MAGE genes in the kidney: identification of MAGED2 as upregulated during kidney injury and in stressed tubular cells

Abstract

Background. Mutations in Melanoma Antigen-encoding Gene D2 (MAGED2) promote tubular dysfunction, suggesting that MAGE proteins may play a role in kidney pathophysiology. We have characterized the expression and regulation of MAGE genes in normal kidneys and during kidney disease. Methods. The expression of MAGE genes and their encoded proteins was explored by systems biology multi-omics (kidney transcriptomics and proteomics) in healthy adult murine kid neys and following induction of experimental acute kidney injury (AKI) by a folic acid overdose. Changes in kidney expres sion during nephrotoxic AKI were validated by quantitative re verse transcription-polymerase chain reaction (qRT-PCR), western blot and immunohistochemistry. Factors regulating gene expression were studied in cultured tubular cells. Results. Five MAGE genes (MAGED1, MAGED2, MAGED3, MAGEH1, MAGEE1) were expressed at the mRNA level in healthy adult mouse kidneys, as assessed by RNA-Seq. Additionally, MAGED2 was significantly upregulated during experimental AKI as assessed by array transcriptomics. Kidney proteomics also identified MAGED2 as upregulated during AKI. The increased kidney expression of MAGED2 mRNA and protein was confirmed by qRT-PCR and western blot, respec tively, in murine folic acid- and cisplatin-induced AKI. Immunohistochemistry located MAGED2 to tubular cells in ex perimental and human kidney injury. Tubular cell stressorsserum deprivation and the inflammatory cytokine tumour ne crosis factor-like weak inducer of apoptosis (TWEAK)] upregu lated MAGED2 in cultured tubular cells. Conclusions. MAGED2 is upregulated in tubular cells in exper imental and human kidney injury and is increased by stressors in cultured tubular cells. This points to a role of MAGED2 in tubular cell injury during kidney disease that should be dis sected by carefully designed functional approaches.