Phospholipase Cγ1 Mediates Intima Formation Through Akt-Notch1 Signaling Independent of the Phospholipase Activity

Remodeling of T-cell mitochondrial metabolism to treat autoimmune diseases

T cells are key drivers of the pathogenesis of autoimmune diseases by producing cytokines, stimulating the generation of autoantibodies, and mediating tissue and cell damage. Distinct mitochondrial metabolic pathways govern the direction of T-cell differentiation and function and rely on specific nutrients and metabolic enzymes. Metabolic substrate uptake and mitochondrial metabolism form the foundational elements for T-cell activation, proliferation, differentiation, and effector function, contributing to the dynamic interplay between immunological signals and mitochondrial metabolism in coordinating adaptive immunity. Perturbations in substrate availability and enzyme activity may impair T-cell immunosuppressive function, fostering autoreactive responses and disrupting immune homeostasis, ultimately contributing to autoimmune disease pathogenesis. A growing body of studies has explored how metabolic processes regulate the function of diverse T-cell subsets in autoimmune diseases such as systemic lupus erythematosus (SLE), multiple sclerosis (MS), autoimmune hepatitis (AIH), inflammatory bowel disease (IBD), and psoriasis. This review describes the coordination of T-cell biology by mitochondrial metabolism, including the electron transport chain (ETC), oxidative phosphorylation, amino acid metabolism, fatty acid metabolism, and one‑carbon metabolism. This study elucidated the intricate crosstalk between mitochondrial metabolic programs, signal transduction pathways, and transcription factors. This review summarizes potential therapeutic targets for T-cell mitochondrial metabolism and signaling in autoimmune diseases, providing insights for future studies.

High-Dose Ionizing Radiation Accelerates Atherosclerotic Plaque Progression by Regulating P38/NCOA4-Mediated Ferritinophagy/Ferroptosis of Endothelial Cells

PURPOSE

Radiation therapy (RT) significantly increased the incidence of coronary artery diseases, especially atherosclerosis. Endothelial dysfunction has been the major side effect of RT among tumor patients who received RT. However, the involvement between endothelial dysfunction and radiation-induced atherosclerosis (RIA) remains unclear. Here, we constructed a murine model of RIA, aiming to uncover its underlying mechanisms and identify novel strategies for RIA prevention and treatment.

METHODS AND MATERIALS

Eight-week-old ApoE-/- mice that were fed a Western diet were subjected to partial carotid ligation (PCL). Four weeks later, ionizing radiation (IR) of 10 Gy was performed to verify the detrimental role of IR on atherogenesis. Ultrasound imaging, RT quantitative polymerase chain reaction, histopathology and immunofluorescence, and biochemical analysis were performed 4 weeks after IR. To study the involvement of endothelial ferroptosis induced by IR in RIA, mice after IR were administrated with ferroptosis agonist (cisplatin) or antagonist (ferrostatin-1) intraperitoneally. Western blotting, autophagic flux measurement, reactive oxygen species level detection, and coimmunoprecipitation assay were carried out in vitro. Furthermore, to determine the effect of ferritinophagy inhibition on RIA, in vivo knockdown of NCOA4 was carried out by pluronic gel.

RESULTS

We verified that accelerated plaque progression was concomitant with endothelial cell (EC) ferroptosis after IR induction, as suggested by a higher level of lipid peroxidation and changes in ferroptosis-associated genes in the PCL + IR group than in the PCL group within vasculature. In vitro experiments further validated the devastating effects of IR on oxidative stress and ferritinophagy in ECs. Mechanistic experiments revealed that IR induced EC ferritinophagy and subsequent ferroptosis in a P38/NCOA4-dependent manner. Both in vitro and in vivo experiments confirmed the therapeutic effect of NCOA4 knockdown in alleviating IR-induced ferritinophagy/ferroptosis of EC and RIA.

CONCLUSIONS

Our findings provide novel insights into the regulatory mechanisms of RIA and first prove that IR accelerates atherosclerotic plaque progression by regulating ferritinophagy/ferroptosis of ECs in a P38/NCOA4-dependent manner.

