation of β-catenin promoted by XBP1u was independent of glycogen synthase kinase 3β (GSK-3β)-involved destruction complex. Conclusions: Our study identified XBP1u as a novel endogenous inhibitor of vascular calcification by counteracting β-catenin and promoting its ubiquitin-proteasomal degradation, which represents a new regulatory pathway of β-catenin and a promising target for vascular calcification treatment.

Xbp1s-Ddit3 promotes MCT-induced pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening disease characterized by vascular remodeling. Exploring new therapy target is urgent. The purpose of the present study is to investigate whether and how spliced x-box binding protein 1 (xbp1s), a key component of endoplasmic reticulum stress (ERS), contributes to the pathogenesis of PH. Forty male SD rats were randomly assigned to four groups: Control, Monocrotaline (MCT), MCT+AAV-CTL (control), and MCT+AAV-xbp1s. The xbp1s protein levels were found to be elevated in lung tissues of the MCT group. Intratracheal injection of adeno-associated virus serotype 1 carrying xbp1s shRNA (AAV-xbp1s) to knock down the expression of xbp1s effectively ameliorated the MCT-induced elevation of right ventricular systolic pressure (RVSP), total pulmonary resistance (TPR), right ventricular hypertrophy and medial wall thickness of muscularized distal pulmonary arterioles. The abnormally increased positive staining rates of proliferating cell nuclear antigen (PCNA) and Ki67 and decreased positive staining rates of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) in pulmonary arterioles were also reversed in the MCT+AAV-xbp1s group. For mechanistic exploration, bioinformatics prediction of the protein network was performed on the STRING database, and further verification was performed by qRT-PCR, Western blots and co-immunoprecipitation (Co-IP). DNA damage-inducible transcript 3 (Ddit3) was identified as a downstream protein that interacted with xbp1s. Overexpression of Ddit3 restored the decreased proliferation, migration and cell viability caused by silencing of xbp1s. The protein level of Ddit3 was also highly consistent with xbp1s in the animal model. Taken together, our study demonstrated that xbp1s-Ddit3 may be a potential target to interfere with vascular remodeling in PH.

The special unfolded protein response in plasma cells

The high rate of antibody production places considerable metabolic and folding stress on plasma cells (PC). Not surprisingly, they rely on the unfolded protein response (UPR), a universal signaling, and transcriptional network that monitors the health of the secretory pathway and mounts cellular responses to stress. Typically, the UPR utilizes three distinct stress sensors in the ER membrane, each regulating a subset of targets to re-establish homeostasis. PC use a specialized UPR scheme-they preemptively trigger the UPR via developmental signals and suppress two of the sensors, PERK and ATF6, relying on IRE1 alone. The specialized PC UPR program is tuned to the specific needs at every stage of development-from early biogenesis of secretory apparatus, to massive immunoglobulin expression later. Furthermore, the UPR in PC integrates with other pathways essential in a highly secretory cell-mTOR pathway that ensures efficient synthesis, autophagosomes that recycle components of the synthetic machinery, and apoptotic signaling that controls cell fate in the face of excessive folding stress. This specialized PC program is not shared with other secretory cells, for reasons yet to be defined. In this review, we give a perspective into how and why PC need such a unique UPR program.

Gastric cancer-secreted exosomal X26nt increases angiogenesis and vascular permeability by targeting VE-cadherin

Angiogenesis is closely associated with tumorigenesis, invasion, and metastasis by providing oxygen and nutrients. Recently, increasing evidence indicates that cancer-derived exosomes which contain proteins, coding, and noncoding RNAs (ncRNAs) were shown to have proangiogenic function in cancer. A 26-nt-long ncRNA (X26nt) is generated in the process of inositol-requiring enzyme 1 alpha (IRE1α)-induced unspliced XBP1 splicing. However, the role of X26nt in the angiogenesis of gastric cancer (GC) remains largely unknown. In the present study, we found that X26nt was significantly elevated in GC and GC exosomes. Then, we verified that X26nt could be delivered into human umbilical vein endothelial cells (HUVECs) via GC cell exosomes and promote the proliferation, migration, and tube formation of HUVECs. We revealed that exosomal X26nt decreased vascular endothelial cadherin (VE-cadherin) by directly combining the 3'UTR of VE-cadherin mRNA in HUVECs, thereby increasing vascular permeability. We further demonstrated that X26nt accelerates the tumor growth and angiogenesis in a mouse subcutaneous tumor model. Our findings investigate a unique intercellular communication mediated by cancer-derived exosomes and reveal a novel mechanism of exosomal X26nt in the regulation of tumor vasculature.

