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Fig. 1. Working hypothesis summarizing the relationships of molecular events that
drive CR. This synopsis is drawn from several recent review articles
(Swynghedauw, 1999 ;
Bogoyevitch, 2000;
Akazawa and Komuro, 2003;
Sugden, 2003;
Knöll et al., 2003;
Barki-Harrington and Rockman,
2003; Katsumi et al.,
2004). The hypothesis is based on the sequence of events proposed
elsewhere (MacLellan and Schneider,
2000). It includes a mechanical trigger, a cytoplasmic cascade,
and then a series of phosphorylations/dephosphorylations that finally activate
several transcription factors. These factors are known to act synergistically
in a combinatorial fashion. It is hypothesized that (i) the foetal
reprogramming depends upon transcription factors expressed during
embryogenesis, and (ii) non-specific gene activation is a consequence of
growth factor secretion. The scheme does not include autocrine/paracrine
factors. The functions of the immediate early genes are unknown; several of
them are not translated into proteins
(Snoeckx et al., 1991).
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