Plant & zo
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Gene expression, a case of regulation
Expression of genes is regulated on multiple levels. Well known of these are the transcription factors, gene on/off switches. In addition, accessibility of the DNA determines if a gene can be transcribed or not. Moreover, there is regulation at the RNA level. Determining if and which part of the gene may be translated into a protein. Then there are long-non-coding RNAs, those interfere with transcription, mostly causing lower or stopping of the transcription. All by all a whole arsenal of possibilities to precisely regulate gene transcription. Now Polish researchers found a new kind of regulator.
The research started with studying the delayed germination of seeds grown in a salty environment. The researchers studied plants with and without the DOG1, a gene that delays germination. When salt was present, seeds with the DOG1 gene germinated slower than they normally would. But this was not the case in plants without a DOG1 gene. While seeds that made extra DOG1 proteins germinated extra slow.
This way of regulation was unknown till now
Subsequently the researchers analysed the gene expression during the germination in a salty environment. Here the noticed something out of the ordinary. On the DNA the region in front of the DOG1 gene showed a strong expression during salt stress. Only, no known genes were located on this part of the DNA. After analysis it turned out that this region of the DNA encoded multiple long-non-coding RNAs, which the researchers named PUPPIES.
Now the big question was: What does PUPPIES do? The researchers observed that PUPPIES is turned on when there is salt stress. And when PUPPIES is on, then DOG1 is also turned on. But this is not the case the other way around. DOG1 is also turned on during heat stress, but not PUPPIES. More transcription of PUPPIES results in more transcription of DOG1 during salt stress.
It turns out that the higher transcription of PUPPIES causes more molecules of polymerase II (the enzyme that transcribes the DNA into RNA) to accumulate at the start site of the DOG1 gene. This in turn results in more transcripts of the DOG1 gene, and subsequently in a delay in germination. This way of regulation was unknown till now. So can the studying the delay of germination during salt stress led to the discovery of a new way of gene regulation.
Miguel Montez, Maria Majchrowska, Michal Krzyszton, Grzegorz Bokota, Sebastian Sacharowski, Magdalena Wrona, Ruslan Yatusevich, Ferran Massana, Dariusz Plewczynski, and Szymon Swiezewski (2023) Promoter-pervasive transcription causes RNA polymerase II pausing to boost DOG1 expression in response to salt. The EMBO Journal e112443 https://doi.org/10.15252/embj.2022112443