Bioactive glass activates VEGF paracrine signaling of cardiomyocytes to promote cardiac angiogenesis

The heart contains a wide range of cell types, which are not isolated but interact with one another via multifarious paracrine, autocrine and endocrine factors. In terms of cardiac angiogenesis, previous studies have proved that regulating the communication between cardiomyocytes and endothelial cells is efficacious to promote capillary formation. Firstly, this study investigated the effect and underlying mechanism of bioactive glass (BG) acted on vascular endothelial growth factor (VEGF) paracrine signaling in cardiomyocytes. We found that bioactive ions released from BG significantly promoted the VEGF production and secretion of cardiomyocytes. Subsequently, we proved that cardiomyocyte-derived VEGF played an important role in mediating the behavior of endothelial cells. Further research showed that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway was upregulated by BG, which was involved in VEGF expression of cardiomyocytes. This study revealed that by means of modulating cellular crosstalk via paracrine signaling of host cells in heart is a new direction for the application of BGs in cardiac angiogenesis.

Functional relationship between CFTR and RAC3 expression for maintaining cancer cell stemness in human colorectal cancer

PURPOSE

CFTR mutations not only cause cystic fibrosis, but also increase the risk of colorectal cancer. A putative role of CFTR in colorectal cancer patients without cystic fibrosis has so far, however, not been investigated. RAC3 is a nuclear receptor coactivator that has been found to be overexpressed in several human tumors, and to be required for maintaining cancer stemness. Here, we investigated the functional relationship between CFTR and RAC3 for maintaining cancer stemness in human colorectal cancer.

METHODS

Cancer stemness was investigated by analysing the expression of stem cell markers, clonogenic growth and selective retention of fluorochrome, using stable transfection of shCFTR or shRAC3 in HCT116 colorectal cancer cells. In addition, we performed pathway enrichment and network analyses in both primary human colorectal cancer samples (TCGA, Xena platform) and Caco-2 colorectal cancer cells including (1) CD133+ or CD133- side populations and (2) CFTRwt or CFTRmut cells (ConsensusPathDB, STRING, Cytoscape, GeneMANIA).

RESULTS

We found that the CD133+ side population expresses higher levels of RAC3 and CFTR than the CD133- side population. RAC3 overexpression increased CFTR expression, whereas CFTR downregulation inhibited the cancer stem phenotype. CFTR mRNA levels were found to be increased in colorectal cancer samples from patients without cystic fibrosis compared to those with CFTR mutations, and this correlated with an increased expression of RAC3. The expression pattern of a gene set involved in inflammatory response and nuclear receptor modulation in CD133+ Caco-2 cells was found to be shared with that in CFTRwt Caco-2 cells. These genes may contribute to colorectal cancer development.

CONCLUSIONS

CFTR may play a non-tumor suppressor role in colorectal cancer development and maintenance involving enhancement of the expression of a set of genes related to cancer stemness and development in patients without CFTR mutations.

A meta-analysis of microRNA expression profiling studies in heart failure

Heart failure (HF) is a major consequence of many cardiovascular diseases with high rate of morbidity and mortality. Early diagnosis and prevention are hampered by the lack of informative biomarkers. The aim of this study was to perform a meta-analysis of the miRNA expression profiling studies in HF to identify novel candidate biomarkers or/and therapeutic targets. A comprehensive literature search of the PubMed for miRNA expression studies related to HF was carried out. The vote counting and robust rank aggregation meta-analysis methods were used to identify significant meta-signatures of HF-miRs. The targets of HF-miRs were identified, and network construction and gene set enrichment analysis (GSEA) were performed to identify the genes and cognitive pathways most affected by the dysregulation of the miRNAs. The literature search identified forty-five miRNA expression studies related to CHF. Shared meta-signature was identified for 3 up-regulated (miR-21, miR-214, and miR-27b) and 13 down-regulated (miR-133a, miR-29a, miR-29b, miR-451, miR-185, miR-133b, miR-30e, miR-30b, miR-1, miR-150, miR-486, miR-149, and miR-16-5p) miRNAs. Network properties showed miR-29a, miR-21, miR-29b, miR-1, miR-16, miR-133a, and miR-133b have the most degree centrality. GESA identified functionally related sets of genes in signaling and community pathways in HF that are the targets of HF-miRs. The miRNA expression meta-analysis identified sixteen highly significant HF-miRs that are differentially expressed in HF. Further validation in large patient cohorts is required to confirm the significance of these miRs as HF biomarkers and therapeutic targets.

