Levels Of Connexin Research Articles

Liraglutide improves follicle development in polycystic ovary syndrome by inhibiting CXCL10 secretion

BackgroundAt present, a number of clinical trials have been carried out on GLP-1 receptor agonist liraglutide in the treatment of polycystic ovary syndrome (PCOS). However, the effect of liraglutide on follicle development and its specific mechanism are still unclear.MethodsRNA sequencing was used to explore the molecular characteristics of granulosa cells from patients with PCOS treated with liraglutide. The levels of C-X-C motif chemokine ligand 10 (CXCL10) in follicular fluid were detected by ELISA, the expression levels of ovulation related genes and inflammatory factor genes in follicles and granulosa cells were detected by qPCR and the protein levels of connexin 43 (Cx43), Janus Kinase 2 (JAK2) and phosphorylated JAK2 were detected by Western blot. The mouse ovarian follicles culture system in vitro was used to detect the status of follicle development and ovulation.ResultsIn the present study, we found that liraglutide inhibited the secretion of inflammatory factors in PCOS granulosa cells, among which CXCL10 was the most significant. In addition, CXCL10 was significantly higher in granulosa cells and follicular fluid in PCOS patients than in non-PCOS patients. We applied in vitro follicle culture and other techniques to carry out the mechanism exploration which revealed that CXCL10 disrupted the homeostasis of gap junction protein alpha 1 (GJA1) between oocyte and granulosa cells before physiological ovulation, thus inhibiting follicular development and ovulation. Liraglutide inhibited CXCL10 secretion in PCOS granulosa cells by inhibiting the JAK signaling pathway and can improved dehydroepiandrosterone (DHEA)-induced follicle development disorders, which is reversed by CXCL10 supplementation.ConclusionsThe present study suggests that liraglutide inhibits CXCL10 secretion in granulosa cells through JAK signaling pathway, thereby improving the homeostasis of GJA1 between oocyte and granulosa cells before physiological ovulation and ultimately improving the follicular development and ovulation of PCOS, which provides more supportive evidence for the clinical application of liraglutide in the treatment of ovulatory disorders in PCOS.Trial registrationNot applicable.

Wound Healing Efficacy of Cucurbitaceae Seed Oils in Rats: Comprehensive Phytochemical, Pharmacological, and Histological Studies Tackling AGE/RAGE and Nrf2/Ho-1 Cue.

The Cucurbitaceae family includes several edible species that are consumed globally as fruits and vegetables. These species produce high volumes of seeds that are often discarded as waste. In this study, we investigate the chemical composition and biological activity of three seed oils from Cucurbitaceae plants, namely, cantaloupe, honeydew, and zucchini, in comparison to the widely used pumpkin seed oil for their ability to enhance and accelerate wound healing in rats. Our results showed that honeydew seed oil (HSO) was effective in accelerating wound closure and enhancing tissue repair, as indicated by macroscopic, histological, and biochemical analyses, as compared with pumpkin seed oil (PSO). This effect was mediated by down-regulation of the advanced glycation end products (AGE) and its receptor (RAGE) cue, activating the cytoprotective enzymes nuclear factor erythroid 2 (Nrf2) and heme oxygenase-1 (HO-1), suppressing the inflammatory mediators tumor necrosis factor (TNF)-α, nuclear factor kappa B (NF-κB), and nod-like receptor protein 3 (NLRP3), and reducing the levels of the skin integral signaling protein connexin (CX)-43. Furthermore, immunohistochemical staining for epidermal growth factor (EGF) showed the lowest expression in the skin after treatment with HSO, indicating a well-organized and complete healing process. Other seed oils from cantaloupe and zucchini exhibited favorable activity when compared with untreated rats; however, their efficacy was comparatively lower than that of PSO and HSO. Gas chromatographic analysis of the derivatized oils warranted the superior activity of HSO to its high nutraceutical content of linoleic acid, which represented 65.9% of the fatty acid content. This study's findings validate the use of honeydew seeds as a wound-healing fixed oil and encourage further investigation into the potential of Cucurbitaceae seeds as sources of medicinally valuable plant oils.

Overexpression of Plakophilin2 Mitigates Capillary Leak Syndrome in Severe Acute Pancreatitis by Activating the p38/MAPK Signaling Pathway.

