Unveiling the enigmatic role of MYH9 in tumor biology: a comprehensive review.

Non-muscle myosin heavy chain IIA (MYH9), a member of the non-muscle myosin II (NM II) family, is widely expressed in cells. The interaction of MYH9 with actin in the cytoplasm can hydrolyze ATP, completing the conversion of chemical energy to mechanical motion. MYH9 participates in various cellular processes, such as cell adhesion, migration, movement, and even signal transduction. Mutations in MYH9 are often associated with autosomal dominant platelet disorders and kidney diseases. Over the past decade, tumor-related research has gradually revealed a close relationship between MYH9 and the occurrence and development of tumors. This article provides a review of the research progress on the role of MYH9 in cancer regulation. We also discussed the anti-cancer effects of MYH9 under special circumstances, as well as its regulation of T cell function. In addition, given the importance of MYH9 as a key hub in oncogenic signal transduction, we summarize the current therapeutic strategies targeting MYH9 as well as the ongoing challenges.

ACOX1 deficiency-induced lipid metabolic disorder facilitates chronic interstitial fibrosis development in renal allografts.

Chronic interstitial fibrosis presents a significant challenge to the long-term survival of transplanted kidneys. Our research has shown that reduced expression of acyl-coenzyme A oxidase 1 (ACOX1), which is the rate-limiting enzyme in the peroxisomal fatty acid ß-oxidation pathway, contributes to the development of fibrosis in renal allografts. ACOX1 deficiency leads to lipid accumulation and excessive oxidation of polyunsaturated fatty acids (PUFAs), which mediate epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) reorganization respectively, thus causing fibrosis in renal allografts. Furthermore, activation of Toll-like receptor 4 (TLR4)-nuclear factor kappa-B (NF-κB) signaling induced ACOX1 downregulation in a DNA methyltransferase 1 (DNMT1)-dependent manner. Overconsumption of PUFA resulted in endoplasmic reticulum (ER) stress, which played a vital role in facilitating ECM reorganization. Supplementation with PUFAs contributed to delayed fibrosis in a rat model of renal transplantation. The study provides a novel therapeutic approach that can delay chronic interstitial fibrosis in renal allografts by targeting the disorder of lipid metabolism.

A novel recombinant human microplasminogen induced complete posterior vitreous detachment without morphological change of retina in juvenile rabbits.

Vitreomacular traction syndrome results from persistent vitreoretinal adhesions in the setting of partial posterior vitreous detachment (PVD). Vitrectomy and reattachment of retina is an effective therapeutic approach. The adhesion between vitreous cortex and internal limiting membrane (ILM) of the retina is stronger in youth, which brings difficulties to induce PVD in vitrectomy. Several clinical investigations demonstrated that intravitreous injection of plasmin before vitrectomy could reduce the risk of detachment. In our study, a novel recombinant human microplasminogen (rhµPlg) was expressed by Pichia pastoris. Molecular docking showed that the binding of rhµPlg with tissue plasminogen activator (t-PA) was similar to plasminogen, suggesting rh µPlg could be activated by t-PA to generate microplasmin (µPlm). Moreover, rhµPlg had higher catalytic activity than plasminogen in amidolytic assays. Complete PVD was found at vitreous posterior pole of 125 µg rhµPlg-treated eyes without morphological change of retina in juvenile rabbits via intraocular injection. Our results demonstrate that rhµPlg has a potential value in the treatment of vitreoretinopathy.

Photocatalytic Oxidative Coupling of Methane to Ethane Using Water and Oxygen on Ag3PO4-ZnO.

