Yes-associated protein mediates human embryonic stem cell-derived cardiomyocyte proliferation: Involvement of epidermal growth factor receptor signaling.

Unlike mature cardiomyocytes, human pluripotent stem cell-derived cardiomyocytes exhibit higher proliferative capacity; however, the underlying mechanisms involved are yet to be elucidated. Here, we revealed that the Yes-associated protein (YAP) plays a critical role in regulating cell proliferation in association with epidermal growth factor receptor (EGFR) in human embryonic stem cell-derived cardiomyocytes (hESC-CMs). Our results show that low-density culture significantly promotes the proliferation of hESC-CMs via YAP. Interestingly, the low-density culture-induced YAP expression further induced EGFR expression, without any alterations in the activity of EGFR and its two major downstream kinases, ERK, and AKT. However, treatment of a low-density-culture of hESC-CMs with epidermal growth factor (EGF) increased proliferation via phosphorylation of EGFR, ERK, and AKT, and the EGF-induced phosphorylation of EGFR, ERK, and AKT was significantly higher in low-density hESC-CMs than in high-density hESC-CMs. Furthermore, the EGF-induced activation of EGFR, ERK, and AKT increased YAP expression and subsequently proliferation. In conclusion, YAP mediates both low-density culture-induced and EGF-induced proliferation of hESC-CMs in low-density culture conditions.

The First Report on the Complete Sequence Characterization of Bluetongue Virus Serotype 3 in the Republic of Korea.

The bluetongue virus (BTV) is a significant animal pathogen with economic implications in the ruminant industry. Despite global reports on BTV detection and epidemiologic investigations, limited studies have focused on the virus in the ROK. In this study, BTV epidemiological research was conducted on blood samples from cattle and goat farms across nine regions during 2013-2014. The results showed that 3.33% of bovine blood samples (194/5824) and 0.19% of goat blood samples (2/1075) tested positive for BTV antibodies using ELISA. In Jeju-do, BTV RNA amplification occurred in 51 of 422 samples (12.1%) using real-time reverse transcription (RT-qPCR). The isolation of one sample revealed it as serotype 3, as indicated by the sequence of segments 2 (Seg-2) and 6 (Seg-6), associated with the eastern BTV topotype. However, based on Seg-1, -3, -4, -5, -7, -8, -9, and -10 analyses, the BTV-3/JJBB35 strain is more closely related to distinct BTV strains. These findings imply BTV circulation and that the Korean-isolated BTV might originate from Asian BTV strains due to multiple reassortment events. This study provides foundational data for ongoing BTV monitoring and disease-control policies in the ROK.

Fermented Soybean Paste Attenuates Biogenic Amine-Induced Liver Damage in Obese Mice.

Biogenic amines are cellular components produced by the decarboxylation of amino acids; however, excessive biogenic amine production causes adverse health problems. The relationship between hepatic damage and biogenic amine levels in nonalcoholic fatty liver disease (NAFLD) remains unclear. In this study, mice were fed a high-fat diet (HFD) for 10 weeks to induce obesity, presenting early-stage of NAFLD. We administered histamine (20 mg/kg) + tyramine (100 mg/kg) via oral gavage for 6 days to mice with HFD-induced early-stage NAFLD. The results showed that combined histamine and tyramine administration increased cleaved PARP-1 and IL-1ß in the liver, as well as MAO-A, total MAO, CRP, and AST/ALT levels. In contrast, the survival rate decreased in HFD-induced NAFLD mice. Treatment with manufactured or traditional fermented soybean paste decreased biogenically elevated hepatic cleaved PARP-1 and IL-1ß expression and blood plasma MAO-A, CRP, and AST/ALT levels in HFD-induced NAFLD mice. Additionally, the biogenic amine-induced reduction in survival rate was alleviated by fermented soybean paste in HFD-induced NAFLD mice. These results show that biogenic amine-induced liver damage can be exacerbated by obesity and may adversely affect life conservation. However, fermented soybean paste can reduce biogenic amine-induced liver damage in NAFLD mice. These results suggest a beneficial effect of fermented soybean paste on biogenic amine-induced liver damage and provide a new research perspective on the relationship between biogenic amines and obesity.

Anti-Obesity Effect of Pine Needle Extract on High-Fat Diet-Induced Obese Mice.

