Expression level of Rps4 mRNA in 39,X mice and 40,XX mice

Contrary to the effects of X-chromosome monosomy in humans (Turner syndrome), XO mice are fertile and anatomically normal. The human RPS4X gene encodes ribosomal protein S4 and escapes X-chromosome inactivation, and its haplo-insufficiency has been suspected to contribute to Turner syndrome. Therefore, we compared the expression level of mRNA of Rps4 (the mouse homolog of RPS4X) between XX and XO mice using Northern blot analysis. The XO/XX ratio of Rps4 mRNA obtained from Northern blot analysis was 0.9. There was no difference in the expression level of Rps4 mRNA between XX and XO mice. The difference in the RPS4/Rps4 transcription pattern between humans and mice may contribute, at least in part, to the phenotypic difference in monosomy X between humans and mice.