Lectin histochemistry for detecting cadmium-induced changes in the glycosylation pattern of rat placenta

Cadmium (Cd) is an industrial and environmental pollutant that produces toxic effects on gametogenesis, pre- and post-implantation embryos, and the placenta. Because the effects of acute Cd intoxication on the placenta are not well understood, we investigated changes in its glycosylated components in Cd treated dams at days 4, 7, 10 and 15 of gestation using lectin histochemistry. CdCl₂ was administered to pregnant rats; control animals received sterile normal saline. Placentas were processed for DBA, Con A, SBA, PNA, UEA-I, RCA-I and WGA lectin histochemistry to evaluate changes in the carbohydrate pattern of the placenta that might modify cell interactions and contribute to embryonic alterations. Lectin binding was analyzed in the yolk sac; trophoblast giant cells; trophoblast I, II and III; spongiotrophoblast cells and endovascular trophoblast cells in the chorioallantoic placenta. Our lectin binding patterns showed that Cd caused alteration of SBA and DBA labeling of trophoblast-derived cells, which suggested increased expressions of α and β GalNAc. Cd also caused decreased UEA-1 binding affinity, which indicated fewer α-L-Fuc residues in placentas of Cd treated dams. The nonreactivity in trophoblast I of the control placentas incubated with Con-A contrasted with the labeling in placentas of experimental dams, which indicated increased expression of terminal α-D-Man, and α-D-Glc residues. We found that Cd altered the reactivity of placenta to several lectins, which indicated modification of the glycotype presented by the fetal component of the placenta. We report that Cd exerts a deleterious effect on the glycosylation pattern of the placenta.     

Phenomenon of DNA-abzyme cross-reactivity and its significance for the mechanisms of cytotoxicity and apoptosis

The physiological role of DNA-abzymes and their involvement in pathogenesis of different autoimmune disorders is still unknown. At the same time, a variety of properties and features of DNA-hydrolyzing autoantibodies have been studied. Here, the phenomenon of the cross-reactivity of DNA-abzymes with the nuclear matrix proteins was studied. The possible value of the phenomenon for the cytotoxic activity of DNA-hydrolyzing autoantibodies was debated as well. A new hypothesis is put forward regarding the DNA-abzymes formation based on the phenomenon of the cross-reactivity of polyclonal DNA-abzymes with nuclear matrix proteins free of native DNA. Preliminary results suggest that there are mechanisms of cytotoxicity mediated by DNA-abzymes and independent from the system of complement and cytotoxic T-lymphocytes.     

Functional properties of a new Wnt11 isoform expressed in colon carcinoma cell line HT29

Colon carcinoma is a common type of neoplastic transformation. The mechanisms of its establishment and progression have been studied for several decades. Aberrant activation of canonical Wnt signaling is frequently observed in colon carcinoma cells. Moreover, expression of “noncanonical” Wnt ligands is also detected in this type of cancer. However, the role of noncanonical Wnt signaling in carcinogenesis and colorectal cancer (CRC) progression is still unclear. To study the characteristics of noncanonical Wnt signaling activation in CRC, expression of “noncanonical” ligand hWnt11 was examined in HT29 human colon carcinoma cells. For the first time it was shown that alternative splicing accompanies hWnt11 expression in CRC. A new hWnt11 isoform (hWnt11sp3) was identified. Unlike hWnt11, the isoform is not secreted and lacks the ability to inhibit canonical Wnt signaling. Different functional properties of the ligand hWnt11 and its isoform may reflect a special role of alternative splicing in carcinogenesis and tumor progression, since aberrant activity of canonical Wnt signaling is observed in many tumor cells. The existence of several Wnt isoforms and the difference in their functional properties should be taken into account when investigating the role of Wnt ligands.     

Cell death of L-929 cells induced by cytotoxic complex Tag7-Hsp70 is analogous to the death of the same cells induced by TNF-α

The identification and studying the molecular bases of functioning of new cytotoxic agents finds an important implication in developing drugs for fighting with tumors. While investigating the cytotoxic action of protein complex Tag7-Hsp70 which was opened in our laboratory previously we found that Tag7-Hsp70 demonstrated the same specificity in regard to different tumor target cells as it was for classical cytokine TNF-α. L-929 cells and Jurkat cells appeared to be good targets representing up to 30% of dead cells within a population and HeLa cells-bad targets representing less than 5% of dead cells after 20 h of incubation with either of the cytotoxic agents. While investigating the action of either TNF-α or Tag7-Hsp70 on L-929 cells we detected two peaks of death: after 3 h and after 20 h. For both cytotoxic agents we observed the first, smaller (13–15%), peak to be eliminated after the addition of caspase inhibitor YVAD-CHO and the second, greater (25–30%), peak to become even bigger in presence of caspase inhibitor. Probably, protein complex Tag7-Hsp70 interacts like TNF-α with a receptor on the surface of tumor cells that results in triggering two alternative mechanisms of programmed cell death: apoptosis and necroptosis.     

A Phenomenon of DNA-Abzyme Cross-Reactivity and Its Significance for the Mechanisms of Cytoxicity and Apoptosis

The physiological role of DNA-abzymes and their involvement in pathogenesis of different autoimmune disorders is still unknown. At the same time, a variety of properties and features of DNA-hydrolyzing autoantibodies have been studied. Here, the phenomenon of the cross-reactivity of DNA-abzymes with the nuclear matrix proteins was studied. The possible value of the phenomenon for the cytotoxic activity of DNA-hydrolyzing autoantibodies was debated as well. A new hypothesis is put forward regarding the DNA-abzymes formation based on the phenomenon of the cross-reactivity of polyclonal DNA-abzymes with nuclear matrix proteins free of native DNA. Preliminary results suggest that there are mechanisms of cytotoxicity mediated by DNA-abzymes and independent from the system of complement and cytotoxic T-lymphocytes.