Phosphorylation of p38 mitogen-activated protein kinase downstream of bax-caspase-3 pathway leads to cell death induced by high D-glucose in human endothelial cells

Grifola frondosa Extract Containing Bioactive Components Blocks Skin Fibroblastic Inflammation and Cytotoxicity Caused by Endocrine Disrupting Chemical, Bisphenol A

Grifola frondosa (GF), a species of Basidiomycotina, is widely distributed across Asia and has been used as an immunomodulatory, anti-bacterial, and anti-cancer agent. In the present study, the pharmacological activity of the GF extract against an ecotoxicological industrial chemical, bisphenol A (BPA) in normal human dermal fibroblasts (NHDFs), was investigated. GF extract containing naringin, hesperidin, chlorogenic acid, and kaempferol showed an inhibitory effect on cell death and inflammation induced by BPA in the NHDFs. For the cell death caused by BPA, GF extract inhibited the production of reactive oxygen species responsible for the unique activation of the extracellular signal-regulated kinase. In addition, GF extract attenuated the expression of apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase-3) and the pro-inflammatory cytokine IL-1β by the suppression of the redox-sensitive transcription factor, nuclear factor-kappa B (NF-κB) in BPA-treated NHDFs. For the inflammation triggered by BPA, GF extract blocked the inflammasome-mediated caspase-1 activation that leads to the secretion of IL-1β protein. These results indicate that the GF extract is a functional antioxidant that prevents skin fibroblastic pyroptosis induced by BPA.

MiR-191-5p alleviates microglial cell injury by targeting Map3k12 (mitogen-activated protein kinase kinase kinase 12) to inhibit the MAPK (mitogen-activated protein kinase) signaling pathway in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease. Multiple reports have elucidated that microRNAs are promising biomarkers for AD diagnosis and treatment. Herein, the effect of miR-191-5p on microglial cell injury and the underlying mechanism were explored. APP/PS1 transgenic mice were utilized to establish mouse model of AD. Amyloid-β protein 1-42 (Aβ1-42)-treated microglia were applied to establish in vitro cell model of AD. MiR-191-5p expression in hippocampus and microglia was measured by reverse transcription quantitative polymerase chain reaction. The viability and apoptosis of microglia were evaluated by Cell Counting Kit-8 assays and flow cytometry analyses, respectively. The binding relationship between miR-191-5p and its downstream target mitogen-activated protein kinase kinase kinase 12 (Map3k12) was determined by luciferase reporter assays. Pathological degeneration of hippocampus was tested using hematoxylin-eosin staining and Nissl staining. Aβ expression in hippocampus was examined via immunohistochemistry. In this study, miR-191-5p was downregulated in Aβ1-42-stimulated microglia and hippocampal tissues of APP/PS1 mice. MiR-191-5p overexpression facilitated cell viability and inhibited apoptosis rate of Aβ1-42-treated microglia. Mechanically, miR-191-5p targeted Map3k12 3'-untranslated region to downregulate Map3k12 expression. MiR-191-5p inhibited Aβ1-42-induced microglial cell injury and inactivated the MAPK signaling by downregulating Map3k12. Overall, miR-191-5p alleviated Aβ1-42-induced microglia cell injury by targeting Map3k12 to inhibit the MAPK signaling pathway in microglia.

Dexmedetomidine Alleviates Lipopolysaccharide-Induced Hippocampal Neuronal Apoptosis via Inhibiting the p38 MAPK/c-Myc/CLIC4 Signaling Pathway in Rats

Dexmedetomidine (DEX) has multiple biological effects. Here, we investigated the neuroprotective role and molecular mechanism of DEX against lipopolysaccharide (LPS)-induced hippocampal neuronal apoptosis. Sprague Dawley rats were intraperitoneally injected with LPS (10 mg/kg) and/or DEX (30 µg/kg). We found that DEX improved LPS-induced alterations of hippocampal microstructure (necrosis and neuronal loss in the CA1 and CA3 regions) and ultrastructure (mitochondrial damage). DEX also attenuated LPS-induced inflammation and hippocampal apoptosis by inhibiting the increase of interleukin-1β, interleukin-6, interleukin-18, and tumor necrosis factor-α levels and downregulating the expression of mitochondrial apoptosis pathway-related proteins. Moreover, DEX prevented the LPS-induced activation of the c-Myc/chloride intracellular channel 4 (CLIC4) pathway. DEX inhibited the p38 MAPK pathway, but not JNK and ERK. To further clarify whether DEX alleviated LPS-induced neuronal apoptosis through the p38 MAPK/c-Myc/CLIC4 pathway, we treated PC12 cells with p38 MAPK inhibitor SB203582 (10 µM). DEX had the same effect as SB203582 in reducing the protein and mRNA expression of c-Myc and CLIC4. Furthermore, DEX and SB203582 diminished LPS-induced apoptosis, indicated by decreased Bax and Tom20 fluorescent double-stained cells, reduced annexin V-FITC/PI apoptosis rate, and reduced protein expression levels of Bax, cytochrome C, cleaved caspase-9, and cleaved caspase-3. Taken together, the findings indicate that DEX attenuates LPS-induced hippocampal neuronal apoptosis by regulating the p38 MAPK/c-Myc/CLIC4 signaling pathway. These findings provide new insights into the mechanism of Alzheimer's disease and depression and may help aid in drug development for these diseases.

The Importance of Being PI3K in the RAS Signaling Network

Ras proteins are essential mediators of a multitude of cellular processes, and its deregulation is frequently associated with cancer appearance, progression, and metastasis. Ras-driven cancers are usually aggressive and difficult to treat. Although the recent Food and Drug Administration (FDA) approval of the first Ras G12C inhibitor is an important milestone, only a small percentage of patients will benefit from it. A better understanding of the context in which Ras operates in different tumor types and the outcomes mediated by each effector pathway may help to identify additional strategies and targets to treat Ras-driven tumors. Evidence emerging in recent years suggests that both oncogenic Ras signaling in tumor cells and non-oncogenic Ras signaling in stromal cells play an essential role in cancer. PI3K is one of the main Ras effectors, regulating important cellular processes such as cell viability or resistance to therapy or angiogenesis upon oncogenic Ras activation. In this review, we will summarize recent advances in the understanding of Ras-dependent activation of PI3K both in physiological conditions and cancer, with a focus on how this signaling pathway contributes to the formation of a tumor stroma that promotes tumor cell proliferation, migration, and spread.

Concurrent diabetes and heart failure: interplay and novel therapeutic approaches

Diabetes mellitus increases the risk of developing heart failure, and the co-existence of both diseases worsens cardiovascular outcomes, hospitalization and the progression of heart failure. Despite current advancements on therapeutic strategies to manage hyperglycemia, the likelihood of developing diabetes-induced heart failure is still significant, especially with the accelerating global prevalence of diabetes and an ageing population. This raises the likelihood of other contributing mechanisms beyond hyperglycemia in predisposing diabetic patients to cardiovascular disease risk. There has been considerable interest in understanding the alterations in cardiac structure and function in the diabetic patients, collectively termed as "diabetic cardiomyopathy". However, the factors that contribute to the development of diabetic cardiomyopathies is not fully understood. This review summarizes the main characteristics of diabetic cardiomyopathies, and the basic mechanisms that contribute to its occurrence. This includes perturbations in insulin resistance, fuel preference, reactive oxygen species generation, inflammation, cell death pathways, neurohormonal mechanisms, advanced glycated end-products accumulation, lipotoxicity, glucotoxicity, and posttranslational modifications in the heart of the diabetic. This review also discusses the impact of antihyperglycemic therapies on the development of heart failure, as well as how current heart failure therapies influence glycemic control in diabetic patients. We also highlight the current knowledge gaps in understanding how diabetes induces heart failure.

