Extracellular vesicles released by glioma cells are decorated by Annexin A2 allowing for cellular uptake via heparan sulfate.

Extracellular vesicles (EVs) play a crucial role in regulating cell behavior by delivering their cargo to target cells. However, the mechanisms underlying EV-cell interactions are not well understood. Previous studies have shown that heparan sulfate (HS) on target cell surfaces can act as receptors for exosomes uptake, but the ligand for HS on EVs has not been identified. In this study, we isolated EVs from glioma cell lines and glioma patients and identified Annexin A2 (AnxA2) on EVs as a key HS-binding ligand and mediator of EV-cell interactions. Our findings suggest that HS plays a dual role in EV-cell interactions, where HS on EVs captures AnxA2, and on target cells, it acts as a receptor for AnxA2. Removal of HS from the EV surface inhibits EV-target cell interaction by releasing AnxA2. Furthermore, we found that AnxA2-mediated binding of EVs to vascular endothelial cells promotes angiogenesis, and that antibody against AnxA2 inhibited the ability of glioma-derived EVs to stimulate angiogenesis by reducing the uptake of EVs. Our study also suggests that the AnxA2-HS interaction may accelerate the glioma-derived EVs-mediated angiogenesis and that combining AnxA2 on glioma cells with HS on endothelial cells may effectively improve the prognosis evaluation of glioma patients.

miR-373 inhibits autophagy and further promotes apoptosis of cholangiocarcinoma cells by targeting ULK1.

Intrahepatic cholangiocarcinoma is a malignant tumor originating from intrahepatic bile ducts. Surgical therapy, radiotherapy, and chemotherapy are taken to treat this disease, but it is prone to recurrence and metastasis, with poor prognosis. Therefore, it is of great significance to explore new targets and molecular mechanisms for the development of cholangiocarcinoma cells. Clinical cholangiocarcinoma tissues from patients and four human cholangiocarcinoma cell lines were analyzed for microRNA-373 (miR-373) expression. For investigating whether miR-373 directly modulated unc-51 like autophagy activating kinase 1 (ULK1), dual-luciferase reporter assay was performed. In addition, CCK-8 assay, flow cytometry, western blot, and immunofluorescence were applied to evaluate the proliferation, apoptosis, and autophagy of cholangiocytic hepatocellular carcinoma cells. miR-373 downregulation was observed in clinical tissues and cell lines of cholangiocarcinoma. Overexpression of miR-373 reduced proliferation, enhanced apoptosis, and raised expression levels of pro-apoptosis proteins including BCL2 associated X (Bax), Caspase-3, and Caspase-9. Moreover, overexpression of miR-373 downregulated expression levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II, Beclin-1, and promoted P62 expression on mRNA and protein levels. After miR-373 knockdown, all indexes of apoptosis and autophagy mentioned above were reversed. Luciferase activity was decreased after cotransfection of miR-373 mimic and wild-type ULK1 vector. Also, miR-373 overexpression inhibited ULK1 expression. Importantly, overexpression of miR-373 weakened expressions of ULK1, LC3, Beclin-1, and Bcl-2, and enhanced expressions of P62, Bax, Caspase-3, and Caspase-9. miR-373 mimic treatment and subsequent ULK1 overexpression, induced reverse regulation in expressions of these proteins, compared with overexpression of miR-373 only. miR-373 targeted ULK1 to initiate inhibition of autophagy and subsequent promotion of apoptosis in cholangiocarcinoma cells.

The autophagic degradation of Cav-1 contributes to PA-induced apoptosis and inflammation of astrocytes.

The accumulation of palmitic acid (PA), implicated in obesity, can induce apoptotic cell death and inflammation of astrocytes. Caveolin-1 (Cav-1), an essential protein for astrocytes survival, can be degraded by autophagy, which is a double-edge sword that can either promote cell survival or cell death. The aim of this study was to delineate whether the autophagic degradation of Cav-1 is involved in PA-induced apoptosis and inflammation in hippocampal astrocytes. In this study we found that: (1) PA caused apoptotic death and inflammation by autophagic induction; (2) Cav-1 was degraded by PA-induced autophagy and PA induced autophagy in a Cav-1-independent manner; (3) the degradation of Cav-1 was responsible for PA-induced autophagy-dependent apoptotic cell death and inflammation; (4) chronic high-fat diet (HFD) induced Cav-1 degradation, apoptosis, autophagy, and inflammation in the hippocampal astrocytes of rats. Our results suggest that the autophagic degradation of Cav-1 contributes to PA-induced apoptosis and inflammation of astrocytes. Therefore, Cav-1 may be a potential therapeutic target for central nervous system injuries caused by PA accumulation.