Capillary leak syndrome (CLS) is an intermediary phase between severe acute pancreatitis (SAP) and multiple organ failure. As a result, CLS is of clinical importance for enhancing the prognosis of SAP. Plakophilin2 (PKP2), an essential constituent of desmosomes, plays a critical role in promoting connections between epithelial cells. However, the function and mechanism of PKP2 in CLS in SAP are not clear at present. We detected the expression of PKP2 in mice pancreatic tissue by transcriptome sequencing and bioinformatics analysis. PKP2 was overexpressed and knocked down to assess its influence on cell permeability, the cytoskeleton, tight junction molecules, cell adhesion junction molecules, and associated pathways. PKP2 expression was increased in the pancreatic tissues of SAP mice and human umbilical vein endothelial cells (HUVECs) after lipopolysaccharide (LPS) stimulation. PKP2 overexpression not only reduced endothelial cell permeability but also improved cytoskeleton relaxation in response to acute inflammatory stimulation. PKP2 overexpression increased levels of ZO-1, occludin, claudin1, β-catenin, and connexin43. The overexpression of PKP2 in LPS-induced HUVECs counteracted the inhibitory effect of SB203580 (a p38/MAPK signaling pathway inhibitor) on the p38/MAPK signaling pathway, thereby restoring the levels of ZO-1, β-catenin, and claudin1. Additionally, PKP2 suppression eliminated the enhanced levels of ZO-1, β-catenin, occludin, and claudin1 induced by dehydrocorydaline. We predicted that the upstream transcription factor PPARγregulates PKP2 expression, and our findings demonstrate that the PPARγactivator rosiglitazone significantly upregulates PKP2, whereas its antagonist GW9662 down-regulates PKP2. Administration of rosiglitazone significantly reduced the increase in HUVECs permeability stimulated by LPS. Conversely, PKP2 overexpression counteracted the GW9662-induced reduction in ZO-1, phosphorylated p38/p38, and claudin1. The activation of the p38/MAPK signaling pathway by PKP2 mitigates CLS in SAP. PPARγactivator rosiglitazone can up-regulate PKP2. Overall, directing efforts toward PKP2 could prove to be a feasible treatment approach for effectively managing CLS in SAP.

In vitro cytotoxic and genotoxic effects of Phyllanthus niruri extract loaded chitosan nanoparticles in TM4 cells and their influence on spermatogenesis

Purpose: This paper introduces a complete in vitro investigation of cytotoxic and genotoxic effects of Phyllanthus niruri extract loaded chitosan nanoparticles (PNNP) on mouse Sertoli cell line (TM4), as well as their impact on spermatogenesis. Methods: Chitosan nanoparticles (ChNP) and PNNP were prepared using an ionic gelation process, while their cytotoxicity on TM4 cells was assessed using the Cell Counting Kit-8 (CCK-8) assay. Comet and fast halo assays were used to quantify single-strand DNA breaks in TM4 cells. To detect changes in cell morphology during apoptosis, nuclear staining with Hoechst 33342 was performed. An immunofluorescence assay was employed to examine the expression level of proteins connexin 43 and Claudin 11 in TM4 cells after exposure to PNNP concentration of 125 µg/mL. Results: The synthesized PNNP had a size of 170.6 nm, a polydispersity index of 0.269, a zeta potential of +37.8 mV, and a good entrapment efficiency of 71.0%. Encapsulation of Phyllanthus niruri into ChNP induced DNA damage in TM4 cells as determined by alkaline comet and fast halo assay (FHA). Additionally, it stimulated apoptosis, as determined by changes in cell morphology by Hoechst 33342 staining. There was significant down regulation of blood-testis barrier (BTB) proteins in TM4 cells after exposure to PNNP which could compromise the integrity of BTB and subsequently disrupt spermatogenesis process in male. Conclusion: Our investigation confirms the cytotoxic and genotoxic effects of PNNP in TM4 cells, which could lead to spermatogenesis disruption and male infertility.

Atrial cardiomyocytes contribute to the inflammatory status associated with atrial fibrillation in right heart disease.

Right heart disease (RHD), characterized by right ventricular (RV) and atrial (RA) hypertrophy, and cardiomyocytes' (CM) dysfunctions have been described to be associated with the incidence of atrial fibrillation (AF). Right heart disease and AF have in common, an inflammatory status, but the mechanisms relating RHD, inflammation, and AF remain unclear. We hypothesized that right heart disease generates electrophysiological and morphological remodelling affecting the CM, leading to atrial inflammation and increased AF susceptibility. Pulmonary artery banding (PAB) was surgically performed (except for sham) on male Wistar rats (225-275 g) to provoke an RHD. Twenty-one days (D21) post-surgery, all rats underwent echocardiography and electrophysiological studies (EPS). Optical mapping was performed in situ, on Langendorff-perfused hearts. The contractility of freshly isolated CM was evaluated and recorded during 1 Hz pacing in vitro. Histological analyses were performed on formalin-fixed RA to assess myocardial fibrosis, connexin-43 levels, and CM morphology. Right atrial levels of selected genes and proteins were obtained by qPCR and Western blot, respectively. Pulmonary artery banding induced severe RHD identified by RV and RA hypertrophy. Pulmonary artery banding rats were significantly more susceptible to AF than sham. Compared to sham RA CM from PAB rats were significantly elongated and hypercontractile. Right atrial CM from PAB animals showed significant augmentation of mRNA and protein levels of pro-inflammatory interleukin (IL)-6 and IL1β. Sarcoplasmic-endoplasmic reticulum Ca2+-ATPase-2a (SERCA2a) and junctophilin-2 were decreased in RA CM from PAB compared to sham rats. Right heart disease-induced arrhythmogenicity may occur due to dysfunctional SERCA2a and inflammatory signalling generated from injured RA CM, which leads to an increased risk of AF.