Regulation of docosahexaenoic acid-induced apoptosis of confluent endothelial cells: Contributions of MAPKs and caspases

Endothelial cells, which help to maintain vascular homeostasis, can be functionally modulated by polyunsaturated fatty acids. Previously, we reported that docosahexaenoic acid (DHA) reduced the viability of confluent EA.hy926 endothelial cells with caspase-3 activation. This study therefore examined the molecular mechanism by which DHA affects the viability of confluent cells, with a focus on the interaction between caspase-9, caspase-8, caspase-3, p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) by Western blotting. Our results revealed that DHA induces apoptosis of confluent cells through both intrinsic and extrinsic pathways, which requires activation of p38 MAPK, and involves activation of JNK, caspase-9, caspase-8 and caspase-3 with the exception that cleavage of caspase-8 was incomplete and truncated BID was not detected at the maximum time (8 h) examined. Apoptosis induced by high levels of DHA in healthy endothelial cells is achieved through positive feedback loops linking these MAPKs to multiple caspases, as well as negative feedback from p38 MAPK to JNK. However, only p38 MAPK is crucial in apoptosis induction in comparison with JNK or any other caspase examined. This study has expanded the knowledge on the molecular mechanism of DHA-induced apoptosis in human endothelial cells and has also implied the differential roles of MAP kinases and caspases in apoptosis.

RPS4Y1 Promotes High Glucose-Induced Endothelial Cell Apoptosis and Inflammation by Activation of the p38 MAPK Signaling

AIM

Endothelial dysfunction is a key pathological basis for diabetes mellitus complications, including diabetic nephropathy, diabetic retinopathy, and diabetic cardiomyopathy. This study aimed to reveal the functional role of ribosomal protein S4 Y-linked 1 (RPS4Y1) in endothelial dysfunction.

METHODS

Human umbilical vein endothelial cells (HUVECs) were subjected to high glucose. The expression of RPS4Y1 in cells was overexpressed or silenced by plasmid or siRNA transfection. MTT assay, flow cytometry, JC-1 probe, scratch test, tube formation, and ELISA were conducted to assess the effects of RPS4Y1 on cell. Western blot was performed to assay the downstream signaling of RPS4Y1. The inhibitors of p38, ERK, and Jnk were used to treat cells to validate the involvement of them in RPS4Y1-mediated endothelial dysfunction.

RESULTS

RPS4Y1 was upregulated in HUVECs in response to high glucose in both dose- and time-dependent manners. Overexpression of RPS4Y1 induced viability loss, apoptosis, and inflammation, but inhibited cell migration and tube formation. Silence of RPS4Y1 impacted these aspects in a contrary trend. The phosphorylation of p38 rather than ERK and Jnk was activated by RPS4Y1. In addition, the dysfunction of HUVECs mediated by RPS4Y1 was attenuated by SB203580 (a specific inhibitor of p38 signaling).

CONCLUSION

The highly expressed RPS4Y1 in endothelial cells may contribute to high glucose-induced dysfunction through regulating p38 MAPK signaling. RPS4Y1 might be a potential therapeutic target for treating diabetes mellitus complications.

Exendin-4 reverses high glucose-induced endothelial progenitor cell dysfunction via SDF-1β/CXCR7-AMPK/p38-MAPK/IL-6 axis

AIM

Exendin-4, a glucagon-like peptide-1 (GLP-1) analog, has been used for treating diabetes mellitus (DM). However, its effects on improving the dysfunction of high glucose (HG)-induced endothelial progenitor cells (EPCs) remain unclear. The present study explored the effects of Exendin-4 on improving dysfunction of EPCs and the underlying mechanism.

METHODS

EPCs were isolated from SD rats and identified by flow cytometry. Next, the EPCs were treated by HG and high or low concentration of Exendin-4, and cell viability, migration and tube formation were, respectively, examined by performing MTT assay, wound-healing assay and tube formation assay. Interleukin-6 (IL-6) secretion was measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions of relative stromal-derived growth factor-1β (SDF-1β), C-X-C chemokine receptor type 7 (CXCR7), AMP-activated protein kinase (AMPK), p38 and expressions of CXCR7 and IL-6 in EPCs were measured by Western blot. The cell behaviors of EPCs treated by HG and Exendin-4 with or without silencing of CXCR7 and IL-6 were detected.

RESULTS

Exendin-4 reversed the inhibitory effects of HG on viability, migration and tube formation of EPCs and on SDF-1β/CXCR7-AMPK pathway in EPCs in a dose-dependent manner. Moreover, Exendin-4 promoted the effects of HG on IL-6 level in EPCs through the promotion of p38-MAPK phosphorylation and reduction of cleaved caspase-3 protein expressions in EPCs. However, silencing of CXCR7 and IL-6 reversed the effects of Exendin-4 on cell behaviors, inactivated SDF-1β/CXCR7-AMPK pathway and increased cleaved caspase-3 expression in EPCs.

CONCLUSIONS

Exendin-4 could ameliorate HG-induced EPC dysfunction through regulating the production of IL-6 via SDF-1β/CXCR7-AMPK/p38-MAPK axis.

ERK activation precedes Purkinje cell loss in mice with Spinocerebellar ataxia type 17

Spinocerebellar ataxia type 17 (SCA17) is an autosomal dominant neurodegenerative disease caused by CAG expansion in the gene encoding the TATA-binding protein (TBP). The neurological features of SCA17 are Purkinje cell loss and gliosis. We have generated SCA17 transgenic mice which recapitulate the patients' phenotypes and are suitable for the study of the SCA17 pathomechanism. Our previous study identified the activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) occurred in the SCA17 cerebella, this study aims to study the role of ERK activation in SCA17. The levels of pERK, calbindin, and gliosis markers on the mouse cerebellum at 4-8 weeks old were analyzed to elucidate the correlation among behavioral performance, ERK activation and Purkinje cell degeneration. The motor incoordination was initiated in SCA17 mice at 6 weeks old. We found that the presence of TBP nuclear aggregation and microglia activation were observed at 4 weeks old. Gliosis of astrocytes and Bergmann glia, pERK, Bax/Bcl2 ratio, and caspase-3 were significantly increased in the 6-week-old SCA17 mouse cerebellum. In addition to the polyglutamine-protein aggregation in Purkinje cells caused apoptosis cell-autonomously, a significant body of evidence have shown that ERK pathways involves in neuronal apoptosis. Our study showed that the activation of ERK in the astrocytes and Bergmann glia was identified as preceding motor deficits, which suggest the elevated gliosis by ERK activation may contribute to neuronal apoptosis in SCA17 mice.

Qingxin Kaiqiao Fang Inhibits Aβ 25-35-Induced Apoptosis in Primary Cultured Rat Hippocampal Neuronal Cells via the p38 MAPK Pathway: An Experimental Validation and Network Pharmacology Study

Qingxin kaiqiao fang (QKF), a traditional Chinese medicine compound, has been applied to treat Alzheimer's disease (AD) for many years and has exhibited remarkable effects. However, the underlying mechanism is still not explicit. The current study aims to investigate whether QKF exerts an antiapoptotic role through the p38 MAPK pathway in the course of AD. Network pharmacology analysis was applied to study the effective components, possible therapeutic targets, and AD-related pathway of QKF. Further, the AD cell model was established using amyloid-beta (Aβ)_25-35 peptide and primary hippocampal neuronal cells extracted from newborn Sprague-Dawley rats. Microtubule-associated protein-2 (MAP-2) imaging was used to detect the morphology of hippocampal neurons. Western blot (WB) analysis was applied to detect the protein expression levels of p38 MAPK, p-p38 MAPK, Bcl-2, Bax, caspase-3, and cleaved caspase-3. Cell viability and apoptosis were determined using cell counting kit-8 (CCK-8) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assays, respectively. SB203580 and U46619 were used to detect changes in cell morphology, cell viability, and apoptosis upon inhibiting or activating p38 MAPK. Our present work showed that QKF protects hippocampal neuronal morphology, enhances cell viability, and reduces the number of TUNEL-positive cells. In addition, our results showed that QKF increased the expression levels of antiapoptotic proteins and decreased the expression of proapoptotic proteins. QKF at 25 mg·mL⁻¹ best inhibited neuronal apoptosis among the three doses of QKF by suppressing p38 MAPK activity. Collectively, QKF plays an antiapoptotic role via the p38 MAPK pathway.

miR-3188 (rs7247237-C>T) Single-Nucleotide Polymorphism Is Associated With the Incidence of Vascular Complications in Chinese Patients With Type 2 Diabetes

miR-3188, one of the earliest discovered microRNAs, is involved in regulating the mTOR-p-PI3K/AKT pathway, thus affecting the progression of diabetic complications. In this study, we observed that the miR-3188 (rs7247237-C>T) polymorphism not only affected the production of nitric oxide (NO) production in endothelial cells, but also significantly associated with the incidence of vascular complications in Chinese patients with type 2 diabetes. Mechanistic analyses indicate that miR-3188 (rs7247237-T) polymorphism inhibited its own expression and upregulated the expression of gstm1 and trib3, which impairs NO production in human endothelial cells through inactivating AKT/eNOS signal transduction pathway. In addition, our clinical retrospective study indicated that, compared with patients with the CC genotype (n = 351), patients with rs7247237 TT + CT genotypes (n = 580) exhibited an increased risk of major vascular events during intensive glucose control treatment (hazard ratio = 1.560; 95% CI: 1.055-2.307, P = 0.025). Simultaneously, the risk of major vascular events was marginally decreased in patients with the CC genotype during intensive glucose control treatment compared with standard treatment (hazard ratio = 0.666; 95% CI: 0.433-1.016, P = 0.053). Our findings indicate that the miR-3188 (rs7247237-C>T) polymorphism is associated with the incidence of vascular complications in Chinese patients with type 2 diabetes, likely due to its remarkable effect on miR-3188 expression.