High glucose forces a positive feedback loop connecting ErbB4 expression and mTOR/S6K pathway to aggravate the formation of tau hyperphosphorylation in differentiated SH-SY5Y cells.

High glucose (HG)-induced mammalian target of rapamycin (mTOR) overactivation acts as a signaling hub for the formation of tau hyperphosphorylation, which contributes to the development of diabetes-associated cognitive deficit. How HG induces the sustained activation of mTOR in neurons is not clearly understood. ErbB4, a member of the receptor tyrosine kinase family, plays critical roles in development and function of neural circuitry, relevant to behavioral deficits. Here, we showed HG-induced ErbB4 overexpression in differentiated SH-SY5Y cells and primary hippocampal neurons and hippocampal pyramidal neurons of streptozotocin-induced diabetic rats. Inhibition of ErbB4 signaling prevented the HG-induced activation of mTOR/S6K signaling to suppress tau hyperphosphorylation. In contrast, ErbB4 overexpression increased the activation of mTOR/S6K signaling, resulting in tau hyperphosphorylation similar to HG treatment. We also demonstrated that HG upregulated the expression of ErbB4 at a mTOR-dependent posttranscriptional level. Together, our results provide the first evidence for the presence of a positive feedback loop for the sustained activation of mTOR involving overexpressed ErbB4, leading to the formation of tau hyperphosphorylation under HG condition. Therefore, ErbB4 is a potential therapeutic target for diabetes-associated neurodegeneration.

High glucose induces formation of tau hyperphosphorylation via Cav-1-mTOR pathway: A potential molecular mechanism for diabetes-induced cognitive dysfunction.

The abnormally hyperphosphorylated tau is thought to be implicated in diabetes-associated cognitive deficits. The role of mammalian target of rapamycin (mTOR) / S6 kinase (S6K) signalling in the formation of tau hyperphosphorylation has been previously studied. Caveolin-1 (Cav-1), the essential structure protein of caveolae, promotes neuronal survival and growth, and inhibits glucose metabolism. In this study, we aimed to investigate the role of Cav-1 in the formation of tau hyperphosphorylation under chronic hyperglycemic condition (HGC). Diabetic rats were induced by streptozotocin (STZ). Primary hippocampal neurons with or without molecular intervention such as the transient over-expression or knock-down were subjected to HGC. The obtained experimental samples were analyzed by real time quantitative RT-PCR, Western blot, immunofluorescence or immunohistochemisty. We found: 1) that a chronic HGC directly decreases Cav-1 expression, increases tau phosphorylation and activates mTOR/S6K signalling in the brain neurons of diabetic rats, 2) that overexpression of Cav-1 attenuates tau hyperphosphorylation induced by chronic HGC in primary hippocampal neurons, whereas down-regulation of Cav-1 using Cav-1 siRNA dramatically worsens tau hyperphosphorylation via mTOR/S6K signalling pathway, and 3) that the down-regulation of Cav-1 induced by HGC is independent of mTOR signalling. Our results suggest that tau hyperphosphorylation and the sustained over-activated mTOR signalling under hyperglycemia may be due to the suppression of Cav-1. Therefore, Cav-1 is a potential therapeutic target for diabetes-induced cognitive dysfunction.

Tau pathology in diabetes mellitus.

Neurodegenerative tauopathy characterized by hyperphosphorylation tau has been implicated in the pathophysiology of diabetic central nervous system (CNS) complication. Emerging evidence has suggested that hyperphosphorylation tau is caused by an imbalance of protein kinase and phosphatase activity. This review focuses on the contributions of impaired insulin signaling to diabetes-related tauopathy through disrupting the balance of tau-related protein kinases and phosphatases. In addition, we describe tau pathology as a potential target for central neuronal degeneration in diabetes mellitus.