Development of targeted therapy therapeutics to sensitize triple-negative breast cancer chemosensitivity utilizing bacteriophage phi29 derived packaging RNA

Background

To date, triple-negative breast cancer (TNBC) treatment options are limited because of the loss of target receptors and, as a result, are only managed with chemotherapy. What is worse is that TNBC is frequently developing resistance to chemotherapy. By using small interfering RNA (siRNA)-based therapeutics, our recent work demonstrated X-box-binding protein 1 (XBP1) was linked to human epidermal growth factor receptor 2 positive (HER2+) breast cancer development and chemoresistance. Given the instability, off-target effects, net negative charge, and hydrophobicity of siRNA in vivo utilization and clinical transformation, its use in treatment is hampered. Thus, the development of a siRNA-based drug delivery system (DDS) with ultra-stability and specificity is necessary to address the predicament of siRNA delivery.

Results

Here, we assembled RNase resistant RNA nanoparticles (NPs) based on the 3WJ structure from Phi29 DNA packaging motor. To improved targeted therapy and sensitize TNBC to chemotherapy, the RNA NPs were equipped with an epidermal growth factor receptor (EGFR) targeting aptamer and XBP1 siRNA. We found our RNA NPs could deplete XBP1 expression and suppress tumor growth after intravenous administration. Meanwhile, RNA NPs treatment could promote sensitization to chemotherapy and impede angiogenesis in vivo.

Conclusions

The results further demonstrate that our RNA NPs could serve as an effective and promising platform not only for siRNA delivery but also for chemotherapy-resistant TNBC therapy.

X-box binding protein 1-mediated COL4A1s secretion regulates communication between vascular smooth muscle and stem/progenitor cells

Vascular smooth muscle cells (VSMCs) contribute to the deposition of extracellular matrix proteins (ECMs), including Type IV collagen, in the vessel wall. ECMs coordinate communication among different cell types, but mechanisms underlying this communication remain unclear. Our previous studies have demonstrated that X-box binding protein 1 (XBP1) is activated and contributes to VSMC phenotypic transition in response to vascular injury. In this study, we investigated the participation of XBP1 in the communication between VSMCs and vascular progenitor cells (VPCs). Immunofluorescence and immunohistology staining revealed that Xbp1 gene was essential for type IV collagen alpha 1 (COL4A1) expression during mouse embryonic development and vessel wall ECM deposition and stem cell antigen 1-positive (Sca1⁺)-VPC recruitment in response to vascular injury. The Western blot analysis elucidated an Xbp1 gene dose-dependent effect on COL4A1 expression and that the spliced XBP1 protein (XBP1s) increased protease-mediated COL4A1 degradation as revealed by Zymography. RT-PCR analysis revealed that XBP1s in VSMCs not only upregulated COL4A1/2 transcription but also induced the occurrence of a novel transcript variant, soluble type IV collagen alpha 1 (COL4A1s), in which the front part of exon 4 is joined with the rear part of exon 42. Chromatin-immunoprecipitation, DNA/protein pulldown and in vitro transcription demonstrated that XBP1s binds to exon 4 and exon 42, directing the transcription from exon 4 to exon 42. This leads to transcription complex bypassing the internal sequences, producing a shortened COL4A1s protein that increased Sca1⁺-VPC migration. Taken together, these results suggest that activated VSMCs may recruit Sca1⁺-VPCs via XBP1s-mediated COL4A1s secretion, leading to vascular injury repair or neointima formation.

The interaction of lead exposure and CCM3 defect plays an important role in regulating angiogenesis through eNOS/NO pathway

In this study, we aimed to explore the role of nitric oxide (NO) in regulating angiogenesis in cerebral cavernous malformations 3 gene (CCM3)-deficient mice exposed to lead during vascular development; further, we aimed to identify and study the potential mechanism involved as well. Angiogenesis was detected by whole mount immunofluorescent staining of retinal vessels in WT and CCM3^+/- mice. Brain microvascular endothelial cells (BMECs) isolated from WT and CCM3^+/- mice, primary HUVECs, and immortalized HUVECs (imHUVECs) (CCM3^+/+ and CCM3^-/-) were used and treated with lead acetate (PbAc). RT-PCR and Western blotting were used to detect the mRNA and protein expression of iNOS, eNOS, and VEGF genes. The results showed that both lead exposure and CCM3 gene deficiency adversely affected endothelial cell function, causing abnormal angiogenesis and vascular remodeling. The mRNA expression of eNOS and iNOS was significantly different in WT and CCM3^+/- BMECs (0.04 ± 0.001 vs. 0.016 ± 0.002; 0.26 ± 0.002 vs. 0.306 ± 0.002, respectively), and the expression of eNOS and iNOS in imHUVECs (CCM3^+/+ and CCM3^-/-) also increased after PbAc exposure. In conclusion, CCM3 gene-deficient mice were more susceptible to abnormal vascular development after low-level lead exposure, probably due to the release of NO.

