The role of autophagy in cadmium-induced acute toxicity in glomerular mesangial cells and tracking polyubiquitination of cytoplasmic p53 as a biomarker

• Published in: Experimental & molecular medicine 2022, 54(0), , pp.1-12
• Main Authors: Jung, Ki-Tae, Oh, Seon-Hee
• Format: Article
• Language: English
• Subjects: 13/2; 13/51; 13/89; 14/34; 631/80/82/39/2346; 692/53/2421; 82/80; Acute toxicity; Apoptosis; Autophagy; Biomarkers; Biomedical and Life Sciences; Biomedicine; Cadmium; Cell death; Chemical modification; Cytoplasm; Cytotoxicity; Gene expression; Immunofluorescence; Immunoprecipitation; Kidney cancer; Kidneys; Localization; Medical Biochemistry; Mesangial cells; Molecular Medicine; p53 Protein; Phagosomes; Pollutants; Proteasomes; Proteins; Renal cell carcinoma; Stem Cells; Tumor cell lines; Tumor suppressor genes; Tumors; 생화학
• ISSN: 2092-6413; 1226-3613; 2092-6413
• DOI: 10.1038/s12276-022-00782-4

Cadmium (Cd) is a highly toxic environmental pollutant that can severely damage the kidneys. Here, we show that Cd-induced apoptosis is promoted by the cytoplasmic polyubiquitination of p53 (polyUb-p53), which is regulated by the polyubiquitination of SQSTM1/p62 (polyUb-p62) and autophagy in mouse kidney mesangial cells (MES13E cells). p53 was detected in monomeric and different high-molecular-weight (HMW) forms after Cd exposure. Monomeric p53 levels decreased in a concentration- and time-dependent manner. HMW-p53 transiently accumulated in the cytoplasm independent of proteasome inhibition. The expression patterns of p53 were similar to those of p62 upon Cd exposure, and the interactions between polyUb-p53 and polyUb-p62 were observed using immunoprecipitation. P62 knockdown reduced polyUb-p53 and upregulated nuclear monomeric p53, whereas p53 knockdown reduced polyUb-p62. Autophagy inhibition induced by ATG5 knockdown reduced Cd-induced polyUb-p62 and polyUb-p53 but upregulated the levels of nuclear p53. Pharmacological inhibition of autophagy by bafilomycin A1 increased polyUb-p62 and polyUb-p53 in the cytoplasm, indicating that p53 protein levels and subcellular localization were regulated by polyUb-p62 and autophagy. Immunoprecipitation and immunofluorescence revealed an interaction between p53 and LC3B, indicating that p53 was taken up by autophagosomes. Cd-resistant RMES13E cells and kidney tissues from mice continuously injected with Cd had reduced polyUb-p53, polyUb-p62, and autophagy levels. Similar results were observed in renal cell carcinoma cell lines. These results indicate that cytoplasmic polyUb-p53 is a potential biomarker for Cd-induced acute toxicity in mesangial cells. In addition, upregulation of nuclear p53 may protect cells against Cd cytotoxicity, but abnormal p53 accumulation may contribute to tumor development. Toxicology: A cellular signature of cadmium poisoning The cellular localization and chemical modification of a protein that acts as a critical safeguard against cellular damage may directly contribute to the toxic effects of cadmium. P53 is an essential tumor suppressor that is also involved in numerous other important biological functions. Ki-Tae Jung and Seon-Hee Oh of Chosun University, Gwangju, South Korea have now demonstrated that this protein also undergoes rapid changes in response to the environmental pollutant cadmium. P53 normally manages gene expression in the nucleus, but the authors found that it is rapidly