DYRK1A ortholog mbk-1 knockout in Caenorhabditis elegans as a tool for genetics research of developmental disorders
Dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) is a dosage sensitive gene located on human chromosome 21 (Hsa21) that contributes to phenotypes associated with developmental disorders like Down syndrome and DYRK1A haploinsufficiency syndrome. Complete genetic knockout of Dyrk1a from conception is embryonic lethal, presenting a barrier in its study. The mbk-1 gene in Caenorhabditis elegans has been identified as an ortholog to mammalian Dyrk1a, and genetic knockout of mbk-1 in C. elegans is not lethal. We hypothesized that deletion of the mbk-1 gene would alter chemosensory function, learning, and motility in C. elegans, and that these phenotypes would be recovered using a humanized DYRK1A replacement at the endogenous mbk-1 locus. Using behavioral preference index assays, analyses of locomotion, and learning in classical conditioning procedures, an mbk-1 knockout strain of C. elegans, EK228, was characterized to identify potential behavioral roles of mbk-1. Preference index assays assessing chemosensory capabilities determined that mbk-1 deletion yielded no detrimental effects. Thrashing and foraging behavior analyses uncovered significant deficits in movement in the EK228 C. elegans, which were not present in two mbk-1 replacement strains containing humanized DYRK1A, suggesting an essential role of mbk-1 in locomotion and motility. Lastly, classical conditioning revealed no significant deficits in the abilities of the EK228 strain in forming associative connections between stimuli. Overall, these results imply functional conservation of the mbk-1/DYRK family kinases, and provide support for the use of humanized replacement strains of C. elegans for the study of mammalian genes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=82 SRC="FIGDIR/small/686526v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@13616f4org.highwire.dtl.DTLVardef@1d2d64org.highwire.dtl.DTLVardef@18f36a9org.highwire.dtl.DTLVardef@14da275_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract (Created with BioRender) C_FIG Article summaryThis work provides insight into evolutionarily conserved functions of the protein kinase DYRK1A, which is linked to developmental disorders including Down syndrome and DYRK1A syndrome. Caenorhabditis elegans with a genetic ablation of the DYRK1A ortholog, mbk-1, were used to examine potential roles in movement, chemosensing, and associative learning and memory, and demonstrated selective deficits in thrashing and foraging locomotion that were not observed in strains with mbk-1 replacement with humanized DYRK1A at the endogenous loci. The findings indicate a role of mbk-1 in C. elegans in adaptive movement, which may provide insight into some of the cellular and neural mechanisms being influenced by DYRK1A. Understanding of the protein kinase DYRK1A may help to elucidate novel therapeutic pathways for developmental disorders.