Genetic Variants and Haplotypes in OPG Gene Are Associated with Premature Coronary Artery Disease and Traditional Cardiovascular Risk Factors in Mexican Population: The GEA Study

Basic and clinical research have demonstrated that osteoprotegerin (OPG) plays an important role in the development and progression of cardiovascular diseases. The aim of this study was to evaluate the association of four polymorphic sites (rs2073618, rs3134069, rs3134070, and rs3102735) of OPG gene with premature coronary artery disease (pCAD), and with cardiometabolic parameters. The polymorphisms were genotyped using 5' exonuclease TaqMan genotyping assays with real-time PCR in 1098 individuals with pCAD and 1041 healthy controls. rs2073618 polymorphism was associated with a high risk of developing pCAD according to different inheritance models: additive (p = 0.001; odds ratio [OR] = 1.283), dominant (p = 0.006; OR = 1.383), recessive (p = 0.011; OR = 1.423), and codominant 2 (p = 0.001; OR = 1.646). The four polymorphisms were associated with different cardiovascular risk factors in individuals with pCAD and controls. Our results suggest that OPG rs2073618 polymorphism is associated with an increased risk of pCAD. In addition, two haplotypes were associated with pCAD, one increasing the risk (CACT) and another one as protective (GACC).

Systemic Delivery of Aptamer-Conjugated XBP1 siRNA Nanoparticles for Efficient Suppression of HER2+ Breast Cancer

siRNA therapeutics as an emerging class of drug development is successfully coming to clinical utilization. The RNA-based therapy is widely utilized to explore the mechanism and cure a variety of gene-specific diseases. Tumor is an oncogene-driven disease; many genes are related to tumor progression and chemoresistance. Although human epidermal growth factor receptor 2 (HER2)-targeted monoclonal antibody therapy has dramatically improved the survival rate, chemotherapy remains essential to HER2-positive (HER2+) breast cancer patients. Recently, X-box binding protein 1 (XBP1) has been involved in triple-negative breast cancer (TNBC) chemoresistance and progression, but its function in HER2+ breast cancer is poorly explored. Here, we silenced XBP1 expression using RNase-resistant RNA nanoparticles (NPs). Intravenous injection of RNA NPs with HER2-specific aptamers resulted in strong binding to tumors but not to healthy tissues. XBP1 deletion by RNA NPs impaired angiogenesis and inhibited cell proliferation, significantly suppressed breast cancer growth, and promoted the sensitization of chemotherapy in an HER2+ breast cancer mouse model. Overall, these results reveal the function of XBP1 in HER2+ breast cancer development and chemoresistance and imply that targeting XBP1 by RNA NPs may offer an easy and promising strategy for a combination treatment of breast cancer in the future.

MicroRNA-674-5p induced by HIF-1α targets XBP-1 in intestinal epithelial cell injury during endotoxemia

Intestinal mucosal integrity dysfunction during endotoxemia can contribute to translocation of intestinal bacteria and a persistent systemic inflammatory response, which both fuel the pathophysiological development of sepsis or endotoxemia. The pathogenesis of intestinal damage induced by endotoxemia remains poorly understood. Here, we identified the microRNA (miR)-674-5p/X-box binding protein 1 (XBP-1) axis as a critical regulator and therapeutic target in preventing intestinal crypt cell proliferation during endotoxemia. MiR-674-5p was markedly increased in intestinal epithelial cells (IECs) during endotoxemia and its induction depended on hypoxia-inducible factor-1α (HIF-1α). Intriguingly, gene expression microanalysis revealed that expression of XBP-1 was down-regulated in IECs with over-expression of miR-674-5p. miR-674-5p was found to directly target XBP-1 protein expression. Upon in vitro, anti-miR-674-5p enhanced sXBP-1 expression and facilitated intestinal crypt cell proliferation. Blockade of miR-674-5p promoted XBP-1 activity, attenuated intestinal inflammation, and expedited intestinal regeneration, resulting in protection against endotoxemia-induced intestinal injury in mice. More importantly, the survival in endotoxemia mice was significantly improved by inhibiting intestinal miR-674-5p. Collectively, these data indicate that control of a novel miR-674-5p/XBP-1 signaling axis may mitigate endotoxemia -induced intestinal injury.

