MiR-204/miR-211 downregulation contributes to candidemia-induced kidney injuries via derepression of Hmx1 expression.

AIMS:This study was aimed to exploit the role of heme oxygenase Hmx1 and the potential miRNA mechanisms in the kidney injuries induced by urinary tract infection by Candida species/Candidemia. MAIN METHODS:We employed a mouse model of systemic Candidiasis by injection of the Candida albicans strain SC5314 into C57BL/6 mice. Kidney injuries were assessed by measuring serum cystatin C (CysC), serum β2-microglobulin (β2-MG) and blood urea nitrogen (BUN). Validation of miRNA target gene was conducted by luciferase reporter gene assay, Western blot analysis and real-time RT-PCR. KEY FINDINGS:We showed here that Candidemia caused significant downregulation of microRNAs miR-204 and miR-211. In sharp contrast, Hmx1 expression was remarkably upregulated, particularly at the protein level. Computational analysis predicted Hmx1 as a target gene for both miR-204 and miR-211 that share the same seed site sequence. We then experimentally validated the targeting relationship between miR-204/miR-211 and Hmx1, which explains the reciprocal changes of expression of miR-204/miR-211 and Hmx1 in Candidemia. Administration of miR-204/miR-211 mimics substantially downregulated Hmx1 and mitigated the severity of the kidney injuries induced by Candidemia, as reflected by improved renal glomerular filtration rate (GFR) determined by serum cystatin C (CysC), serum β2-microglobulin (β2-MG) and blood urea nitrogen (BUN). Knockdown of miR-204/miR-211 worsened while forced expression of miR-204/miR-211 ameliorated kidney injuries in mice with systemic Candidiasis. SIGNIFICANCE:Our findings indicate that miR-204/miR-211 downregulation accounts at least partially for the Hmx1 upregulation and the miR-204/miR-211-Hmx1 signaling axis may contribute to immune-suppression in the host thereby the Candidemia-induced kidney dysfunction.

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