Optical control of MAP kinase kinase 6 (MKK6) reveals that it has divergent roles in pro-apoptotic and anti-proliferative signaling

The selective pressure imposed by extrinsic death signals and stressors adds to the challenge of isolating and interpreting the roles of proteins in stress-activated signaling networks. By expressing a kinase with activating mutations and a caged lysine blocking the active site, we can rapidly switch on catalytic activity with light and monitor the ensuing dynamics. Applying this approach to MAP kinase 6 (MKK6), which activates the p38 subfamily of MAPKs, we found that decaging active MKK6 in fibroblasts is sufficient to trigger apoptosis in a p38-dependent manner. Both in fibroblasts and in a murine melanoma cell line expressing mutant B-Raf, MKK6 activation rapidly and potently inhibited the pro-proliferative extracellular signal-regulated kinase (ERK) pathway; to our surprise, this negative cross-regulation was equally robust when all p38 isoforms were inhibited. These results position MKK6 as a new pleiotropic signal transducer that promotes both pro-apoptotic and anti-proliferative signaling, and they highlight the utility of caged, light-activated kinases for dissecting stress-activated signaling networks.

MD2 activation by direct AGE interaction drives inflammatory diabetic cardiomyopathy

Hyperglycemia activates toll-like receptor 4 (TLR4) to induce inflammation in diabetic cardiomyopathy (DCM). However, the mechanisms of TLR4 activation remain unclear. Here we examine the role of myeloid differentiation 2 (MD2), a co-receptor of TLR4, in high glucose (HG)- and diabetes-induced inflammatory cardiomyopathy. We show increased MD2 in heart tissues of diabetic mice and serum of human diabetic subjects. MD2 deficiency in mice inhibits TLR4 pathway activation, which correlates with reduced myocardial remodeling and improved cardiac function. Mechanistically, we show that HG induces extracellular advanced glycation end products (AGEs), which bind directly to MD2, leading to formation of AGEs-MD2-TLR4 complex and initiation of pro-inflammatory pathways. We further detect elevated AGE-MD2 complexes in heart tissues and serum of diabetic mice and human subjects with DCM. In summary, we uncover a new mechanism of HG-induced inflammatory responses and myocardial injury, in which AGE products directly bind MD2 to drive inflammatory DCM.

The mechanisms underlying cardiac inflammation in diabetic cardiomyopathy are incompletely understood. Here the authors show that advanced glycation end products bind to the TLR4 co-receptor MD2 initiating pro-inflammatory pathways.

Myricetin inhibits endometriosis growth through cyclin E1 down-regulation in vitro and in vivo

Endometriosis is a benign gynecological condition prevalent among reproductive-aged women. Although active research and studies have been carried out to discover new drugs, surgery and hormone therapy are still the gold standard for endometriosis treatment. Nowadays, various flavonoids are considered long-term supplements for different diseases. Myricetin, a flavonol, has antiproliferative, anti- or pro-oxidant, and anticancer effects in gynecological diseases. Here, we reveal for the first time, to our knowledge, the antigrowth effects of myricetin in endometriosis. Myricetin inhibited cell proliferation and cell cycle progression of human VK2/E6E7 and End1/E6E7 cells and induced apoptosis, with the loss of mitochondrial membrane potential and accumulation of reactive oxygen species and calcium ions. Additionally, myricetin decreased the activation of AKT and ERK1/2 proteins, whereas it induced p38 activation in both cell lines. Moreover, myricetin decreased lesion size in the endometriosis mouse model via Ccne1 inhibition. Thus, myricetin has antiproliferative effects on endometriosis through cell cycle regulation.

The inhibition of Bax activation-induced apoptosis by RasGRP2 via R-Ras-PI3K-Akt signaling pathway in the endothelial cells

Apoptosis of endothelial cells is a very important event in various diseases and angiogenesis. We recently reported that ras guanyl nucleotide releasing protein 2 (RasGRP2), which is a guanine nucleotide exchange factor, was expressed in the human umbilical vein endothelial cells (HUVECs) and that Rap1 activation by its overexpression inhibited apoptosis by suppressing tumor necrosis factor-α induced-reactive oxygen species (ROS) production. However, other signaling pathways and roles of RasGRP2 not mediated via Rap1 are not well understood. Therefore, we compared the Mock (M) and the RasGRP2-stable overexpression (R) immortalized HUVECs using BAM7 and anisomycin, which are apoptosis inducers. BAM7 and anisomycin induced apoptosis without causing ROS production, and such apoptosis was significantly increased in M cells, but not in R cells. RasGRP2 suppressed BAM7- and anisomycin-induced apoptosis, but not via the Rap1 pathway as observed using Rap1 knockdown. Furthermore, RasGRP2 activated not only Rap1 but also R-Ras, and suppressed apoptosis by activating R-Ras-phosphoinositide 3-kinase (PI3K)-Akt signaling pathway. The phosphorylation of Akt by RasGRP2 inhibited Bax translocation by promoting translocation of hexokinase-2 (HK-2) from cytoplasm to mitochondria. Taken together, it was suggested that RasGRP2 suppresses the Bax activation-induced apoptosis by promoting HK-2 translocation to mitochondria via R-Ras-PI3K-Akt signaling pathway.

Development of analytical methods GC-MS vs LC-UV for the serum monitoring of an inflammatory glycotoxin (methylglyoxal): A new biomarker of bovine hepatobiliary distomatosis

Two analytical methods; high performance liquid chromatography and gas chromatography were used to determine the content of 2-methylquinoxaline, a methylglyoxal-derived agent in sera from cattle with fascioliasis. Methylglyoxal is a highly mutagenic and cytotoxic reactive dicarbonyl compound formed by non-enzymatic fragmentation of triose phosphate GAP and DHAP during glycolysis which regularly contributes to repositioning the energetic balance between physiological and pathological situations. The aim of this study was to propose the MGO as a new biomarker in the bovine fasciolosis. Strongly infected animals showed a correlation between the relatively high levels of Fasciola hepatica anti-f2 antibody and methylglyoxal compared to unharmed animals. Also, an acute hyperglycemia was recorded and closely related to hepatic parenchyma hyperplasia, inflammation, bile ducts obstruction and scléro-fibrous foci formation.Unlike HPLC, which has shown analytical flaws and irregularities, GC-MS remains an excellent diagnostic tool for detecting and quantifying methylglyoxal in biological fluids. The developed method has been validated under FDA guidelines. A full scan-range was set from m/z 39 to 144/999 and the molecular weight of the 2-methylquinoxaline was identified according to NIST Database and ES. Methylglyoxal was the only analyte successfully quantified in a relatively short run time. It was linear over a concentration range of 0.057-5.7  μg.ml-1with mean recoveries and RSD of 118% and 3.63% respectively. The intra and inter-day assays were satisfying and not exceed 3.00%. Results reflect the degree of precision of our method and indicate that MGO was an important contributor to understand the hepatic failure independently of other serum markers.

ALG-2/AGO-Dependent mir-35 Family Regulates DNA Damage-Induced Apoptosis Through MPK-1/ERK MAPK Signaling Downstream of the Core Apoptotic Machinery in Caenorhabditis elegans

MicroRNAs (miRNAs) associate with argonaute (AGO) proteins to post-transcriptionally modulate the expression of genes involved in various cellular processes. Herein, we show that loss of the Caenorhabditis elegans AGO gene alg-2 results in rapid and significantly increased germ cell apoptosis in response to DNA damage inflicted by ionizing radiation (IR). We demonstrate that the abnormal apoptosis phenotype in alg-2 mutant animals can be explained by reduced expression of mir-35 miRNA family members. We show that the increased apoptosis levels in IR-treated alg-2 or mir-35 family mutants depend on a transient hyperactivation of the C. elegans ERK1/2 MAPK ortholog MPK-1 in dying germ cells. Unexpectedly, MPK-1 phosphorylation occurs downstream of caspase activation and depends at least in part on a functional cell corpse-engulfment machinery. Therefore, we propose a refined mechanism, in which an initial proapoptotic stimulus by the core apoptotic machinery initiates the engulfment process, which in turn activates MAPK signaling to facilitate the demise of genomically compromised germ cells.

