Transdifferentiation – direct reprogramming of cells
Cells can change specialization without becoming stem cells
Kirill Stasevich, CompulentaHaving once acquired some kind of specialization, cells can no longer turn into any other type.
Indeed, it would be strange to expect a heart muscle to suddenly become a brain. However, you can contrive and first turn a differentiated cell into an immature, stem cell, and only then turn this stem cell into whatever your heart desires. But, as we can see, an intermediate stage is still implied here – a stem cell.
Researchers from the University of California at Santa Barbara (USA) did, as it may seem, the impossible: they turned one specialized cell into another specialized one directly, without an intermediate "stem" stage.
Immediately it should be said that Joel Rothman and his colleagues experimented not with human cells, but with the cells of the nematode Caenorhabditis elegans, and only the pharyngeal cells succumbed to such an operation, which managed to turn into intestinal cells.
The fact that the cell type has become different was established, among other things, by the change in fluorescence –
from purple, characteristic of pharyngeal cells (on the left), to red, typical of the intestine (in the center).
On the right is a full-length nematode with a real intestine, also glowing red. (Photos of the authors of the work.)
As you know, all cells of the same organism have the same set of genes, but these genes work differently. The order of operation and activity of different genes depend on many mechanisms, and one of the main roles here is played by transcription factors – proteins that control transcription, that is, the synthesis of RNA on a DNA template. The researchers had in their hands a set of transcription factors that control the formation of the intestine in nematodes: one of the last in this series was the protein ELT-7, which remained active throughout the life of animals and was necessary not only for the development of the intestine, but also for its functioning.
When the synthesis of this protein was turned on in the pharyngeal cells, they turned into intestinal cells, and this could be done both in young worms and in adults. The researchers called this transformation "in one move" transdifferentiation.
These results suggest that many cell types retain enough common features among themselves so that they can be turned into each other without completely dismantling the entire existing system of genetic regulation. However, it is unlikely that all cells in the body will succumb to this transdifferentiation: obviously, the degree of typological kinship between them matters here, and, say, the transformation of heart muscle cells into neurons may be real, but a single transcription factor is unlikely to do here.
The results of the study are published in the journal Development (Riddle et al., Transdifferentiation and remodeling of post-embryonic C. elegans cells by a single transcription factor).
Prepared based on the materials of the University of California at Santa Barbara: Remodeling at the Cellular Level.
Portal "Eternal youth" http://vechnayamolodost.ru06.12.2013