Fig. 6

Fgfr AS is regulated by Esrp genes in vertebrates and amphioxus. a RT-PCR assays showing differential Fgfr exon IIIb and IIIc inclusion in WT versus DMUT 5 d.p.f. zebrafish embryos. b RT-PCR assays for Fgfr AS in different amphioxus adult tissues, depicted in a transversal section. nc, nerve cord, ms, muscle, gl, gills, hd, hepatic diverticulum, nt, notochord, sk, skin. Reverse primers were designed in both exons IIIb and IIIc (arrows) and used together in the same PCR reaction. c Top: schematic representation of pcDNA3.1-based minigene constructs containing the genomic region spanning the Fgfr AS event of Branchiostoma lanceolatum, with (pcDNA3.1-BlaFGFR) and without (pcDNA3.1-BlaFGFRΔIIIx) exon IIIx. Bottom: relative intensity of fluorescent RT-PCR bands supporting differential inclusion of exons IIIb and IIIc when transfecting the minigenes alone (Control) or together with a plasmid containing either amphioxus or zebrafish full-length Esrp transcripts (BlaEsrp and DreEsrp1, respectively). Despite significant mis-splicing of the minigene in all conditions, only the amphioxus construct was able to induce a dramatic switch toward exon IIIb inclusion. Primers were designed in the neighboring constitutive exons (arrows). d RT-PCR assays for endogenous human AS events in the same control, BlaEsrp or DreEsrp1 transfected 293T cells showing that the amphioxus and zebrafish Esrp constructs are able to modulate endogenous Esrp-dependent events in a similar manner. Error bars correspond to standard errors of three biological replicates. Esrp-enhanced isoforms are marked with an isoform cartoon