Color vision study to assess the impaired retina-brain cortex pathway in type 2 diabetes: a pilot study in Calabria (Southern Italy)

The present pilot study was undertaken to investigate the impaired acquired color vision on Calabrian male sample showing this parameter as a biological marker in type 2 diabetes. All patients and controls underwent three pseudo-isochromatic clinical test batteries: Ishihara test, Farnsworth test, and City University test. The results show a specific loss of short-wavelength (blue sensitivity) and typical tritan responses in diabetic patients. Generally, in later stages of the disease, the red-green mechanisms are involved. By the impaired color vision study in diabetic patients, we can confirm the impaired retina-brain cortex pathway. We believe that the above not invasive test analysis can support the other instrumental and imaging analysis to study the impaired retina-brain cortex pathway. Moreover, we think that the present clinical method can be useful in terms of preventive medicine.

Diabetes-Induced DUSP4 Reduction Promotes Podocyte Dysfunction and Progression of Diabetic Nephropathy

Diabetic nephropathy (DN) remains the leading cause of end-stage renal disease. Hyperglycemia-induced podocyte dysfunction is a major contributor of renal function impairment in DN. Previous studies showed that activation of mitogen-activated protein kinase (MAPK) in diabetes promotes podocyte dysfunction and cell death. Dual specificity phosphatases (DUSPs) are a family of phosphatases mainly responsible for MAPK inhibition. In this study, we demonstrated that diabetes and high glucose exposure decreased DUSP4 expression in cultured podocytes and glomeruli. Diabetes-induced DUSP4 reduction enhanced p38 and c-Jun N-terminal kinase (JNK) activity and podocyte dysfunction. The overexpression of DUSP4 prevented the activation of p38, JNK, caspase 3/7 activity, and NADPH oxidase 4 expression induced by high glucose level exposure. Deletion of DUSP4 exacerbated albuminuria and increased mesangial expansion and glomerular fibrosis in diabetic mice. These morphological changes were associated with profound podocyte foot process effacement, cell death, and sustained p38 and JNK activation. Moreover, inhibition of protein kinase C-δ prevented DUSP4 expression decline and p38/JNK activation in the podocytes and renal cortex of diabetic mice. Analysis of DUSP4 expression in the renal cortex of patients with diabetes revealed that decreased DUSP4 mRNA expression correlated with reduced estimated glomerular filtration rate (<60 mL/min/1.73 m²). Thus, this study demonstrates that preserving DUSP4 expression could protect against podocyte dysfunction and preserve glomerular function in DN.

Analog Derivatization of Cannabidiol for Improved Ocular Permeation

Purpose: Cannabidiol (CBD), active component of plant Cannabis sativa, has anti-inflammatory properties that could potentially help treat diabetic retinopathy-induced pain and inflammation. However, CBD is a lipophilic molecule making its topical delivery to back of the eye challenging. This study aims at improving ocular penetration of CBD by means of analog derivatization. Methods: Analogs were designed using various ligands, such as amino acids (AAs) and dicarboxylic acids (DCAs) and their combinations. Select analogs were screened in vitro with respect to their stability in ocular tissue homogenates. Based on in vitro stability, analogs were selected for in rabbits testing. Formulations containing these compounds were tested in rabbits to determine ocular tissue disposition of CBD and the analogs after topical application. The rabbits were sacrificed 90 min post-topical application and the aqueous humor, vitreous humor (VH), iris-ciliary bodies (IC), and retina-choroid (RC) were analyzed for CBD and analog content. Results: CBD-divalinate-dihemisuccinate (CBD-Di-VHS) and CBD-divalinate (CBD-Di-Val) were stable in the ocular tissue homogenates. Post-topical application, CBD and CBD-Di-Val analog levels were detected only in RC. Dosing of CBD-Di-VHS nanoemulsion generated analog levels both in the VH and in the RC, respectively. In contrast, post dosing of CBD-monovalinate-monohemisuccinate (CBD-Mono-VHS), both the analog and CBD were detected in the IC and RC. Conclusion: The analogs demonstrated superior penetration into ocular tissues in comparison with CBD. CBD-Di-VHS and CBD-Mono-VHS exhibited better permeation properties, possibly due to improved stability and physicochemical characteristics imparted by AA and DCA combination derivatives.

Neuroprotective effects of Scrophularia buergeriana extract against glutamate-induced toxicity in SH-SY5Y cells

The aim of this study was to investigate the antioxidant and anti-apoptotic activities, as well as the underlying mechanisms of action, of Scrophularia buergeriana (S. buergeriana) extract (SBE) in glutamate-induced SH-SY5Y cell death. The roots of S. buergeriana were extracted with 70% ethanol, and standardized SBE was used in this study. To induce cytotoxicity, the SH-SY5Y cells were exposed to glutamate for 3 h, or pre-treated with SBE for 1 h, and subsequently incubated with glutamate for 3 h. The neuro-protective effects were assessed by measuring cell viability and the total glutathione contents using commercial kits. The antioxidant and anti-apoptotic mechanisms of action of SBE were evaluated by western blot analysis. The results confirmed that glutamate-induced toxicity was caused by reactive oxygen species (ROS) production, leading to oxidative stress and DNA damage, thus leading to cell death. However, treatment of the SH-SY5Y cells with SBE significantly increased the viability of the cells exposed to glutamate by upregulating the levels of antioxidant proteins, such as superoxide dismutase (SOD)1, SOD2 and glutathione peroxidase-1 (GPx-1), and directly enhancing the total glutathione contents. Furthermore, SBE attenuated DNA impairment and decreased B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax), cleaved caspase-3 and cleaved poly(adenosine diphosphate (ADP)-ribose) polymerase (PARP) activation. In addition, SBE upregulated Bcl-2 expression via p38 mitogen-activated protein kinases (MAPKs). On the whole, the findings of this study demonstrated that SBE exerts neuroprotective effects against glutamate-induced cell toxicity through its antioxidant and anti-apoptotic activities.

Qingxin kaiqiao fang ameliorates memory impairment and inhibits apoptosis in APP/PS1 double transgenic mice through the MAPK pathway

Background

Qingxin kaiqiao fang (QKF) has been found to treat Alzheimer’s disease (AD) through apoptosis inhibition. The mitogen-activated protein kinase (MAPK) pathway is closely related to apoptosis in the course of AD. This study aimed to investigate whether QKF-induced apoptosis depression is achieved through MAPK pathway.

Materials and methods

C57BL/6 J and APP/PS1 mice were used as control and model groups. APP/PS1 mice were treated with different dosages of QKF (4.75, 9.5, and 19 g⋅kg⁻¹⋅d⁻¹⋅ig, respectively) for 12 weeks as L-QKF, M-QKF, and H-QKF groups. The M-QKF-treated APP/ PS1 mice were administrated with 2 µg/kg of U46619 and saline, intra ventricular ventricle injection, as M-QKF+U46619 and M-QKF+saline groups and were injected with PD98059 0.3 mg/kg and the same volume of dimethyl sulfoxide (DMSO), intravenous, as M-QKF+PD98059 and M-QKF+DMSO groups. After 12 weeks treatment, Morris water maze was performed for behavior study. Pathological degeneration was examined by H&E staining, Nissl staining, and transmission electron microscope observation of hippocampus; immunohistochemistry and Western blot (WB) were tested for amyloid β (Aβ) expression. Apoptosis was measured through TUNEL assay; Bax, Bcl-2, and caspase-3 expression through WB; and cleaved caspase-3 expression through ELISA. MAPK pathway was detected via WB for the expressions of ERK1/2, JNK, and p38 MAPK and their phosphorylation patterns.

Results

QKF improved the learning and memory capability, as well as inhibited neuronal apoptosis and then reduced the pathological degeneration of APP/PS1 mice. M-QKF reduced neuron apoptosis by inhibiting p38 MAPK and activating ERK1/2 but had no significant effect on JNK.

