Brain microvascular endothelial cell-derived exosomes transmitting circ_0000495 promote microglial M1-polarization and endothelial cell injury under hypoxia condition.

Human brain microvascular endothelial cells (HBMVECs) and microglia play critical roles in regulating cerebral homeostasis during ischemic stroke. However, the role of HBMVECs-derived exosomes in microglia polarization after stroke remains unknown. We isolated exosomes (Exos) from oxygen glucose deprivation (OGD)-exposed HBMVECs, before added them into microglia. Microglia polarization markers were tested using RT-qPCR or flow cytometry. Inflammatory cytokines were measured with ELISA. Endothelial cell damage was assessed by cell viability, apoptosis, apoptosis-related proteins, oxidative stress, and angiogenic activity using CCK-8, flow cytometry, western blot, ELISA, and endothelial tube formation assay, respectively. We also established middle cerebral artery occlusion (MCAO) mice model to examine the function of circ_0000495 on stroke in vivo. Our study found that HBMVECs-Exos reduced M2 markers (IL-10, CD163, and CD206), increased M1 markers (TNF-α, IL-1ß, and IL-12), CD86-positive cells, and inflammatory cytokines (TNF-α and IL-1ß), indicating the promotion of microglial M1-polarization. Microglial M1-polarization induced by HBMVECs-Exos reduced viability and promoted apoptosis and oxidative stress, revealing the aggravation of endothelial cell damage. However, circ_0000495 silencing inhibited HBMVECs-Exos-induced alterations. Mechanistically, circ_0000495 adsorbed miR-579-3p to upregulate toll-like receptor 4 (TLR4) in microglia; miR-579-3p suppressed HBMVECs-Exos-induced alterations via declining TLR4; furthermore, Yin Yang 1 (YY1) transcriptionally activated circ_0000495 in HBMVECs. Importantly, circ_0000495 aggravated ischemic brain injury in vivo via activating TLR4/nuclear factor-κB (NF-κB) pathway. Collectively, OGD-treated HBMVECs-Exos transmitted circ_0000495 to regulate miR-579-3p/TLR4/NF-κB axis in microglia, thereby facilitating microglial M1-polarization and endothelial cell damage.

Pancreatic islet transplantation: current advances and challenges.

Diabetes is a prevalent chronic disease that traditionally requires severe reliance on medication for treatment. Oral medication and exogenous insulin can only temporarily maintain blood glucose levels and do not cure the disease. Most patients need life-long injections of exogenous insulin. In recent years, advances in islet transplantation have significantly advanced the treatment of diabetes, allowing patients to discontinue exogenous insulin and avoid complications.Long-term follow-up results from recent reports on islet transplantation suggest that they provide significant therapeutic benefit although patients still require immunotherapy, suggesting the importance of future transplantation strategies. Although organ shortage remains the primary obstacle for the development of islet transplantation, new sources of islet cells, such as stem cells and porcine islet cells, have been proposed, and are gradually being incorporated into clinical research. Further research on new transplantation sites, such as the subcutaneous space and mesenteric fat, may eventually replace the traditional portal vein intra-islet cell infusion. Additionally, the immunological rejection reaction in islet transplantation will be resolved through the combined application of immunosuppressant agents, islet encapsulation technology, and the most promising mesenchymal stem cells/regulatory T cell and islet cell combined transplantation cell therapy. This review summarizes the progress achieved in islet transplantation, and discusses the research progress and potential solutions to the challenges faced.

PHB2 promotes SHIP2 ubiquitination via the E3 ligase NEDD4 to regulate AKT signaling in gastric cancer.

BACKGROUND: Prohibitin 2 (PHB2) exhibits opposite functions of promoting or inhibiting tumour across various cancer types. In this study, we aim to investigate its functions and underlying mechanisms in the context of gastric cancer (GC). METHODS: PHB2 protein expression levels in GC and normal tissues were examined using western blot and immunohistochemistry. PHB2 expression level associations with patient outcomes were examined through Kaplan-Meier plotter analysis utilizing GEO datasets (GSE14210 and GSE29272). The biological role of PHB2 and its subsequent regulatory mechanisms were elucidated in vitro and in vivo. GC cell viability and proliferation were assessed using MTT cell viability analysis, clonogenic assays, and BrdU incorporation assays, while the growth of GC xenografted tumours was measured via IHC staining of Ki67. The interaction among PHB2 and SHIP2, as well as between SHIP2 and NEDD4, was identified through co-immunoprecipitation, GST pull-down assays, and deletion-mapping experiments. SHIP2 ubiquitination and degradation were assessed using cycloheximide treatment, plasmid transfection and co-immunoprecipitation, followed by western blot analysis. RESULTS: Our analysis revealed a substantial increase in PHB2 expression in GC tissues compared to adjacent normal tissues. Notably, higher PHB2 levels correlated with poorer patient outcomes, suggesting its clinical relevance. Functionally, silencing PHB2 in GC cells significantly reduced cell proliferation and retarded GC tumour growth, whereas overexpression of PHB2 further enhanced GC cell proliferation. Mechanistically, PHB2 physically interacted with Src homology 2-containing inositol 5-phosphatase 2 (SHIP2) in the cytoplasm of GC cells, thus leading to SHIP2 degradation via its novel E3 ligase NEDD4. It subsequently activated the PI3K/Akt signaling pathway and thus promoted GC cell proliferation. CONCLUSIONS: Our findings highlight the importance of PHB2 upregulation in driving GC progression and its association with adverse patient outcomes. Understanding the functional impact of PHB2 on GC growth contributes valuable insights into the molecular underpinnings of GC and may pave the way for the development of targeted therapies to improve patient outcomes.