Photocatalytic oxidative coupling is an effective way of converting CH4 to high-value-added multi-carbon chemicals under mild conditions, where the breaking of the C-H bond is the main rate-limiting step. In this paper, the Ag3PO4-ZnO heterostructure photocatalyst was synthesized for photocatalytic oxidative coupling of methane (OCM) to C2H6. In addition, an excellent C2H6 yield (16.62 mmol g-1 h-1) and a remarkable apparent quantum yield (15.8% at 350 nm) at 49:1 CH4/Air and 20% RH are obtained, which is more than three times that of the state-of-the-art photocatalytic systems. Ag3PO4 improves the adsorption and dissociation ability of O2 and H2O, benefiting the formation of surface hydroxyl species. As a result, the C-H bond activation energy of CH4 on ZnO was obviously reduced. Meanwhile, the improved separation of photogenerated carriers on the Ag3PO4-ZnO heterostructure also accelerates the OCM process. Moreover, Ag nanoparticles (NPs) derived from Ag3PO4 reduction by photoelectrons promote the coupling of *CH3, which can inhibit the overoxidation of CH4 and increase C2H6 selectivity. This research provides a guide for the design of catalyst and reaction systems in the photocatalytic OCM process.

Simultaneous Generation of Ammonia during Nitrile Waste Gas Purification over a Silver Single-Atom-Doped Ceria Catalyst.

Catalytic elimination of toxic nitrile waste gas is of great significance for preserving the atmospheric environment, but achieving resource utilization during its destruction has been less explored. Herein, this study proposed a universal strategy for nitrile waste gas purification and NH3 generation simultaneously. The developed silver single-atom-doped ceria nanorod (Ag1/R-CeO2) was endowed with near complete mineralization and around 90% NH3 yield at 300-350 °C for the catalytic oxidation of both acetonitrile and acrylonitrile. The introduction of the Ag single atom created more surface oxygen vacancies, thereby promoting water activation to form abundant surface hydroxyl groups. As a benefit from this, the hydrolysis reaction of nitrile to generate NH3 was accelerated. Meanwhile, the electron transfer effect from the Ag atom to Ce and hydroxyl species facilitated NH3 desorption, which inhibited the oxidation of NH3. Moreover, the increased surface oxygen vacancies also promoted the mineralization of hydrolysis carbonaceous intermediates to CO2. In contrast, the Ag nanoparticle-modified sample possessed stronger reducibility and NH3 adsorption, leading to the excessive oxidation of NH3 to N2 and NOx. This work provided a useful guidance for resourceful purification of nitrile waste gas.

Targeted changes in blood lipids improves fibrosis in renal allografts.

BACKGROUND: Chronic interstitial fibrosis is the primary barrier against the long-term survival of transplanted kidneys. Extending the lifespan of allografts is vital for ensuring the long-term health of patients undergoing kidney transplants. However, few targets and their clinical applications have been identified. Moreover, whether dyslipidemia facilitates fibrosis in renal allograft remains unclear. METHODS: Blood samples were collected from patients who underwent kidney transplantation. Correlation analyses were conducted between the Banff score and body mass index, and serum levels of triacylglycerol, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. A rat model of renal transplantation was treated with the lipid-lowering drug, fenofibrate, and kidney fibrosis levels were determined by histochemical staining. Targeted metabolomic detection was conducted in blood samples from patients who underwent kidney transplantation and were divided into fibrotic and non-fibrotic groups. Rats undergoing renal transplantation were fed either an n-3 or n-6 polyunsaturated fatty acid (PUFA)-enriched diet. Immunohistochemical and Masson's trichrome staining were used to determine the degree of fibrosis. RESULTS: Hyperlipidemia was associated with fibrosis development. Treatment with fenofibrate contributed to improve fibrosis in a rat model of renal transplantation. Moreover, n-3 PUFAs from fibrotic group showed significant downregulation compared to patients without fibrotic renal allografts, and n-3 PUFAs-enriched diet contributed to delayed fibrosis in a rat model of renal transplantation. CONCLUSIONS: This study suggests that hyperlipidemia facilitates fibrosis of renal allografts. Importantly, a new therapeutic approach was provided that may delay chronic interstitial fibrosis in transplanted kidneys by augmenting the n-3 PUFA content in the diet.

Photocatalytic Oxidative Coupling of Methane over Au1 Ag Single-Atom Alloy Modified ZnO with Oxygen and Water Vapor: Synergy of Gold and Silver.

