Changes in temporal and spatial patterns of Gi protein expression in postimplantation mouse embryos

Area of Science:

• Developmental Biology
• Molecular Biology
• G protein signaling

Background:

• Guanine nucleotide-binding proteins (G proteins) are crucial signaling molecules.
• Previous work established G protein presence in preimplantation mouse embryos.

Purpose of the Study:

• To investigate G protein expression and activation during early mouse embryonic development (Days 6.5-8.5).
• To determine the spatial distribution of G protein activation along the anterior-posterior axis.

Main Methods:

• Pertussis toxin (PT)-catalyzed ADP-ribosylation to assess G protein activity.
• Immunoblotting and immunoprecipitation to quantify G protein subunits.
• Utilized antisera specific for alpha i1, alpha i2, and alpha i3 subtypes.

Main Results:

• Embryonic alpha i subunit amount increased from Day 6.5 to 7.5, then plateaued at Day 8.5.
• PT-catalyzed ADP-ribosylation of Gi alpha proteins decreased from Day 6.5 to 7.5, then increased by Day 8.5.
• A gradient of Gi protein activation was observed along the anterior-posterior axis in Day 8.5 embryos.
• All three alpha i subtypes (i1, i2, i3) were detected in Day 8.5 embryos and earlier stages.

Conclusions:

• Gi protein activation occurs during gastrulation (Days 6.5-7.5) in postimplantation mouse embryos.
• A spatial gradient of Gi protein activation along the anterior-posterior axis is established by Day 8.5.
• All three alpha i subtypes are present from oocytes through early postimplantation stages.