Company of Biologists Workshop – Growth, Division and Differentiation – Day 3, morning session
Posted by Ben Martynoga, on 5 October 2011
Better late than never! This excellent workshop took place a couple of weeks ago, but it is still nice to have a record of what was discussed, here on The Node.
Fabienne Pituello started the day by describing how the Shh pathway can induce cell cycle regulators such as Cdc25b to increase the rate of neurogenesis in the developing ventral spinal cord of the chick. In keeping with other talks throughout the meeting her data supports the idea that modulating the length of specific cell cycle phases can affect the outcome of progenitor division. Working in a completely different model, the Xenopus retina, Muriel Perron explained how Hedgehog signaling has a highly analogous function in promoting rapid, neurogenic divisions in her cellular system of choice. She went on to show that this pro-differentiation activity of Hedgehog is counteracted by Wnt signaling, which instead promotes stem/progenitor cell maintenance. Furthermore Wnt and Hh seem to mutually antagonize one another, probably via the induction of direct target genes that modulate the other pathway.
Bill Harris, who also studies the development of the retina, gave a very convincing illustration of just how powerful live imaging in vivo can be understand the real dynamics of cell cycle progression and cell fate choices. For example, a simple genetic reporter where PCNA is fused to GFP can be imaged to quantify how long individual retinal progenitors spend in each phase of the cell cycle in real time.
In keeping with the mainly retina-centric nature of this session Rod Bremner wrapped the session up by showing how the eye is also an excellent model system in which to study the susceptibility to and onset of tumours. Using the mouse as a model system he described his elegant genetic strategies to unravel how the members of the Retinoblastoma (Rb) family of proteins interact with various components of cell cycle and signaling pathways to carry out their vital functions as tumour suppressors.
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