Anti-diabetic drug canagliflozin hinders skeletal muscle regeneration in mice.

Canagliflozin is an antidiabetic medicine that inhibits sodium-glucose cotransporter 2 (SGLT2) in proximal tubules. Recently, it was reported to have several noncanonical effects other than SGLT2 inhibiting. However, the effects of canagliflozin on skeletal muscle regeneration remain largely unexplored. Thus, in vivo muscle contractile properties recovery in mice ischemic lower limbs following gliflozins treatment was evaluated. The C2C12 myoblast differentiation after gliflozins treatment was also assessed in vitro. As a result, both in vivo and in vitro data indicate that canagliflozin impairs intrinsic myogenic regeneration, thus hindering ischemic limb muscle contractile properties, fatigue resistance recovery, and tissue regeneration. Mitochondrial structure and activity are both disrupted by canagliflozin in myoblasts. Single-cell RNA sequencing of ischemic tibialis anterior reveals a decrease in leucyl-tRNA synthetase 2 (LARS2) in muscle stem cells attributable to canagliflozin. Further investigation explicates the noncanonical function of LARS2, which plays pivotal roles in regulating myoblast differentiation and muscle regeneration by affecting mitochondrial structure and activity. Enhanced expression of LARS2 restores the differentiation of canagliflozin-treated myoblasts, and accelerates ischemic skeletal muscle regeneration in canagliflozin-treated mice. Our data suggest that canagliflozin directly impairs ischemic skeletal muscle recovery in mice by downregulating LARS2 expression in muscle stem cells, and that LARS2 may be a promising therapeutic target for injured skeletal muscle regeneration.

The interplay between mitochondria and store-operated Ca2+ entry: Emerging insights into cardiac diseases.

Store-operated Ca2+ entry (SOCE) machinery, including Orai channels, TRPCs, and STIM1, is key to cellular calcium homeostasis. The following characteristics of mitochondria are involved in the physiological and pathological regulation of cells: mitochondria mediate calcium uptake through calcium uniporters; mitochondria are regulated by mitochondrial dynamic related proteins (OPA1, MFN1/2, and DRP1) and form mitochondrial networks through continuous fission and fusion; mitochondria supply NADH to the electron transport chain through the Krebs cycle to produce ATP; under stress, mitochondria will produce excessive reactive oxygen species to regulate mitochondria-endoplasmic reticulum interactions and the related signalling pathways. Both SOCE and mitochondria play critical roles in mediating cardiac hypertrophy, diabetic cardiomyopathy, and cardiac ischaemia-reperfusion injury. All the mitochondrial characteristics mentioned above are determinants of SOCE activity, and vice versa. Ca2+ signalling dictates the reciprocal regulation between mitochondria and SOCE under the specific pathological conditions of cardiomyocytes. The coupling of mitochondria and SOCE is essential for various pathophysiological processes in the heart. Herein, we review the research focussing on the reciprocal regulation between mitochondria and SOCE and provide potential interplay patterns in cardiac diseases.

Improvement of cardiac and systemic function in old mice by agonist of growth hormone-releasing hormone.

Age-related diseases such as cardiovascular diseases portend disability, increase health expenditures, and cause late-life mortality. Synthetic agonists of growth hormone-releasing hormone (GHRH) exhibit several favorable effects on heart function and remodeling. Here we assessed whether GHRH agonist MR409 can modulate heart function and systemic parameters in old mice. Starting at the age of 15 months, mice were injected subcutaneously with MR409 (10 µg/day, n = 8) or vehicle (n = 7) daily for 6 months. Mice treated with MR409 showed improvements in exercise activity, cardiac function, survival rate, immune function, and hair growth in comparison with the controls. More stem cell colonies were grown out of the bone marrow recovered from the MR409-treated mice. Mitochondrial functions of cardiomyocytes (CMs) from the MR409-treated mice were also significantly improved with more mitochondrial fusion. Fewer ß-gal positive cells were observed in endothelial cells after 10 passages with MR409. In Doxorubicin-treated H9C2 cardiomyocytes, cell senescence marker p21 and reactive oxygen species were significantly reduced after cultured with MR409. MR409 also improved cellular ATP production and oxygen consumption rate in Doxorubicin-treated H9C2 cells. Mitochondrial protein OPA1 long isoform was significantly increased after treatment with MR409. The effects of MR409 were mediated by GHRH receptor and protein kinase A (PKA). In short, GHRH agonist MR409 reversed the aging-associated changes with respect of heart function, mobility, hair growth, cellular energy production, and senescence biomarkers. The improvement of heart function may be related to a better mitochondrial functions through GHRH receptor/cAMP/PKA/OPA1 signaling pathway and relieved cardiac inflammation.

