X-Linked EGFP Reporter as a Tool to Examine X-Chromosome Inactivation in Mouse Embryos and Embryonic Fibroblasts

Area of Science:

• Developmental Biology
• Genetics
• Molecular Biology

Background:

• X chromosome inactivation is a crucial process in mammalian development.
• Investigating X inactivation requires accurate and reliable model systems.

Purpose of the Study:

• To establish a transgenic mouse model for studying X chromosome inactivation.
• To validate the utility of this model for in vivo and in vitro investigations.

Main Methods:

• Generation of transgenic mouse strains (XGFP and EGFP) expressing green fluorescent protein (GFP).
• Analysis of GFP expression patterns in embryos and embryonic fibroblasts at different developmental stages.
• Crossbreeding of XGFP males with CD-1 females to observe X inactivation patterns.

Main Results:

• Mosaic GFP expression observed in female offspring from CD-1 × XGFP crosses, consistent with random X chromosome inactivation.
• Uniform GFP expression in EGFP strain due to autosomal integration.
• Paternal X-chromosome reactivation identified in trophoblast cells and primordial germ cells (PGCs) at E6.5.
• Widespread GFP expression in various tissues of CD-1 × XGFP embryos at 14.5 days.
• 56% of embryonic fibroblast cells from CD-1 × XGFP embryos showed GFP expression.

Conclusions:

• The CD-1 × XGFP mouse model is validated for studying X chromosome inactivation during early embryonic development and PGC specification.
• CD-1 × XGFP embryonic fibroblasts provide a suitable in vitro model for investigating X-chromosome activation and inactivation mechanisms.