BACKGROUND: Obesity due to an excessive intake of nutrient disturbs the hypothalamus-mediated energy metabolism subsequently develops metabolic disorders. In this study, we investigated the effect of pine needle extract (PNE) on the hypothalamic proopiomelanocortin (POMC) neurons involved in the regulation of energy balance via melanocortin system and fat tissue metabolism. METHODS: We performed electrophysiological and immunohistochemical analyses to determine the effect of PNE on POMC neurons. Mice were fed a normal or high-fat diet for 12 weeks, then received PNE for the last 2 weeks to measure the following physiological indices: Body weight, food intake, fat/lean mass, glucose metabolism, and plasma leptin levels. In addition, changes of thermogenic, lipolytic, and lipogenetic markers were evaluated in brown adipose tissue (BAT) and white adipose tissue (WAT) by western blotting, respectively. RESULTS: PNE increased hypothalamic POMC neuronal activity, and the effect was abolished by blockade of melanocortin 3/4 receptors (MC3/4Rs). PNE decreased body weight, fat mass, plasma leptin levels, and improved glucose metabolism after high-fat-induced obesity. However, PNE did not change the expression of thermogenic markers of the BAT in HFD fed groups, but decreased only the lipogenetic markers of WAT. This study suggests that PNE has a potent anti-obesity effect, inhibiting lipogenesis in WAT, even though HFD-induced leptin resistance-mediated disruption of POMC neuronal activity.

Cripto Enhances Proliferation and Survival of Mesenchymal Stem Cells by Up-Regulating JAK2/STAT3 Pathway in a GRP78-Dependent Manner.

Cripto is a small glycosylphosphatidylinositol-anchored signaling protein that can detach from the anchored membrane and stimulate proliferation, migration, differentiation, vascularization, and angiogenesis. In the present study, we demonstrated that Cripto positively affected proliferation and survival of mesenchymal stem cells (MSCs) without affecting multipotency. Cripto also increased expression of phosphorylated janus kinase 2 (p-JAK2), phosphorylated signal transducer and activator of transcription 3 (p-STAT3), 78 kDa glucose-regulated protein (GRP78), c-Myc, and cyclin D1. Notably, treatment with an anti-GRP78 antibody blocked these effects. In addition, pretreatment with STAT3 short interfering RNA (siRNA) inhibited the increase in p-JAK2, c-Myc, cyclin D1, and BCL3 levels caused by Cripto and attenuated the pro-survival action of Cripto on MSCs. We also found that incubation with Cripto protected MSCs from apoptosis caused by hypoxia or H2O2 exposure, and the level of caspase-3 decreased by the Cripto-induced expression of B-cell lymphoma 3-encoded protein (BCL3). These effects were sensitive to down-regulation of BCL3 expression by BCL3 siRNA. Finally, we showed that Cripto enhanced expression levels of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and hepatocyte growth factor (HGF). In summary, our results demonstrated that Cripto activated a novel biochemical cascade that potentiated MSC proliferation and survival. This cascade relied on phosphorylation of JAK2 and STAT3 and was regulated by GRP78. Our findings may facilitate clinical applications of MSCs, as these cells may benefit from positive effects of Cripto on their survival and biological properties.

Enhanced Susceptibility to 5-Fluorouracil in Human Colon Cancer Cells by Silencing of GRP78.