Growth differentiation factor 11 promotes differentiation of MSCs into endothelial-like cells for angiogenesis.

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-ß super family. It has multiple effects on development, physiology and diseases. However, the role of GDF11 in the development of mesenchymal stem cells (MSCs) is not clear. To explore the effects of GDF11 on the differentiation and pro-angiogenic activities of MSCs, mouse bone marrow-derived MSCs were engineered to overexpress GDF11 (MSCGDF11 ) and their capacity for differentiation and paracrine actions were examined both in vitro and in vivo. Expression of endothelial markers CD31 and VEGFR2 at the levels of both mRNA and protein was significantly higher in MSCGDF11 than control MSCs (MSCVector ) during differentiation. More tube formation was observed in MSCGDF11 as compared with controls. In an in vivo angiogenesis assay with Matrigel plug, MSCGDF11 showed more differentiation into CD31+ endothelial-like cells and better pro-angiogenic activity as compared with MSCVector . Mechanistically, the enhanced differentiation by GDF11 involved activation of extracellular-signal-related kinase (ERK) and eukaryotic translation initiation factor 4E (EIF4E). Inhibition of either TGF-ß receptor or ERK diminished the effect of GDF11 on MSC differentiation. In summary, our study unveils the function of GDF11 in the pro-angiogenic activities of MSCs by enhancing endothelial differentiation via the TGFß-R/ERK/EIF4E pathway.

Regulation of Vascular Calcification by Growth Hormone-Releasing Hormone and Its Agonists.

RATIONALE: Vascular calcification (VC) is a marker of the severity of atherosclerotic disease. Hormones play important roles in regulating calcification; estrogen and parathyroid hormones exert opposing effects, the former alleviating VC and the latter exacerbating it. To date no treatment strategies have been developed to regulate clinical VC. OBJECTIVE: The objective of this study was to investigate the effect of growth hormone-releasing hormone (GHRH) and its agonist (GHRH-A) on the blocking of VC in a mouse model. METHODS AND RESULTS: Young adult osteoprotegerin-deficient mice were given daily subcutaneous injections of GHRH-A (MR409) for 4 weeks. Significant reductions in calcification of the aortas of MR409-treated mice were paralleled by markedly lower alkaline phosphatase activity and a dramatic reduction in the expression of transcription factors, including the osteogenic marker gene Runx2 and its downstream factors, osteonectin and osteocalcin. The mechanism of action of GHRH-A was dissected in smooth muscle cells isolated from human and mouse aortas. Calcification of smooth muscle cells induced by osteogenic medium was inhibited in the presence of GHRH or MR409, as evidenced by reduced alkaline phosphatase activity and Runx2 expression. Inhibition of calcification by MR409 was partially reversed by MIA602, a GHRH antagonist, or a GHRH receptor-selective small interfering RNA. Treatment with MR409 induced elevated cytosolic cAMP and its target, protein kinase A which in turn blocked nicotinamide adenine dinucleotide phosphate oxidase activity and reduced production of reactive oxygen species, thus blocking the phosphorylation of nuclear factor κB (p65), a key intermediate in the ligand of receptor activator for nuclear factor-κ B-Runx2/alkaline phosphatase osteogenesis program. A protein kinase A-selective small interfering RNA or the chemical inhibitor H89 abolished these beneficial effects of MR409. CONCLUSIONS: GHRH-A controls osteogenesis in smooth muscle cells by targeting cross talk between protein kinase A and nuclear factor κB (p65) and through the suppression of reactive oxygen species production that induces the Runx2 gene and alkaline phosphatase. Inflammation-mediated osteogenesis is thereby blocked. GHRH-A may represent a new pharmacological strategy to regulate VC.