Conclusion

QKF, especially at the middle dose, alleviated the learning and memory impairment and played an antiapoptotic role in AD through MAPK pathways.

Activation of the apoptotic pathway during prolonged prometaphase blocks daughter cell proliferation

When untransformed human cells spend >1.5 h in prometaphase under standard culture conditions, all daughters arrest in G1 despite normal division of their mothers. We investigate what happens during prolonged prometaphase that leads to daughter cell arrest in the absence of DNA damage. We find that progressive loss of anti-apoptotic MCL-1 activity and oxidative stress act in concert to partially activate the apoptosis pathway, resulting in the delayed death of some daughters and senescence for the rest. At physiological oxygen levels, longer prometaphase durations are needed for all daughters to arrest. Partial activation of apoptosis during prolonged prometaphase leads to persistent caspase activity, which activates the kinase cascade mediating the post–mitotic activation of p38. This in turn activates p53, and the consequent expression of p21stops the cell cycle. This mechanism can prevent cells suffering intractable mitotic defects, which modestly prolong mitosis but allow its completion without DNA damage, from producing future cell generations that are susceptible to the evolution of a transformed phenotype.

Chronic hyperglycemia mediated physiological alteration and metabolic distortion leads to organ dysfunction, infection, cancer progression and other pathophysiological consequences: An update on glucose toxicity

Chronic exposure of glucose rich environment creates several physiological and pathophysiological changes. There are several pathways by which hyperglycemia exacerbate its toxic effect on cells, tissues and organ systems. Hyperglycemia can induce oxidative stress, upsurge polyol pathway, activate protein kinase C (PKC), enhance hexosamine biosynthetic pathway (HBP), promote the formation of advanced glycation end-products (AGEs) and finally alters gene expressions. Prolonged hyperglycemic condition leads to severe diabetic condition by damaging the pancreatic β-cell and inducing insulin resistance. Numerous complications have been associated with diabetes, thus it has become a major health issue in the 21st century and has received serious attention. Dysregulation in the cardiovascular and reproductive systems along with nephropathy, retinopathy, neuropathy, diabetic foot ulcer may arise in the advanced stages of diabetes. High glucose level also encourages proliferation of cancer cells, development of osteoarthritis and potentiates a suitable environment for infections. This review culminates how elevated glucose level carries out its toxicity in cells, metabolic distortion along with organ dysfunction and elucidates the complications associated with chronic hyperglycemia.

In vitro analysis of drugs that improve hyperglycemia-induced blood-brain barrier dysfunction

BACKGROUND

Blood-brain barrier (BBB) disruptions are a key feature of hyperglycemia (HG)-induced cerebral damage. Patients with diabetes mellitus often have other cerebrovascular disease risk factors including hypertension, dyslipidemia, arrhythmia, and atherosclerosis obliterans. However, whether the drugs for these comorbidities are effective for improving HG-induced BBB damage is unclear.

METHODS

We investigated the effect of pitavastatin, candesartan, cilostazol, propranolol, and eicosapentaenoic acid on HG-induced BBB damage. In vitro BBB models consisting of primary cultures of rat brain capillary endothelial cells were subjected to HG (55 mM d-glucose).

RESULTS

We observed a significant decrease in transendothelial electrical resistance (TEER) with HG, showing that HG compromised the integrity of the in vitro BBB model. No significant decrease in cell viability was seen with HG, but HG increased the production of reactive oxygen species. Pitavastatin and candesartan inhibited decreases in TEER induced by HG.

CONCLUSIONS

In summary, pitavastatin and candesartan improved HG-induced BBB damage and this in vitro model of HG-induced BBB dysfunction contributes to the search for BBB protective drugs.

Deficiency of dietary pyridoxine disturbed the intestinal physical barrier function of young grass carp (Ctenopharyngodon idella)

The aim of this study was to assess the effects of dietary pyridoxine (PN) deficiency on intestinal antioxidant capacity, cell apoptosis and intercellular tight junction in young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp (231.85 ± 0.63 g) were fed six diets containing graded levels of PN (0.12-7.48 mg/kg diet) for 10 weeks. At the end of the feeding trial, the fish were challenged with Aeromonas hydrophila for 2 weeks. The results showed that compared with the optimal PN level, PN deficiency (1) increased the contents of reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl (PC), decreased the activities and mRNA levels of antioxidant enzymes such as copper, zinc superoxide dismutase (CuZnSOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) (P < .05); (2) up-regulated the mRNA levels of cysteinyl aspartic acid-protease-3 (caspase-3), caspase-7, caspase-8, caspase-9, Bcl-2 associated X protein (Bax), apoptotic protease activating factor-1 (Apaf-1) and Fas ligand (FasL), and down-regulated the mRNA levels of inhibitor of apoptosis proteins (IAP), B-cell lymphoma protein-2 (Bcl-2) and myeloid cell leukaemia-1 (Mcl-1) (P < .05); (3) down-regulated the mRNA levels of ZO-1, occludin [only in middle intestine (MI)], claudin-b, claudin-c, claudin-f, claudin-3c, claudin-7a, claudin-7b and claudin-11, and up-regulated the mRNA levels of claudin-12 and claudin-15a (P < .05), which might be partly linked to Kelch-like-ECH-associated protein 1a (Keap1a)/NF-E2-related factor 2 (Nrf2), p38 mitogen-activated protein kinase (p38MAPK) and myosin light chain kinase (MLCK) signalling in the intestines of fish. However, the activities and mRNA levels of MnSOD, the mRNA levels of Keap1b, c-Jun N-terminal protein kinase (JNK) and claudin-15b in three intestinal segments, and the mRNA levels of occludin in the proximal intestine (PI) and distal intestine (DI) were not affected by graded levels of PN. These data indicate that PN deficiency could disturb the intestinal physical barrier function of fish. Additionally, based on the quadratic regression analysis for MDA content and GST activity, the dietary PN requirements for young grass carp were estimated as 4.85 and 5.02 mg/kg diet, respectively.

Postprandial Blood Glucose Outweighs Fasting Blood Glucose and HbA1c in screening Coronary Heart Disease

The objective of the present study is to assess the performance of fasting blood glucose (FBG), postprandial blood glucose (PBG), and glycated hemoglobin (HbA1c) as screening for coronary heart disease (CHD) in an inpatient population undergoing coronary angiography. 1852 consecutive patients scheduled for coronary angiography were classified into Normal Glucose Tolerance (NGT), Impaired Glucose Regulation (IGR), and diabetes, based on FBG, PBG, and HbA1c. Correlations of Gensini score with glucose metabolism and insulin resistance were analyzed. The associations between glycemic variables and Gensini score or the presence of CHD were analyzed by multiple linear regression and logistic regression, respectively. CHD was diagnosed in 488, 622, and 414 patients with NGT, IGR, and diabetes, respectively. Gensini score was positively correlated with FBG (r = 0.09, p < 0.01), PBG (r = 0.20, p < 0.01), and HbA1c (r = 0.19, p < 0.01). Gensini score was not correlated with fasting insulin (r = −0.081, p = 0.36), post-prandial insulin (r = −0.02, p = 0.61), or HOMAIR (r = −0.0059, p = 0.13). When FBG, PBG and HbA1c were pooled altogether, only PBG persisted in its association with Gensini score and the prevalence of CHD. The severity of CHD was associated with glucose rather than insulin resistance in this Chinese population. PBG was optimally correlated with the presence and severity of CHD.

High glucose derived endothelial microparticles increase active caspase-3 and reduce microRNA-Let-7a expression in endothelial cells

The experimental aim of this study was to determine the effects of high glucose-induced endothelial microparticles (EMPs) on endothelial cell susceptibility to apoptosis. Human umbilical vein endothelial cells (HUVECs) were cultured (3rd passage) and plated in 6-well plates at a density of 5.0 × 10⁵ cells/condition. Cells were incubated with media containing 25 mM d-glucose (concentration representing a diabetic glycemic state) or 5 mM d-glucose (normoglycemic condition) for 48 h to generate EMPs. EMP identification (CD144⁺ expression) and concentration was determined by flow cytometry. HUVECs (3 × 10⁶ cells/condition) were treated with EMPs generated from either the normal or high glucose conditions for 24 h. Intracellular concentration of active caspase-3 was determined by enzyme immunoassay. Cellular expression of miR-Let7a, an anti-apoptotic microRNA, was determined by RT-PCR using the ΔΔCT normalized to RNU6. High glucose-derived EMPs significantly increased both basal (1.5 ± 0.1 vs 1.0 ± 0.1 ng/mL) and staurosporine-stimulated (2.2 ± 0.2 vs 1.4 ± 0.1 ng/mL) active caspase-3 compared with normal glucose EMPs. Additionally, the expression of miR-Let-7a was markedly reduced (∼140%) by high glucose EMPs (0.43 ± 0.17 fold vs control). These results demonstrate that hyperglycemic-induced EMPs increase endothelial cell active caspase-3. This apoptotic effect may be mediated, at least in part, by a reduction in miR-Let-7a expression.

