Tunicamycin

M. ZAMFIR, R. CALLEWAERT, P.C. CORNEA, L. SAVU, I. VATAFU and L. DE VUYST.1999.Lactobacillus acidophilus IBB 801 produces a small bacteriocin, designated acidophilin 801, with an estimated molecular mass of less than 6·5 kDa. It displays a narrow inhibitory spectrum (only related lactobacilli but including the Gram-negative pathogenic bacteria Escherichia coli Row and Salmonella panama 1467) with a bactericidal activity. The antimicrobial activity of cell-free culture supernatant fluid was insensitive to catalase but sensitive to proteolytic enzymes such as trypsin, proteinase K and pronase, heat-stable (30 min at 121 °C), and maintained in a wide pH range. The proteinaceous compound was isolated from cell-free culture supernatant fluid and purified. Crude bacteriocin was isolated as a floating pellicle after ammonium sulphate precipitation (40% saturation) and partially purified by extraction/precipitation with chloroform/methanol (2/1, v/v). Further purification to homogeneity was performed by reversed phase Fast Performance Liquid Chromatography. The amino acid composition was determined. Amino acid sequencing revealed that the N-terminal end was blocked.

Objectives: To investigate the neuroprotective efficacy of  Valeriana
wallichii  DC rhizome extract against 1-methyl-4-phenlypyridinium
(MPP
+
) and  tunicamycin induced cell death.  Methods:  The 50%
methanolic extract of  V. wallichii  rhizome (VWE) was evaluated for
free radical scavenging properties. Cell viability analysis and IC50
determination for VWE in SH-SY5Y neuroblastoma cell line was
performed by MTT assay. The neuroprotective efficacy of VWE in
SH-SY5Y cells against the damages induced by the neurotoxin,
MPP
+
and the endoplasmic reticulum stress inducer, tunicamycin was
assessed by MTT assay and by morphological analysis with phase
contrast microscope. MTT assay was performed using 3 different
concentrations (0.1, 0.5 and 1 mg/mL) of VWE that were added at 0,
8 and 16 h post MPP
+
and tunicamycin treatment.  Results:  VWE
showed good free radical scavenging properties. From the cell
viability analysis the IC50
value of VWE was calculated as 2.207
mg/mL in SH-SY5Y cells. In MPP
+
treated cells 0.5mg and 1mg/mL
concentrations of VWE brought significant improvement in cell
viability at 0h, while at 8h and 16h post MPP
+
treatment the effect
was significant at 1mg/ml concentration. VWE exhibited significant
protective effect in tunicamycin treated cells only at 0h but not at 8h
and 16h post treatment. MPP
+
and tunicamycin induced cell
shrinkage and condensation were inhibited by treatment with
1mg/mL of VWE.  Conclusions:  The present work is the first study
that sheds light on the cytoprotective effect of  Valeriana wallichii
DC rhizome and provides lead for identification and isolation of
novel drugs for various neurodegenerative diseases

Purpose Aberrant protein glycosylation and disassembly of E-cadherin-mediated cell–cell adhesion are characteristics of epithelial cancer. However, the relationship between these two events in colorectal cancer remains to be defined. In this study, we analyzed whether N-glycan expression is crucial for the loss of E-cadherin-mediated cell–cell adhesion in human colorectal cancer cells. Methods Differentiated Caco-2 and undifferentiated HCT-116 colon cancer cells were used as models of stable and unstable adherens junctions (AJs), respectively. Complex-type N-glycans were detected using the lectins E-PHA (Phaseolus vulgaris E.) and L-PHA (Phaseolus vulgaris L.). To study E-cadherin-mediated AJ assembly, we examined the effects of swainsonine, an inhibitor of α-mannosidase II, and tunicamycin, a drug that inhibits the biosynthesis of N-glycans, via western blot, immunofluorescence, differential extraction in Triton X-100, and electron microscopy. Cell proliferation and apoptosis were examined by crystal violet staining and flow cytometry, respectively. Results We observed positive labeling for E-PHA and L-PHA lectins in both cell lines; however, HCT-116 cells had increased E-cadherin-linked complex-type N-glycans. Interestingly, tunicamycin, but not swainsonine, was able to induce functional E-cadherin-mediated cell–cell adhesion in undifferentiated HCT-116 cells, as shown by the increased association of E-cadherin with the actin cytoskeleton. Moreover, in HCT-116 cells, tunicamycin also induced the formation of tight cell–cell contacts, and it inhibited cell proliferation without triggering apoptosis. Conclusions Collectively, our results demonstrate for the first time that altered N-glycan expression plays an important role in the loss of AJ stability in undifferentiated colorectal cancer cells and that this loss may be associated with the progression of colorectal cancer.

Search by Subject Search using Medical Subject Headings (< b> MeSH</b>), a controlled vocabulary for indexing life sciences content.< br/> Note that some records do not have MeSH. These include Patents and the latest PubMed and PubMed Central records.

Human bitter taste receptors of the TAS2R gene family play a crucial role as warning sensors against the ingestion of toxic food compounds. Moreover, the genetically highly polymorphic hTAS2Rs recognize an enormous number of structurally diverse toxic and non-toxic bitter substances, and hence, may substantially influence our individual eating habits. Heterologous expression in mammalian cells is a useful tool to investigate interactions between these receptors and their agonists. However, many bitter taste receptors are poorly expressed at the cell surface of heterologous cells requiring the addition of plasma membrane export promoting epitopes to the native receptor proteins. Currently, nothing is known about amino acid motifs or other receptor-intrinsic features of TAS2Rs affecting plasma membrane association. In the present study, we analyzed the Asn-linked glycosylation of hTAS2Rs at a consensus sequence in the second extracellular loop, which is conserved among all 25 hTAS2Rs....

Parkin is a ubiquitin ligase that facilitates proteasomal protein degradation and is involved in a common autosomal recessive form of Parkinson's disease. Its expression is part of the unfolded protein response in cell lines where its overexpression protects against unfolded protein stress. How parkin expression is regulated in brain primary cells under stress situations is however, less well established. Here, the cellular and subcellular localization of parkin under basal conditions and during unfolded protein stress was investigated in primary cultures of rat astrocytes and hippocampal neurons. Immunofluorescense microscopy and biochemical analysis demonstrated that parkin is mainly associated with the endoplasmic reticulum (ER) in hippocampal neurons while it is associated with Golgi membranes, the nuclei and light vesicles in astrocytes. The constitutive parkin expression was high in neurons as compared with astrocytes. However, unfolded protein stress elicited a selective increase in astrocytic parkin expression and a change in distribution, whereas neuronal parkin remained largely unmodified. The cell specific differences argue in favour of different cellular binding sites and substrates for the protein and a pathogenic role for astrocytes in Parkinson's disease caused by parkin dysfunction.

Programmed cell death occurs in plants during several developmental processes and during the expression of resistance to pathogen attack (i.e., the hypersensitive response). An unsolved question of plant programmed cell death is whether a unique signaling pathway or different, possibly convergent pathways exist. This problem was addressed in cultured sycamore (Acer pseudoplatanus L.) cells by comparing the effects of fusicoccin, Tunicamycin and Brefeldin A, inducers of programmed cell death with well-defined molecular and cellular targets, on some of the parameters involved in the regulation of this process. In addition to cell death, the inducers are able to stimulate the production of H2O2, the leakage of cytochrome c from mitochondria, the accumulation of cytosolic 14-3-3 proteins, and changes at the endoplasmic reticulum level, such as accumulation of the molecular chaperone binding protein and modifications in the organelle architecture. Interestingly, no additive effect on any...