In all tissues, at both PND1 and PND5 (Figure 5 and 6).Since retention of the intron could lead to degradation of the transcript via the NMD pathway due to a premature termination codon (PTC) in the U12-dependent intron (Supplementary Figure S10), our observations point out that aberrant retention of the U12-dependent intron in the Rasgrp3 gene might be an underlying mechanism contributing to deregulation of the cell cycle in SMA mice. U12-dependent intron retention in genes important for neuronal function Loss of Myo10 has recently been shown to inhibit axon outgrowth (78,79), and our RNA-seq data indicated that the U12-dependent intron 6 in Myo10 is retained, although not to a statistically significant degree. However, qPCR analysis showed that the U12-dependent intron 6 in Myo10 wasNucleic Acids CUDC-907 web Research, 2017, Vol. 45, No. 1Figure 4. U12-intron retention increases with disease progression. (A) Volcano plots of U12-intron retention SMA-like mice at PND1 in spinal cord, brain, liver and muscle. Significantly differentially expressed introns are indicated in red. Non-significant introns with foldchanges > 2 are indicated in blue. Values exceeding chart limits are plotted at the corresponding edge and indicated by either up or downward facing triangle, or left/right facing arrow heads. (B) Volcano plots of U12-intron retention in SMA-like mice at PND5 in spinal cord, brain, liver and muscle. Significantly differentially expressed introns are indicated in red. Non-significant introns with fold-changes >2 are indicated in blue. Values exceeding chart limits are plotted at the corresponding edge and indicated by either up or downward facing triangle, or left/right facing arrow heads. (C) Venn diagram of the overlap of common significant alternative U12-intron retention across tissue at PND1. (D) Venn diagram of the overlap of common significant alternative U12-intron retention across tissue at PND1.in fact retained more in SMA mice than in their control littermates, and we observed significant intron retention at PND5 in spinal cord, liver, and muscle (Figure 6) and a significant decrease of spliced Myo10 in spinal cord at PND5 and in brain at both PND1 and PND5. These data suggest that Myo10 missplicing could play a role in SMA pathology. Similarly, with qPCR we validated the up-regulation of U12-dependent intron retention in the Cdk5, Srsf10, and CUDC-427 site Zdhhc13 genes, which have all been linked to neuronal development and function (80?3). Curiously, hyperactivityof Cdk5 was recently reported to increase phosphorylation of tau in SMA neurons (84). We observed increased 10508619.2011.638589 retention of a U12-dependent intron in Cdk5 in both muscle and liver at PND5, while it was slightly more retained in the spinal cord, but at a very low level (Supporting data S11, Supplementary Figure S11). Analysis using specific qPCR assays confirmed up-regulation of the intron in liver and muscle (Figure 6A and B) and also indicated downregulation of the spliced transcript in liver at PND1 (Figure406 Nucleic Acids Research, 2017, Vol. 45, No.Figure 5. Increased U12-dependent intron retention in SMA mice. (A) qPCR validation of U12-dependent intron retention at PND1 and PND5 in spinal cord. (B) qPCR validation of U12-dependent intron retention at PND1 and journal.pone.0169185 PND5 in brain. (C) qPCR validation of U12-dependent intron retention at PND1 and PND5 in liver. (D) qPCR validation of U12-dependent intron retention at PND1 and PND5 in muscle. Error bars indicate SEM, n 3, ***P-value < 0.In all tissues, at both PND1 and PND5 (Figure 5 and 6).Since retention of the intron could lead to degradation of the transcript via the NMD pathway due to a premature termination codon (PTC) in the U12-dependent intron (Supplementary Figure S10), our observations point out that aberrant retention of the U12-dependent intron in the Rasgrp3 gene might be an underlying mechanism contributing to deregulation of the cell cycle in SMA mice. U12-dependent intron retention in genes important for neuronal function Loss of Myo10 has recently been shown to inhibit axon outgrowth (78,79), and our RNA-seq data indicated that the U12-dependent intron 6 in Myo10 is retained, although not to a statistically significant degree. However, qPCR analysis showed that the U12-dependent intron 6 in Myo10 wasNucleic Acids Research, 2017, Vol. 45, No. 1Figure 4. U12-intron retention increases with disease progression. (A) Volcano plots of U12-intron retention SMA-like mice at PND1 in spinal cord, brain, liver and muscle. Significantly differentially expressed introns are indicated in red. Non-significant introns with foldchanges > 2 are indicated in blue. Values exceeding chart limits are plotted at the corresponding edge and indicated by either up or downward facing triangle, or left/right facing arrow heads. (B) Volcano plots of U12-intron retention in SMA-like mice at PND5 in spinal cord, brain, liver and muscle. Significantly differentially expressed introns are indicated in red. Non-significant introns with fold-changes >2 are indicated in blue. Values exceeding chart limits are plotted at the corresponding edge and indicated by either up or downward facing triangle, or left/right facing arrow heads. (C) Venn diagram of the overlap of common significant alternative U12-intron retention across tissue at PND1. (D) Venn diagram of the overlap of common significant alternative U12-intron retention across tissue at PND1.in fact retained more in SMA mice than in their control littermates, and we observed significant intron retention at PND5 in spinal cord, liver, and muscle (Figure 6) and a significant decrease of spliced Myo10 in spinal cord at PND5 and in brain at both PND1 and PND5. These data suggest that Myo10 missplicing could play a role in SMA pathology. Similarly, with qPCR we validated the up-regulation of U12-dependent intron retention in the Cdk5, Srsf10, and Zdhhc13 genes, which have all been linked to neuronal development and function (80?3). Curiously, hyperactivityof Cdk5 was recently reported to increase phosphorylation of tau in SMA neurons (84). We observed increased 10508619.2011.638589 retention of a U12-dependent intron in Cdk5 in both muscle and liver at PND5, while it was slightly more retained in the spinal cord, but at a very low level (Supporting data S11, Supplementary Figure S11). Analysis using specific qPCR assays confirmed up-regulation of the intron in liver and muscle (Figure 6A and B) and also indicated downregulation of the spliced transcript in liver at PND1 (Figure406 Nucleic Acids Research, 2017, Vol. 45, No.Figure 5. Increased U12-dependent intron retention in SMA mice. (A) qPCR validation of U12-dependent intron retention at PND1 and PND5 in spinal cord. (B) qPCR validation of U12-dependent intron retention at PND1 and journal.pone.0169185 PND5 in brain. (C) qPCR validation of U12-dependent intron retention at PND1 and PND5 in liver. (D) qPCR validation of U12-dependent intron retention at PND1 and PND5 in muscle. Error bars indicate SEM, n 3, ***P-value < 0.