Function and mutual interaction of BiP-, PERK-, and IRE1α-dependent signalling pathways in vascular tumours

Spontaneously regressing infantile haemangiomas and aggressive angiosarcomas are vascular tumours with excessive angiogenesis. When analysing haemangiomas and angiosarcomas immunohistochemically with respect to their chaperone profiles we found that angiosarcomas have significantly elevated protein levels of binding immunoglobulin protein (BIP) and PERK with concomitant attenuated IRE1α levels, whereas haemangioma tissue exhibits the same pattern as embryonal skin tissue. We show that BiP is essential for the maintenance of VEGFR2 protein, which is expressed in the endothelium of both tumour types. When studying the effects of BiP, the IRE1α/Xbp1 -, and PERK/ATF4-signalling pathways on the migration and tube-forming potential of endothelial cells, we show that downregulation of BiP, as well as inhibition of the kinase activity of IRE1α, inhibit in vitro angiogenesis. Downregulation of PERK (PKR-like kinase; PKR = protein kinase R) levels promotes Xbp1 splicing in endoplasmic reticulum (ER)-stressed cells, indicating that in angiosarcoma the elevated PERK levels might result in high levels of unspliced Xbp1, which have been reported to promote cell proliferation and increase tumour malignancy. The data presented in this study revealed that in addition to BiP or PERK, the kinase domains of IRE1α and Xbp1 could be potential targets for the development of novel therapeutic approaches for treating angiosarcomas and to control tumour angiogenesis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

A histone deacetylase 7-derived peptide promotes vascular regeneration via facilitating 14-3-3γ phosphorylation

Histone deacetylase 7 (HDAC7) plays a pivotal role in the maintenance of the endothelium integrity. In this study, we demonstrated that the intron-containing Hdac7 mRNA existed in the cytosol and that ribosomes bound to a short open reading frame (sORF) within the 5'-terminal noncoding area of this Hdac7 mRNA in response to vascular endothelial growth factor (VEGF) stimulation in the isolated stem cell antigen-1 positive (Sca1⁺ ) vascular progenitor cells (VPCs). A 7-amino acid (7A) peptide has been demonstrated to be translated from the sORF in Sca1⁺ -VPCs in vitro and in vivo. The 7A peptide was shown to receive phosphate group from the activated mitogen-activated protein kinase MEKK1 and transfer it to 14-3-3 gamma protein, forming an MEKK1-7A-14-3-3γ signal pathway downstream VEGF. The exogenous synthetic 7A peptide could increase Sca1⁺ -VPCs cell migration, re-endothelialization in the femoral artery injury, and angiogenesis in hind limb ischemia. A Hd7-7sFLAG transgenic mice line was generated as the loss-of-function model, in which the 7A peptide was replaced by a FLAG-tagged scrabbled peptide. Loss of the endogenous 7A impaired Sca1⁺ -VPCs cell migration, re-endothelialization of the injured femoral artery, and angiogenesis in ischemic tissues, which could be partially rescued by the addition of the exogenous 7A/7Ap peptide. This study provides evidence that sORFs can be alternatively translated and the derived peptides may play an important role in physiological processes including vascular remodeling.

Unfolded Protein Response (UPR) in Survival, Dormancy, Immunosuppression, Metastasis, and Treatments of Cancer Cells

The endoplasmic reticulum (ER) has diverse functions, and especially misfolded protein modification is in the focus of this review paper. With a highly regulatory mechanism, called unfolded protein response (UPR), it protects cells from the accumulation of misfolded proteins. Nevertheless, not only does UPR modify improper proteins, but it also degrades proteins that are unable to recover. Three pathways of UPR, namely PERK, IRE-1, and ATF6, have a significant role in regulating stress-induced physiological responses in cells. The dysregulated UPR may be involved in diseases, such as atherosclerosis, heart diseases, amyotrophic lateral sclerosis (ALS), and cancer. Here, we discuss the relation between UPR and cancer, considering several aspects including survival, dormancy, immunosuppression, angiogenesis, and metastasis of cancer cells. Although several moderate adversities can subject cancer cells to a hostile environment, UPR can ensure their survival. Excessive unfavorable conditions, such as overloading with misfolded proteins and nutrient deprivation, tend to trigger cancer cell death signaling. Regarding dormancy and immunosuppression, cancer cells can survive chemotherapies and acquire drug resistance through dormancy and immunosuppression. Cancer cells can also regulate the downstream of UPR to modulate angiogenesis and promote metastasis. In the end, regulating UPR through different molecular mechanisms may provide promising anticancer treatment options by suppressing cancer proliferation and progression.

