miR-200b-3p

The expression of miR-200b-3p is correlated with obesity, but its biological function in the pathogenesis of obesity remains poorly understood. Here, we investigated the function of miR-200b-3p in white adipose browning. The C3H10T1/2 and 3T3-L1 cell lines were infected with lentiviruses carrying miR-200b-3p mimic or antisense; then, the mRNA and protein expression of adipogenic differentiation genes and brown adipose tissue-specific genes was detected. These lentiviruses were also directly injected into the inguinal white adipose tissue (iWAT) of C57BL/6 mice fed a normal chow diet or high-fat diet (HFD). Body weight, adipose tissue weight, glycolipid metabolism, and related gene expression were measured. Overexpression of miR-200b-3p impaired, whereas inhibition of miR-200b-3p improved white adipose browning both in vitro and in vivo . Mice with overexpression of miR-200b-3p in iWAT showed elevated levels of serum insulin and total cholesterol and were insulin resistant under HFD. Inhibition of miR-200b-3p in iWAT prevented mice from insulin resistance induced by HFD. Mechanistically, dual-luciferase reporter assay showed that miR-200b-3p directly inhibited Prdm16 expression in the Smad and p38Mapk signaling pathways. In conclusion, our findings suggest that miR-200b-3p regulates adipocyte browning by targeting Prdm16 . This could be a potential therapeutic target for obesity.

To elucidate the mechanism underlying the involvement of miR‐200b‐3p in the bone destruction in cholesteatoma.

Expression levels of miR‐200b‐3p, parathyroid hormone‐related protein (PTHrP), and receptor activator for nuclear factor‐kappa B ligand (RANKL) in cholesteatoma and normal skin of the external auditory canal were examined. HaCaT cells were transfected with miR‐200b‐3p mimic, miR‐200b‐3p mimic NC, miR‐200b‐3p inhibitor, and miR‐200b‐3p inhibitor NC. Meanwhile, RAW264.7 cells were cultured with RANKL and PTHrP + RANKL combined intervention. A bone resorption lacunae experiment was performed to assess the bone absorption function of the osteoclasts.

The expression level of miR‐200b‐3p significantly decreased in cholesteatoma and was obviously correlated with the degree of bone destruction. However, the expression levels of PTHrP and RANKL significantly increased. An upregulation of miR‐200b‐3p expression in the miR‐200b‐3p mimic group of HaCaT cells was observed, accompanied by a significant downregulation of PTHrP expression. The miR‐200b‐3p inhibitor group showed downregulated miR‐200b‐3p expression and significantly upregulated PTHrP expression, suggesting a negative regulatory effect of miR‐200b‐3p on PTHrP expression. Scanning electron microscopic analysis of the bone resorption lacunae revealed a significant increase in the number and size of bone resorption lacunae in the PTHrP + RANKL combined intervention group compared to those in the RANKL intervention group.

MiR‐200b‐3p was underexpressed in cholesteatoma, resulting in the upregulation of PTHrP secreted by keratinocytes, activation of the downstream RANKL pathway, and promotion of differentiation of monocyte macrophages in the cholesteatoma perimatrix into osteoclasts, thus contributing to bone destruction in cholesteatoma.Level of Evidence: N/A.