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Dev Biol March 1, 2007; 303 (1): 311-24.
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Cell cycling and differentiation do not require the retinoblastoma protein during early Xenopus development.

Cosgrove RA , Philpott A .

The retinoblastoma protein (pRb) is a central regulator of the cell cycle, controlling passage through G1 phase. Moreover, pRb has also been shown to play a direct role in the differentiation of multiple tissues, including nerve and muscle. Rb null mice display embryonic lethality, although recent data have indicated that at least some of these defects are due to placental insufficiency. To investigate this further, we have examined the role of pRb in early development of the frog Xenopus laevis, which develops without the need for a placenta. Surprisingly, we see that loss of pXRb has no effect on either cell cycling or differentiation of neural or muscle tissue, while overexpression of pXRb similarly has no effects. We demonstrate that, in fact, pXRb is maintained in a hyperphosphorylated and therefore inactive state early in development. Therefore, Rb protein is not required for cell cycle control or differentiation in early embryos, indicating unusual control of these G1/G0 events at this developmental stage.

PubMed ID: 17188261
Article link: Dev Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: actl6a foxg1 ncam1 otx2 pax6 rb1
Morpholinos: rb1 MO1

Article Images: [+] show captions