Selenoprotein I is essential for murine embryogenesis

Selenoprotein I (SELENOI) is an ethanolamine phosphotransferase that catalyzes the third reaction of the Kennedy pathway for the synthesis of phosphatidylethanolamine. Since the role of SELENOI in murine embryogenesis has not been investigated, SELENOI−/+ mating pairs were used to generate global KO offspring. Of 323 weanling pups, no homozygous KO genotypes were found. E6.5-E18.5 embryos (165 total) were genotyped, and only two E18.5 KO embryos were detected with no discernable anatomical defects. To screen embryos prior to uterine implantation that occurs ~ E6, blastocyst embryos (E3.5-E4.4) were flushed from uteruses of pregnant females and analyzed for morphology and genotype. KO embryos were detected in 5 of 6 pregnant females, and 7 of the 32 genotyped embryos were found to be SELENOI KO that exhibited no overt pathological features. Overall, these results demonstrate that, except for rare cases (2/490 = 0.4%), global SELENOI deletion leads to early embryonic lethality.