Acute and Chronic Hyperglycemia Elicit JIP1/JNK-Mediated Endothelial Vasodilator Dysfunction of Retinal Arterioles

Purpose

Hyperglycemia, a hallmark of diabetes mellitus, is associated with retinal inflammation and impairment of endothelium-dependent nitric oxide (NO)–mediated dilation of retinal arterioles. However, molecular mechanisms involved in this diminished endothelial vasodilator function remain unclear. We examined whether inflammatory stress-activated kinases, c-Jun N-terminal kinase (JNK) and p38, contribute to retinal arteriolar dysfunction during exposure to acute and chronic hyperglycemia.

Methods

Retinal arterioles were isolated from streptozocin-induced diabetic pigs (2 weeks; chronic hyperglycemia, 471 ± 23 mg/dL) or age-matched control pigs (euglycemia, 79 ± 5 mg/dL), and then cannulated and pressurized for vasoreactivity study. For acute hyperglycemia study, vessels from nondiabetic pigs were exposed intraluminally to high glucose (25 mM ≈ 450 mg/dL) for 2 hours, and normal glucose (5 mM ≈ 90 mg/dL) served as the control.

Results

Endothelium-dependent vasodilation to bradykinin was reduced in a similar manner after exposure to acute or chronic hyperglycemia. Administration of NO synthase inhibitor N^G-nitro-L-arginine methyl ester (L-NAME) nearly abolished vasodilations either in control (euglycemia and normal glucose) or hyperglycemic (acute and chronic) vessels. Treatment of either acute or chronic hyperglycemic vessels with JNK inhibitor SP600125 or JNK-interacting protein-1 (JIP1) inhibitor BI-78D3, but not p38 inhibitor SB203580, preserved bradykinin-induced dilation in an L-NAME–sensitive manner. By contrast, endothelium-independent vasodilation to sodium nitroprusside was unaffected by acute or chronic hyperglycemia.

Conclusions

Activation of JIP1/JNK signaling in retinal arterioles during exposure to acute or chronic hyperglycemia leads to selective impairment of endothelium-dependent NO-mediated dilation. Therapeutic targeting of the vascular JNK pathway may improve retinal endothelial vasodilator function during early diabetes.

MicroRNA-378 enhances inhibitory effect of curcumin on glioblastoma

Glioblastoma multiforme is the most aggressive and common primary brain tumor, and is virtually incurable due to its therapeutic resistance to radiation and chemotherapy. Curcumin is a well-known phytochemical exhibiting antitumor activity on many human cancers including glioblastoma multiforme. Given the unique miRNA expression profiles in cancer cells compared to non-cancerous cells, we investigated whether these miRNA could be used to cancer therapy. In this report we show that miR-378, a glioblastoma multiforme down regulated miRNA, may enhance the inhibitory effect of curcumin on this cancer growth. Our results indicated that the inhibitory effect of curcumin was enhanced in miR-378-expressing stable U87 cells in vitro and in vivo, compared to control cells. MiR-378 was found to target p-p38 expression, underlying the observed phenotypic changes. Thus, we concluded that miR-378 enhances the response of glioblastoma multiforme to curcumin treatment, by targeting p38.

Protective Effect of Saccharomyces boulardii on Deoxynivalenol-Induced Injury of Porcine Macrophage via Attenuating p38 MAPK Signal Pathway

The aims of our study were to evaluate the effects of Saccharomyces boulardii (S. boulardii) on deoxynivalenol (DON)-induced injury in porcine alveolar macrophage cells (PAMCs) and to explore the underlying mechanisms. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometric analysis, ELISA, qRT-PCR, and western blot were performed to assess whether S. boulardii could prevent DON-induced injury by p38 mitogen-activated protein kinase (p38 MAPK) signal pathway. The results showed that pretreatment with 8 μM DON could decrease the viability of PAMC and significantly increase the apoptosis rate of PAMC, whereas S. boulardii could rescue apoptotic PAMC cells induced by DON. Further experiments revealed that S. boulardii effectively reversed DON-induced cytotoxicity via downregulating the expression of TNF-α, IL-6, and IL-lβ. In addition, S. boulardii significantly alleviated DON-induced phosphorylation and mRNA expression of p38 and further increased the expression of apoptosis regulation genes Bcl-xl and Bcl-2 and inhibited the activation of Bax. Our results suggest that S. boulardii could suppress DON-induced p38 MAPK pathway activation and reduce the expression of downstream inflammatory cytokines, as well as promote the expression of anti-apoptotic genes to inhibit apoptosis induced by DON in PAMC.

Conditioned Medium from Placental Mesenchymal Stem Cells Reduces Oxidative Stress during the Cryopreservation of Ex Vivo Expanded Umbilical Cord Blood Cells

Background

The limited cell dose in umbilical cord blood (UCB) necessitates ex vivo expansion of UCB. Further, the effective cryopreservation of these expanded cells is important in widening their use in the clinics. During cryopreservation, cells experience oxidative stress due to the generation of reactive oxygen species (ROS). Conditioned medium from mesenchymal stem cells (MSCs-CM) has been shown to alleviate the oxidative stress during wound healing, Alzheimer’s disease and ischemic disease. This premise prompted us to investigate the influence of MSCs-CM during cryopreservation of expanded UCB cells.

Methodology/Principle findings

CM-was collected from cord/placental MSCs(C-MSCs-CM, P-MSC-CM). UCB CD34⁺cells were expanded as suspension cultures in serum free medium containing cytokines for 10 days. Cells were frozen with/without C-MSCs-CM and or P-MSCs-CM in the conventional freezing medium containing 20%FCS +10%DMSO using a programmable freezer and stored in liquid nitrogen. Upon revival, cells frozen with MSCs-CM were found to be superior to cells frozen in conventional medium in terms of viability, CD34⁺content and clonogenecity. Priming of revived cells for 48 hrs with MSCs-CM further improved their transplantation ability, as compared to those cultured without MSCs-CM. P-MSCs-CM radically reduced the oxidative stress in cryopreserved cells, resulting in better post thaw functionality of CD34⁺ cells than with C-MSCs-CM. The observed cryoprotective effect of MSCs-CM was primarily due to anti-oxidative and anti-apoptotic properties of the MSCs-CM and not because of the exosomes secreted by them.

Conclusions/Significance

Our data suggest that MSCs-CM can serve as a valuable additive to the freezing or the priming medium for expanded UCB cells, which would increase their clinical applicability.

MEKK1 Associated with Neuronal Apoptosis Following Intracerebral Hemorrhage

The JNKs have been implicated in a variety of biological functions in mammalian cells, including apoptosis and the responses to stress. However, the physiological role of these pathways in the intracerebral hemorrhage (ICH) has not been fully elucidated. In this study, we identified a MAPK kinase kinase (MAPKKK), MEKK1, may be involved in neuronal apoptosis in the processes of ICH through the activation of JNKs. From the results of western blot, immunohistochemistry and immunofluorescence, we obtained a significant up-regulation of MEKK1 in neurons adjacent to the hematoma following ICH. Increasing MEKK1 level was found to be accompanied with the up-regulation of p-JNK 3, p53, and c-jun. Besides, MEKK1 co-localized well with p-JNK in neurons, indicating its potential role in neuronal apoptosis. What's more, our in vitro study, using MEKK1 siRNA interference in PC12 cells, further confirmed that MEKK1 might exert its pro-apoptotic function on neuronal apoptosis through extrinsic pathway. Thus, MEKK1 may play a role in promoting the brain damage following ICH.

