MyMedR

Displaying all 6 publications

Abstract:

Sort:

Resistance against apoptosis by the cellular prion protein is dependent on its glycosylation status in oral HSC-2 and colon LS 174T cancer cells

Yap YH, Say YH

Cancer Lett, 2011 Jul 1;306(1):111-9.
PMID: 21439722 DOI: 10.1016/j.canlet.2011.02.040

Most studies have focused on the role of the cellular prion protein (PrP(C)) in neurodegenerative diseases, whereas the function of this ubiquitous protein outside the nervous system remains elusive. Therefore, the anti-apoptotic property of PrP(C) in oral squamous cell carcinoma (HSC-2) and colon adenocarcinoma (LS 174T) was evaluated in this study, by stable shRNA knockdown and overexpression, respectively. PrP(C) confers resistance against oxidative stress-apoptosis as indicated by MTT assay, Annexin V-FITC/PI and DCFH-DA staining, but this property is abolished upon N-glycosylation inhibition by tunicamycin. Our results indicate that the inhibition of glycosylation in cancer cells overexpressing PrP(C) could represent a potential therapeutic target.

Matched MeSH terms: Tunicamycin/pharmacology
Fulltext Chronic treatment with paeonol improves endothelial function in mice through inhibition of endoplasmic reticulum stress-mediated oxidative stress

Choy KW, Lau YS, Murugan D, Mustafa MR

PLoS One, 2017;12(5):e0178365.
PMID: 28562691 DOI: 10.1371/journal.pone.0178365

Endoplasmic reticulum (ER) stress leads to endothelial dysfunction which is commonly associated in the pathogenesis of several cardiovascular diseases. We explored the vascular protective effects of chronic treatment with paeonol (2'-hydroxy-4'-methoxyacetophenone), the major compound from the root bark of Paeonia suffruticosa on ER stress-induced endothelial dysfunction in mice. Male C57BL/6J mice were injected intraperitoneally with ER stress inducer, tunicamycin (1 mg/kg/week) for 2 weeks to induce ER stress. The animals were co-administered with or without paeonol (20 mg/kg/oral gavage), reactive oxygen species (ROS) scavenger, tempol (20 mg/kg/day) or ER stress inhibitor, tauroursodeoxycholic acid (TUDCA, 150 mg/kg/day) respectively. Blood pressure and body weight were monitored weekly and at the end of treatment, the aorta was isolated for isometric force measurement. Protein associated with ER stress (GRP78, ATF6 and p-eIF2α) and oxidative stress (NOX2 and nitrotyrosine) were evaluated using Western blotting. Nitric oxide (NO) bioavailability were determined using total nitrate/nitrite assay and western blotting (phosphorylation of eNOS protein). ROS production was assessed by en face dihydroethidium staining and lucigenin-enhanced chemiluminescence assay, respectively. Our results revealed that mice treated with tunicamycin showed an increased blood pressure, reduction in body weight and impairment of endothelium-dependent relaxations (EDRs) of aorta, which were ameliorated by co-treatment with either paeonol, TUDCA and tempol. Furthermore, paeonol reduced the ROS level in the mouse aorta and improved NO bioavailability in tunicamycin treated mice. These beneficial effects of paeonol observed were comparable to those produced by TUDCA and tempol, suggesting that the actions of paeonol may involve inhibition of ER stress-mediated oxidative stress pathway. Taken together, the present results suggest that chronic treatment with paeonol preserved endothelial function and normalized blood pressure in mice induced by tunicamycin in vivo through the inhibition of ER stress-associated ROS.

Matched MeSH terms: Tunicamycin/pharmacology
Fulltext 3',4'-dihydroxyflavonol ameliorates endoplasmic reticulum stress-induced apoptosis and endothelial dysfunction in mice

Lau YS, Mustafa MR, Choy KW, Chan SMH, Potocnik S, Herbert TP, et al.

Sci Rep, 2018 01 29;8(1):1818.
PMID: 29379034 DOI: 10.1038/s41598-018-19584-8

Endoplasmic reticulum (ER) stress has been implicated in the development of hypertension 3 through the induction of endothelial impairment. As 3',4'-dihydroxyflavonol (DiOHF) 4 reduces vascular injury caused by ischaemia/reperfusion or diabetes, and flavonols have been demonstrated to attenuate ER stress, we investigated whether DiOHF can protect mice from ER stress-induced endothelial dysfunction. Male C57BLK/6 J mice were injected with tunicamycin to induce ER stress in the presence or absence of either DiOHF or tauroursodeoxycholic acid (TUDCA), an inhibitor of ER stress. Tunicamycin elevated blood pressure and impaired endothelium-dependent relaxation. Moreover, in aortae there was evidence of ER stress, oxidative stress and reduced NO production. This was coincident with increased NOX2 expression and reduced phosphorylation of endothelial nitric oxide synthase (eNOS) on Ser1176. Importantly, the effects of tunicamycin were significantly ameliorated by DiOHF or TUDCA. DiOHF also inhibited tunicamycin-induced ER stress and apoptosis in cultured human endothelial cells (HUVEC). These results provide evidence that ER stress is likely an important initiator of endothelial dysfunction through the induction of oxidative stress and a reduction in NO synthesis and that DiOHF directly protects against ER stress- induced injury. DiOHF may be useful to prevent ER and oxidative stress to preserve endothelial function, for example in hypertension.

Matched MeSH terms: Tunicamycin/pharmacology
Fulltext N-glycosylation and expression in human tissues of the orphan GPR61 receptor

Kozielewicz P, Alomar H, Yusof S, Grafton G, Cooper AJ, Curnow SJ, et al.

