[Mechanisms of nephrotoxicity of novel anticancer compound maleimide derivative MI-1].

The features of the impact of the maleimide derivative 1-(4-Cl-benzyl)-3-chloro-4-(CF3-fenilamino)-1H-pyrrole-2,5-dione (MI-1) on the viability and apoptosis-induced cell death of renal proximal and distal tubular epithelial cells and the amount of total and phosphorylated ERK1/2 were studied in order to establish possible mechanisms of nephrotoxicity induced by of MI-1. The viability and apoptosis of renal epithelial tubular cells after incubation with MI-1 were perfomed by 3,4,5-dymetyltiazol-2-yl-2,5-diphenyl-tetrazolium bromide (MTT)-test and by flow cytometry after staining with specific antibodies to annexin V, respectively. The amount of ERK 1/2 was determined by Western blotting. The data indicate that MI-1 was more toxic with respect to the epithelial cells of distal than proximal tubule cells. The apoptosis-induced cell death pathway is involved in the mechanisms of MI-1 cytotoxicity. One of the possible mechanisms of MI-1 nephrotoxicity is increase in phosphorylation of ERK1/2 in the distal tubules. At the same time the increase amount of total ERK1/2 in proximal tubules under the influence of MI-1 may contribute to the survival of proximal tubular epithelial cells under the impact of a toxic factor or oxidative stress.

Concomitant endothelin-1 overexpression in lung transplant donors and recipients predicts primary graft dysfunction.

Primary graft dysfunction (PGD) causes significant morbidity following lung transplantation (LTX). Mortality is high in PGD and therapeutic strategies are limited. To investigate whether endothelin-1 (ET-1) that mediates increased vascular permeability and edema formation in lung grafts can predict PGD, ET-1 mRNA expression was examined in lung tissue biopsies of 105 donors and recipients obtained shortly before LTX. Serum ET-1 concentration was assessed by ELISA. PGD grade was diagnosed and scored by oxygenation and radiological characteristics according to ISHLT guidelines. PGD grade 3 developed in 11% of patients. ET-1 mRNA expression was significantly increased in both donor (p < 0.0001) and recipient (p = 0.01) developing PGD as compared to no PGD group. Pretransplant ET-1 serum concentrations were elevated in recipients with PGD as compared to no PGD group (p < 0.0001), although serum ET-1 was not different between donors whose grafts developed PGD grades 0-3. In regression analysis, concomitant elevated donor tissue ET-1 and recipient serum ET-1 predicted PGD grade 3. This study indicates that pretransplant ET-1 mRNA overexpression in donors associated with elevated pretransplant serum ET-1 in recipients contribute to PGD development and that their assessment might be beneficial to predict PGD and to identify recipients who could benefit from a targeted ET-1 blockade.

[Effect of nitric oxide on 5'-nucleotidase activity of the membrane rafts in the smooth muscle cells].

We investigated the effect of nitric oxide on the catalytic activity of 5'-nucleotidase associated with insoluble membrane domains (rafts) of pig stomach smooth muscle. The low concentration (0.1-10.0 microM) of nitric oxide donor sodium nitroprusside led to essential increase of catalytic activity of 5'-nucleotidase. Maximal increase was observed at concentration of sodium nitroprusside of 1 microM. The enzyme's catalytic activity decreased to about control value at higher concentration of this substance. The catalytic activity of 5'-nucleotidase was also increased at presence of NaNO2, but only at high concentration (10 mM). The specific thiol-alkylating agent N-ethylmaleinimide (1-100 microM) led to essential decrease of enzyme catalytic activity. Our data shows that nitric oxide changes the AMP-ase activity of 5'-nucleotidase, that is thought to be due to direct effect of this substance on protein. We suppose, that such effect of nitric oxide could be physiologicaly important in functioning of smooth muscle.

[Catalytic characteristics of 5'-nucleotidase in the structure of cell membrane rafts in smooth muscles]. / Katalitychni vlastyvosti 5'-nukleotydazy u skladi membrannykh raftiv klityn hladen'kykh m'iaziv.

5'-nucleotidase (EN 3.1.3.5) is widely distributed enzyme occurring in vertebrate, bacterial and plant cells. The main physiological function of 5'-nucleotidase is hydrolysis of 5'-AMP to adenosine and Pi. It was found that the detergent-insoluble membrane domains (rafts) are enriched by proteins possessing high 5'-AMPase activity. This study is aimed to investigate some physical and chemical properties of 5'-nucleotidase, which is present in detergent insoluble membrane domains isolated from pig stomach and lung. It was shown for the first time that catalytic properties of the raft-associated 5'-nucleotidase and of the pure enzyme described in literature differ. Our results demonstrate that the greatest activity of the raft-associated enzyme takes place in the physiological conditions contrary to the pure enzyme. Our data suggest that such changes of 5'-nucleotidase catalytic activity might be due to the disruption of its interaction with membrane rafts.