CX43-Mediated Mitochondria Transfer Enhances the Stemness of Leukemia Stem Cells Though Metabolic Remodeling

Background :Despite improvements in treatment options for acute myeloid leukemia (AML), chemotherapy resistance remains an important clinical concern with a high recurrence rate in patients.Leukemia stem cells (LSCs) play a decisive role in the relapse resistance of leukemia. Bone marrow mesenchymal stem cells(BMSCs) protect LSCs from being completely removed from the bone marrow, but the underlying mechanisms are poorly understood.In this study, we aimed to uncover the mechanism of BMSCs-regulated the stemness of leukemia stem cells through mitochondrial transfer mediated by Connexin43(CX43), thus providing a promising clinical therapy target. Methods: Primary BMSCs were isolated from the primary bone marrow specimens of patients with AML and cultured in MSCM culture base within 10% serum.CX43 overexpressing BMSCs (CX43-BMSCS) were constructed by lentivirus transfection.The efficiency of CX43 overexpression was verified by immunofluorescence, qPCR and Western Blot.In vitro, CX43-BMSCs and control BMSCs (EV-BMSCs) were cocultured with KG-1a cells.In some experiments,vincristine (1nM) was added to inhibit the mitochondrial transferring.Bidirectional mitochondrial transfer was detected by flow cytometry and confocal microscopy.The mechanism of mitochondria transfer was analyzed by inhibitor assays.The proliferation of KG-1a from the coculture system were assessed by Flow cytometry and EdU assay.After co-culture, the clone formation of KG-1a was detected by using semisolid cloning assay.The mitochondrial respiration of KG-1a was analyzed by using Seahorse.The transcriptomes of KG-1a after co-culture using RNA-seq.Finally,we verified our findings using LC-MS non-targeted metabolomics to detect the metabolites changes of KG-1a after co-culture. Results: Compared with Control-BMSCs and EV-BMSCs,the mRNA and protein expression levels of CX43 in CX43-MSCs were significantly increased (P<0.05).In the co-culture system without serum for 48h,BMSCs transfer mitochondria to KG-1a cells but receive no mitochondria from KG-1a.Moreover,CX43-BMSCs transferred more mitochondria to KG-1a than EV-BMSCs group (P<0.05),while there was no obvious mitochondrial transfer was observed in the transwell and 10% serum co-culture system.In addition,compared with EV-BMSCs,CX43-BMSCs significantly increased the proliferation and adhesion of KG-1a (P<0.05) and clone formation ability (P<0.05).Vincristine significantly reduced the mitochondrial transfer from CX43-BMSCs to KG-1a,and decreased the adhesion of CX43-BMSCs to KG-1a,as well as the proliferation and clone formation of KG-1a after co-culture.The metabolic capacity of KG-1a cells in CX43-BMSCs was significantly increased compared with EV-BMSCs (P<0.05),and this metabolic enhancement could be reversed by vincristine.Hierarchical cluster analysis (HC) of metabolites showed that there were significant differences in metabolites among treatment groups (p<0.05),showed unique metabolic characteristics related to CX43-induced changes.The GO analysis revealed that the enrichments occurring in KG-1a after co-cultured with CX43-BMSCs mainly included cell adhesion and migration,cell proliferation and regulation,signal transduction,PI3K/Akt pathway,transmembrane transport and intracellular protein metabolism.Metabolism-related pathways,like nucleotide metabolism,lipid metabolism and amino acid metabolism,were enriched in KG-1a after co-cultured with CX43-BMSCs.Furthermore,KG-1a after co-cultured with CX43-BMSCs showed up-regulated of promoting the proliferation and the stemness of AML-LSCs,including N-cadherin (CDH2),CD244,SLC43A2,CYBB and IGLL1. Conclusion: We show evidence that CX43 mediated mitochondria transfer from BMSCs to LSCs which promoting the adhesion of BMSCs to LSCs under nutrient deficiency condition,and then enhanced the proliferation and cloning ability of LSCs,altered gene expression profiles related to cell proliferation,adhesion,and energy metabolism,and increased the expression of genes related to maintaining stemness of LSCs, allows metabolic remodeling to regulate LSCs stemness, may be a potential therapeutic target for AML treatment. Keywords:Leukemia stem cells;Bone marrow microenvironment;Connexin;Mitochondrial transfer;Metabolic remodeling

FGF21 protects against doxorubicin-induced cardiotoxicity by inhibiting connexin 43 ubiquitination