Endothelial PHACTR1 Promotes Endothelial Activation and Atherosclerosis by Repressing PPARγ Activity Under Disturbed Flow in Mice

BACKGROUND

Numerous genome-wide association studies revealed that SNPs (single nucleotide polymorphisms) at the PHACTR1 (phosphatase and actin regulator 1) locus strongly correlate with coronary artery disease. However, the biological function of PHACTR1 remains poorly understood. Here, we identified the proatherosclerotic effect of endothelial PHACTR1, contrary to macrophage PHACTR1.

METHODS

We generated global (Phactr1-/-) and endothelial cell (EC)-specific (Phactr1ECKO) Phactr1 KO (knockout) mice and crossed these mice with apolipoprotein E-deficient (Apoe-/-) mice. Atherosclerosis was induced by feeding the high-fat/high-cholesterol diet for 12 weeks or partially ligating carotid arteries combined with a 2-week high-fat/high-cholesterol diet. PHACTR1 localization was identified by immunostaining of overexpressed PHACTR1 in human umbilical vein ECs exposed to different types of flow. The molecular function of endothelial PHACTR1 was explored by RNA sequencing using EC-enriched mRNA from global or EC-specific Phactr1 KO mice. Endothelial activation was evaluated in human umbilical vein ECs transfected with siRNA targeting PHACTR1 and in Phactr1ECKO mice after partial carotid ligation.

RESULTS

Global or EC-specific Phactr1 deficiency significantly inhibited atherosclerosis in regions of disturbed flow. PHACTR1 was enriched in ECs and located in the nucleus of disturbed flow areas but shuttled to cytoplasm under laminar flow in vitro. RNA sequencing showed that endothelial Phactr1 depletion affected vascular function, and PPARγ (peroxisome proliferator-activated receptor gamma) was the top transcription factor regulating differentially expressed genes. PHACTR1 functioned as a PPARγ transcriptional corepressor by binding to PPARγ through the corepressor motifs. PPARγ activation protects against atherosclerosis by inhibiting endothelial activation. Consistently, PHACTR1 deficiency remarkably reduced endothelial activation induced by disturbed flow in vivo and in vitro. PPARγ antagonist GW9662 abolished the protective effects of Phactr1 KO on EC activation and atherosclerosis in vivo.

CONCLUSIONS

Our results identified endothelial PHACTR1 as a novel PPARγ corepressor to promote atherosclerosis in disturbed flow regions. Endothelial PHACTR1 is a potential therapeutic target for atherosclerosis treatment.

Post-translational dysregulation of glucose uptake during exhaustive cycling exercise in vastus lateralis muscle of healthy homozygous carriers of the ACE deletion allele

Homozygous carriers of the deletion allele in the gene for angiotensin-converting enzyme (ACE-DD) demonstrate an elevated risk to develop inactivity-related type II diabetes and show an overshoot of blood glucose concentration with enduring exercise compared to insertion allele carriers. We hypothesized that ACE-DD genotypes exhibit a perturbed activity of signaling processes governing capillary-dependent glucose uptake in vastus lateralis muscle during exhaustive cycling exercise, which is associated with the aerobic fitness state. 27 healthy, male white Caucasian subjects (26.8 ± 1.1 years; BMI 23.6 +/− 0.6 kg m⁻²) were characterized for their aerobic fitness based on a threshold of 50 ml O₂ min⁻¹ kg⁻¹ and the ACE-I/D genotype. Subjects completed a session of exhaustive one-legged exercise in the fasted state under concomitant measurement of cardiorespiratory function. Capillary blood and biopsies were collected before, and ½ and 8 h after exercise to quantify glucose and lipid metabolism-related compounds (lipoproteins, total cholesterol, ketones) in blood, the phosphorylation of 45 signaling proteins, muscle glycogen and capillaries. Effects of aerobic fitness, ACE-I/D genotype, and exercise were assessed with analysis of variance (ANOVA) under the hypothesis of a dominant effect of the insertion allele. Exertion with one-legged exercise manifested in a reduction of glycogen concentration ½ h after exercise (−0.046 mg glycogen mg⁻¹ protein). Blood glucose concentration rose immediately after exercise in association with the ACE-I/D genotype (ACE-DD: +26%, ACE-ID/II: +6%) and independent of the fitness state (p = 0.452). Variability in total cholesterol was associated with exercise and fitness. In fit subjects, the phosphorylation levels of glucose uptake-regulating kinases [AKT-pT308 (+156%), SRC-pY419, p38α-pT180/T182, HCK-pY411], as well as cytokine/angiotensin 1-7 signaling factors [(STAT5A-pY694, STAT5B-pY699, FYN-pY420, EGFR-pY1086] were higher in angiotensin converting enzyme I-allele carriers than ACE-DD genotypes after exercise. Conversely, the AKT-S473 phosphorylation level (+117%) and angiotensin 2’s blood concentration (+191%) were higher in ACE-DD genotypes. AKT-S473 phosphorylation levels post-exercise correlated to anatomical parameters of muscle performance and metabolic parameters (p < 0.05 and │r│>0.70). The observations identify reciprocal alterations of S473 and T308 phosphorylation of AKT as gatekeeper of a post-translational dysregulation of transcapillary glucose uptake in ACE-DD genotypes which may be targeted in personalized approaches to mitigate type II diabetes.

