Figure 3.

Schematic representation of regulators of IR isoform expression. The figure summarizes the principal IR regulators acting at the promoter (transcription factors) and mRNA level (splicing factors and miRNAs). Transcription factors act by promoting (in red) or blocking (in blue) IR gene transcription. Several splicing factors and miRNAs are involved in the posttranscriptional regulation of IR expression. Once the IR mRNA is formed, splicing factors remove introns and let exons bind together. They regulate the differential splicing of exon 11, thereby generating IR-A (ex11⁻) or IR-B (ex11⁺). Several miRNAs can bind to the 3′-UTR of the IR mRNA, favoring its degradation.