BackgroundFibroblast growth factor 21 (FGF21) regulates glycolipid metabolism and insulin homeostasis and acts as a cardioprotective factor by protecting against myocardial ischemia/reperfusion injury, hypertension, and vascular dysfunction. FGF21 has been reported to prevent Doxorubicin (Dox)-induced cardiotoxicity, and the related signaling pathway is worthy of further study. Connexin43 (Cx43) protein was reduced by Dox treatment, especially low phosphorylated form of Cx43. Thus the aim of study is to explore the protection effect of FGF21 on Dox induced cardiotoxicity by improving the expression of Cx43 and the involved signaling pathway. Methods and resultsFGF21 inhibited apoptosis in Dox-treated mice and cardiomyocytes. FGF21 increased the levels of connexin43 phosphorylated at serine (S) 282 (p-Cx43 S282) and total Cx43 to inhibit Dox-induced apoptosis. By RNA sequencing, we found that deubiquitinase monocyte chemoattractant protein-induced protein 1 (MCPIP1) expression was increased by FGF21. We further found that FGF21 induced the phosphorylation of fibroblast growth factor receptor 1 (FGFR1), extracellular signal-regulated kinase 1 and 2 (Erk1/2), and Elk. Phosphorylated Elk translocated to the nucleus and increased the expression of MCPIP1. Then, MCPIP1 bound neural precursor cell expressed developmentally downregulated protein 4 (Nedd4), an E3 ubiquitination ligase, as shown by co-immunoprecipitation (Co-IP), and suppressed Cx43 ubiquitination and degradation, competitively inhibiting the binding of Cx43 with Nedd4. Thus Nedd4 could not bind and ubiquitinate Cx43, leading to the up-regulation of Cx43 and phosphorylation of Cx43 at S282. ConclusionsFGF21 inhibited the effects of Dox on cardiomyocytes by elevating the phosphorylation of Cx43 at S282 and total Cx43 expression. This study suggests a previously unknown mechanism for the FGF21-mediated enhancement of cardiomyocyte survival and provides an effective approach to protect against the adverse cardiac effects of Dox.

Phloretin ameliorates heart function after myocardial infarction via NLRP3/Caspase-1/IL-1β signaling

Objectives/AimsInflammation is crucial in structural and electrical remodeling after myocardial infarction (MI), affecting cardiac pump function and conduction pathways. Phloretin possesses an anti-inflammation role by inhibiting the NLRP3/Caspase-1/IL-1β pathway. However, the effects of Phloretin on cardiac contractile and electrical conduction function after MI remained unclear. Therefore, we aimed to investigate the potential role of Phloretin in a rat model of MI. MethodsRats were assigned into four groups: Sham, Sham+Phloretin, MI and MI+Phloretin, with ad libitum food and water. In the MI and MI+Phloretin groups, the left anterior descending coronary artery was occluded for 4 weeks, while the Sham and Sham+Phloretin groups received sham operation. The Sham+Phloretin group and the MI+Phloretin group received oral administration of Phloretin. In vitro, H9c2 cells were subjected to hypoxic conditions to simulate an MI model, with Phloretin for 24 h. Cardiac electrophysiological properties were assessed following MI, including the effective refractory period (ERP), action potential duration (APD)90 and ventricular fibrillation (VF) incidence. Echocardiography evaluated left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), left ventricular internal diameter at end-diastole (LVIDd), left ventricular internal diameter at end-systole (LVIDs), left ventricular end-systolic volume (LVESV) and left ventricular end-diastolic volume (LVEDV) to assess cardiac function. Serum type B natriuretic peptide (BNP) level was applied to evaluate the degree of Heart failure (HF). The fibrosis area and severity were assessed by Masson staining and protein expression levels of collagen 3, collagen 1, TGF-β and α-SMA. Western blot analysis estimated the protein expression levels of NLRP3, Pro Caspase-1, Caspase-1, ASC, IL-18, IL-1β, pp38, p38, and Connexin43(Cx43) to elucidate the influence of inflammation on electrical remodeling after MI. ResultsOur findings demonstrate that Phloretin inhibits the NLRP3/Caspase-1/IL-1β pathway, leading to the upregulation of Cx43 by limiting p38 phosphorylation, which further decreases susceptibility to ventricular arrhythmias (VAs). Additionally, Phloretin attenuated fibrosis by inhibiting inflammation to prevent HF. In vitro experiments also provided strong evidence supporting the inhibitory effects of Phloretin on the NLRP3/Caspase-1/IL-1β pathway. ConclusionOur results suggest that Phloretin could suppress the NLRP3/Caspase-1/IL-1β pathway to reverse structural and electrical remodeling after MI to prevent the occurrence of VAs and HF.

Regulation of uterus and placenta remodeling under high estradiol levels in gestational diabetes mellitus models†.

