• Toxicological Research
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• v.32 no.1
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• pp.73-80
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• 2016

Chronic exposure to cadmium (Cd) is known to adversely affect renal function. Our previous studies indicated that Cd induces p53-dependent apoptosis by inhibiting gene expression of the ubiquitin-conjugating enzyme (Ube) 2d family in both human and rat proximal tubular cells. In this study, the effects of Cd on protein expression of p53 and apoptotic signals in the kidney and liver of mice exposed to Cd for 12 months were examined, as well as the effects of Cd on p53 protein levels and gene expression of the Ube2d family in various cell lines. Results showed that in the kidney of mice exposed to 300 ppm Cd for 12 months, there was overaccumulation of p53 proteins in addition to the induction of apoptosis, which was triggered specifically in the proximal tubules. Interestingly, the site of apoptosis was the same as that of p53 accumulation in the proximal tubules. In the liver of mice chronically exposed to Cd, gene expression of the Ube2d family tended to be slightly decreased, together with slight apoptosis without the accumulation of p53 protein. In rat small intestine epithelial (IEC-6) cells, Cd decreased not only the p53 protein level but also gene expression of Ube2d1, Ube2d2 and Ube2d4. In human brain microvascular endothelial cells (HBMECs), Cd did not suppress gene expression of the Ube2d family, but increased the p53 protein level. In human brain astrocytes (HBASTs), Cd only increased gene expression of UBE2D3. These results suggest that Cd-induced apoptosis through p53 protein is associated with renal toxicity but not hepatic toxicity, and the modification of p53 protein by Cd may vary depending on cell type.

• Development and Reproduction
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• v.12 no.3
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• pp.289-296
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• 2008

BPES (Blepharophimosis/Ptosis/Epicanthus inversus Syndrome) is an autosomal dominant disorder caused by mutations in FOXL2. Affected individuals have premature ovarian failure (POF) in addition to small palpebral fissures, drooping eyelids, and broad nasal bridge. FOXL2 is a member of the forkhead family transcription factors. In FOXL2-deficient ovaries, granulosa cell differentiation dose not progress, leading to arrest of folliculogenesis and oocytes atresia. Using yeast two-hybrid screening of rat ovarian cDNA library with FOXL2 as bait, we found that small ubiquitin-related modifier (SUMO)-conjugating E2 enzyme UBE2I protein interacted with FOXL2 protein. UBE2I also known as UBC9 is an essential protein for processing SUMO modification. Sumoylation is a form of post-translational modification involved in diverse signaling pathways including the regulation of transcriptional activities of many transcriptional factors. In the present study, we confirmed the protein-protein interaction between FOXL2 and UBE2I in human cells, 293T, by in vivo immunoprecipitation. In addition, we generated truncated FOXL2 mutants and identified the region of FOXL2 required for its association with UBE2I using yeast-two hybrid system. Therefore, the identification of UBE2I as an interacting protein of FOXL2 further suggests a presence of novel regulatory mechanism of FOXL2 by sumoylation.