Dysregulated mTOR-dependent signaling in neurodegeneration or carcinogenesis: implication for Alzheimer's disease and brain tumors.

Recent evidence implicated aberrant mammalian target of rapamycin (mTOR)-dependent signaling in both Alzheimer's disease (AD) and brain tumors. This review focuses on the potential mechanisms shared by both neurodegeneration and carcinogenesis. In particular, attention was paid to the possible roles of mTOR-dependent signaling in these two fundamental pathophysiological processes. We hypothesize that common stresses could lead either to progressive degeneration or uncontrolled carcinogenesis via cell type specific upregulation of mTOR-dependent signaling in the central nervous system while mTOR-mediated carcinogenesis might permit glial cells to escape from degeneration.

Dimethylarginine dimethylaminohydrolase 1 regulates nerve growth factor-promoted differentiation of PC12 cells in a nitric oxide-dependent but asymmetric dimethylargenine-independent manner.

There are significant morphological and biochemical alterations during nerve growth factor (NGF)-promoted neuronal differentiation, and the process is regulated by molecules, including nitric oxide (NO). Dimethylarginine dimethylaminohydrolase (DDAH) is thought to play a critical role in regulating NO production via hydrolyzing the endogenous NO synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA). Thus, we tested the role of DDAH in NGF-promoted differentiation of PC12 (pheochromocytoma) cells. The present results show that both mRNA and protein levels of DDAH1 were increased, whereas those of DDAH2 were decreased, during NGF-promoted cell differentiation. Both the DDAH activity and the ADMA level in cultured medium were unchanged in this process. NGF promoted neurite formation and induced the expression of microtubule-associated protein 2 (MAP2), a neuronal marker, which were both significantly repressed by DDAH1 silence with small interfering RNA but not by DDAH2 silence. The expressions of three isoforms of NOS were markedly upregulated after NGF stimulation with a time course similar to that of DDAH1, which were attenuated by DDAH1 silence. Conversely, overexpression of DDAH1 accelerated neurite formation in PC12 cells, concomitantly with upregulating the expression of three NOS isoforms. In summary, our data reveal the critical regulatory effect of DDAH1 on NGF-promoted differentiation of PC12 cells in an NOS/NO-dependent but ADMA-independent manner.

Effect of genetic polymorphism of UCP2-866 G/A on repaglinide response in Chinese patients with type 2 diabetes.

The aim of the present study was to evaluate the impact of the UCP2-866 G/A polymorphism on the efficacy of repaglinide in treating patients with diabetes mellitus type 2 (T2DM). 370 patients with T2DM and 166 healthy volunteers were enrolled to identify UCP2-866 G/A genotypes. 16 patients with GG genotype, 14 with GA genotype and 11 with AA genotype of UCP2-866 G/A underwent an 8-week repaglinide treatment regimen. There were no differences in allele frequency of UCP2-866 G/A between T2DM patients and control subjects. The patient with AA genotype of UCP2-866 G/A had higher levels of fasting plasma glucose (FPG), 30-min and 2-h postload plasma glucose, glycated haemoglobin (HbA1c), and lower concentrations of 30-min and 2-h postload plasma insulin, homeostasis model assessment of beta cell function (HOMA-beta), deltaI30/deltaG30 compared with GG genotype. After repaglinide treatment for 8 consecutive weeks, we found that A allele carriers of UCP2 in the T2DM patients had smaller decrease in FPG (P < 0.05) and HbA1c (P < 0.05), and smaller increase in 30-min postload plasma insulin (P < 0.01) compared with GG genotypes. We demonstrated that UCP2-866 G/A polymorphism is associated with the therapeutic efficacy of repaglinide in Chinese T2DM patients.

Primary human hepatocyte transplantation in the therapy of hepatic failure: 2 cases report.

Liver failure is the end stage of hepatopathy with unfavorable prognosis. In two patients with liver failure, viable primary human hepatocytes, obtained from resected liver tissue of patients with hepatolithiasis, were transplanted into the spleen by interventional therapy through femoral arterial cannula. After transplantation, the patients' clinical symptoms and liver function were significantly improved. However, their bilirubin increased within six days following transplantation. One suffered from hepatic coma and give up treatment and the other patient died fourteen days after transplantation. It is technically safe to treat liver failure by intrasplenic transplantation of adult hepatocytes and the clinical efficacy has been confirmed. How to make transplanted hepatic cells proliferate and functionally survive is the key point to maintain continuous improvement of the recipient's hepatic function.