C-H dissociation and C-C coupling are two key steps in converting CH4 into multi-carbon compounds. Here we report a synergy of Au and Ag to greatly promote C2 H6 formation over Au1 Ag single-atom alloy nanoparticles (Au1 Ag NPs)-modified ZnO catalyst via photocatalytic oxidative coupling of methane (POCM) with O2 and H2 O. Atomically dispersed Au in Au1 Ag NPs effectively promotes the dissociation of O2 and H2 O into *OOH, promoting C-H activation of CH4 on the photogenerated O- to form *CH3 . Electron-deficient Au single atoms, as hopping ladders, also facilitate the migration of electron donor *CH3 from ZnO to Au1 Ag NPs. Finally, *CH3 coupling can readily occur on Ag atoms of Au1 Ag NPs. An excellent C2 H6 yield of 14.0 mmol g-1 h-1 with a selectivity of 79 % and an apparent quantum yield of 14.6 % at 350 nm is obtained via POCM with O2 and H2 O, which is at least two times that of the photocatalytic system. The bimetallic synergistic strategy offers guidance for future catalyst design for POCM with O2 and H2 O.

Dual-function chimeric antigen receptor T cells targeting c-Met and PD-1 exhibit potent anti-tumor efficacy in solid tumors.

Purpose Programmed cell death 1 (PD-1), which is upregulated under the continuous induction of the tumor microenvironment, causes chimeric antigen receptor (CAR)-T cell hypofunction via interaction with programmed death ligand 1 (PD-L1). This study aimed to construct CAR-T cells that are resistant to PD-1 inhibition to improve the effect of CAR-T cells in solid tumors. Methods We constructed a type of dual-function CAR-T cell that targets tumor-associated antigen c-Met and blocks the binding of PD-1 with PD-L1. The expression of c-Met, PD-L1, and inhibitory receptors was measured using flow cytometry. The cytotoxicity, cytokine release, and differentiation level of CAR-T cells were determined using lactate dehydrogenase release assay, enzyme-linked immunosorbent assay, and flow cytometry, respectively. The levels of p-Akt, p-MAPK, caspase-3, and Bcl2 were detected by western blot. The in vivo anti-tumor effect was evaluated using tumor xenograft models. Results Dual-function CAR-T cells could mediate enhanced active signals upon encountering target antigens and had targeted cytotoxicity to target cells. However, the cytotoxicity of c-Met-CAR-PD-1+ T cells was impaired due to the interaction of PD-1 with PD-L1. By blocking the binding of PD-1 and PD-L1, the novel dual-function CAR-PD-1+ T cells could maintain cytotoxicity to PD-L1+ tumor cells. In tumor tissue, the dual-function CAR-T cells showed lower inhibitory receptor expression and lower differentiation characteristics, which resulted in potent anti-tumor effects and prolonged survival in PD-L1+ tumor xenograft models compared to single-target CAR-T cells. Conclusion These results confirm that the novel dual-function CAR-T cells exhibit stronger anti-tumor activity against solid tumors than traditional single-target CAR-T cells and present a new approach that enhance the activity of CAR-T cells in solid tumors.

A novel tetravalent bispecific antibody targeting programmed death 1 and tyrosine-protein kinase Met for treatment of gastric cancer.

Background Redirecting T cells to tumor cells using bispecific antibodies (BsAbs) is emerging as a potent cancer therapy. The main concept of this strategy is to cross-link tumor cells and T cells by simultaneously binding to cell surface tumor-associated antigen (TAA) and the CD3ƹ chain. However, immune checkpoint programmed cell death ligand-1 (PD-L1) on tumor cells or other myeloid cells upreglulated remarkablely after the treatment of CD3-binding BsAbs, leads to the generation of suppressed microenvironment for immune evasion and tumor progression. Although this resistance could be partially reversed by anti-PD-L1 treatment, targeting two pathways through one antibody-based molecule may provide a strategic advantage over the combination of BsAbs and immune checkpoint inhibitors. Methods We developed two novel BsAbs PD-1/c-Met DVD-Ig and IgG-scFv both targeting PD-1 to restore the immune effector function of T cells and engaging them to tumor cells via binding to cellular-mesenchymal to epithelial transition factor (c-Met). Binding activities, T cell activation and proliferation were analyzed by flow cytometry. Cell Cytotoxicity and cytokine release were measured using LDH release assay and ELISA, respectively. Anti-tumor response in vivo was evaluated by generate xenograft models in NOD-SCID mice. Results These bispecific antibodies exhibited effective antitumor activity against high- and low- c-Met-expressing gastric cancer cell lines in vitro and mediated strong tumor growth inhibition in human gastric cancer xenograft models. Conclusion The engagement of the PD-1/PD-L1 blockade to c-Met-overexpressing cancer cells is a promising strategy for the treatment of gastric cancer and potentially other malignancies.

