Int. J. Dev. Biol. 41: 485 - 490 (1997)
Myogenesis in cultures of uniparental mouse embryonic stem cells: differing patterns of expression of myogenic regulatory factors
The expression of myogenic regulatory factors (MRFs) in cultures of androgenetic (AG) and parthenogenetic (PG) embryonic stem (ES) cells were analyzed to identify a role for imprinted genes in the myogenic program. The time course and levels of expression of myf5, myogenin, MyoD1 and myf6 were assessed by semi-quantitative RT-PCR. A more rapid induction of myogenin expression was seen in AG ES cell cultures compared to control D3 ES cells, and myf6 was expressed by AG but not D3 cells. Persistence of myf5 and MyoD1 expression at late stages of AG cell culture suggests that proliferation and differentiation are maintained. Myogenic differentiation was delayed in PG ES cells, but abundant levels of myogenin and myf6transcripts were subsequently observed. Absence of myf5 expression and only low MyoD1 expression at later stages of culture demonstrate a decline in proliferation in PG cultures. Igf2 was induced to high levels in the late phase of both AG and D3 but not PG cell cultures, indicating paternal allele-specific expression. Igf2 expression correlated with expression of MRF genes associated with myoblast proliferation rather than terminal differentiation. H19 was expressed at very low levels in both AG and PG ES cell cultures. The delay in myogenesis in PG cultures suggests that imprinted genes other than Igf2 and H19 play a role at early stages of the myogenic program.