Lipofectamine 2000/siRNA complexes cause endoplasmic reticulum unfolded protein response in human endothelial cells.

Lipofectamine 2000 (Lipo2000) delivery system is commonly used for short interfering RNA (siRNA) transfection, whereas the cellular responses have attracted little attention. The purpose of this study is to evaluate the effect of siRNA transfection using Lipo2000 on cellular functions and the possible underlying mechanism. Primary human umbilical vein endothelial cells (HUVECs) and adult human coronary artery endothelial cell line (HCAECs) were treated with different concentrations of a Lipo2000/negative control siRNA (NC siRNA) complex or Lipo2000 for specific durations. The cell proliferation, apoptosis rate, and protein expression of claudin5 (CLDN5) and ETS-related gene (ERG) were analyzed as indicators of cellular function. The effects of the Lipo2000/NC siRNA complex on cellular autophagy and endoplasmic reticulum (ER) unfolded protein response (UPR) were investigated by western blot and real-time polymerase chain reaction analyses; autophagy was also evaluated by transmission electron microscopy. The Lipo2000/NC siRNA complex inhibited proliferation, downregulated various proteins, and increased the apoptosis in both HUVECs and HCAECs. Both autophagy and UPR were observed in HUVECs treated with the Lipo2000/NC siRNA complex, ER stress-induced autophagy acted as a cellular protective factor against apoptosis, as inhibition of autophagy by chemical inhibitors increased the cell apoptosis rate. Chemical chaperones failed to prevent the Lipo2000/siRNA complex-induced UPR. However, knockdown of protein kinase RNA-like ER kinase and inositol-requiring protein 1, instead of activating transcription factor-6, partially ameliorated the UPR and reversed the protein level of CLDN5 and ERG downregulated by Lipo2000/NC siRNA complex. This study provides the first evidence that the Lipo2000-mediated transport of siRNA leads to an increase in UPR and ER stress-related apoptosis in endothelial cells.

Synthesis and biological evaluation of 1,3,4-thiadiazole derivatives as type III secretion system inhibitors against Xanthomonas oryzae.

Xanthomonas oryzae pv. oryzae (Xoo) infection directly leads to a severe disease known as leaf blight, which is a major cause of yield loss of rice. Use of traditional bactericides has resulted in severe resistance in pathogenic bacteria. A new approach screening compounds that target the virulence factors rather than killing bacterial pathogens is imperative. In gram-negative bacteria, the type III secretion system (T3SS) is a conserved and significant virulence factor considered as a target for drug development. Therefore, we designed and synthesized a new series of 5-phenyl-2-furan carboxylic acid derivatives stitched with 2-mercapto-1,3,4-thiadiazole. Bioassays revealed that the title candidates attenuated the hypersensitive response through suppressing the promoter activity of a harpin gene hpa1 without affecting bacterial growth. Quantitative real time polymerase chain reaction (qRT-PCR) analysis demonstrated reduced the expression of several genes associated with T3SS, when title compounds were applied. Additionally, hrp gene cluster members, including hrpG and hrpX, had reduced mRNA levels. In vivo greenhouse tests showed that candidate compounds could alleviate the effects of Xoo infection in rice (Oryza sativa) and possess better protective activity against rice bacterial leaf blight than bismerthiazol and thiodiazole copper. All tested compounds were safe to rice. This work suggests there are new safe options for Xoo control in rice from these 1,3,4-thiadiazole derivatives.

Characterize direct protein interactions with enrichable, cleavable and latent bioreactive unnatural amino acids.

Latent bioreactive unnatural amino acids (Uaas) have been widely used in the development of covalent drugs and identification of protein interactors, such as proteins, DNA, RNA and carbohydrates. However, it is challenging to perform high-throughput identification of Uaa cross-linking products due to the complexities of protein samples and the data analysis processes. Enrichable Uaas can effectively reduce the complexities of protein samples and simplify data analysis, but few cross-linked peptides were identified from mammalian cell samples with these Uaas. Here we develop an enrichable and multiple amino acids reactive Uaa, eFSY, and demonstrate that eFSY is MS cleavable when eFSY-Lys and eFSY-His are the cross-linking products. An identification software, AixUaa is developed to decipher eFSY mass cleavable data. We systematically identify direct interactomes of Thioredoxin 1 (Trx1) and Selenoprotein M (SELM) with eFSY and AixUaa.