The present study aimed to investigate the regulation of placentas and uterus remodeling and involvement of E2 in gestational diabetes mellitus (GDM). To achieve this, we established in vitro and in vivo models for GDM placentas by culturing BeWo cells under hyperglycemic concentration, and treating pregnant rats with streptozotocin (STZ). We evaluated the expression of angiogenesis-related proteins. The expression of the anti-angiogenic factor, excess placental soluble fms-like tyrosine kinase 1 (sFLT1) was increased in our in vitro GDM model compared to the control. Moreover, the expressions of placental sFLT1 and the von willebrand factor (VWF) were also significantly elevated in the placenta of STZ-treated rats. These data indicate the disruption of angiogenesis in the GDM placentas. The expression levels of connexin 43 (Cx43), a component of the gap junction and collagen type I alpha 2 chain (Col1a2), a component of the extracellular matrix, were decreased in the GDM uterus. These results suggest that uterus decidualization and placental angiogenesis are inhibited in GDM rats. Our results also showed upregulation of the expression of genes regulating E2 synthesis as well as estrogen receptors (ER) in vivo models. Accordingly, the concentration of E2 measured in the culture medium under hyperglycemic conditions, as well as in the serum and placenta of the STZ-treated rats, was significantly elevated compared to the control groups. These results suggest that the dysregulated remodeling of the placenta and uterus may result in the elevation of E2 and its signaling pathway in the GDM animal model to maintain pregnancy.

Atrial cardiomyocytes orchestrate the development of profibrotic inflammatory profile associated with atrial fibrillation vulnerability

Atrial fibrillation (AF) is the most common type of arrhythmia encountered clinically. AF risk factors include hypertension, respiratory diseases, obesity, or heart failure. Right heart disease (RHD) has also been described among AF risk factors associated with an atrial inflammatory profile leading to AF. Studies focusing on the cardiomyocytes (CM) orchestration of the tri-factorial relation between RHD, inflammation, and AF are rare. This project aims to characterize the proarrhythmogenic remodeling affecting atrial cardiomyocyte in a rat model of RHD induced by permanent pulmonary trunk constriction. Characterize RHD induced electrophysiological and morphological CM remodeling leading to atrial inflammation and fibrosis, responsible for increased AF susceptibility. Pulmonary artery banding (PAB) was performed on Wistar rats weighing 225–275 g to induce right-sided cardiac hypertrophy and dilation. Sham animals did not receive the PAB surgery. Cardiac echography and electrophysiological studies were performed in vivo on all animals before sacrifice, 21 days post-surgery. Optical mapping was performed ex-vivo on Langendorff-perfused hearts. Freshly isolated right ventricular (RV), as well as right and left atrial (RA and LA) CM, underwent contractility recording in vitro. Histological analyses were performed to assess myocardial fibrosis and Connexin-43 levels. Genes and protein levels were obtained by qPCR and Western-blot analyses respectively. PAB animals developed severe ventricular and atrial myocardial hypertrophy and dilation compared to Sham, as assessed by echocardiography. PAB animals were significantly more susceptible to AF compared to Sham. Freshly isolated CM revealed that overall CM size was increased in PAB animals, and contractile activity of CM was increased compared to the Sham rats. Analyses of targeted protein and gene expression levels by immunohistochemistry and qPCR analyses showed enhanced expression of fibrosis and inflammation-related compounds in whole-RA and RA CM from PAB, compared to Sham. RHD induces electro-physiological remodeling influencing the RA CM contractile machinery which in turn, leads to the development of pro-arrhythmogenic substrate including atrial inflammation, fibrosis, and enhanced AF inducibility.

Hydroxychloroquine induces long QT syndrome by blocking hERG channel

Abstract Objective In March 2022, more than 600 million cases of Corona Virus Disease 2019 (COVID-19) and about 6 million deaths have been reported worldwide. Unfortunately, while effective antiviral therapy has not yet been available, chloroquine (CQ)/hydroxychloroquine (HCQ) has been considered an option for the treatment of COVID-19. While many studies have demonstrated the potential of HCQ to decrease viral load and rescue patients’ lives, controversial results have also been reported. One concern associated with HCQ in its clinical application to COVID-19 patients is the potential of causing long QT interval (LQT), an electrophysiological substrate for the induction of lethal ventricular tachyarrhythmias. Yet, the mechanisms for this cardiotoxicity of HCQ remained incompletely understood. Materials and methods Adult New Zealand white rabbits were used for investigating the effects of HCQ on cardiac electrophysiology and expression of ion channel genes. HEK-293T cells with sustained overexpression of human-ether-a-go-go-related gene (hERG) K+ channels were used for whole-cell patch-clamp recordings of hERG K+ channel current (IhERG). Quantitative RT-PCR analysis and Western blot analysis were employed to determine the expression of various genes at mRNA and protein levels, respectively. Results electrocardiogram (ECG) recordings revealed that HCQ prolonged QT and RR intervals and slowed heart rate in rabbits. Whole-cell patch-clamp results showed that HCQ inhibited the tail current of hERG channels and slowed the reactivation process from inactivation state. HCQ suppressed the expression of hERG and hindered the formation of the heat shock protein 90 (Hsp90)/hERG complex. Moreover, the expression levels of connexin 43 (CX43) and Kir2.1, the critical molecular/ionic determinants of cardiac conduction thereby ventricular arrythmias, were decreased by HCQ, while those of Cav1.2, the main Ca2+ handling proteins, remained unchanged and SERCA2a was increased. Conclusion HCQ could induce LQT but did not induce arrhythmias, and whether it is suitable for the treatment of COVID-19 requires more rigorous investigations and validations in the future.

