The effects of N-linked glycosylation on the activation and secretion of lipoprotein lipase were studied in Ob17 cells. The cells were first depleted of any activity and enzyme content by cycloheximide treatment and of precursors of oligosaccharide chains by tunicamycin. The repletion of lipoprotein lipase content was studied in these cells maintained in the presence of tunicamycin after cycloh...

The selective cytotoxicity of tunicamycin homologues against SV40-transformed 3T3 cells (SV40-3T3) was examined. Incubation of 3T3 or virally transformed 3T3 cells with four different homologues (A~, A2, B1, and B2 at 0.1 to 0.25 #g/ml) caused detachment and death of transformed cells after 1 to 3 days, while the nontransformed cells were almost unaffected. Cytotoxicity against nontransformed c...

The expression of the ischemia-responsive protein (irp94) was enhanced by endoplasmic reticulum (ER) stress inducing drugs such as brefeldin A (BFA), calcium ionophor A23187, dithiothreitol (DTT) and tunicamycin in fisher rat thyroid epithelial cell line (FRTL-5 cells). In particular, irp94 mRNA expression was increased dose dependently by tunicamycin, and there was increased irp94 expression w...

Endoplasmic reticulum (ER) stress is linked with development and maintenance of cancer, and serves as a therapeutic target for treatment of cancer. Verrucarin A, isolated from the broth of Fusarium sp. F060190, showed potential inhibitory activity on tunicamycin-induced ER stress in FaO rat liver cells. In addition, the compound decreased tunicamycin-induced GRP78 promoter activity in a dose de...

The selective cytotoxicity of tunicamycin homologues against SV40-transformed 3T3 cells (SV40-3T3) was examined. Incubation of 3T3 or virally transformed 3T3 cells with four different homologues (A~, A2, B1, and B2 at 0.1 to 0.25 #g/ml) caused detachment and death of transformed cells after 1 to 3 days, while the nontransformed cells were almost unaffected. Cytotoxicity against nontransformed c...

Tunicamycin, an antibiotic that inhibits the transfer of N-acetyglucosamine-1-phosphate from UDP-N-acetylglucosamine to dolichol monophosphate and thereby blocks the formation of protein-carbohydrate linkages of the N-glycosidic type, is not a single compound but a mixture of homologous antibiotics. Two major and eight minor homologs have been identified, all of which possess the ability to inh...

The treatment of gram-positive bacteria and yeasts with tunicamycin induces morphological changes such as elongation, conversion from rod-form to cocci-form and enlargement of microbial cells. Even when bacteria grew normally or to a somewhat lesser extent than controls as determined bymeasurement of optical density, the increase in viable cells was suppressed to a great extent. Such effects of...

Hepatocellular carcinoma is highly chemoresistant, and ATP-binding cassette subfamily G member 2 (ABCG2) is thought to play a critical role in this drug resistance. The present study aims to develop effective therapeutic strategies to decrease ABCG2 expression level and to surmount drug resistance in hepatocellular carcinoma chemotherapy. First, we verified a positive correlation between the AB...

BACKGROUND Anabolic resistance is the inability to increase protein synthesis in response to an increase in amino acids following a meal. One potential mediator of anabolic resistance is endoplasmic reticulum (ER) stress. The purpose of the present study was to test whether ER stress impairs the response to growth factors and leucine in muscle cells. METHODS Muscle cells were incubated overni...