BACKGROUND: Glucose-regulated protein (GRP78), also known as immunoglobulin heavy chain binding protein and as heat shock 70 kDa protein 5, is present in the endoplasmic reticulum (ER) membrane. GRP78 is generally expressed at low concentrations, but is increased by physiological stress. GRP78 is thought to protect against tissue or organ damage under pathological conditions, such as neurotoxic stress, myocardial infarction, or arteriosclerosis. In addition, in tumors, GRP78 expression is much higher than in normal tissues. Furthermore, high levels of GRP78 expression have been shown to increase the risk of malignancy and metastasis in prostate and colon cancer. Because both anticancer drugs and down-regulation of GRP78 expression inhibit cancer progression and growth, we hypothesized that down-regulation of GRP78 expression might lead to enhanced susceptibility of cancer cells to cytotoxic action of 5-fluorouracil (5-FU). MATERIALS AND METHODS: GRP78 expression was suppressed in LoVo colon cancer cells by utilizing small-interfering RNA (si-GRP78), and the cells were subsequently used to study the antiproliferative and anticancer effects of 5-FU treatment. The signaling pathways responsible for the increase of LoVo cell susceptibility to 5-FU treatment after exposure to GRP78 siRNA were determined by western blot. RESULTS: GRP78 silencing significantly inhibited cell viability and increased apoptosis of LoVo cells. Furthermore, combined treatment with 5-FU and GRP78 siRNA for 12 h reduced cell viability, and increased apoptosis and generation reactive oxygen species more strongly than either of the two treatments applied separately. In order to examine the role of ER stress in increased susceptibility of LoVo cells to 5-FU after pretreatment with GRP78 siRNA, we analyzed expression levels of ER stress marker proteins, such as phosphorylated protein kinase-like endoplasmic reticulum kinase (PERK), phosphorylated eukaryotic initiation factor 2 alpha (eIF2α), activating transcription factor 4 (ATF4), phosphorylated inositol-requiring enzyme 1 alpha (IRE1α), phosphorylated p38, and C/EBP homologous protein (CHOP). Treatment with 5-FU alone increased the expression of ER stress marker proteins, whereas combined exposure to both 5-FU and GRP78 siRNA led to an even stronger effect on these markers. Similar to the pattern of modulation of ER stress protein expression, the levels of apoptosis-related proteins were also more strongly affected by combined exposure to 5-FU and GRP78 siRNA than by single treatments. In particular, expression of Bcl-2-associated X protein (BAX), cleaved caspase-3, and cleaved poly (ADP-ribose) polymerase 1 (PARP1) were increased, whereas the expression of B-cell lymphoma 2 (BCL2) was reduced by these treatments. CONCLUSION: GRP78 silencing and incubation with 5-FU have synergistic effects on the inhibition of LoVo colon cancer cell growth via the induction of ER stress-dependent apoptosis.

Silencing Prion Protein in HT29 Human Colorectal Cancer Cells Enhances Anticancer Response to Fucoidan.

BACKGROUND: The putative functions of the cellular prion protein (PrP(c)) are believed to be associated with cell signaling, differentiation, survival, and cancer progression. With respect to cancer development and progression, elevations and mutations of PrP(c) expression have been shown to increase the risk for malignancy and metastasis in breast and colorectal cancer. Since both natural supplements and direct regulation of PrP(c) expression contribute to inhibition of cancer progression and growth, we hypothesized that knockdown of PrP(c) could lead to an enhanced synergic effect on the inhibition of cancer growth by fucoidan. MATERIALS AND METHODS: PrP(c) expression was suppressed in HT29 human colon cancer cells by utilizing small-interfering RNA (si-PRNP), and cells were subsequently used to study the antiproliferative and anticancer effects of fucoidan treatment of HT29 human colon cancer cells. RESULTS: Fucoidan treatment significantly inhibited growth and reduced cyclin and cyclin-dependent kinase (CDK) expression in HT29 colon cancer cells. Furthermore, silencing PrP(c) expression with si-PRNP amplified the fucoidan-induced changes in cell proliferation, apoptosis, and migration. Intraperitoneal injection of si-PRNP with fucoidan reduced proliferation and tumor volume in Balb/c nude mice. This enhanced antitumor efficacy was associated with decreased angiogenesis. CONCLUSION: Combination of fucoidan with silencing of PrP(c) has a synergic effect on the inhibition of HT29 colon cancer cell growth. Furthermore, we provide evidence for the therapeutic application of PrP(c) silencing with other anticancer drugs for cancer.

Lysosomal Enzyme Glucocerebrosidase Protects against Aß1-42 Oligomer-Induced Neurotoxicity.

Glucocerebrosidase (GCase) functions as a lysosomal enzyme and its mutations are known to be related to many neurodegenerative diseases, including Gaucher's disease (GD), Parkinson's disease (PD), and Dementia with Lewy Bodies (DLB). However, there is little information about the role of GCase in the pathogenesis of Alzheimer's disease (AD). Here we demonstrate that GCase protein levels and enzyme activity are significantly decreased in sporadic AD. Moreover, Aß1-42 oligomer treatment results in neuronal cell death that is concomitant with decreased GCase protein levels and enzyme activity, as well as impairment in lysosomal biogenesis and acidification. Importantly, overexpression of GCase promotes the lysosomal degradation of Aß1-42 oligomers, restores the lysosomal impairment, and protects against the toxicity in neurons treated with Aß1-42 oligomers. Our findings indicate that a deficiency of GCase could be involved in progression of AD pathology and suggest that augmentation of GCase activity may be a potential therapeutic option for the treatment of AD.