Modulation of imprinted gene expression following superovulation

Area of Science:

• Reproductive biology
• Developmental biology
• Genetics

Background:

• Assisted reproductive technologies (ART) are linked to increased risks of low birth weight and genomic imprinting disorders.
• The exact mechanisms causing these ART-associated risks are not fully understood.
• Previous studies showed superovulation affects placental imprinted gene expression early in gestation.

Purpose of the Study:

• To determine if superovulation's effects on genomic imprinting persist into later stages of fetal development.
• To assess surviving fetuses for growth and morphological abnormalities following superovulation and embryo transfer.
• To investigate the expression patterns of specific imprinted genes (H19, Snrpn, Kcnq1ot1, Igf2) in placentae and fetuses at later developmental time points.

Main Methods:

• Utilized a mouse model comparing superovulation followed by embryo transfer to spontaneous ovulation (controls).
• Assessed embryonic and fetal growth, size, and weight at mid-gestation (E14.5) and late-gestation (E18.5).
• Analyzed the expression of imprinted genes (H19, Snrpn, Kcnq1ot1, Igf2) in placental and embryonic tissues at E9.5, E14.5, and E18.5 using molecular techniques.

Main Results:

• Superovulation did not result in significant differences in embryo/fetal size or weight at E14.5 and E18.5 compared to controls.
• Monoallelic expression of H19, Snrpn, and Kcnq1ot1 remained normal in placentae and embryos at E14.5 and E18.5.
• Superovulation led to reduced Igf2 protein production in placentae at E9.5 and increased mRNA variability at E14.5.

Conclusions:

• Superovulation may lead to the release of oocytes with altered imprinted gene expression.
• Despite early placental changes in Igf2, overall fetal growth and morphology were not detectably affected at later stages.
• The coordinated regulation within imprinted gene networks might modulate or compensate for initial expression alterations.