Coadjuvants in the Diabetic Complications: Nutraceuticals and Drugs with Pleiotropic Effects

Because diabetes mellitus (DM) is a multifactorial metabolic disease, its prevention and treatment has been a constant challenge for basic and clinical investigators focused on translating their discoveries into clinical treatment of this complex disorder. In this review, we highlight recent experimental and clinical evidences of potential coadjuvants in the management of DM, such as polyphenols (quercetin, resveratrol and silymarin), cultured probiotic microorganisms and drugs acting through direct/indirect or pleiotropic effects on glycemic control in DM. Among several options, we highlight new promising therapeutic coadjuvants, including chemical scavengers, the probiotic kefir and the phosphodiesterase 5 inhibitors, which besides the reduction of hyperglycemia and ameliorate insulin resistance, they reduce oxidative stress and improve endothelial dysfunction in the systemic vascular circulation. In the near future, experimental studies are expected to clear the intracellular pathways involving coadjuvants. The design of clinical trials may also contribute to new strategies with coadjuvants against the harmful effects of diabetic complications.

Inducible HGF-secreting Human Umbilical Cord Blood-derived MSCs Produced via TALEN-mediated Genome Editing Promoted Angiogenesis

Mesenchymal stem cells (MSCs) promote therapeutic angiogenesis to cure serious vascular disorders. However, their survival period and cytokine-secretory capacity are limited. Although hepatocyte growth factor (HGF) can accelerate the rate of angiogenesis, recombinant HGF is limited because of its very short half-life (<3–5 minutes). Thus, continuous treatment with HGF is required to obtain an effective therapeutic response. To overcome these limitations, we produced genome-edited MSCs that secreted HGF upon drug-specific induction. The inducible HGF expression cassette was integrated into a safe harbor site in an MSC chromosome using the TALEN system, resulting in the production of TetOn-HGF/human umbilical cord blood-derived (hUCB)-MSCs. Functional assessment of the TetOn-HGF/hUCB-MSCs showed that they had enhanced mobility upon the induction of HGF expression. Moreover, long-term exposure by doxycycline (Dox)-treated TetOn-HGF/hUCB-MSCs enhanced the anti-apoptotic responses of genome-edited MSCs subjected to oxidative stress and improved the tube-formation ability. Furthermore, TetOn-HGF/hUCB-MSCs encapsulated by arginine-glycine-aspartic acid (RGD)-alginate microgel induced to express HGF improved in vivo angiogenesis in a mouse hindlimb ischemia model. This study showed that the inducible HGF-expressing hUCB-MSCs are competent to continuously express and secrete HGF in a controlled manner. Thus, the MSCs that express HGF in an inducible manner are a useful therapeutic modality for the treatment of vascular diseases requiring angiogenesis.

Effect of Ligustrazine on rat peritoneal mesothelial cells treated with lipopolysaccharide

The apoptosis of peritoneal mesothelial cells (PMCs) and peritoneal fibrosis may induce failure of peritoneal membrane function. The study explored the changes of apoptosis and fibrosis in PMCs under lipopolysaccharides (LPS) culture and investigated whether Ligustrazine can affect LPS-induced apoptosis and fibrosis. We found that exposure of rat PMCs to 5 mg·L(-1) LPS for 24 h resulted in a significant induction of apoptosis and increased levels in Reactive oxygen species, and caspase-3 activity. Fibronectin, Collagen I, p-p38, and matrix metalloprotein-9 (MMP-9) levels were also significantly increased by LPS. But superoxide dismutase levels were remarkably decreased. Ligustrazine can restore the changes induced by LPS. The protective effect of Ligustrazine on LPS-induced apoptosis and fibrosis may act through inhibition of oxidative stress and p38/MAPKS, ROS/MMP-9 activation in PMCs.

Advanced Glycation End Products Impair Glucose-Stimulated Insulin Secretion of a Pancreatic β-Cell Line INS-1-3 by Disturbance of Microtubule Cytoskeleton via p38/MAPK Activation

Advanced glycation end products (AGEs) are believed to be involved in diverse complications of diabetes mellitus. Overexposure to AGEs of pancreatic β-cells leads to decreased insulin secretion and cell apoptosis. Here, to understand the cytotoxicity of AGEs to pancreatic β-cells, we used INS-1-3 cells as a β-cell model to address this question, which was a subclone of INS-1 cells and exhibited high level of insulin expression and high sensitivity to glucose stimulation. Exposed to large dose of AGEs, even though more insulin was synthesized, its secretion was significantly reduced from INS-1-3 cells. Further, AGEs treatment led to a time-dependent increase of depolymerized microtubules, which was accompanied by an increase of activated p38/MAPK in INS-1-3 cells. Pharmacological inhibition of p38/MAPK by SB202190 reversed microtubule depolymerization to a stabilized polymerization status but could not rescue the reduction of insulin release caused by AGEs. Taken together, these results suggest a novel role of AGEs-induced impairment of insulin secretion, which is partially due to a disturbance of microtubule dynamics that resulted from an activation of the p38/MAPK pathway.

Nanomolar Caffeic Acid Decreases Glucose Uptake and the Effects of High Glucose in Endothelial Cells

Epidemiological studies suggest that moderate and prolonged consumption of coffee is associated with a reduced risk of developing type 2 diabetes but the molecular mechanisms underlying this effect are not known. In this study, we report the effects of physiological concentrations of caffeic acid, easily achievable by normal dietary habits, in endothelial cells cultured in 25 mM of glucose (high glucose, HG). In HG, the presence of 10 nM caffeic acid was associated with a decrease of glucose uptake but not to changes of GLUT-1 membrane localization or mRNA levels. Moreover, caffeic acid countered HG-induced loss of barrier integrity, reducing actin rearrangement and FITC-dextran passage. The decreased flux of glucose associated to caffeic acid affected HG induced apoptosis by down-regulating the expression of initiator (caspase 8 and 9) and effector caspases (caspase 7 and 3) and by increasing the levels of phosphorylated Bcl-2. We also observed that caffeic acid in HG condition was associated to a reduction of p65 subunit nuclear levels with respect to HG alone. NF-κB activation has been shown to lead to apoptosis in HG treated cells and the analysis of the expression of a panel of about 90 genes related to NF-κB signaling pathway revealed that caffeic acid significantly influenced gene expression changes induced by HG. In conclusion, our results suggest that caffeic acid, decreasing the metabolic stress induced by HG, allows the activation of survival mechanisms mediated by a different modulation of NF-κB-related signaling pathways and to the activation of anti-apoptotic proteins.

MAP3K1 function is essential for cytoarchitecture of the mouse organ of Corti and survival of auditory hair cells

MAP3K1 is a serine/threonine kinase that is activated by a diverse set of stimuli and exerts its effect through various downstream effecter molecules, including JNK, ERK1/2 and p38. In humans, mutant alleles of MAP3K1 are associated with 46,XY sex reversal. Until recently, the only phenotype observed in Map3k1^tm1Yxia mutant mice was open eyelids at birth. Here, we report that homozygous Map3k1^tm1Yxia mice have early-onset profound hearing loss accompanied by the progressive degeneration of cochlear outer hair cells. In the mouse inner ear, MAP3K1 has punctate localization at the apical surface of the supporting cells in close proximity to basal bodies. Although the cytoarchitecture, neuronal wiring and synaptic junctions in the organ of Corti are grossly preserved, Map3k1^tm1Yxia mutant mice have supernumerary functional outer hair cells (OHCs) and Deiters' cells. Loss of MAP3K1 function resulted in the downregulation of Fgfr3, Fgf8, Fgf10 and Atf3 expression in the inner ear. Fgfr3, Fgf8 and Fgf10 have a role in induction of the otic placode or in otic epithelium development in mice, and their functional deficits cause defects in cochlear morphogenesis and hearing loss. Our studies suggest that MAP3K1 has an essential role in the regulation of these key cochlear morphogenesis genes. Collectively, our data highlight the crucial role of MAP3K1 in the development and function of the mouse inner ear and hearing.

Summary:Map3k1 mutant mice exhibit early-onset profound hearing loss and supernumerary outer hair cells, along with dysregulation of the FGF signaling pathway, accentuating its function in otic epithelium development and morphogenesis.

