Mutant p53 Attenuates the Anti-Tumorigenic Activity of Fibroblasts-Secreted Interferon Beta

Mutations in the p53 tumor suppressor protein are highly frequent in tumors and often endow cells with tumorigenic capacities. We sought to examine a possible role for mutant p53 in the cross-talk between cancer cells and their surrounding stroma, which is a crucial factor affecting tumor outcome. Here we present a novel model which enables individual monitoring of the response of cancer cells and stromal cells (fibroblasts) to co-culturing. We found that fibroblasts elicit the interferon beta (IFNβ) pathway when in contact with cancer cells, thereby inhibiting their migration. Mutant p53 in the tumor was able to alleviate this response via SOCS1 mediated inhibition of STAT1 phosphorylation. IFNβ on the other hand, reduced mutant p53 RNA levels by restricting its RNA stabilizer, WIG1. These data underscore mutant p53 oncogenic properties in the context of the tumor microenvironment and suggest that mutant p53 positive cancer patients might benefit from IFNβ treatment.     

Acetic Acid, Ethanol and Steam Effects on the Growth of Botrytis cinerea in vitro and Combination of Steam and Modified Atmosphere Packaging to Control Decay in Kiwifruit

The effects of acetic acid fumigation, ethanol fumigation, and steam heat treatment on growth of Botrytis cinerea in vitro were investigated. The effect of steam heat treatments in combination with modified atmosphere packaging (MAP) on Botrytis decay development on 'Hayward' kiwifruit was also studied. The fungus was grown in Petri dishes on potato dextrose agar. Ethanol fumigation with 100  μ l/l for 3 or 6 min, or 200  μ l/l for 6 min enhanced the growth of B. cinerea . The effect of acetic acid on growth of B. cinerea was time and dosage-dependent. Fumigation with 1  μ l/l for 6 min, 2  μ l/l for 3 min, and 4  μ l/l for 3 min promoted radial growth of the fungus when compared to the growth of the untreated control. Fumigation with 2  μ l/l for 6 min delayed the growth of the fungus for the first 6 days, while fumigation with 6  μ l/l for 3 min delayed the growth of the fungus after the sixth day. Fumigation with 4 or 6  μ l/l acetic acid for 6 min, and 8  μ l/l acetic acid for 3 or 6 min resulted in complete inhibition of fungal growth. Steam heat treatment at 45°C for 6 min, and at 48, 51, and 54°C for 3 or 6 min completely inhibited fungal growth in vitro . Furthermore, steam treatments at 47, 50, and 53°C for 3 or 6 min completely inhibited decay at the stem end of kiwifruit kept at 10°C in MAP for 12 days. However, none of the steam treatments inhibited decay in wounds on the surface of the fruit kept in MAP.     

Evaluation of TLR4 expression and chosen parameters of oxidative-antioxidative balance in young children with food allergy

The authors evaluated mRNA TLR4 expression on neutrophils and the chosen parameters of oxidative-antioxidative balance in blood of 35 children with food allergy (17 of them with IgE-dependent allergy and 18 with IgE-independent allergy) and 15 healthy children without any allergy. The age of these children ranged from 1 to 36 months. Children with food allergy in comparison with healthy children were found to have lower mRNA TLR4 expression, higher average value of chemiluminescence (CL) and its increase after stimulation by fMLP, PMA and OZ as well as lower TAS values. Disturbances of oxidative-antioxidative balance were found in children with food allergy. We suggest that natural immunity is involved in the development of food allergy mechanisms. Moreover, chemiluminescence can be used as an additional diagnostic test.     