Overexpression of steroid receptor coactivators alleviates hyperglycemia-induced endothelial cell injury in rats through activating the PI3K/Akt pathway

Hyperglycemia is a major factor in vascular endothelial injury that finally leads to a cardiovascular event. Steroid receptor coactivators (SRCs) are a group of non-DNA binding proteins that induce structural changes in steroid receptors (nuclear receptors) critical for transcriptional activation. SRCs, namely, SRC-1, SRC-2, and SRC-3, are implicated in the regulation of vascular homeostasis. In this study we investigate the role of SRCs in hyperglycemia-induced endothelial injury. Aortic endothelial cells were prepared from normal and diabetic rats, respectively. Diabetic rats were prepared by injection of streptozotocin (50 mg/kg, i.p.). The expression levels of SRC-1 and SRC-3 were significantly decreased in endothelial cells from the diabetic rats. Similar phenomenon was also observed in aortic endothelial cells from the normal rats treated with a high glucose (25 mM) for 4 h or 8 h. The expression levels of SRC-2 were little affected by hyperglycemia. Overexpression of SRC-1 and SRC-3 in high glucose-treated endothelial cells significantly increased the cell viability, suspended cell senescence, and inhibited cell apoptosis compared with the control cells. We further showed that overexpression of SRC-1 and SRC-3 markedly suppressed endothelial injury through restoring nitric oxide production, upregulating the expression of antioxidant enzymes (SOD, GPX, and CAT), and activating the PI3K/Akt pathway. The beneficial effects of SRC-1 and SRC-3 overexpression were blocked by treatment with the PI3K inhibitor LY294002 (10 mM) or with the Akt inhibitor MK-2206 (100 nM). In conclusion, hyperglycemia decreased SRC-1 and SRC-3 expression levels in rat aortic endothelial cells. SRC-1 and SRC-3 overexpression might protect against endothelial injury via inhibition of oxidative stress and activation of PI3K/Akt pathway.

Δ9-Tetrahydrocannabinol leads to endoplasmic reticulum stress and mitochondrial dysfunction in human BeWo trophoblasts

While studies have demonstrated that the main psychoactive component of cannabis, Δ9-tetrahydrocannabinol (Δ9-THC) alone induces placental insufficiency and fetal growth restriction, the underlying mechanisms remain elusive. Given that both (i) endoplasmic reticulum (ER) stress in pregnancy and (ii) gestational exposure to Δ9-THC leads to placental deficiency, we hypothesized that Δ9-THC may directly induce placental ER stress, influencing trophoblast gene expression and mitochondrial function. BeWo human trophoblast cells treated with Δ9-THC (3-30 μM) led to a dose-dependent increase in all ER stress markers and CHOP; these effects could be blocked with CB1R/CB2R antagonists. Moreover, expression of ER stress-sensitive genes ERRγ, VEGFA, and FLT-1 were increased by Δ9-THC, and abrogated with the ER stress inhibitor TUDCA. Δ9-THC also diminished mitochondrial respiration and ATP-coupling due to decreased abundance of mitochondrial chain complex proteins. Collectively, these findings indicate that Δ9-THC can directly augment ER stress resulting in aberrant placental gene expression and impaired mitochondrial function.