Yohimbine, an α2-Adrenoceptor Antagonist, Suppresses PDGF-BB-Stimulated Vascular Smooth Muscle Cell Proliferation by Downregulating the PLCγ1 Signaling Pathway

Yohimbine (YOH) has antiproliferative effects against breast cancer and pancreatic cancer; however, its effects on vascular proliferative diseases such as atherosclerosis remain unknown. Accordingly, we investigated the inhibitory mechanisms of YOH in vascular smooth muscle cells (VSMCs) stimulated by platelet-derived growth factor (PDGF)-BB, a major mitogenic factor in vascular diseases. YOH (5–20 μM) suppressed PDGF-BB-stimulated a mouse VSMC line (MOVAS-1 cell) proliferation without inducing cytotoxicity. YOH also exhibited antimigratory effects and downregulated matrix metalloproteinase-2 and -9 expression in PDGF-BB-stimulated MOVAS-1 cells. It also promoted cell cycle arrest in the initial gap/first gap phase by upregulating p27Kip1 and p53 expression and reducing cyclin-dependent kinase 2 and proliferating cell nuclear antigen expression. We noted phospholipase C-γ1 (PLCγ1) but not ERK1/2, AKT, or p38 kinase phosphorylation attenuation in YOH-modulated PDGF-BB-propagated signaling pathways in the MOVAS-1 cells. Furthermore, YOH still inhibited PDGF-BB-induced cell proliferation and PLCγ1 phosphorylation in MOVAS-1 cells with α2B-adrenergic receptor knockdown. YOH (5 and 10 mg/kg) substantially suppressed neointimal hyperplasia in mice subjected to CCA ligation for 21 days. Overall, our results reveal that YOH attenuates PDGF-BB-stimulated VSMC proliferation and migration by downregulating a α2B-adrenergic receptor–independent PLCγ1 pathway and reduces neointimal formation in vivo. Therefore, YOH has potential for repurposing for treating atherosclerosis and other vascular proliferative diseases.

Evening Primrose Extracts Inhibit PDGF-BB-Induced Vascular Smooth Muscle Cell Proliferation and Migration by Regulating Cell-Cycle-Related Proteins