All-trans retinoic acid inhibits cobalt chloride-induced apoptosis in PC12 cells: role of the dimethylarginine dimethylaminohydrolase/asymmetric dimethylarginine pathway.

Previous studies have shown that the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) and its specific hydrolase dimethylarginine dimethylaminohydrolase (DDAH) are involved in the regulation of apoptosis in different cell types. In the present study, we investigated the role of the DDAH/ADMA pathway in cobalt chloride (CoCl(2))-induced apoptosis and the antiapoptotic effect of all-trans retinoic acid (atRA) in undifferentiated pheochromocytoma (PC12) cells. Treatment of CoCl(2) (125 microM) for 48 hr significantly induced the apoptosis of PC12 cells, concomitantly with increased intracellular reactive oxygen species (ROS) production and caspase-3 activity. CoCl(2) treatment also decreased the activity of DDAH and the expression of DDAH2 (mRNA and protein), resulting in an increased level of ADMA. All these alterations induced by CoCl(2) were attenuated by atRA (0.1, 1, or 10 microM). Interestingly, the antiapoptotic effects of atRA were inhibited by DDAH2 small RNA interference. In contrast, DDAH2 overexpression inhibited the proapoptotic effects of CoCl(2). We also found that treatment of exogenous ADMA (3, 10, or 30 microM) induced the apoptosis of PC12 cells in a concentration- and time-dependent manner, which was inhibited by the antioxidant or the caspase-3 inhibitor. These findings suggest that the modulation of the DDAH/ADMA/ROS pathway plays an important role in CoCl(2)-induced apoptosis and the antiapoptotic effects of atRA in undifferentiated PC12 cells.

Reversal of tolerance to nitroglycerin with vinpocetine: a role of calcitonin gene-related peptide.

Previous studies have shown that the development of tolerance to nitroglycerin is related to reduction of endogenous calcitonin gene-related peptide (CGRP) release. In the present study, Nitroglycerin caused a concentration-dependent relaxation concomitantly with a significant increase in the release of CGRP in the isolated rat thoracic aorta, an effect that was reduced by preincubation with capsaicin. Pretreatment with nitroglycerin significantly decreased its vasodilation and depressor effect and the release of CGRP, which was restored in the presence of vinpocetine, an inhibitor of phosphodiesterase. The present results suggest that reversal of tolerance to nitroglycerin with vinpocetine is related to the increased release of CGRP in the rat.

Decrease in endogenous CGRP release in nitroglycerin tolerance: role of ALDH-2.

In the present study, we tested whether the decreased release of calcitonin gene-related peptide (CGRP) observed in nitroglycerin tolerance is associated with the decrease in aldehyde dehydrogenase (ALDH-2) activity. We further investigated the possible involvement of reactive oxygen species in the decrease in ALDH-2 activity. Tolerance was induced by exposure of isolated rat thoracic aortas and human umbical vein endothelial cells (HUVEC) to nitroglycerin in vitro or by pretreatment with nitroglycerin for 8 days in vivo. Pretreatment with ALDH-2 inhibitors and nitroglycerin significantly attenuated vasodilator responses to nitroglycerin concomitantly with a decrease in the release of CGRP from the isolated thoracic aorta. Nitroglycerin produced a depressor effect concomitantly with an increase in plasma concentrations of CGRP, and the effect of nitroglycerin was attenuated after pretreatment with an inhibitor of ALDH-2 or nitroglycerin for 8 days. Exposure of HUVEC to nitroglycerin for 16 h increased reactive oxygen species production and decreased ALDH-2 activity as well as cGMP production in a time-and concentration-dependent manner. Pretreatment with an ALDH-2 inhibitor also significantly decreased the cGMP production. However, tolerance to nitroglycerin in HUVEC was restored in the presence of N-acetylcysteine or captopril. The present results suggest that nitrate tolerance is, at least partially, associated with a decrease in endogenous CGRP release via a decrease in ALDH-2 activity as a result of stimulation of reactive oxygen species production.