Bromodomain-containing protein 2 promotes lipolysis via ERK/HSL signalling pathway in white adipose tissue of mice.

White adipose tissue (WAT) dysfunction is prevalent among patients with type 2 diabetes mellitus (T2DM). Uncontrolled free fatty acid (FFA) release from WAT stores has detrimental effects on lipid metabolism, leading to insulin resistance. Bromodomain-containing protein 2 (Brd2) has emerged as a central transcriptional regulator of adipocyte differentiation and pancreatic ß-cell bioactivity. A recent study shows that Brd2 overexpression leads to insulin resistance in mice. However, the mechanisms underlying these effects have not been fully elucidated. This study provides the first evidence that adenoviral-mediated Brd2 overexpression in the WAT of mice increases lipolysis-related gene expression in addition to significantly reducing WAT size and promoting plasma FFA release. Brd2 overexpression in adipocytes also inhibits fat synthesis-related gene expression, while activating hormone-sensitive lipase (HSL) expression and ERK-dependent perilipin 1 inhibition as well as promoting glycerol release, which are all involved in lipolysis. Collectively, these results indicate that Brd2 triggers insulin resistance via lipolysis-mediated FFA release.

DNA methylation regulates bromodomain-containing protein 2 expression during adipocyte differentiation.

Obesity is characterized by excessive accumulation of white adipose tissue. Bromodomain-containing protein 2 (Brd2), which belongs to the bromodomain and extraterminal domain family of proteins, suppresses adipocyte differentiation. DNA methylation is critical for several differentiation processes and possibly in adipocyte differentiation. However, whether DNA methylation regulates the expression of Brd2 is not clear. In our study, we demonstrated that DNA methylation contributes to the regulation of Brd2 expression during pre-adipocyte differentiation. Brd2 mRNA levels were low in pre-adipocytes, increased in early adipocytes, and declined in mature adipocytes. To test whether and how Brd2 expression is regulated by DNA methylation during the differentiation of 3T3-L1 pre-adipocytes to adipocytes, cells were cultured in the presence of the methylation inhibitor 5-aza-2'-deoxycytidine (5-Aza). Pre-adipocytes and adipocytes exposed to 5-Aza exhibited a dose-dependent increase in Brd2 transcription levels, while only mature adipocytes exhibited increased expression of Brd2 protein. Subsequently, we tested the DNA methylation status of the Brd2 promoter region. Bisulfite-sequencing analysis revealed that six CpG sites in two predicted promoters of Brd2 were demethylated in early adipocytes and highly methylated in mature adipocytes. Digestion of bisulfite-converted PCR products of the Brd2 promoter region from 3T3-L1 cells with BstU1 (CGGC) revealed that the demethylation rate of the Brd2 promoter was consistent with Brd2 mRNA expression in differentiating 3T3-L1 cells. In conclusion, DNA demethylation of the Brd2 promoter region induced Brd2 expression during differentiation of 3T3-L1 cells into adipocytes.

The impact of JC viruria on renal transplant recovery and prognosis.

Postoperative JC viruria is common in kidney transplant recipients, however there remains a dearth of research on perioperative JCV infection in this population. The clinical significance of JCV monitoring in kidney transplant recipients remains unclear. Based on JCV urine monitoring during the perioperative phase, renal transplant recipients who underwent perioperative and postoperative monitoring at our center were categorized into two groups: the perioperative JC virus infection group and the control group consisting of recipients without detectable JCV DNA in plasma or urine during the two-year follow-up period. A comparative analysis of baseline data was initially performed, followed by a 1:1 propensity score matching of 80 cases from each group. Within the first month after transplantation, the JC viruria group exhibited a significant decrease in the incidence of delayed graft function compared to the control group (P = 0.031).Over the two-year postoperative period, the JC viruria group displayed a significantly lower rate of acute rejection (P = 0.027). Notably, the JC viruria group demonstrated higher estimated glomerular filtration rate levels compared to the control group, particularly within the first year post-transplantation. Moreover, recipient and transplant kidney survival rates did not significantly differ between the two groups (P = 0.642). Perioperative JC viruria in kidney transplant recipients may persist beyond the initial two postoperative years. The presence of JCV is associated with lower rates of DGF and acute rejection, indicating a favorable post-transplant recovery. These findings provide novel insights into the importance of postoperative JCV monitoring.

