Figure 1.
Alternative splicing of microexon (exon #64) in reelin gene.
(A) Schematic representation of the last exons of RELN. Boxes are for exons and lines are for introns (not to scale). The 6-nucleotides microexon (red box) and the alternative polyadenylation site (63A) are shown. The arrows indicate the positions of PCR primers that were used to measure the alternative splicing of the microexon. The right primer is conjugates to FAM fluorescent dye (represented as a star) to enable detection with a DNA analyzer. (B) Representative results obtained using this assay with RNA from liver cells (HEP G2) and from the dorsolateral prefrontal cortex (DLPFC). In liver cells the microexon is completely skipped, while in brain samples it is mostly retained. (C) The effect of the interaction between rs7341475 genotype and sex on microexon retention. The proportion of microexon retention was first fitted to the level of brain pH. The residuals from the fitted model are plotted on the Y axis and the genotypes of rs7341475 (GG vs AG or AA) on the X axis. An opposite trend is seen in men (n = 61) and women (n = 33): an increase of microexon skipping in women with the GG genotype and in men with the A bearing genotype.
Figure 2.
The proportion of transcripts with alternative polyadenylation.
(A) Schematic representation of the last exons of RELN (as in Figure 1). The alternative polyadenylation site is located in an alternative terminal exon (63A), which could be amplified by PCR with primers as indicated by arrows. (B) The proportion of the short RELN isoform, missing the C-terminal region of reelin, in brain samples from bipolar disorder (n = 32), normal control (n = 35) and schizophrenia (n = 35). The bars heights correspond to the mean proportion of transcripts with the alternative polyadenylation event; and error bars are the standard error of the mean. A significant reduction of the proportion of the short RELN isoform is observed in bipolar disorder samples (P = 0.010).
Figure 3.
Allelic expression of RELN in brain samples from bipolar disorder (n = 10), normal control (n = 15) and schizophrenia (n = 8).
Allelic expression was measured six times in each cDNA sample using a coding SNP (rs2229864). The mean allelic ratio (major allele frequency divided by minor frequency) for each informative sample (heterozygote) is presented as a blue diamond. The red horizontal line is the mean for each diagnostic group. Allelic expression imbalance is more pronounced in brain samples from individuals with schizophrenia (P = 0.015).