MicroRNA-30 and SOX9 participate in a negative feedback loop to regulate intestinal proliferation

Precise regulation of SOX9 expression is critical for normal proliferation and differentiation in the intestinal epithelium. microRNAs (miRNAs) have emerged as prominent fine‐tuners of gene expression. In silico sequence analyses revealed a putative binding site for SOX9 in the promoter of miR‐30, as well as a conserved target site for miR‐30 in the SOX9 3’ UTR. Therefore, we sought to test the hypothesis that miR‐30 mediates feedback control of SOX9 in intestinal epithelial cells. We first sorted functionally distinct cell populations from the jejunum of Sox9‐EGFP reporter mice based on different levels of Sox9‐EGFP. Real‐time PCR analysis on RNA from these sorted cells demonstrated that miR‐30 and Sox9 expression are positively correlated in the mouse intestine. Knockdown of SOX9 in a human intestinal epithelial cell line (HIECs) significantly decreased miR‐30 expression, suggesting that SOX9 positively regulates miR‐30 in the intestine. Antisense inhibition of miR‐30 in HIECs led to significantly elevated levels of SOX9 and reduced 3H‐thymidine incorporation into DNA. Collectively, these data point to a SOX9‐miR‐30 auto‐regulatory loop that controls proliferation in the intestinal epithelium. Grant Funding Source : Supported by UNC GMB T32 Training Grant GM007092‐39 (B.P., NIGMS/NIH), 5R00DK0913118 (P.S., NIDDK/NIH), R01DK091427 (S.M., NIDDK/NIH), and R01DK040247 (P.K.L., NIDDK/NIH)