Down syndrome (DS) patients overexpress human DS critical region gene 1 (hDSCR-1), whose translational product inhibits calcineurin-dependent signaling pathways of genetic transcription. Compared to hDSCR-1, C. elegans rcn-1
has 40% sequence similarity and its proteins share an analogous function with hDSCR-1 in regulating calcineurin. Taurine has had a positive effect on DS patients. According to animal research studies, taurine reduces the expression of MCIP1, a calcineurin inhibitory protein, on C2C12 myotubes and fibroblast in mouse. This study utilizes two C. elegans models for DS: rcn-1
overexpression model, displaying a calcineurin-deficient phenotype, and calcineurin loss-of function mutants. C. elegans larvae were treated with taurine to characterize its effect and mechanism in helping DS patients. RCN-1 expression and behavioral changes were examined in rcn-1
overexpression and calcineurin-deficient models at different concentrations of taurine. When treated with taurine, transgenic worms harboring an rcn-1
reporter (RCN-1::GFP) showed a reduced level of rcn-1
mRNA expression and improved behaviors that were comparable to those in the wild type. These results indicate that taurine exerts a down-regulating effect on the expression of rcn-1
and, consequently, a positive effect on the expression of calcineurins. In summary, taurine may improve the DS symptoms by prompting a positive interaction between RCN-1 and calcineurin. Furthermore, these results suggest that novel mechanisms may regulate interactions among taurine, RCN-1 and calcineurin.