NRF2-HIF2α Signaling Attenuates Endothelial Cell Senescence and Maintains Intercellular Junctions in Diabetes.

In the context of diabetes, endothelial cells frequently exhibit compromised intercellular junctions and accelerated cellular senescence simultaneously. The precise mechanisms underlying these issues and the identification of effective treatments remain largely undefined. Our findings reveal that human umbilical vein endothelial cells (HUVECs) can counteract senescence and uphold the integrity of intercellular junctions under mildly to moderately elevated glucose levels (10 mM and 15 mM) via two primary mechanisms: i) The acetylation of NRF2 at lysine residues K56, K68, and K52 prevents its ubiquitination, enhancing the transcription of antioxidant genes GST, SOD1, and GPX1. This activity diminishes cytoplasmic oxidative stress, thereby mitigating endothelial cell senescence. ii) The interaction between the Neh2 domain of NRF2 and the PAS-B domain of HIF-2α within the nucleus curtails the attachment of HIF-2α to the NOX4/p22phox promoter. This action lessens oxidative stress near the cell membrane, maintaining intercellular junctions by safeguarding the disulfide bonds in occludin and E-cadherin from disruption. However, these protective strategies prove insufficient under severe hyperglycemic conditions (25 mM). Further investigation has identified Oltipraz, an activator of NRF2, as also promoting the degradation of HIF-2α. Through its simultaneous modulation of NRF2 and HIF-2α, Oltipraz significantly reduces cellular senescence and prevents the deterioration of intercellular junctions in HUVECs subjected to high glucose concentrations (25 mM). Our research positions Oltipraz as a promising therapeutic candidate for mitigating diabetes-induced vascular endothelial damage, potentially offering benefits against diabetes-related atherosclerosis and valvular calcification.

Investigation of Metabolic and Inflammatory Disorder in the Aging FGF21 Knockout Mouse.

Aging is a physiological condition accomplished with persistent low-grade inflammation and metabolic disorders. FGF21 has been reported to act as a potent longevity determinant, involving inflammatory response and energy metabolism. In this study, we engineered aging FGF21 knockout mice of 36-40 weeks and observed that FGF21 deficiency manifests a spontaneous inflammatory response of lung and abnormal accumulation of lipids in liver. On one hand, inflamed state in lungs and increased circulating inflammatory cytokines were found in FGF21 knockout mice of 36-40 weeks. To evaluate the ability of FGF21 to suppress inflammation, a subsequent study found that FGF21 knockout aggravated LPS-induced pulmonary exudation and inflammatory infiltration in mice, while exogenous administration of FGF21 reversed these malignant phenotypes by enhancing microvascular endothelial junction. On the other hand, FGF21 knockout induces fatty liver in aging mice, characterized by excessive accumulation of triglycerides within hepatocytes. Further quantitative metabolomics and lipidomics analysis revealed perturbed metabolic profile in liver lacking FGF21, including disrupted glucose and lipids metabolism, glycerophospholipid metabolism, and amino acid metabolism. Taken together, this investigation reveals the protective role of FGF21 during aging by weakening the inflammatory response and balancing energy metabolism.

[Effect of crucumin on vascular endothelial function in atherosclerotic rabbits].

