Glucose-regulated circular RNA Rabep1 regulates pancreatic beta-cell growth by modulating miR-335-3p/PTEN axis

HighlightsO_LIIdentified circRNAs expressed in {beta}TC6 cell line C_LIO_LIFirst report identifying glucose-regulated circRNAs in pancreatic {beta}-cell C_LIO_LICircRabep1 regulates {beta}-cell growth by binding to miR-335-3p C_LI Circular RNAs (circRNAs) are a large family of closed-loop RNA molecules emerging as novel regulators of gene expression. Although several circRNAs are known to regulate various biological processes, the functions of most circRNAs expressed in pancreatic {beta}-cells remain to be discovered. Since short-term glucose treatment induces pancreatic {beta}-cell growth and promotes insulin production, we wanted to explore the role of glucose-regulated circRNAs in pancreatic {beta}-cell physiology. Our RNA-seq analysis identified more than 300 differentially expressed circRNAs in high-glucose compared to low-glucose treated {beta}TC6 cells. A subset of differentially expressed and abundant circRNAs was validated by various biochemical methods, including circular RNA Rabep1 (circRabep1). Moreover, the downregulation of circRabep1 in high glucose-treated {beta}TC6 cells suggested a possible function in {beta}-cell physiology. Furthermore, analysis of the circRabep1-miRNA-mRNA regulatory network discovered the association of circRabep1 with miR-335-3p, a suppressor of Pten expression. Importantly, inhibition of miRNA function by miR-335-3p inhibitor results in upregulation of PTEN levels, suppressing {beta}-cell growth and proliferation. Furthermore, silencing circRabep1 decreased PTEN expression by sponging miR-335-3p, promoting cell proliferation. We propose that the downregulation of circRabep1 in high-glucose treated {beta}-cell leads to an increase in {beta}-cell proliferation by suppressing PTEN expression through derepression of miR-335-3p. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=62 SRC="FIGDIR/small/600308v1_ufig1.gif" ALT="Figure 1"> View larger version (10K): org.highwire.dtl.DTLVardef@542b03org.highwire.dtl.DTLVardef@1d3f3faorg.highwire.dtl.DTLVardef@36b476org.highwire.dtl.DTLVardef@181c7b4_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO Schematic showing the molecular function of glucose-regulated circRabep1 in pancreatic -cell growth by binding to miR-335-3p. C_FIG