KMT2A and chronic inflammation as potential drivers of sporadic parathyroid adenoma.

BACKGROUND: Sporadic parathyroid adenoma (PA) is the most common cause of hyperparathyroidism, yet the mechanisms involved in its pathogenesis remain incompletely understood. METHODS: Surgically removed PA samples, along with normal parathyroid gland (PG) tissues that were incidentally dissected during total thyroidectomy, were analysed using single-cell RNA-sequencing with the 10× Genomics Chromium Droplet platform and Cell Ranger software. Gene set variation analysis was conducted to characterise hallmark pathway gene signatures, and single-cell regulatory network inference and clustering were utilised to analyse transcription factor regulons. Immunohistochemistry and immunofluorescence were performed to validate cellular components of PA tissues. siRNA knockdown and gene overexpression, alongside quantitative polymerase chain reaction, Western blotting and cell proliferation assays, were conducted for functional investigations. RESULTS: There was a pervasive increase in gene transcription in PA cells (PACs) compared with PG cells. This is associated with high expression of histone-lysine N-methyltransferase 2A (KMT2A). High KMT2A levels potentially contribute to promoting PAC proliferation through upregulation of the proto-oncogene CCND2, which is mediated by the transcription factors signal transducer and activator of transcription 3 (STAT3) and GATA binding protein 3 (GATA3). PA tissues are heavily infiltrated with myeloid cells, while fibroblasts, endothelial cells and macrophages in PA tissues are commonly enriched with proinflammatory gene signatures relative to their counterparts in PG tissues. CONCLUSIONS: We revealed the previously underappreciated involvement of the KMT2A‒STAT3/GATA3‒CCND2 axis and chronic inflammation in the pathogenesis of PA. These findings underscore the therapeutic promise of KMT2A inhibition and anti-inflammatory strategies, highlighting the need for future investigations to translate these molecular insights into practical applications. HIGHLIGHTS: Single-cell RNA-sequencing reveals a transcriptome catalogue comparing sporadic parathyroid adenomas (PAs) with normal parathyroid glands. PA cells show a pervasive increase in gene expression linked to KMT2A upregulation. KMT2A-mediated STAT3 and GATA3 upregulation is key to promoting PA cell proliferation via cyclin D2. PAs exhibit a proinflammatory microenvironment, suggesting a potential role of chronic inflammation in PA pathogenesis.

MILIP Binding to tRNAs Promotes Protein Synthesis to Drive Triple-Negative Breast Cancer.

Patients with triple-negative breast cancer (TNBC) have a poor prognosis due to the lack of effective molecular targets for therapeutic intervention. Here we found that the long noncoding RNA (lncRNA) MILIP supports TNBC cell survival, proliferation, and tumorigenicity by complexing with transfer RNAs (tRNA) to promote protein production, thus representing a potential therapeutic target in TNBC. MILIP was expressed at high levels in TNBC cells that commonly harbor loss-of-function mutations of the tumor suppressor p53, and MILIP silencing suppressed TNBC cell viability and xenograft growth, indicating that MILIP functions distinctively in TNBC beyond its established role in repressing p53 in other types of cancers. Mechanistic investigations revealed that MILIP interacted with eukaryotic translation elongation factor 1 alpha 1 (eEF1α1) and formed an RNA-RNA duplex with the type II tRNAs tRNALeu and tRNASer through their variable loops, which facilitated the binding of eEF1α1 to these tRNAs. Disrupting the interaction between MILIP and eEF1α1 or tRNAs diminished protein synthesis and cell viability. Targeting MILIP inhibited TNBC growth and cooperated with the clinically available protein synthesis inhibitor omacetaxine mepesuccinate in vivo. Collectively, these results identify MILIP as an RNA translation elongation factor that promotes protein production in TNBC cells and reveal the therapeutic potential of targeting MILIP, alone and in combination with other types of protein synthesis inhibitors, for TNBC treatment. SIGNIFICANCE: LncRNA MILIP plays a key role in supporting protein production in TNBC by forming complexes with tRNAs and eEF1α1, which confers sensitivity to combined MILIP targeting and protein synthesis inhibitors.

Challenges and opportunities in the islet transplantation microenvironment: a comprehensive summary of inflammatory cytokine, immune cells, and vascular endothelial cells.

It is now understood that islet transplantation serves as a ß-cell replacement therapy for type 1 diabetes. Many factors impact the survival of transplanted islets, especially those related to the microenvironment. This review explored microenvironmental components, including vascular endothelial cells, inflammatory cytokines, and immune cells, and their profound effects on post-islet transplantation survival rates. Furthermore, it revealed therapeutic strategies aimed at targeting these elements. Current evidence suggests that vascular endothelial cells are pivotal in facilitating vascularization and nutrient supply and establishing a new microcirculation network for transplanted islets. Consequently, preserving the functionality of vascular endothelial cells emerges as a crucial strategy to enhance the survival of islet transplantation. Release of cytokines will lead to activation of immune cells and production and release of further cytokines. While immune cells hold undeniable significance in regulating immune responses, their activation can result in rejection reactions. Thus, establishing immunological tolerance within the recipient's body is essential for sustaining graft functionality. Indeed, future research endeavors should be directed toward developing precise strategies for modulating the microenvironment to achieve higher survival rates and more sustained transplantation outcomes. While acknowledging certain limitations inherent to this review, it provides valuable insights that can guide further exploration in the field of islet transplantation. In conclusion, the microenvironment plays a paramount role in islet transplantation. Importantly, we discuss novel perspectives that could lead to broader clinical applications and improved patient outcomes in islet transplantation.