Overexpression of insulin-like growth factor-II in mouse embryonic stem cells promotes myogenic differentiation

Embryonic stem (ES) cells derived from androgenetic or parthenogenetic mous e embryos are important tools for studying the roles of imprinted genes in early development. Androgenetic ES cells have been shown to preferentially differentiate into the myogenic lineage both in vitro and after formation o f teratocarcinomas in vivo. To clarify if the maternally imprinted Igf2 gen e which is expected to be overexpressed in androgenetic ES cells is suffici ent to induce myogenic differentiation, R1 ES cells were transfected with h uman IGF-II expression vectors. Stable ES cell clones exhibiting human IGF- II mRNA and protein expression were studied vs ES cell clones without IGF-I I overexpression in a standard in vitro differentiation system involving cu lture in "hanging drops" and observation of differentiation of the recovere d embryoid bodies (EBs). EBs derived from IGF-II overexpressing ES cells sh owed stimulated myogenic differentiation evident by the appearance of myobl asts already 3 days after plating and by higher levels of skeletal muscle-s pecific transcripts (myf5, myoD, myogenin) at earlier stages. Our study dem onstrates for the first time that overexpression of IGF-II enhances and acc elerates myogenic differentiation of ES cells, which has implications for E S cell-derived tissue engineering (C) 2000 Academic Press.