HSP-4/BiP expression in secretory cells is regulated by a developmental program and not by the unfolded protein response

Differentiation of secretory cells leads to sharp increases in protein synthesis, challenging endoplasmic reticulum (ER) proteostasis. Anticipatory activation of the unfolded protein response (UPR) prepares cells for the onset of secretory function by expanding the ER size and folding capacity. How cells ensure that the repertoire of induced chaperones matches their postdifferentiation folding needs is not well understood. We find that during differentiation of stem-like seam cells, a typical UPR target, the Caenorhabditis elegans immunoglobulin heavy chain-binding protein (BiP) homologue Heat-Shock Protein 4 (HSP-4), is selectively induced in alae-secreting daughter cells but is repressed in hypodermal daughter cells. Surprisingly, this lineage-dependent induction bypasses the requirement for UPR signaling. Instead, its induction in alae-secreting cells is controlled by a specific developmental program, while its repression in the hypodermal-fated cells requires a transcriptional regulator B-Lymphocyte–Induced Maturation Protein 1 (BLMP-1/BLIMP1), involved in differentiation of mammalian secretory cells. The HSP-4 induction is anticipatory and is required for the integrity of secreted alae. Thus, differentiation programs can directly control a broad-specificity chaperone that is normally stress dependent to ensure the integrity of secreted proteins.

A study in the nematode Caenorhabditis elegans shows that dedicated developmental programs can bypass the requirements for the unfolded protein response during the differentiation of secretory cells, anticipating their future high folding needs.

During differentiation, cells that specialize in secretion of proteins, such as antibody-secreting B cells, prepare for the onset of secretory function by expanding the size of the major secretory organelle, the endoplasmic reticulum (ER), and by increasing the expression of molecular chaperones and folding enzymes. This pre-emptive expansion of the ER depends on activation of the ER stress response pathways and is required for the secretory phenotype. In addition, cells may also need to up-regulate a selected subset of chaperones because different secreted proteins may require different chaperones for their folding and secretion. Except in specialized cases, how this selective up-regulation is achieved, and whether it depends on the ER stress pathways, is not well understood. Using Caenorhabditis elegans, we find that a chaperone BiP/HSP-4, which is usually induced in most cells by stress, is selectively induced during differentiation of stem cells into the alae-secreting cells while being repressed in their sister lineage, the hypodermal cells. We find that induction of this chaperone is independent of the known ER stress pathways, while its repression requires a known regulator of development in mammals, BLIMP1/BLMP-1. The pre-emptive induction of BiP/HSP-4 is important for the integrity of secreted alae and cuticle, suggesting that a general molecular chaperone that is a canonical target of ER stress pathways can be selectively regulated by development to ensure the quality of secreted proteome and functionality of the cells postdifferentiation.

The oncogenic role of GNL3 in the progression and metastasis of osteosarcoma

Background

GNL3 has been reported to be up-regulated in cancers and function in tumor progression, whereas the role of GNL3 in the progression of osteosarcoma remains unclear.

Materials and methods

In this study, we blocked the expression of GNL3 by siRNA interference in osteosarcoma cell lines MG63 and U20S. CCK8, colony formation, wound-healing, Transwell, flow cytometry, and Hoechst/PI staining assays were used to examine the effects of GNL3 knockdown on cell proliferation, migration, invasion and apoptosis in MG63 and U20S cells. The relative activity of MMP9 was detected using Gelatin zymography assay. Western blot was performed to detect the expression of related proteins.

Results

We found that silencing of GNL3 reduced the growth, migration, and invasion abilities of MG63 and U20S cells. Moreover, silencing GNL3 triggered cell cycle arrest in MG63 and U20S cells, as well as promoted cell apoptosis. In addition, depletion of GNL3 was observed to reduce the activity of MMP9 and suppress the process of epithelial–mesenchymal transition (EMT) through up-regulation of E-cadherin and down-regulation of N-cadherin. Furthermore, we found that X-box-binding protein 1 (XBP1) could bind to GNL3 using dual-luciferase reporter assay, and XBP1 overexpression could restore the inhibitory effects on proliferation, invasion, and EMT in MG63 and U20S cells caused by GNL3 knockdown.

Conclusion

These data suggest that GNL3 functions as an oncogene in the progression of osteosarcoma by regulation of EMT, and XBP1 is also involved in its mechanism.

Transcription of the NKG2D ligand MICA is suppressed by the IRE1/XBP1 pathway of the unfolded protein response through the regulation of E2F1