FEBS Open Bio, 2017 12;7(12):1982-1993.
PMID: 29226084 DOI: 10.1002/2211-5463.12339

A number of members of the G protein-coupled receptor class of cell surface receptors are 'orphans' with no known endogenous ligand. One of these orphan receptors is GPR61; there are little data about its expression in human cells and tissues. In this study, we investigated the post-translational modification of GPR61 by N-glycosylation at an identified consensus N-glycosylation site (N12) and the impact of this modification upon the subcellular expression of the protein. The N-glycosylation inhibitor tunicamycin reduced the apparent molecular weight of immunoreactivity associated with myc-tagged GPR61 by 1-2 kDa, which was comparable to the evident molecular weight of the myc-tagged N12S GPR61 mutant with disrupted consensus N-glycosylation site. Analysis of GPR61 expression demonstrated that tunicamycin treatment reduced considerably heterologous expression of GPR61 in the cell membrane despite the N12S GPR61 mutant being readily expressed at the cell surface. These results demonstrate that GPR61 is subject to N-glycosylation but suggest this is not a prerequisite for cell surface expression, although N-glycosylation of other proteins may be important for cell membrane expression of GPR61. Expression of GPR61 protein was demonstrated at the cellular level in human hippocampus and human peripheral blood mononuclear cells. In the latter, there was a significantly higher expression of GPR61 in the Th17 cell subset in comparison with resting CD4+ cells, which may point toward a potential role for the GPR61 receptor in autoimmune diseases. This is the first report that GPR61 protein is subject to post-translational modification and is expressed in immune cell subsets and the hippocampus. These findings will help guide studies to investigate the function of GPR61.

Matched MeSH terms: Tunicamycin
Fulltext The Effect of Amygdalin on Endoplasmic Reticulum (ER) Stress Induced Hepatic Steatosis in Mice

Moslehi A, Farahabadi M, Chavoshzadeh SA, Barati A, Ababzadeh S, Mohammadbeigi A

Malays J Med Sci, 2018 Feb;25(1):16-23.
PMID: 29599631 DOI: 10.21315/mjms2018.25.1.3

Background: Endoplasmic reticulum (ER) stress creates abnormalities in the insulin action, inflammatory responses, lipoprotein B100 degradation, and hepatic lipogenesis. Hepatic steatosis leads to a broad spectrum of hepatic disorders such as nonalcoholic fatty liver disease (NAFLD) and NASH. Amygdalin has beneficial effects on asthma, bronchitis, diabetes, and atherosclerosis. We designed this study to evaluate the effect of amygdalin on the ER stress induced hepatic steatosis.
Methods: Inbred mice received saline, DMSO and amygdalin, as control groups. ER stress was induced by tunicamycin (TM) injection. Amygdalin was administered 1 h before the TM challenge (Amy + TM group). Mice body and liver weights were measured. Hematoxylin and eosin (H&E) and oil red O staining from liver tissue, were performed. Alanin aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride and cholesterol levels were measured.
Results: Histological evaluation revealed that amygdalin was unable to decrease the TM induced liver steatosis; however, ALT and AST levels decreased [ALT: 35.33(2.15) U/L versus 92.33(6.66) U/L; (57.000, (50.63, 63.36),P< 0.001) and AST: 93(5.09) U/L versus 345(97.3) U/L, (252, (163.37, 340.62),P< 0.001)]. Amygdalin also decreased triglyceride and cholesterol plasma levels in the Amy + TM group [TG: 42.66(2.15) versus 53.33(7.24) mg/dL; (10.67, (3.80, 17.54),P= 0.006) and TC: 9.33(3.55) versus 112.66(4.31) mg/dL, (103.33, (98.25, 108.40)P< 0.001)].
Conclusion: Amygdalin improved the ALT, AST, and lipid serum levels after the TM challenge; however, it could not attenuate hepatic steatosis.

Matched MeSH terms: Tunicamycin
Fulltext Angiotensin 1-7 Protects against Angiotensin II-Induced Endoplasmic Reticulum Stress and Endothelial Dysfunction via Mas Receptor

Murugan D, Lau YS, Lau CW, Lau WC, Mustafa MR, Huang Y

PLoS One, 2015;10(12):e0145413.
PMID: 26709511 DOI: 10.1371/journal.pone.0145413

Angiotensin 1-7 (Ang 1-7) counter-regulates the cardiovascular actions of angiotensin II (Ang II). The present study investigated the protective effect of Ang 1-7 against Ang II-induced endoplasmic reticulum (ER) stress and endothelial dysfunction. Ex vivo treatment with Ang II (0.5 μM, 24 hours) impaired endothelium-dependent relaxation in mouse aortas; this harmful effect of Ang II was reversed by co-treatment with ER stress inhibitors, l4-phenylbutyric acid (PBA) and tauroursodeoxycholic acid (TUDCA) as well as Ang 1-7. The Mas receptor antagonist, A779, antagonized the effect of Ang 1-7. The elevated mRNA expression of CHOP, Grp78 and ATF4 or protein expression of p-eIF2α and ATF6 (ER stress markers) in Ang II-treated human umbilical vein endothelial cells (HUVECs) and mouse aortas were blunted by co-treatment with Ang 1-7 and the latter effect was reversed by A779. Furthermore, Ang II-induced reduction in both eNOS phosphorylation and NO production was inhibited by Ang 1-7. In addition, Ang 1-7 decreased the levels of ER stress markers and augmented NO production in HUVECs treated with ER stress inducer, tunicamycin. The present study provides new evidence for functional antagonism between the two arms of the renin-angiotensin system in endothelial cells by demonstrating that Ang 1-7 ameliorates Ang II-stimulated ER stress to raise NO bioavailability, and subsequently preserves endothelial function.

Matched MeSH terms: Tunicamycin/pharmacology