A New Approach to Studying Ochratoxin A (OTA)-Induced Nephrotoxicity: Expression Profiling in Vivo and in Vitro Employing cDNA Microarrays

Abstract

Ochratoxin A (OTA) is a mycotoxin often found in cereals as a contaminant, and it is known to cause severe nephrotoxicity in animals and humans. There have been several investigations studying the mode of action of this toxicant, suggesting inhibition of protein synthesis, formation of DNA adducts, and provocation of DNA single-strand breaks as a result of oxidative stress, but little is known about the transcriptional alterations underlying OTA-derived nephrotoxicity so far. We carried out DNA microarray analyses to assess OTA-specific expression profiles in vivo and in vitro. Cultures of primary rat proximal tubular cells and male Wistar rats were treated with a low dose (5 microM and 1 mg/kg, respectively) or a high dose (12.5 microM and 10 mg/kg, respectively) of OTA for 24 or 72 h. Microarray experiments were carried out after dual fluorescent labeling of sample cDNA, and data analysis was performed utilizing different statistical methods. Validity of selected microarray data was confirmed by quantitative real-time PCR. We were able to demonstrate that microarray data derived from our proximal tubule cell (PTC) culture model were highly comparable to the in vivo situation. Marked treatment-specific transcriptional changes were detected for genes involved in DNA damage response and apoptosis (upregulation of GADD 153, GADD 45, annexin V), response to oxidative stress (differential expression of hypoxia-inducible factor 1 and catalase), and inflammatory reactions (upregulation of alpha 2 macroglobulin, ceruloplasmin, and cathepsin S). We conclude that our results provide a molecular basis for interpretation of OTA-induced nephrotoxicity.

Hypoxia‐like transcriptional activation in TMT‐induced degeneration: microarray expression analysis on PC12 cells

“…Similar stress-response molecular mechanisms have been reported to occur during tumor progression and in other models of cell toxicity in vitro (Salnikow et al 2002;Bando et al 2003;Luhe et al 2003;Fei et al 2004;Erler et al 2006;Hatzivassiliou et al 2005;Kanzawa et al 2005;Burton et al 2006). These findings suggest the possible involvement of hypoxia-related transcriptional activation in general cell survival strategies.…”

“…In our experimental model, a large number of up-regulated genes belonging to different functional pathways have previously been reported to be induced by the action of various noxious agents, which are able to produce stress insults resembling those occurring in hypoxic conditions (Goda et al 2003;Luhe et al 2003;Kanzawa et al 2005). In effect, a common denominator can be identified among the modulated genes (Table 1): many of them (23 out of 57) either are target genes of the hypoxia-inducible factor-1 (Hif-1), a heterodimeric (a/b) transcription factor playing a pivotal role in hypoxia, or share expression modulation under hypoxic conditions (Semenza et al 1994;Greijer et al 2005;LopezLazaro 2006;Papandreou et al 2006).…”

Carcinogen-Specific Gene Expression Profiles in Short-term Treated Eker and Wild-type Rats Indicative of Pathways Involved in Renal Tumorigenesis

“…OTA-induced oxidative stress and ensuing DNA damage in combination with enhanced cell proliferation could increase the likelihood of neoplastic transformation (29). The presence of oxidative DNA damage, as also suggested by earlier findings (30)(31)(32), is supported by the up-regulation of the p53 pathway genes SUPT16H in both strains, MDM2 and CHEK2 in Eker rats, and RBBP6 in wild-type rats as well as by the time-dependent down-regulation of HSP 40-3, CN1, MSRA, and MGST1, responsible for the protection of cells against oxidative stress. Indeed, recent findings showed that overexpression of glia maturation growth factor h (GMFB) resulted in reduced antioxidant enzyme activities, subsequent accumulation of H 2 O 2 , and finally enhanced oxidative injury of renal proximal tubular cells (33).…”

Ochratoxin A Toxic Effect on Rat Kidneys and the Potential Protective Effect of Ginseng: Histopathologic, Histochemical, and Image Analysis Morphometric Studies

“…In addition, Obrecht-Pflumio and Dirheimer [39] reported that ochratoxin is metabolized to genotoxic metabolites which interact with DNA may cause genetic damage in both target tissue independent of direct covalent binding to DNA. According to Luhe et al [40], the decrease cell proliferation could be due to OA toxicity, which alters trancripitional level of several genes known to be involved in DNA damage.…”