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Characterization of an ochratoxin-A-dedifferentiated and cloned renal epithelial cell line
M Gekle1, B Gassner, R Freudinger
1Department of Physiology, University of Würzburg, Würzburg, D-97070, Germany.
Abstract:
Ochratoxin A (OTA) is a ubiquitous fungal metabolite with predominant nephrotoxic action. OTA impairs postproximal renal electrolyte handling and increases the incidence of renal adenoma and carcinoma. Furthermore, it is supposed to be involved in the pathogenesis of different forms of human renal diseases. Previously we have shown that OTA activates extracellular signal-regulated kinase 1 (ERK1) and ERK2 in the C7 clone but not in the C11 clone of renal epithelial MDCK cells. Here we show that nanomolar concentrations of OTA lead to stable and irreversible phenotypical and genotypical alterations, resulting in sustained dedifferentiation of MDCK-C7 cells but not of MDCK-C11 cells. Dedifferentiated MDCK-C7 cells (OTA-C7 cells) display a distinct morphology from the parent cell line (spindle-shape, pleiomorphic, narrow intercellular spaces, increased cell size) and show a reduced proliferation rate and numerical chromosomal aberrations. Functionally, OTA-C7 cells are characterized by a dramatic reduction of transepithelial electrolyte transport and the complete loss of responsiveness to the mineralocorticoid hormone aldosterone. Our data provide further evidence that OTA can lead to cell dedifferentiation and eventually to transformation of cloned quiescent cells. The changes in phenotype due to this dedifferentiation could explain some of the OTA-induced changes in renal function.
Insights
Ochratoxin A (OTA) causes irreversible cell dedifferentiation in kidney cells, altering their function and potentially leading to cancer. This study reveals how OTA impacts renal epithelial cells, offering insights into kidney disease pathogenesis.
Area of Science:
- Nephrology
- Toxicology
- Cell Biology
Background:
- Ochratoxin A (OTA) is a fungal toxin known for its nephrotoxic effects.
- OTA is implicated in the pathogenesis of human renal diseases and increases renal tumor incidence.
- Previous research showed OTA activates specific kinases (ERK1/ERK2) in certain kidney cell lines.
Purpose of the Study:
- To investigate the long-term effects of Ochratoxin A on renal epithelial cells.
- To determine if OTA induces stable phenotypical and genotypical alterations in kidney cells.
- To understand the functional consequences of OTA-induced cell dedifferentiation.
Main Methods:
- Exposure of Madin-Darby Canine Kidney (MDCK) cell clones (C7 and C11) to nanomolar concentrations of OTA.
- Analysis of cell morphology, proliferation rates, and chromosomal aberrations.
- Assessment of transepithelial electrolyte transport and aldosterone responsiveness in OTA-treated cells.
Main Results:
- Nanomolar OTA induced stable, irreversible dedifferentiation in MDCK-C7 cells, but not MDCK-C11 cells.
- OTA-treated cells (OTA-C7) exhibited altered morphology, reduced proliferation, and chromosomal abnormalities.
- OTA-C7 cells showed significantly reduced electrolyte transport and lost aldosterone responsiveness.
Conclusions:
- Ochratoxin A can induce sustained cell dedifferentiation and potential transformation in cloned renal cells.
- The observed phenotypical changes in OTA-treated cells may explain OTA-induced alterations in kidney function.
- These findings contribute to understanding the mechanisms underlying OTA nephrotoxicity and renal carcinogenesis.