Arsenic interferes with spermatogenesis involving Rictor/mTORC2-mediated blood-testis barrier disruption in mice

Ingestion of arsenic interferes with spermatogenesis and increases the risk of male infertility, but the underlying mechanism remines unclear. In this study, we investigated spermatogenic injury with a focus on blood-testis barrier (BTB) disruption by administrating 5 mg/L and 15 mg/L arsenic orally to adult male mice for 60 d. Our results showed that arsenic exposure reduced sperm quality, altered testicular architecture, and impaired Sertoli cell junctions at the BTB. Analysis of BTB junctional proteins revealed that arsenic intake downregulated Claudin-11 expression and increased protein levels of β-catenin, N-cadherin, and Connexin-43. Aberrant localization of these membrane proteins was also observed in arsenic-treated mice. Meanwhile, arsenic exposure altered the components of Rictor/mTORC2 pathway in mouse testis, including inhibition of Rictor expression, reduced phosphorylation of protein kinase Cα (PKCα) and protein kinase B (PKB), and elevated matrix metalloproteinase-9 (MMP-9) levels. Furthermore, arsenic also induced testicular lipid peroxidative damage, inhibited antioxidant enzyme (T-SOD) activity, and caused glutathione (GSH) depletion. Our findings suggest that disruption of BTB integrity is one of the main factors responsible for the decline in sperm quality caused by arsenic. PKCα-mediated rearrangement of actin filaments and PKB/MMP-9-increased barrier permeability jointly contribute to arsenic-induced BTB disruption.

Upregulation of astroglial connexin 30 impairs hippocampal synaptic activity and recognition memory.

Astrocytes crucially contribute to synaptic physiology and information processing. One of their key characteristics is to express high levels of connexins (Cxs), the gap junction-forming protein. Among them, Cx30 displays specific properties since it is postnatally expressed and dynamically upregulated by neuronal activity and modulates cognitive processes by shaping synaptic and network activities, as recently shown in knockout mice. However, it remains unknown whether local and selective upregulation of Cx30 in postnatal astrocytes within a physiological range modulates neuronal activities in the hippocampus. We here show in mice that, whereas Cx30 upregulation increases the connectivity of astroglial networks, it decreases spontaneous and evoked synaptic transmission. This effect results from a reduced neuronal excitability and translates into an alteration in the induction of synaptic plasticity and an in vivo impairment in learning processes. Altogether, these results suggest that astroglial networks have a physiologically optimized size to appropriately regulate neuronal functions.

Effect of progesterone on in vitro meiotic maturation of canine oocytes associated with Cx37 and Cx43 gene expression

Progesterone (P4) concentrations in canines are exceptionally high in the periovulatory period. However, the mechanisms by which P4 modulates final oocyte development in dogs remain to be characterized. The aim of this study was to evaluate the effect of P4 on meiotic development related to the gene expression of connexin 37 (Cx37) and connexin 43 (Cx43) in the canine cumlus oocyte complexes (COCs). COCs were isolated from 120 canine ovaries after a routine ovariohysterectomy. In each experiment, groups of COCs retrieved from the antral follicles were subjected to in vitro maturation (IVM) for 72 h without (control) or with P4 (50 μg/mL and 100 μg/mL) or the P4 receptor antagonist, aglepristone (RU534 at 1 μM and 10 μM). Some of the COCs recovered (from each group) after 72 h of IVM were subjected to meiotic evaluation; the remaining COCs, and those not subjected to IVM, were used to analyze the gene expression of Cx37 and Cx43 by qPCR. The results were evaluated using ANOVA. The addition of P4 increased (P < 0.05) the meiotic development compared to that in the control or aglepristone groups. The highest (P < 0.05) percentage of oocytes in the MII stage was observed upon P4 supplementation. In contrast, the highest percentage (P < 0.05) of oocytes arrested in the GV stage and the lowest (P < 0.05) percentages in the MII stage were observed for COCs cultured with aglepristone. Although a significant decrease in the mRNA levels of both connexins was observed after culturing, no effect on Cx37 and Cx43 gene expression was observed when exogenous P4 was added compared to those of the control group. However, COCs cultured with aglepristone exhibited higher (P < 0.05) expression of Cx37 and Cx43 than COCs in the control IVM-group, regardless of the concentration. In conclusion, our results suggest that a high dosage of P4 during IVM enhances the nuclear maturation of canine oocytes without altering the gene expression levels of Cx37 and Cx43. However, the increase in their expression upon treatment with a P4 antagonist indicates an in vivo role for this hormone in the endogenous modulation of both Cx37 and Cx43.

The IgSF Cell Adhesion Protein CLMP and Congenital Short Bowel Syndrome (CSBS).