Protective effects of alpha lipoic acid on high glucose-induced neurotoxicity in PC12 cells

Hyperglycemia plays an important role in the development of diabetic neuropathy. In this study, we investigated the protective effects of alpha lipoic acid (ALA) against high glucose-induced neurotoxicity in PC12 cells as a suitable in vitro model for studying neuronal functions. PC12 cells were treated with high glucose (25 mg/ml for 24 h) in the absence and presence of ALA (100 μM for 24 h). The viability of PC12 cells was estimated by using MTT assay. The expression of pro- apoptotic Bax, anti- apoptotic Bcl-2 and caspase 3 protein were evaluated by western blotting. The reactive oxygen species (ROS) levels were determined with 2,7-dichlorodihydro- fluorescein diacetate (H2DCFDA). Biochemical markers of oxidative stress were assessed by using the total antioxidant power (TAP), lipid peroxidation (LPO), ADP/ATP ratio, activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD). Pretreatment of PC12 cells with ALA, significantly improved high glucose-induced toxicity by increasing activity of antioxidant enzymes CAT and SOD in the PC12 cell. It also increased the concentrations of TAP. An elevated level of cell death and ROS in high glucose conditions, diminished with ALA treatment. Over expression of Bax and caspase 3 protein, elevation of ADP/ATP ratio and LPO level in high glucose- treated PC12 cells, were significantly reduced by ALA. It was concluded that ALA attenuates neurotoxicity induced by high glucose in PC12 cells.

Heterodimer-specific TLR2 stimulation results in divergent functional outcomes in B-cell precursor acute lymphoblastic leukemia

Reports of spontaneous acute lymphoblastic leukemia (ALL) remissions following severe bacterial infections suggest that bacterial components may trigger elimination of ALL. To date, TLR2, which recognizes a broad range of bacterial pathogens through TLR1 or TLR6 heterodimerization, has not been fully evaluated for direct effects on ALL. Studies investigating TLR2 signaling in other tumor cell types utilizing single ligands have yielded contradictory results, and comparative, heterodimer-specific analyses of TLR2 stimulation are lacking. In this study, we report that two well-characterized heterodimer-specific TLR2 ligands, Pam3 CSK4 (TLR2/1), and Pam2 CSK4 (TLR2/6), induce ALL cell lines and primary ALL samples to upregulate CD40 expression. However, only Pam3 CSK4 triggers Caspase-8-mediated apoptosis and sensitizes cells to vincristine-mediated cytotoxicity. Consistent with this result, stimulation of ALL cells through TLR2/1 or TLR2/6 activates Mal, p38 and the NF-κB and PI3K signaling pathways with divergent kinetics that may underlie their distinct downstream effects. Our results reveal a novel branching in downstream responses to heterodimer-specific TLR2 stimulation in ALL cells and emphasize the need for comparative studies to determine differential biological effects observed in specific tumor cells. Based on our results, TLR2/1 ligand Pam3 CSK4 possesses potential for generating anti-ALL activity through its direct effects on leukemic blasts.

Tribbles homolog 3 is induced by high glucose and associated with apoptosis in human endothelial cells

Tribbles homolog 3 (TRIB3) is an intracellular kinase-like molecule that modifies cellular survival and metabolism. The present study aimed to investigate the function of TRIB3 regulation in the process of high glucose-induced apoptosis in endothelial cells, with the aim of identifying a novel intervention target for the prevention and treatment of diabetes mellitus. Human umbilical vein endothelial cells (HUVECs) grown in medium with various concentrations of glucose (5.5, 10, 20, 30 and 40 mmol/l) were assessed for mRNA expression of TRIB1, TRIB2 and TRIB3 using reverse transcription quantitative polymerase chain reaction. In addition, protein expression of TRIB3 was examined using western blot analysis. Immunofluorescence staining was performed in order to determine the distribution and localization of TRIB3 in HUVECs. Furthermore, cells grown in normal (5.5 mmol/l) or high glucose (HG; 30 mmol/l) medium were subjected to TRIB3 inhibition through small interfering (si)RNA knockdown. These cells were then examined in order to determine whether TRIB3 upregulation was associated with endothelial cell apoptosis. HUVECs treated with 30 and 40 mmol/l glucose for 48 h and 72 h showed significantly lower survival rates compared with those treated with normal glucose levels. In addition, slight but not significant increases in TRIB1 and TRIB2 mRNA expression were observed in HUVECs incubated with various concentrations of glucose for different durations. By contrast, TRIB3 mRNA expression was increased 7.2-fold following incubation with HG. Western blot analysis revealed a 5.44-fold increase in TRIB3 protein levels in cells grown in HG medium for 24 h compared with those grown in normal medium. Immunostaining assays revealed a markedly higher and well-defined nucleolar fluorescence intensity for TRIB3 expression at 24 h in HG medium compared with that of the control group. Furthermore, the apoptotic rate of HG-treated TRIB3 siRNA-transfected HUVECs was significantly increased compared with that of those transfected with control siRNA In conclusion, the results of the present study suggested that TRIB3 was associated with high glucose-induced HUVECs apoptosis, which was attenuated following transfection with TRIB3 siRNA.

The endothelium in diabetic nephropathy

Diabetes is characterised by widespread endothelial cell dysfunction that underlies the development of both the micro- and macrovascular complications of the disease, including nephropathy, cardiomyopathy, and non-proliferative retinopathy. In the kidney, major changes are noted in glomerular endothelial cell structure in their fenestrations and glycocalyx. These changes, along with endothelial cell loss and capillary rarefaction in both the glomerulus and tubulointerstitium, lead to the progressive loss of glomerular filtration that render diabetes the most common cause of end-stage renal disease in much of the developed world. New treatments in diabetes that directly address the abnormal structure and function of the endothelial cell are desperately needed.

Mitogen-activated protein kinase p38 induces HDAC4 degradation in hypertrophic chondrocytes

Histone deacetylase 4 (HDAC4) is a critical negative regulator for chondrocyte hypertrophy by binding to and inhibiting Runx2, a critical transcription factor for chondrocyte hypertrophy. It is unclear how HDAC4 expression and stability are regulated during growth plate development. We report here that inhibition of mitogen-activated protein kinase (MAPK) p38 by dominant negative p38 or p38 inhibitor prevents HDAC4 degradation. Mutation of a potential caspase-2 and 3 cleavage site Asp289 stabilizes HDAC4 in chondrocytes. In contrast, constitutively active MAPK kinase 6 (constitutive activator of p38) transgenic mice exhibit decreased HDAC4 content in vivo. We also observed that p38 stimulates caspase-3 activity in chondrocytes. Inhibition of p38 or caspases reduced HDAC4 degradation. HDAC4 inhibited Runx2 promoter activity in a dose-dependent manner and caspase inhibitors further enhanced this inhibition by preventing HDAC4 degradation. Overall, these results demonstrate that p38 promotes HDAC4 degradation by increasing caspase-mediated cleavage, which releases Runx2 from a repressive influence of HDAC4 and promotes the chondrocyte hypertrophy and bone formation.

Hyperglycaemia promotes human brain microvascular endothelial cell apoptosis via induction of protein kinase C-ßI and prooxidant enzyme NADPH oxidase

Blood-brain barrier disruption represents a key feature in hyperglycaemia-aggravated cerebral damage after an ischaemic stroke. Although the underlying mechanisms remain largely unknown, activation of protein kinase C (PKC) is thought to play a critical role. This study examined whether apoptosis of human brain microvascular endothelial cells (HBMEC) might contribute to hyperglycaemia-evoked barrier damage and assessed the specific role of PKC in this phenomenon. Treatments with hyperglycaemia (25 mM) or phorbol myristate acetate (PMA, a protein kinase C activator, 100 nM) significantly increased NADPH oxidase activity, O2 (•-) generation, proapoptotic protein Bax expression, TUNEL-positive staining and caspase-3/7 activities. Pharmacological inhibition of NADPH oxidase, PKC-a, PKC-ß or PKC-ßI via their specific inhibitors and neutralisation of O2 (•-) by a cell-permeable superoxide dismutase mimetic, MnTBAP normalised all the aforementioned increases induced by hyperglycaemia. Suppression of these PKC isoforms also negated the stimulatory effects of hyperglycaemia on the protein expression of NADPH oxidase membrane-bound components, Nox2 and p22-phox which determine the overall enzymatic activity. Silencing of PKC-ßI gene through use of specific siRNAs abolished the effects of both hyperglycaemia and PMA on endothelial cell NADPH oxidase activity, O2 (•-) production and apoptosis and consequently improved the integrity and function of an in vitro model of human cerebral barrier comprising HBMEC, astrocytes and pericytes. Hyperglycaemia-mediated apoptosis of HBMEC contributes to cerebral barrier dysfunction and is modulated by sequential activations of PKC-ßI and NADPH oxidase.