Ovotesticular disorder of sexual development manifested as hematospermia: a case report and literature review.

Background: Ovotesticular disorder of sexual development (OT-DSD) is a rare sexual development disorder defined by the simultaneous existence of testicular and ovarian tissues (including follicular) in the same- or opposite-sex glands of an individual, with an incidence rate of about 1 in 100 000. Aim: This report aims to supplement the clinical presentation, pathology, diagnosis, and treatment of OT-DSD and to improve the diagnostic ability of clinicians for modified disease. Methods: This article is a retrospective analysis of a case of OT-DSD at our institution. Additionally, a comprehensive search of the PubMed database with the keywords "ovotesticular disorder of sexual development" or "true hermaphroditism" was conducted between 1956 and 2024, resulting in approximately 250 cases, and the results of the search are summarized. Results: The patient, a 44-year-old male, sought treatment at our hospital on February 6, 2023, primarily due to "intermittent hematospermia for over a month." He stated that it was discovered during infancy that his right scrotum was empty and lacking a testicle. Due to the low local medical services and the low-income family's economic conditions, he did not seek further diagnosis and treatment. After admission, the patient underwent computed tomography and magnetic resonance imaging and decided to undergo robot-assisted pelvic mass resection, which was pathologically confirmed as OT-DSD. Outcomes: The patient's definitive diagnosis was provided by postoperative pathology, and although the patient ultimately had a favorable outcome, diagnosis and treatment were delayed due to his atypical clinical presentation. Strengths and Limitations: This is a single case report; however, uncommon clinical presentations of rare diseases were identified, and a literature review was conducted. Unfortunately, there are some important missing data in the patient's medical history, including hormone assessment (testosterone, luteinizing hormone, follicle-stimulating hormone), tumor marker examination, semen analysis, scrotal ultrasound, and chromosomal analysis. Conclusion: Patients with OT-DSD have diverse types of gonads, chromosomal karyotypes, and phenotypes of external genitalia, and further exploration and research are needed for early diagnosis and treatment. In addition, cases of OT-DSD with fertility and no ambiguous genitalia are even rarer. This case guides us for adult patients with no ambiguous genitalia: if there is an inability to palpate 1 or both gonads and there is intermittent hematospermia, the possibility of OT-DSD should be suspected.

Anti-thrombotic Effects Mediated by a Novel Dual-Target Peptide Inhibiting Both Platelet Aggregation and Thrombin Activity without Causing Bleeding.

BACKGROUND: Classical anticoagulants and antiplatelets are associated with high frequencies of bleeding complications or treatment failure when used as single agents. Thrombin plays an important role in the blood coagulation system. GP IIb/IIIa is the central receptor of platelets, which can recognize the Arg-Gly-Asp (RGD) sequence and activate platelets. MATERIAL AND METHODS: Molecular simulation and homology modeling were performed to design a novel dual-target anticoagulant short peptide (PTIP ). The activities of PTIP on coagulation and platelet in vitro were analyzed. The antithrombotic activity of PTIP was determined by pulmonary thromboembolism model, ferric chloride injury model and arteriovenous bypass thrombosis model. Bleeding effect and toxicity of PTIP were evaluated. RESULTS: We have constructed a novel dual-target peptide (PTIP) based on the direct thrombin inhibitor peptide (DTIP). PTIP was expressed at high levels in Pichia pastoris. PTIP interfered with thrombin-mediated coagulation and ADP-induced platelet aggregation in vitro. When injected intravenously or subcutaneously, PTIP showed potent and dose-dependent extension of aPTT and PT which were similar to DTIP; but only PTIP was capable of inhibiting platelet aggregation. PTIP (1.0 mg/kg) decelerated thrombosis formation in venous and arterial vessels induced by FeCl3 injury. PTIP (1.0 mg/kg) also prevented deep venous thrombosis and increased the survival rate associated with pulmonary thromboembolism. And PTIP effectively reduced thrombus length in arteriovenous bypass thrombosis model. Moreover, the antithrombotic dose of PTIP could not induce bleeding. CONCLUSION: These data establish that PTIP represents a novel antithrombotic agent whose effects involve both inhibition of platelet activation and reduction of fibrin generation. And PTIP not only can be used in venous thrombosis and arterial thrombosis, it can also replace the combined treatment of antiplatelet and anticoagulant drugs in thrombotic diseases.