The immunoglobulin-like cell adhesion molecule CLMP is a member of the CAR family of cell adhesion proteins and is implicated in human congenital short-bowel syndrome (CSBS). CSBS is a rare but very severe disease for which no cure is currently available. In this review, we compare data from human CSBS patients and a mouse knockout model. These data indicate that CSBS is characterized by a defect in intestinal elongation during embryonic development and impaired peristalsis. The latter is driven by uncoordinated calcium signaling via gap junctions, which is linked to a reduction in connexin43 and 45 levels in the circumferential smooth muscle layer of the intestine. Furthermore, we discuss how mutations in the CLMP gene affect other organs and tissues, including the ureter. Here, the absence of CLMP produces a severe bilateral hydronephrosis-also caused by a reduced level of connexin43 and associated uncoordinated calcium signaling via gap junctions.

Plasma exosome-derived connexin43 as a promising biomarker for melanoma patients

BackgroundTo examine the levels of exosome-derived connexin 43 (Cx43) in plasma and estimate its forecast value in patients with melanoma.MethodsWe measured the plasma exosome-derived Cx43 levels in the plasma of 112 melanoma patients and 50 healthy controls.ResultsThe plasma exosome-derived Cx43 levels in patients with melanoma were substantially downregulated as opposed to the levels in healthy controls (P < 0.001). Kaplan–Meier analysis indicated that overall survival (OS) and disease-free survival (DFS) were poorer in patients with melanoma who exhibited lower levels of plasma exosome-derived Cx43 (both P < 0.001). The levels of plasma exosome-derived Cx43 were considerably elevated in patients with melanoma whose tumor was situated in the skin, tumor size < 10 cm, with Clark level I–III, TNM stages IIb–IV, and had no lymph node metastasis as opposed to patients whose tumor was situated in the viscera or mucosa, tumor size ≥ 10 cm, Clark level IV–V, TNM stages IIb–IV and had lymph node metastasis (all P < 0.05). The receiver operating characteristic (ROC) of plasma exosome-derived Cx43 for forecasting 5-year DFS in patients with melanoma was 0.78 (95% confidence interval (CI): 0.70–0.86), with a specificity of 77.78% and a sensitivity of 81.55%. The ROC of plasma exosome-derived Cx43 for forecasting 5-year OS of patients with melanoma was 0.77 (95% CI: 0.68–0.84), with a specificity of 80.0% and sensitivity of 65.98%.ConclusionThe overall findings indicated that the levels of plasma exosome-derived Cx43 in patients with melanoma were considerably downregulated. It can therefore be inferred that the levels of plasma exosome-derived Cx43 might be a prospective prognostic indicator for 5 5-year OS and 5-year DFS of patients with melanoma.

PITX2 induction leads to impaired cardiomyocyte function in arrhythmogenic cardiomyopathy.

Arrhythmogenic cardiomyopathy (ACM) is an inherited progressive disease characterized by electrophysiological and structural remodeling of the ventricles. However, the disease-causing molecular pathways, as a consequence of desmosomal mutations, are poorly understood. Here, we identified a novel missense mutation within desmoplakin in a patient clinically diagnosed with ACM. Using CRISPR-Cas9, we corrected this mutation in patient-derived human induced pluripotent stem cells (hiPSCs) and generated an independent knockin hiPSC line carrying the same mutation. Mutant cardiomyocytes displayed a decline in connexin 43, NaV1.5, and desmosomal proteins, which was accompanied by a prolonged action potential duration. Interestingly, paired-like homeodomain 2 (PITX2), a transcription factor that acts a repressor of connexin 43, NaV1.5, and desmoplakin, was induced in mutant cardiomyocytes. We validated these results in control cardiomyocytes in which PITX2 was either depleted or overexpressed. Importantly, knockdown of PITX2 in patient-derived cardiomyocytes is sufficient to restore the levels of desmoplakin, connexin 43, and NaV1.5.

Arundic acid (ONO-2506) downregulates neuroinflammation and astrocyte dysfunction after status epilepticus in young rats induced by Li-pilocarpine

Astrocytes, the most abundant glial cells, have several metabolic functions, including ionic, neurotransmitter and energetic homeostasis for neuronal activity. Reactive astrocytes and their dysfunction have been associated with several brain disorders, including the epileptogenic process. Glial Fibrillary Acidic Protein (GFAP) and S100 calcium-binding protein B (S100B) are astrocyte biomarkers associated with brain injury. We hypothesize that arundic acid (ONO-2506), which is known as an inhibitor of S100B synthesis and secretion, protects the hippocampal tissue from neuroinflammation and astrocyte dysfunction after status epileptics (SE) induction by Li-pilocarpine in young rats. Herein, we investigated the effects of arundic acid treatment, at time points of 6 or 24 h after the induction of SE by Li-pilocarpine, in young rats. In SE animals, arundic acid was able to prevent the damage induced by Li-pilocarpine in the hippocampus, decreasing neuroinflammatory signaling (reducing IL-1β, COX2, TLR4 and RAGE contents), astrogliosis (decreasing GFAP and S100B) and astrocytic dysfunction (recovering levels of GSH, glutamine synthetase and connexin-43). Furthermore, arundic acid improved glucose metabolism and reduced the glutamate excitotoxicity found in epilepsy. Our data reinforce the role of astrocytes in epileptogenesis development and the neuroprotective role of arundic acid, which modulates astrocyte function and neuroinflammation in SE animals.