OBJECTIVE: To observe the effect of curcumin on nitric oxide (NO) in plasma of atherosclerotic rabbits, activity of constitutive nitric oxide synthase (cNOS) and asymmetric dimethylarginine (ADMA), and discuss curcumin's effect against AS and its correlation with ADMA. METHOD: Thirty-eight male Japanese white rabbits were randomly divided into four groups: the control group (eight rabbits fed with standard diets), the model group (ten rabbits fed with high-fat diets), the low dose curcumin group (ten rabbits fed with high-fat diets and 100 mg . kg-1 d -1 ) and the high dose curcumin group (ten rabbits fed with high-fat diets and 200 mg kg-1 d-1 curcumin). At the end of the 12th week, their plasmas were tested for TC, LDL-C, NO, endothelin (ET) , ADMA and activity of aortic cNOS. Aortic tissues were collected for histological examinations. RESULT: The three groups fed with high-fat diets showed higher plasma ADMA and ET than the control group (P <0. 01) , but with decrease in plasma NO concentration and arterial cNOS activity (P <0. 01). Compared with the model group (P <0. 05) , the curcumin groups showed lower plasma ADMA and ET (P <0. 05), but higher plasma NO concentration and arterial cNOS activity than the model group (P <0. 01). There was no significant difference between the two curcumin groups. CONCLUSION: Curcumin may play an important protective role in AS process by reducing plasma ADMA level. [Key words] atherosclerosis; asymmetric dimethylarginine; crucumin; nitric oxide; nitric oxide synthase

Mapping protein direct interactome of oxidoreductases with small molecular chemical cross-linkers in live cells.

Identifying direct substrates of enzymes has been a long-term challenge. Here, we present a strategy using live cell chemical cross-linking and mass spectrometry to identify the putative substrates of enzymes for further biochemical validation. Compared with other methods, our strategy is based on the identification of cross-linked peptides supported by high-quality MS/MS spectra, which eliminates false-positive discoveries of indirect binders. Additionally, cross-linking sites allow the analysis of interaction interfaces, providing further information for substrate validation. We demonstrated this strategy by identifying direct substrates of thioredoxin in both E. coli and HEK293T cells using two bis-vinyl sulfone chemical cross-linkers BVSB and PDES. We confirmed that BVSB and PDES have high specificity in cross-linking the active site of thioredoxin with its substrates both in vitro and in live cells. Applying live cell cross-linking, we identified 212 putative substrates of thioredoxin in E. coli and 299 putative S-nitrosylation (SNO) substrates of thioredoxin in HEK293T cells. In addition to thioredoxin, we have shown that this strategy can be applied to other proteins in the thioredoxin superfamily. Based on these results, we believe future development of cross-linking techniques will further advance cross-linking mass spectrometry in identifying substrates of other classes of enzymes.

Maternal Anxiety Symptoms and Chinese Adolescents' Mental Health During the COVID-19 Pandemic: The Protective Role of Adolescents' Self-Compassion.

The COVID-19 outbreak triggered dramatic changes to family life. Parents, especially mothers, were found to experience more psychological distress during the pandemic, which may have had an impact on their children's mental health. The primary goal of this study was to examine the potential protective role of adolescents' self-compassion in the relationship between maternal anxiety and adolescents' mental health during the COVID-19 pandemic. Participants included 5,720 adolescents (48.9% girls; M age = 11.60, SD age = 1.36) and their mothers from Zhengzhou city, Henan province, in Mainland China. Adolescents reported their level of self-compassion, PTSD symptoms, and negative affect during the COVID-19 pandemic. Mothers reported their own anxiety symptoms and their children's depression and anxiety symptoms. Results indicated that older female adolescents reported higher levels of PTSD symptoms and negative affect and lower levels of self-compassion than their counterparts. Maternal anxiety during the COVID-19 pandemic was consistently positively associated with adolescents' psychological maladjustment. These associations were buffered by adolescents' self-compassion. Specifically, adolescents with higher levels of self-compassion were found to be less psychologically affected by their mothers' anxiety during the COVID-19 pandemic. Findings highlighted the possibility of improving adolescents' mental health through fostering their self-compassion during the COVID-19 pandemic.

[Ryanodine downregulates the expression of p-eNOS (Thr495) and improves the functions of rapamycin treated endothelial outgrowth cells].

