Figure 8. Pharmacological inhibition of Dyrk1a partially rescues CHD in the Dp1Tyb mouse model of DS.

(A) C57BL/6J females that had been mated with Dp1Tyb males, were treated daily (vertical arrows) by oral gavage with Leucettinib-21 (LCTB-21) or iso-Leucettinib-21 (iso-LCTB-21) from 5 days after vaginal plug (VP) was found (embryonic day 0.5, E0.5). Embryos were collected at E13.5 for RNAseq, or at E14.5 for HREM. (B) Scatter plots comparing the log₂(fold-change) (Log2FC) of mRNA expression for all genes (black) for Dp1Tyb versus WT embryos both treated with iso-LCTB-21 or Dp1Tyb embryos treated with LCTB-21 versus WT embryos treated with iso-LCTB-21. Genes from the Hallmark genesets for Oxidative Phosphorylation (left), Myc targets V1 (middle) and inflammatory response (right), are highlighted in red. n=5 for each condition. (C) Violin plots showing the Log2FC of expression of the same genesets as in B, Oxidative Phosphorylation (left), Myc targets V1 (middle), and inflammatory response (right), for the following comparisons: untreated Dp1Tyb versus WT, untreated Dp1TybDyrk1a^+/+/- versus WT, Dp1Tyb treated with iso-LCTB-21 versus WT treated with iso-LCTB-21 and Dp1Tyb treated with LCTB-21 versus WT treated with iso-LCTB-21. Black lines indicate median, dotted lines indicate 25th and 75th centiles. Dotted line at 0 indicates no change. n=5 for each condition. (D) Graph of percentage of CHD in E14.5 mouse embryonic hearts from the indicated models. Number of hearts analyzed: WT (n=34) and Dp1Tyb (n=26) treated with iso-LCTB-21, and Dp1Tyb treated with LCTB-21 (n=32). (E) Three copies of Dyrk1a and a second unknown gene (GeneX) lead to impaired proliferation and mitochondrial respiration in cardiomyocytes which is required for correct septation of the heart. Created in Biorender. Statistical tests were carried out with a Kruskal-Wallis (C) or Fisher's exact (D) test; * 0.01 < P < 0.05, **** P < 0.0001; ns, not significant.