KL and renal fibrosis: In renal fibrosis, the increased expression of miR-34a is accompanied by the sharp downregulation of Klotho, the increase of a—SMA and fibronectin, and the decrease of E-cadherin, which promote the process of epithelial mesenchymal transformation (EMT); however, the expression of Klotho was significantly increased and EMT was inhibited in miR-34a−/− mice, so miR-34a negatively regulates Klotho to promote EMT and induce renal fibrosis (Liu et al., 2019).