Thyroid hormone inhibits TGFβ1 induced renal tubular epithelial to mesenchymal transition by increasing miR34a expression.

The interactions between kidney and thyroid functions have been known for many years, but how the thyroid affects the kidney function is largely unknown. Here we analyzed the role of T3 on the tubular epithelial-to-mesenchymal transition (EMT), which is recognized to play pivotal roles in the process of renal fibrosis. T3 was found to significantly inhibit the TGFβ1 induced EMT in human proximal tubular epithelial cell line HK-2. Meanwhile, T3 induced the expression of miR34a. Molecularly, the T3 receptor could directly bind the T3R recognition motif at the -1505 to -1526bp and -604 to -609bp regions in the miR34a promoter and transcriptionally activate the expression of miR34a upon T3 treatment. Inhibition of the miR34a by miR34a knockdown nearly blocked the effects of T3 on EMT. Taken together, our study here revealed that thyroid hormone T3 could inhibit TGFβ1 induced renal tubular epithelial to mesenchymal transition by increasing miR34a expression.