OBJECTIVE: To observe the effects of ryanodine on rapamycin treated endothelial outgrowth cells (EOCs). METHODS: The mononuclear cells were harvested from umbilical cord blood by Ficoll density gradient centrifugation, then induced into EOCs and expanded in vitro. The endothelial characteristics of EOCs were identified by immunostaining and fluorescent staining. The EOCs were pretreated with or without ryanodine (10 µmol/L) for 1 h, and then treated with or without rapamycin (10 nmol/L) for 24 h. Proliferation was evaluated by CCK8 and migration was measured by Transwell. The protein expression of EOCs was evaluated by immunobloting technique with total eNOS antibody and phospho-eNOS (Thr495) antibody. RESULTS: Compared with control group, the proliferation and migration capacities of EOCs were significantly reduced while the phosphorylation of eNOS (Thr495) protein was significantly upregulated in rapamycin group (P < 0.05), expression of total eNOS was not affected by rapamycin (P > 0.05). Compared with rapamycin group, the proliferation and migration capacities of EOCs were significantly increased and the phosphorylation of eNOS (Thr495) protein was significantly downregulated in ryanodine + rapamycin group (P < 0.05). The proliferation and migration capacities, the phosphorylation of eNOS (Thr495) protein and the expression of total eNOS were not affected by ryanodine alone (P > 0.05). CONCLUSIONS: Rapamycin reduced proliferation and migration capacities while upregulated the phosphorylation of eNOS (Thr495) protein of EOCs and these effects could be partly reversed by cotreatment with ryanodine.

Efficiency assessment of coal energy and non-coal energy under bound dynamic DDF DEA.

The demand for energy has continued to increase because of global economic development, which has led to rising fuel prices and continued pollution problems. China is currently the largest coal consumer and is also the largest emitter of coal-fired CO2 emissions. However, past efficiency studies have been mostly limited to static analyses and have not considered undesirable outputs. Therefore, this study developed a bound dynamic directional distance function (DDF) data envelopment analysis (DEA) model to explore the energy and environmental efficiencies in 30 Chinese provinces from 2011 to 2015, from which it was found that (1) the overall efficiency was the best in the eastern region, but relatively low in the western region; (2) Beijing, Guangdong, Jiangsu, Shandong, Shanghai, Tianjin, Jiangxi, Jilin, and some other regions had efficiencies of 1; (3) the revenue and non-coal indicator efficiencies were reasonably good, but the expenditure and emissions efficiencies were generally poor; and (4) the key direction for primary improvements was found to be the emissions index.

Air Pollution's Impact on the Economic, Social, Medical, and Industrial Injury Environments in China.

In this era of rapid economic development, it is inevitable that economic activities eventually cause serious damage to the environment's air quality, making it the focus of global public health. If the treatment efficiency of medical accidents can be improved, then this can significantly stabilize society and improve production efficiency. Past research has mainly focused on work safety and health issues, seldom discussing economic, social, medical, and environmental pollution issues together, and, most generally, adopted static methods that fail to recognize how air pollution affects the overall economy, society, medical care, and external environment. In order to more deeply understand the changes among social, economic activities, and environmental issues due to air pollution, this study proposes a meta-two-stage undesirable dynamic DDF (Direction Distance Function) that, under an exogenous model, divides the 30 provinces of China into high-income regions and middle-income regions and explores the economic, social, medical, and environmental efficiencies between the two areas to resolve the lack of related static analyses. The empirical results are as follows. (1) The AQI (air quality index) significantly impacts the efficiency of medical injuries in various regions. (2) When the AQI is considered, the medical insurance expenditure efficiency score value of high-income areas is lower than the value without the AQI. (3) When the AQI is considered, the efficiency value of the number of work injury insurance benefits in the middle-income area is lower than the efficiency value without the AQI.

FGF21 attenuates hypoxia­induced dysfunction and inflammation in HPAECs via the microRNA­27b­mediated PPARγ pathway.

Pulmonary arterial hypertension (PAH), is a chronic and progressive disorder characterized by pulmonary vascular remodeling, including endothelial cell dysfunction and inflammation. MicroRNAs (miRNAs or miRs) play an important role in the development of PAH. In addition, fibroblast growth factor 21 (FGF21) has been found to have marked anti-dysfunction and anti­inflammatory properties. Therefore, the present study aimed to investigate the latent effects of FGF21 against PAH through the miR­27b/peroxisome proliferator­activated receptor γ (PPARγ) axis. Human pulmonary arterial endothelial cells (HPAECs) subjected to hypoxia were used as PAH models. The results revealed that PPARγ expression was downregulated and miR­27b expression was upregulated in the HPAECs exposed to hypoxia. Luciferase assay suggested that PPARγ was a target gene of miR­27b. Furthermore, miR­27b inhibited the expression of the PPARγ gene, thereby aggravating hypoxia­induced HPAEC dysfunction. Moreover, miR­27b activated the nuclear factor­κB signaling pathway and the expression of inflammatory factors [interleukin (IL)­1ß, IL­6 and tumor necrosis factor­α] by targeting PPARγ. In addition, the expression of miR­27b decreased following treatment of the hypoxia­exposed HPAECs with FGF21. Furthermore, FGF21 alleviated hypoxia­induced HPAEC dysfunction and inflammation by inhibiting miR­27b expression and thereby promoting PPARγ expression. On the whole, the findings of the present study suggest that FGF21 may serve as a therapeutic target for managing PAH through the miR­27b­mediated PPARγ pathway.

