scholarly journals Oligolysine-based saccharide clusters: synthesis and specificity

2002 ◽  
Vol 368 (1) ◽  
pp. 111-119 ◽  
Author(s):  
Natacha FRISON ◽  
Philippe MARCEAU ◽  
Annie-Claude ROCHE ◽  
Michel MONSIGNY ◽  
Roger MAYER
Keyword(s):  
Plasma Membrane ◽  
Hepatoma Cell ◽  
Surface Membrane ◽  
Thiol Group ◽  
Cysteine Residue ◽  
Cell Uptake ◽  
Amide Bond ◽  
Hepatoma Cell Line ◽  
Human Hepatoma Cell ◽  
Plant Lectins

In search of specific and highly selective sugar clusters for cell receptors, such as membrane lectins, various disaccharides were coupled to small peptide cores through an amide bond. In a first step, the reducing disaccharides, i.e. lactose and three different dimannoses, were converted into glycosyl-pyroglutamyl-β-alanine derivatives. The free carboxylic group of these conjugates was then coupled to the α and ∊ amino groups of the core peptide (Lysn-Ala-Cys-NH2) with n = 1 to 5, with complete substitution leading to homogeneous glycoclusters. The thiol group of the cysteine residue was used to tag the glycosylated oligolysines upon reaction with fluorescein iodoacetamide. The affinity of these glycoclusters towards two plant lectins was assessed by surface plasmon resonance. The selectivity of their cell uptake was investigated by flow cytometry using two types of cells: a human hepatoma cell line (HepG2 cells) expressing the plasma membrane galactose-specific lectin, and monocyte-derived dendritic cells expressing the plasma membrane mannose-specific lectin. The glycoclusters containing four or five disaccharides were shown to bind plant lectins and cell surface membrane lectins with a narrow selectivity and with a high affinity.

scholarly journals Differences in the endosomal distributions of the two mannose 6-phosphate receptors.

1993 ◽  
Vol 121 (5) ◽  
pp. 997-1010 ◽  
Author(s):  
J Klumperman ◽  
A Hille ◽  
T Veenendaal ◽  
V Oorschot ◽  
W Stoorvogel ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Hepatoma Cell ◽  
Cell Types ◽  
Hepatoma Cell Line ◽  
Human Hepatoma Cell ◽  
Intracellular Targeting ◽  
Cytoplasmic Vesicles ◽  
Mannose 6 Phosphate ◽  
Double Immunolabeling ◽  
Lateral Segregation

Multiple immunolabeling of cryosections was performed to compare the subcellular distributions of the two mannose 6-phosphate receptors (MPRs) involved in the intracellular targeting of lysosomal enzymes: the cation-dependent (CD) and cation-independent (CI) MPR. In two cell types, the human hepatoma cell line HepG2 and BHK cells double transfected with cDNA's encoding for the human CD-MPR and CI-MPR, we found the two receptors at the same sites: the trans-Golgi reticulum (TGR), endosomes, electron-dense cytoplasmic vesicles, and the plasma membrane. In the TGR the two receptors colocalized and were concentrated to the same extent in the same HA I-adaptor positive coated buds and vesicles. Endosomes were identified by the presence of exogenous tracers. The two MPR codistributed to the same endosomes, but semiquantitative analysis showed a relative enrichment of the CI-MPR in endosomes containing many internal vesicles. Two endosomal subcompartments were discerned, the central vacuole and the associated tubules and vesicles (ATV). We found an enrichment of CD-MPR over CI-MPR in the ATV. Lateral segregation of the two receptors within the plane of membranes was also detected on isolated organelles. Double immunolabeling for the CD-MPR and the asialoglycoprotein receptor, which mainly recycles between endosomes and the plasma membrane, revealed that these two receptors were concentrated in different subpopulations of endosomal ATV. The small GTP-binding protein rab4, which has been shown to mediate recycling from endosomes to the plasma membrane, was localized at the cytosolic face of many endosomal ATV. Quantitative analysis of double-immunolabeled cells revealed only a limited codistribution of the MPRs and rab4 in ATV. These data suggest that the two MPRs exit the TGR via the same coated vesicles, but that upon arrival in the endosomes CD-MPR is more rapidly than CI-MPR, segregated into ATV which probably are destined to recycle MPRs to TGR.