The proliferation and migration of vascular smooth muscle cells (VSMCs) are important factors in the occurrence of cardiovascular diseases, such as blood flow abnormalities, stroke and atherosclerosis. Evening primrose, known as Oenothera biennis, is a plant native to Korea that exerts physiological activities, such as antioxidant effects, the inhibition of lipid accumulation and the prevention of muscle atrophy. However, the function of evening primrose stem (EVP) in the regulation of VSMC proliferation and migration and the underlying mechanisms have not been identified. In this study, the effect of EVP on the platelet-derived growth factor (PDGF)-induced proliferation and migration of VSMCs was investigated. The results show that PDGF-BB-induced proliferation of VSMCs was inhibited by EVP at concentrations of 25, 50 or 100 μg/mL in a concentration-dependent manner, and a migration assay showed that EVP inhibited cell migration. Cell cycle analysis was performed to confirm the mechanism by which cell proliferation and migration was inhibited. The results indicate that proteins involved in the cell cycle, such as cyclin, CDK and phosphorylated Rb, were downregulated by EVP at concentrations of 100 μg/mL, thereby increasing the proportion of cells in the G0/G1 phase and inhibiting cell cycle progression. In the PDGF receptor (PDGFR) signaling pathway, phosphorylation of the PDGFR was inhibited by EVP at concentrations of 100 μg/mL, and PLCγ phosphorylation was also decreased. The PDGF-BB-induced effect of EVP on the proliferation of VSMCs involved the inhibition of Akt phosphorylation and the reduction in the phosphorylation of MAPK proteins such as ERK, P38 and JNK. In conclusion, the results demonstrate that EVP inhibited PDGF-BB-induced VSMC proliferation and migration by regulating cell-cycle-related proteins.

Shared Genetic Liability and Causal Associations Between Major Depressive Disorder and Cardiovascular Diseases

Major depressive disorder (MDD) is phenotypically associated with cardiovascular diseases (CVD). We aim to investigate mechanisms underlying relationships between MDD and CVD in the context of shared genetic variations. Polygenic overlap analysis was used to test genetic correlation and to analyze shared genetic variations between MDD and seven cardiovascular outcomes (coronary artery disease (CAD), heart failure, atrial fibrillation, stroke, systolic blood pressure, diastolic blood pressure, and pulse pressure measurement). Mendelian randomization analysis was used to uncover causal relationships between MDD and cardiovascular traits. By cross-trait meta-analysis, we identified a set of genomic loci shared between the traits of MDD and stroke. Putative causal genes for MDD and stroke were prioritized by fine-mapping of transcriptome-wide associations. Polygenic overlap analysis pointed toward substantial genetic variation overlap between MDD and CVD. Mendelian randomization analysis indicated that genetic liability to MDD has a causal effect on CAD and stroke. Comparison of genome-wide genes shared by MDD and CVD suggests 20q12 as a pleiotropic region conferring risk for both MDD and CVD. Cross-trait meta-analyses and fine-mapping of transcriptome-wide association signals identified novel risk genes for MDD and stroke, including RPL31P12, BORSC7, PNPT11, and PGF. Many genetic variations associated with MDD and CVD outcomes are shared, thus, pointing that genetic liability to MDD may also confer risk for stroke and CAD. Presented results shed light on mechanistic connections between MDD and CVD phenotypes.

Inhibition of heat shock protein 90 attenuates post‑angioplasty intimal hyperplasia

Intimal hyperplasia (IH) is a pathologic process that leads to restenosis after treatment for peripheral arterial disease. Heat shock protein 90 (HSP90) is a molecular chaperone that regulates protein maturation. Activation of HSP90 results in increased cell migration and proliferation. 17‑N‑allylamino‑17‑demethoxygeldanamycin (17‑AAG) and 17‑dimethylaminoethylamino‑17‑demethoxygeldanamycin (17‑DMAG) are low toxicity Food and Drug Association approved HSP90 inhibitors. The current study hypothesized that HSP90 inhibition was predicted to reduce vascular smooth muscle cell (VSMC) migration and proliferation. In addition, localized HSP90 inhibition may inhibit post‑angioplasty IH formation. For proliferation, VSMCs were treated with serum‑free media (SFM), 17‑DMAG or 17‑AAG. The selected proliferative agents were SFM, platelet derived growth factor (PDGF) or fibronectin. After three days, proliferation was measured. For migration, VSMCs were treated with SFM, 17‑AAG or 17‑DMAG with SFM, PDGF or fibronectin as chemoattractants. Balloon injury to the carotid artery was performed in rats. The groups included in the present study were the control, saline control, 17‑DMAG in 20% pluronic gel delivered topically to the adventitia or intraluminal delivery of 17‑DMAG. After 14 days, arteries were fixed and sectioned for morphometric analysis. Data was analyzed using ANOVA or a student's t‑test. P<0.05 was considered to indicate a statistically significant difference. The results revealed that 17‑AAG and 17‑DMAG had no effect on cell viability. PDGF and fibronectin also increased VSMC proliferation and migration. Furthermore, both 17‑AAG and 17‑DMAG decreased cell migration and proliferation in all agonists. Topical adventitial treatment with 17‑DMAG after balloon arterial injury reduced IH. HSP90 inhibitors suppressed VSMC proliferation and migration without affecting cell viability. Topical treatment with a HSP90 inhibitor (DMAG) decreased IH formation after arterial injury. It was concluded that 17‑DMAG may be utilized as an effective therapy to prevent restenosis after revascularization.