GDF11 enhances therapeutic functions of mesenchymal stem cells for angiogenesis.

BACKGROUND: The efficacy of stem cell therapy for ischemia repair has been limited by low cell retention rate. Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-ß super family, which has multiple effects on development, physiology and diseases. The objective of the study is to investigate whether GDF11 could affect the efficacy of stem cell transplantation. METHODS: We explored the effects of GDF11 on proangiogenic activities of mesenchymal stem cells (MSCs) for angiogenic therapy in vitro and in vivo. RESULTS: Mouse bone marrow-derived MSCs were transduced with lentiviral vector to overexpress GDF11 (MSCGDF11). After exposed to hypoxia and serum deprivation for 48 h, MSCGDF11 were significantly better in viability than control MSCs (MSCvector). MSCGDF11 also had higher mobility and better angiogenic paracrine effects. The cytokine antibody array showed more angiogenic cytokines in the conditioned medium of MSCGDF11 than that of MSCvector, such as epidermal growth factor, platelet-derived growth factor-BB, placenta growth factor. When MSCs (1 × 106 cells in 50 µl) were injected into ischemic hindlimb of mice after femoral artery ligation, MSCGDF11 had higher retention rate in the muscle than control MSCs. Injection of MSCGDF11 resulted in better blood reperfusion and limb salvage than that of control MSCs after 14 days. Significantly more CD31+ endothelial cells and α-SMA + smooth muscle cells were detected in the ischemic muscles that received MSCGDF11. The effects of GDF11 were through activating TGF-ß receptor and PI3K/Akt signaling pathway. CONCLUSION: Our study demonstrated an essential role of GDF11 in promoting therapeutic functions of MSCs for ischemic diseases by enhancing MSC viability, mobility, and angiogenic paracrine functions.

Exosomes derived from HeLa cells break down vascular integrity by triggering endoplasmic reticulum stress in endothelial cells.

Exosomes play a critical role in intercellular communication since they contain signalling molecules and genetic materials. During tumorigenesis, tumour-derived exosomes have been demonstrated to promote tumour angiogenesis and metastasis. However, how the exosomes facilitate tumour metastasis is not clear. Here we explored the effect of HeLa cell-derived exosomes (ExoHeLa) on endothelial tight junctions (TJ) and the related mechanisms. After human umbilical vein endothelial cells (HUVEC) were treated with ExoHeLa, TJ proteins zonula occludens-1 (ZO-1) and Claudin-5 in HUVEC were significantly reduced as compared with that treated with exosomes from human cervical epithelial cells, while mRNA levels of ZO-1 and Claudin-5 remained unchanged. Consequently, permeability of endothelial monolayer was increased after the treatment with ExoHeLa. Injection of ExoHeLa into mice also increased vascular permeability and tumour metastasis in vivo. Neither knocking down of Dicer nor use of inhibitors of microRNAs targeting at mRNAs of ZO-1 and Claudin-5 could block the inhibitory effect of ExoHeLa on ZO-1 and Claudin-5. The expression of genes involved in endoplasmic reticulum (ER) stress was significantly increased in HUVECs after treated with ExoHeLa. Inhibition of ER stress by knocking down protein kinase RNA-like endoplasmic reticulum kinase prevented the down-regulation of ZO-1 and Claudin-5 by ExoHeLa. Our study found that HeLa cell-derived exosomes promote metastasis by triggering ER stress in endothelial cells and break down endothelial integrity. Such effect of exosomes is microRNA-independent.