scholarly journals Stimulation of de novo glutathione synthesis by nitrofurantoin for enhanced resilience of hepatocytes

2021 ◽  
Author(s):  
Lukas S. Wijaya ◽  
Carina Rau ◽  
Theresa S. Braun ◽  
Serif Marangoz ◽  
Vincent Spegg ◽  
...  
Keyword(s):  
De Novo ◽  
Hepatoma Cell ◽  
Proteasome Inhibitors ◽  
Essential Element ◽  
Hepatoma Cell Line ◽  
Related Factor ◽  
Human Hepatoma Cell ◽  
Intact Cells ◽  
Intracellular Glutathione ◽  
Endogenous Antioxidant

AbstractToxicity is not only a function of damage mechanisms, but is also determined by cellular resilience factors. Glutathione has been reported as essential element to counteract negative influences. The present work hence pursued the question how intracellular glutathione can be elevated transiently to render cells more resistant toward harmful conditions. The antibiotic nitrofurantoin (NFT) was identified to stimulate de novo synthesis of glutathione in the human hepatoma cell line, HepG2, and in primary human hepatocytes. In intact cells, activation of NFT yielded a radical anion, which subsequently initiated nuclear-factor-erythroid 2-related-factor-2 (Nrf2)-dependent induction of glutamate cysteine ligase (GCL). Application of siRNA-based intervention approaches confirmed the involvement of the Nrf2-GCL axis in the observed elevation of intracellular glutathione levels. Quantitative activation of Nrf2 by NFT, and the subsequent rise in glutathione, were similar as observed with the potent experimental Nrf2 activator diethyl maleate. The elevation of glutathione levels, observed even 48 h after withdrawal of NFT, rendered cells resistant to different stressors such as the mitochondrial inhibitor rotenone, the redox cycler paraquat, the proteasome inhibitors MG-132 or bortezomib, or high concentrations of NFT. Repurpose of the antibiotic NFT as activator of Nrf2 could thus be a promising strategy for a transient and targeted activation of the endogenous antioxidant machinery.

scholarly journals Pyrrolizidine Alkaloids Induce Cell Death in Human HepaRG Cells in a Structure-Dependent Manner

2020 ◽  
Vol 22 (1) ◽  
pp. 202
Author(s):  
Josephin Glück ◽  
Julia Waizenegger ◽  
Albert Braeuning ◽  
Stefanie Hessel-Pras
Keyword(s):  
Cell Death ◽  
Cell Viability ◽  
Pyrrolizidine Alkaloids ◽  
Defense Mechanism ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Dependent Manner ◽  
Human Hepatoma Cell

Pyrrolizidine alkaloids (PAs) are a group of secondary metabolites produced in various plant species as a defense mechanism against herbivores. PAs consist of a necine base, which is esterified with one or two necine acids. Humans are exposed to PAs by consumption of contaminated food. PA intoxication in humans causes acute and chronic hepatotoxicity. It is considered that enzymatic PA toxification in hepatocytes is structure-dependent. In this study, we aimed to elucidate the induction of PA-induced cell death associated with apoptosis activation. Therefore, 22 structurally different PAs were analyzed concerning the disturbance of cell viability in the metabolically competent human hepatoma cell line HepaRG. The chosen PAs represent the main necine base structures and the different esterification types. Open-chained and cyclic heliotridine- and retronecine-type diesters induced strong cytotoxic effects, while treatment of HepaRG with monoesters did not affect cell viability. For more detailed investigation of apoptosis induction, comprising caspase activation and gene expression analysis, 14 PA representatives were selected. The proapoptotic effects were in line with the potency observed in cell viability studies. In vitro data point towards a strong structure–activity relationship whose effectiveness needs to be investigated in vivo and can then be the basis for a structure-associated risk assessment.

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