CX43-Mediated Mitochondria Transfer from Bone Marrow Stromal Cells Promotes the Stemness of Leukemia Stem Cells

Background: Leukemia stem cells (LSCs) play an important role in the occurrence, development, chemoresistance and recurrence of leukemia, but the underlying mechanisms that maintain the stemness of LSCs are poorly understood. Bone marrow stromal cells (BMSCs) are a key component in the hematopoietic microenvironment, which support and regulate the biological behaviors of hematopoietic stem cells (HSCs). Similarly, hematopoietic microenvironment plays an important role in the development of leukemia. In this study, we aimed to uncover the mechanism of BMSCs regulated stemness of leukemia stem cells through Connexin 43 (CX43) -mediated mitochondrial transfer, which might provide a promising clinical therapy target. Methods: Primary BMSCs were isolated from bone marrow of patients with AML and cultured in BMSCs specific medium within 10% fetal bovine serum . CX43 overexpressing BMSCs (CX43-BMSCS) were constructed by lentivirus transfection. The efficiency of CX43 overexpression was verified by immunofluorescence, qPCR and Western Blot. In vitro, CX43-BMSCs and EV-BMSCs (empty virus transfection) were co-cultured with KG-1a cells, respectively. In some experiments, vincristine (1nM) was used to inhibit the formation of tunneling nanotubes (TNTs). The mitochondria transfer was detected by flow cytometry and confocal microscopy. The proliferation of KG-1a from the co-culture system was assessed by flow cytometry and EDU assay. The clone formation of KG-1a was detected by using semisolid cloning assay. Results: Compared with EV-BMSCs, the mRNA and protein expression levels of CX43 in CX43-BMSCs were significantly increased (P < 0.05). Regardless of CX43 expression level, there was no obvious mitochondrial transfer was observed in the co-culture system with 10% fetal bovine serum. In the co-culture system without fetal bovine serum for 48h, we observed mitochondria transfer from BMSCs to KG-1a through TNTs, while hardly any mitochondria from KG-1a to BMSCs. Moreover, CX43-BMSCs transferred more mitochondria to KG-1a than EV-BMSCs group (P < 0.05). In addition, overexpression of CX43 in BMSCs significantly increased the adhesion, proliferation and clone formation ability of KG-1a in co-culture system (P < 0.05). The inhibition of TNTs formation by vincristine significantly reduced the mitochondrial transfer from CX43-BMSCs to KG-1a, and decreased the adhesion of CX43-BMSCs to KG-1a, as well as the proliferation and clone formation of KG-1a after co-culture. Conclusion: Under the condition of nutrient deficiency, CX43 mediated the unidirectional transfer of mitochondria from BMSCs to LSCs by promoting the adhesion of LSCs to BMSCs and the formation of TNTs, and then enhanced the proliferation and clone formation ability of LSCs.

Pinocembrin alleviates the susceptibility to atrial fibrillation in isoproterenol-induced rats

BackgroundInflammation can contribute to the initiation and progression of atrial fibrillation (AF), and pinocembrin can suppress downstream inflammatory cytokine production by inhibiting the inflammation pathway. In our previous studies, pinocembrin was also beneficial in ameliorating cardiac arrhythmia in different models of rats, such as depression, myocardial infarction, and heart failure. This study aims to investigate the effect of pinocembrin on the susceptibility to AF in isoproterenol-induced rats. MethodsRats were randomly divided into four groups. Pinocembrin was injected through the tail vein. Isoproterenol was treated by intraperitoneal injection for one week (5 mg/kg/day). We evaluated the susceptibility to AF by atrial electrophysiological experiments. Masson staining was used to evaluate the fibrosis area. The protein levels of connexin (Cx) 40, Cav1.2, Kv4.2, collagen I, collagen III, α-SMA, transforming growth factor (TGF)-β, NLRP3, caspase 1, and interleukin (IL)-1β were detected by western blot. ResultsOur data demonstrated that pinocembrin could prolong the atrial effective refractory period (ERP) and action potential duration (APD), and decrease AF inducibility. Isoproterenol increased the expression of Cav1.2 and Kv4.2 ion channels whereas pinocembrin could alleviate this change. Pinocembrin could reduce the fibrosis area, fibrosis-related protein collagen I, collagen III, α-SMA, and TGF-β and upregulate gap junction protein Cx40. In addition, pinocembrin reduced the expression of NLRP3, caspase 1, and IL-1β. ConclusionsOur study indicated that pinocembrin was beneficial to alleviate atrial electrical remodeling and fibrosis. Accompanied the downregulation of ion channels and upregulation of gap junction protein Cx40. Pinocembrin may produce these effects by inhibiting the NLRP3 pathway.