Cell fate determination during development

Asymmetric cell division is a universal mechanism utilized for the generation of cellular diversity during development (for reviews see Horvitz Herskowitz 1992, Guo Kemphues 1996, Shapiro Losick 1997, Jan Jan 1998). Asymmetric cell divisions during Drosophila embryonic development involve both extrinsic cues mediated through Notch and Delta and intrinsic cell fate determinants and play a major role in producing the distinct cell types which are... 

Shi Y-B, Fu L, Hasebe T, Ishizuya-Oka A (2007) Regulation of extracellular matrix remodeling and cell fate determination by matrix metalloproteinase stromelysin-3 during thyroid hormone-dependent post-embryonic development. Pharmacol Therapeut 116(3 ) 391-400. doi 10.1016/j. pharmthera.2007.07.005... 

Up to now we have discussed reversible signaling pathways, where inactivation is as important as the initial activation. In contrast are essentially irreversible pathways in which a component is proteolytically cleaved. Here we consider two such pathways the NF-kBpathway, which enables cells to respond immediately and vigorously to a number of stress-inducing conditions, and the Notch/Delta pathway, which determines the fates of many types of cells during development. Proteolytic activation of the cell-surface receptor Notch is facilitated by presenllln 1, a membrane protein that also has been Implicated In the pathology of Alzheimer s disease. 

It can be determined if the protein is associated with the cell membrane, if it is ever transferred from one cell to another, what its fate is during embryonic development, and so on. The key is that the chromophore forms with no assistance, and so the fluorescence develops in almost any environment. In fact, green fluorescent animals have been prepared by transgenically incorporating GFP into the animal s genome. GFP-based assays for various cellular processes have been developed because the fluorescence is so easy to detect. Entire volumes have been written on the diverse ways this structure from a jellyfish has been put to good use. The 2008 Nobel Prize in Chemistry was awarded to Osamu Shimomura, Martin Chalfie, and Roger Tsien for their discovery and development of GFP. 

Electron microscopic observations have shown that the cells of isolated gastrula ectoderm after some days in culture develop in their periphery a zone which contains vacuoles and in some cells the basal bodies of cilia. These are the same structures as found in epidermis. They are not found in the ectoderm, which was induced by the vegetalising factor. Obviously gastrula ectoderm is already determined to special pathways during differentiation, but its developmental fate can still be changed. In ectoderm treated with actinomycin D the vacuolar zone is retarded in its development (Grunz, 1973). A more general problem is raised by these experiments. Obviously, the induction of the ectoderm leads not only to an acquisition of new properties but also to a loss of properties which would have been expressed in the uninduced ectoderm. 

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