Phospholipase C

Phospholipase C (PLC) family members constitute a family of diverse enzymes. Thirteen different family members have been cloned. These family members have unique structures that mediate various functions. Although PLC family members all appear to signal through the bi-products of cleaving phospholipids, it is clear that each family member, and at times each isoform, contributes to unique cellular functions. This chapter provides a review of the current literature on PLC. In addition, references have been provided for more in-depth information regarding areas that are not discussed including tyrosine kinase activation of PLC. Understanding the roles of the individual PLC enzymes, and their distinct cellular functions, will lead to a better understanding of the physiological roles of these enzymes in the development of diseases and the maintenance of homeostasis.

The Notch pathway: a novel therapeutic target for cardiovascular diseases?

Introduction: The Notch pathway is involved in determining cell fate during development and postnatally in continuously renewing tissues, such as the endothelium, the epithelium, and in the stem cells pool. The dysregulation of the Notch pathway is one of the causes of limited response, or resistance, to available cancer treatments and novel therapeutic strategies based on Notch inhibition are being investigated in preclinical and clinical studies in oncology. A large body of evidence now shows that the dysregulation of the Notch pathway is also involved in the pathophysiology of cardiovascular diseases (CVDs). Areas covered: This review discusses the molecular mechanisms involving Notch which underlie heart failure, aortic valve calcification, and aortic aneurysm. Expert opinion: Despite the existence of preventive, pharmacological and surgical interventions approaches, CVDs are the first causes of mortality worldwide. The Notch pathway is becoming increasingly recognized as being involved in heart failure, aortic aneurysm and aortic valve calcification, which are among the most common global causes of mortality due to CVDs. As already shown in cancer, the dissection of the biological processes and molecular mechanisms involving Notch should pave the way for new strategies to prevent and cure these diseases.

Mesenchymal stem cells of Systemic Sclerosis patients, derived from different sources, show a profibrotic microRNA profiling

Systemic Sclerosis (SSc) is a disease with limited therapeutic possibilities. Mesenchymal stem cells (MSCs)-therapy could be a promising therapeutic option, however the ideal MSCs source has not yet been found. To address this problem, we perform comparison between bone marrow (BM)-MSCs and adipose (A)-MSCs, by the miRs expression profile, to identify the gene modulation in these two MSCs source. MicroRNAs (miRs) are RNAs sequences, regulating gene expression and MSCs, derived from different tissues, may differently respond to the SSc microenvironment. The miRs array was used for the miRs profiling and by DIANA-mirPath tool we identified the biological functions of the dysregulated miRs. In SSc-BM-MSCs, 6 miRs were significantly down-regulated and 4 miRs up-regulated. In SSc-A-MSCs, 11 miRs were significantly down-regulated and 3 miRs up-regulated. Interestingly, in both the sources, the involved pathways included the senescence mechanisms and the pro-fibrotic behaviour. Furthermore, both the MSCs sources showed potential compensatory ability. A deeper knowledge of this miRs signature might give more information about some pathogenic steps of the disease and in the same time clarify the possible therapeutic role of autologous MSCs in the regenerative therapy in SSc.

Oncogenic role of phospholipase C-γ1 in progression of hepatocellular carcinoma

AIM

Phospholipase C-γ1 (PLCG1) was previously found to be involved in a variety of oncogenic behaviors such as cell motility, cell proliferation, cell migration, and invasion. However, its function in hepatocellular carcinoma (HCC) was unknown. Here, we explored the expression pattern and function of PLCG1 in HCC progression.