The unfolded protein response (UPR) is an adaptive signaling pathway activated in response to endoplasmic reticulum (ER) stress. The effectors of the UPR are potent transcription activators; however, some genes are suppressed by ER stress at the mRNA level. The mechanisms underlying UPR-mediated gene suppression are less known. Exploration of the effect of UPR on NK cells ligand expression found that the transcription of NK group 2 member D (NKG2D) ligand major histocompatibility complex class I polypeptide-related sequence A/B (MICA/B) is suppressed by the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) pathway of the UPR. Deletion of IRE1 or XBP1 was sufficient to promote mRNA and surface levels of MICA. Accordingly, NKG2D played a greater role in the killing of IRE1/XBP1 knockout target cells. Analysis of effectors downstream to XBP1s identified E2F transcription factor 1 (E2F1) as linking UPR and MICA transcription. The inverse correlation between XBP1 and E2F1 or MICA expression was corroborated in RNA-Seq analysis of 470 primary melanoma tumors. While mechanisms that connect XBP1 to E2F1 are not fully understood, we implicate a few microRNA molecules that are modulated by ER stress and possess dual suppression of E2F1 and MICA. Because of the importance of E2F1 and MICA in cancer progression and recognition, these observations could be exploited for cancer therapy by manipulating the UPR in tumor cells.-Obiedat, A., Seidel, E., Mahameed, M., Berhani, O., Tsukerman, P., Voutetakis, K., Chatziioannou, A., McMahon, M., Avril, T., Chevet, E., Mandelboim, O., Tirosh, B. Transcription of the NKG2D ligand MICA is suppressed by the IRE1/XBP1 pathway of the unfolded protein response through the regulation of E2F1.

Expression profile of long non‑coding RNAs in cardiomyocytes exposed to acute ischemic hypoxia

Acute myocardial infarction (AMI) is a life-threatening disease and seriously influences patient quality of life. Long non-coding RNAs (lncRNAs), an emerging class of non-coding genes, have attracted attention in research, however, whether lncRNAs serve a function in acute ischemic hypoxia remains to be elucidated. In the present study, an lncRNA microarray was used to analyze differential lncRNA expression in acute ischemic hypoxia. A total of 323 lncRNAs were identified, 168 of which were upregulated and 155 of which were downregulated. Gene Ontology and Pathway analyses were also used to identify the potential functions of dysregulated lncRNAs; it was predicted that these dysregulated lncRNAs may contribute to the initiation of AMI. It was demonstrated that an lncRNA termed sloyfley may influence acute ischemic hypoxia through its neighboring gene Peg3, which has been linked to brain ischemia hypoxia. In summary, the present study identified numerous lncRNAs, which may provide further opportunities for the development of novel therapeutic strategies.

Histone Deacetylase 7-Derived Peptides Play a Vital Role in Vascular Repair and Regeneration

Cardiovascular disease is a leading cause of morbidity and mortality globally. Accumulating evidence indicates that local resident stem/progenitor cells play an important role in vascular regeneration. Recently, it is demonstrated that a histone deacetylase 7-derived 7-amino acid peptide (7A, MHSPGAD) is critical in modulating the mobilization and orientated differentiation of these stem/progenitor cells. Here, its therapeutic efficacy in vascular repair and regeneration is evaluated. In vitro functional analyses reveal that the 7A peptide, in particular phosphorylated 7A (7Ap, MH[pSer]PGAD), could increase stem cell antigen-1 positive (Sca1+) vascular progenitor cell (VPC) migration and differentiation toward an endothelial cell lineage. Furthermore, local delivery of 7A as well as 7Ap could enhance angiogenesis and ameliorate vascular injury in ischaemic tissues; these findings are confirmed in a femoral artery injury model and a hindlimb ischaemia model, respectively. Importantly, sustained delivery of 7A, especially 7Ap, from tissue-engineered vascular grafts could attract Sca1+-VPC cells into the grafts, contributing to endothelialization and intima/media formation in the vascular graft. These results suggest that this novel type of peptides has great translational potential in vascular regenerative medicine.

An Overview of Unfolded Protein Response Signaling and Its Role in Cancer

Secretory and transmembrane proteins undergo post-translational modifications and folding in the subcellular organelle, that is, endoplasmic reticulum (ER) to become functionally active. Various factors such as high oxidative stress, low glucose, calcium imbalance, and viral infections interfere with the ER protein folding functions, leading to accumulation of unfolded and misfolded proteins that activate downstream signal transduction pathways, termed as unfolded protein response (UPR). This UPR signaling is adaptive and restored the normal function of cells by decreasing protein synthesis, increasing the folding capacity of ER and degradation of misfolded proteins. If the stress condition is overwhelmed, then UPR signaling shifts to apoptotic pathways. However, cancer cells utilized these UPR signaling for their survival and progression as an adaptive mechanism. In this review, the authors discuss about the overview of ER stress and subsequent UPR signaling and various aspects of cancer as survival, proliferation, and angiogenesis in relation to UPR. Understanding the UPR signaling in relation to cancer will be further helpful in designing therapeutics against cancer.