Pharmacological targeting of AMPK to restore glucose and fatty acid metabolism homeostasis attenuates transplanted kidney fibrosis.

Chronic fibrosis often occurs in transplanted kidneys, leading to progressive functional decline. The underlying mechanisms may involve disruption in the metabolism of renal tubular epithelial cells. The liver kinase B1 (LKB1)-AMPK pathway is a pivotal regulatory hub for glucose and fatty acid metabolism and may play a role in transplanted kidney fibrosis, but it has not been reported. In this study we administered fenofibrate, 2-deoxyglucose, or metformin to modulate metabolism in Brown Norway rat kidney transplants and investigated pathways involved in fibrosis using various assays. We identified an impaired LKB1-AMPK pathway within epithelial cells, resulting in perturbed glucose and fatty acid metabolism, collagen secretion, extracellular matrix remodeling, and epithelial-mesenchymal transition. ACOX1, a pivotal enzyme in the fatty acid peroxisomal ß-oxidation pathway, played an important role in transplanted renal fibrosis. Furthermore, several metabolism-targeting drugs, particularly metformin, emerged as potent fibrosis inhibitors. Metformin attenuated fibrosis, improved renal function, and reduced inflammation and macrophage infiltration in the transplanted kidneys. These results provide new perspectives for understanding the complex molecular basis underlying transplanted renal fibrosis and developing novel therapeutic strategies.

The role of macrophages in fibrosis of chronic kidney disease.

Macrophages are widely distributed throughout various tissues of the body, and mounting evidence suggests their involvement in regulating the tissue microenvironment, thereby influencing disease onset and progression through direct or indirect actions. In chronic kidney disease (CKD), disturbances in renal functional homeostasis lead to inflammatory cell infiltration, tubular expansion, glomerular atrophy, and subsequent renal fibrosis. Macrophages play a pivotal role in this pathological process. Therefore, understanding their role is imperative for investigating CKD progression, mitigating its advancement, and offering novel research perspectives for fibrosis treatment from an immunological standpoint. This review primarily delves into the intrinsic characteristics of macrophages, their origins, diverse subtypes, and their associations with renal fibrosis. Particular emphasis is placed on the transition between M1 and M2 phenotypes. In late-stage CKD, there is a shift from the M1 to the M2 phenotype, accompanied by an increased prevalence of M2 macrophages. This transition is governed by the activation of the TGF-ß1/SMAD3 and JAK/STAT pathways, which facilitate macrophage-to-myofibroblast transition (MMT). The tyrosine kinase Src is involved in both signaling cascades. By thoroughly elucidating macrophage functions and comprehending the modes and molecular mechanisms of macrophage-fibroblast interaction in the kidney, novel, tailored therapeutic strategies for preventing or attenuating the progression of CKD can be developed.

Peroxisome proliferator-activated receptors: A key link between lipid metabolism and cancer progression.