Differential hydrolysis of homocysteine thiolactone by purified human serum (192)Q and (192)R PON1 isoenzymes

Human serum paraoxonase 1 (PON1) is a HDL-associated enzyme that catalyzes the hydrolysis of a variety of aromatic carboxylic acid esters and several organophosphates. Recently it has been suggested that a physiological substrate of serum PON1 is homocysteine thiolactone which is a putative risk factor in atherosclerosis. In this study, human (192)Q and (192)R PON1 isoenzymes were purified from the respective phenotype human serum, using a protocol consisting of ammonium sulfate precipitation and four chromatography steps: gel filtration, ion-exchange, non-specific affinity, and a second ion-exchange. Using paraoxon as substrate, overall purification fold was found as 742 for (192)R PON1 and 590 for (192)Q PON1. The final purified enzymes were shown as single protein bands close to 45kDa on SDS-PAGE and confirmed by Western blot. Substrate kinetics were studied with phenyl acetate, paraoxon and homocysteine thiolactone. Both PON1 isoenzymes showed mixed type inhibition with phenyl acetate. K(m) values of (192)Q and (192)R PON1 for homocysteine thiolactone were 23.5mM and 22.6mM respectively. For (192)R PON1, the V(max) was 2.5-fold and k(cat)/K(m) was 2.6-fold higher than those for (192)Q PON1 when homocysteine thiolactone is used as substrate. The present data suggest that defining (192)Q and (192)R PON1 isoforms could be a good predictor and prognostic marker in the cardiovascular risk assessment.     

On the presence and localization of glycogen accumulations inside coronet cells of the saccus vasculosus of the dogfish (Scylliorhinus caniculus)

Summary In several coronet cells of the saccus vasculosus of Scylliorhinus large quantities of glycogen occur, as shown by light and electron microscopy. The significance of glycogen as an energy storage necessary for a transcellular ion transport process taking place in the coronet cells is discussed.The authors thank Dr. F.C.G. van de Veerdonk, W. F. Jansen and W. F. G. Flight for reading the manuscipt and for their critical remarks. They are also indebted to Mr. H. van Kooten and his staff for their valuable photographic assistance.     

High‐affinity cooperative Ca2+ binding by MICU1–MICU2 serves as an on–off switch for the uniporter

The mitochondrial calcium uniporter is a Ca²⁺‐activated Ca²⁺ channel that is essential for dynamic modulation of mitochondrial function in response to cellular Ca²⁺ signals. It is regulated by two paralogous EF‐hand proteins—MICU1 and MICU2, but the mechanism is unknown. Here, we demonstrate that both MICU1 and MICU2 are stabilized by Ca²⁺. We reconstitute the MICU1–MICU2 heterodimer and demonstrate that it binds Ca²⁺ cooperatively with high affinity. We discover that both MICU1 and MICU2 exhibit affinity for the mitochondria‐specific lipid cardiolipin. We determine the minimum Ca²⁺ concentration required for disinhibition of the uniporter in permeabilized cells and report a close match with the Ca²⁺‐binding affinity of MICU1–MICU2. We conclude that cooperative, high‐affinity interaction of the MICU1–MICU2 complex with Ca²⁺ serves as an on–off switch, leading to a tightly controlled channel, capable of responding directly to cytosolic Ca²⁺ signals.     

MICU1 and MICU2 play nonredundant roles in the regulation of the mitochondrial calcium uniporter

The mitochondrial uniporter is a selective Ca²⁺ channel regulated by MICU1, an EF hand‐containing protein in the organelle's intermembrane space. MICU1 physically associates with and is co‐expressed with a paralog, MICU2. To clarify the function of MICU1 and its relationship to MICU2, we used gene knockout (KO) technology. We report that HEK‐293T cells lacking MICU1 or MICU2 lose a normal threshold for Ca²⁺ intake, extending the known gating function of MICU1 to MICU2. Expression of MICU1 or MICU2 mutants lacking functional Ca²⁺‐binding sites leads to a striking loss of Ca²⁺ uptake, suggesting that MICU1/2 disinhibit the channel in response to a threshold rise in [Ca²⁺]. MICU2's activity and physical association with the pore require the presence of MICU1, though the converse is not true. We conclude that MICU1 and MICU2 are nonredundant and together set the [Ca²⁺] threshold for uniporter activity.     

Two new species of Costus (Costaceae) from Costa Rica

As a result of a review of the Costaceae for theManual de las Plantas de Costa Rica, two new species ofCostus (C. ricus andC. osae) are here described and illustrated. The assignment of the new species ofCostus subgen.Costus is discussed.