METHODS

Expression of PLCG1 was examined by western blotting in hepatoma cells and human tumor tissues. Expression was also detected by immunohistochemistry in 150 HCC clinical samples, and its clinical significance was analyzed. The influence of PLCG1 on HCC carcinogenesis were determined in vitro and in vivo. The underlying mechanisms were explored by detecting the expression of critical molecules of signaling pathways.

RESULTS

The results showed that PLCG1 was overexpressed in hepatoma cell lines and clinical HCC tissues. Increased PLCG1 expression in tumor tissues was remarkably correlated with poor clinical features of HCC. Patients with positive PLCG1 expression in tumor tissues had shorter overall survival and relapse-free survival. Phospholipase C gamma 1 could substantially promote cell proliferation, anchor growth, and cell invasion in vitro. The in vivo study showed that inhibition of PLCG1 in hepatoma cells significantly repressed tumor growth in nude mice. Furthermore, we showed that PLCG1 might exert its function by activating the mitogen-activated protein kinase and nuclear factor-κB signaling pathways.

CONCLUSION

Our data indicated that PLCG1 could act as an oncogene in HCC carcinogenesis and could serve as a valuable prognostic marker and potential therapeutic target for HCC.

Mutated EPHA2 is a target for combating lymphatic metastasis in intrahepatic cholangiocarcinoma

Exploring the genetic aberrations favoring metastasis is important for understanding and developing novel strategies to combat cancer metastasis. It remains lack of effective treatment for the dismal prognosis of intrahepatic cholangiocarcinoma (ICC). Here, we aimed to study genetic alternations during lymph node metastasis of ICC and investigate potential mechanisms and clinical strategy focused on mutations. We performed whole-exome sequencing and transcriptome sequencing on samples from 30 ICC patients, including lymph node metastases from five of the patients. We identified the alterations of genetic pattern related to lymph node metastases of ICC. EPHA2, a member of the tyrosine kinase family, was found to be frequently mutated in ICC. Correlation analysis indicated that EPHA2 mutations were closely associated with lymph node metastasis of ICC. In vitro and in vivo experiments revealed that EPHA2 mutations could lead to ligand independent phosphorylation of Ser897, and promote lymphatic metastasis of ICC, in which NOTCH1 signaling pathway played an important role. In both in vitro assays and patient-derived xenografts, an inhibitor of Ser897 phosphorylation effectively suppressed the metastasis of ICC with mutated EPHA2. Our findings demonstrated that EPHA2 mutants may be an attractive therapeutic target for lymphatic metastasis of ICC.

Propranolol inhibits proliferation and invasion of hemangioma-derived endothelial cells by suppressing the DLL4/Notch1/Akt pathway

Infantile hemangioma (IH) is one of the most common benign vascular tumors of infancy. Propranolol has been recently introduced for the treatment of IH. However, the mechanism of protective effect has not been fully understood. In this study, hemangioma-derived endothelial cells (HemECs) were isolated and treated with propranolol. The cell viability was measured by MTT assay, and the cell cycle arrest was detected using flow cytometry. Cell invasion was determined using transwell assay. The expressions of matrix metalloproteinase (MMP)-2, MMP-9, Delta-like 4 (DLL4), Notch1, Akt, p-Akt, and vascular endothelial growth factor (VEGF) were detected using western blot. HemECs were incubated with recombinant human DLL4 (rhDLL4) to investigate the role of DLL4/Notch1 in the effect of propranolol. The results showed that propranolol inhibited cell viability of HemECs in a time-dependent manner. Propranolol suppressed cell proliferation of HemECs by arresting cell progression at G0/G1 phase. Propranolol inhibited the invasion ability of HemECs and reduced the expression levels of MMP-2 and MMP-9 in HemECs. Besides, propranolol treatment blocked the DLL4/Notch1 and Akt signaling and inhibited VEGF expression in HemECs. Treatment with rhDLL4 activated the Akt signaling and attenuated the effect of propranolol on HemECs. Our data indicated that propranolol inhibited the cell proliferation and invasion of HemECs. The effect was possibly involved in the DLL4/Notch1/Akt signaling pathway.