Lipids represent the essential components of membranes, serve as fuels for high-energy processes, and play crucial roles in signaling and cellular function. One of the key hallmarks of cancer is the reprogramming of metabolic pathways, especially abnormal lipid metabolism. Alterations in lipid uptake, lipid desaturation, de novo lipogenesis, lipid droplets, and fatty acid oxidation in cancer cells all contribute to cell survival in a changing microenvironment by regulating feedforward oncogenic signals, key oncogenic functions, oxidative and other stresses, immune responses, or intercellular communication. Peroxisome proliferator-activated receptors (PPARs) are transcription factors activated by fatty acids and act as core lipid sensors involved in the regulation of lipid homeostasis and cell fate. In addition to regulating whole-body energy homeostasis in physiological states, PPARs play a key role in lipid metabolism in cancer, which is receiving increasing research attention, especially the fundamental molecular mechanisms and cancer therapies targeting PPARs. In this review, we discuss how cancer cells alter metabolic patterns and regulate lipid metabolism to promote their own survival and progression through PPARs. Finally, we discuss potential therapeutic strategies for targeting PPARs in cancer based on recent studies from the last five years.

Role of extracellular vesicles in pathogenesis and therapy of renal ischemia-reperfusion injury.

Renal ischemia-reperfusion injury (RIRI) is a complex disorder characterized by both intrinsic damage to renal tubular epithelial cells and extrinsic inflammation mediated by cytokines and immune cells. Unfortunately, there is no cure for this devastating condition. Extracellular vesicles (EVs) are nanosized membrane-bound vesicles secreted by various cell types that can transfer bioactive molecules to target cells and modulate their function. EVs have emerged as promising candidates for cell-free therapy of RIRI, owing to their ability to cross biological barriers and deliver protective signals to injured renal cells. In this review, we provide an overview of EVs, focusing on their functional role in RIRI and the signaling messengers responsible for EV-mediated crosstalk between various cell types in renal tissue. We also discuss the renoprotective role of EVs and their use as therapeutic agents for RIRI, highlighting the advantages and challenges encountered in the therapeutic application of EVs in renal disease.

The connection between tricarboxylic acid cycle enzyme mutations and pseudohypoxic signaling in pheochromocytoma and paraganglioma.

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors originating from chromaffin cells, holding significant clinical importance due to their capacity for excessive catecholamine secretion and associated cardiovascular complications. Roughly 80% of cases are associated with genetic mutations. Based on the functionality of these mutated genes, PPGLs can be categorized into distinct molecular clusters: the pseudohypoxia signaling cluster (Cluster-1), the kinase signaling cluster (Cluster-2), and the WNT signaling cluster (Cluster-3). A pivotal factor in the pathogenesis of PPGLs is hypoxia-inducible factor-2α (HIF2α), which becomes upregulated even under normoxic conditions, activating downstream transcriptional processes associated with pseudohypoxia. This adaptation provides tumor cells with a growth advantage and enhances their ability to thrive in adverse microenvironments. Moreover, pseudohypoxia disrupts immune cell communication, leading to the development of an immunosuppressive tumor microenvironment. Within Cluster-1a, metabolic perturbations are particularly pronounced. Mutations in enzymes associated with the tricarboxylic acid (TCA) cycle, such as succinate dehydrogenase (SDHx), fumarate hydratase (FH), isocitrate dehydrogenase (IDH), and malate dehydrogenase type 2 (MDH2), result in the accumulation of critical oncogenic metabolic intermediates. Notable among these intermediates are succinate, fumarate, and 2-hydroxyglutarate (2-HG), which promote activation of the HIFs signaling pathway through various mechanisms, thus inducing pseudohypoxia and facilitating tumorigenesis. SDHx mutations are prevalent in PPGLs, disrupting mitochondrial function and causing succinate accumulation, which competitively inhibits α-ketoglutarate-dependent dioxygenases. Consequently, this leads to global hypermethylation, epigenetic changes, and activation of HIFs. In FH-deficient cells, fumarate accumulation leads to protein succination, impacting cell function. FH mutations also trigger metabolic reprogramming towards glycolysis and lactate synthesis. IDH1/2 mutations generate D-2HG, inhibiting α-ketoglutarate-dependent dioxygenases and stabilizing HIFs. Similarly, MDH2 mutations are associated with HIF stability and pseudohypoxic response. Understanding the intricate relationship between metabolic enzyme mutations in the TCA cycle and pseudohypoxic signaling is crucial for unraveling the pathogenesis of PPGLs and developing targeted therapies. This knowledge enhances our comprehension of the pivotal role of cellular metabolism in PPGLs and holds implications for potential therapeutic advancements.