Analog or digital
Often, I speak over gene on/off switches. About proteins that enable a gene to be read either more or less often. These gene on/off switches enable an analog regulation of their genes. In addition, a cell has a system to regulate a gene in a more digital manner, having a gene either switched on or off. Now British, Swedish, Australia, and Chinese researchers showed how these two regulatory options influence each other while regulating the flowering gene FLC.
Flowering of tale cress is regulated by the gene FLC. When FLC is turned on it inhibits the development of flowers. Only when FLC is turned off can the plant flower. FLC regulation is of great importance, you don’t want to start flowering too early or too late. To prevent flowering too late, a plant switches FLC off in a digital manner during the winter. But there are also tale cress plants that do not need a winter at all. The researchers decided to study how the switching FLC on and off in these plants is regulated.
Variation in analog regulation affects digital shutdown
In their study the researchers used plants in which another regulator of FLC, FCA, did not work as well, or not at all. When there was no FCA, then FLC was digital turned on, but cells also showed variation in how often a cell read FLC. When FCA was working less well, then more cells had FLC digitally switched off. But in those cells in which FLC was still turned on, the researchers also observed variation in how often a cell FLC read. Therefore, when FLC was digitally switched on, it showed an analog regulation.
To analyse this further, the researchers studied FLC regulation for a longer time period. They noticed that when the plant gets older, that more and more cells switch off FLC digitally. This occurs slower in plants in which FLC was still digitally on than in plants in which some FLC was already digitally off.
The regulation of FLC is thus both analog and digital. The researchers expect that the speed with which FLC is digitally switched off depends on its analog regulation. The more often a cell is reading FLC, the slower the cell is switching off FLC digitally. Enabling variation in analog regulation to result in a difference in digital regulation.
Literature
Rea L Antoniou-Kourounioti, Anis Meschichi, Svenja Reeck, Scott Berry, Govind Menon, Yusheng Zhao, John Fozard, Terri Holmes, Lihua Zhao, Huamei Wang, Matthew Hartley, Caroline Dean, Stefanie Rosa, and Martin Howard (2023) Integrating analog and digital modes of gene expression at Arabidopsis FLC. eLife 12:e79743. https://doi.org/10.7554/eLife.79743
Plant en Zo 