Junk DNA goodbye!: more about lncRNA functions (Introduction)

by David Turell , Friday, May 15, 2020, 22:06 (1441 days ago) @ David Turell

New techniques elicit more understanding:

https://phys.org/news/2020-05-technology-rna-gene.html

"It was previously believed that RNA functions mostly as an intermediary in building proteins based on a DNA template (fig. 1a), with very rare exceptions such as ribosomal RNAs. However, with the development of genomic analysis, it turned out that not all DNA regions encode RNA, and not all transcribed RNA encodes proteins.

"Although the number of noncoding RNAs and those that encode proteins is about the same, the function of most noncoding RNA is still not entirely clear.

"Scientists are now coming to the conclusion that RNA is one of the factors that determine which genes are expressed, or active.

"Long noncoding RNAs are known to interact with chromatin—DNA tightly packaged with proteins (fig. 1b). Chromatin has the ability to change its conformation, or "shape," so that certain genes are either exposed for transcription or concealed. Long noncoding RNAs contribute to this conformation change and the resulting change in gene activity by interacting with certain chromatin regions. To understand the regulatory potential of RNA—in addition to it being a template for protein synthesis—it is important to know which chromatin region any given RNA interacts with.

"RNAs interact with chromatin inside the cell nucleus by binding to chromatin-associated proteins that fold a DNA molecule.

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"The research confirmed that long noncoding RNAs play an important role in the regulation of gene expression occurring at a considerable distance from the regulated gene.

"This technology can also be used to study cell type-specific RNA-chromatin interactions. The scientists proved it by looking at two noncoding RNAs in a mouse cell, one of them possibly associated with schizophrenia. They found that an interaction pattern between chromatin and those RNAs in two different cells—the embryonic stem cell and the oligodendrocyte progenitor cell—correlated with preferential gene expression in those cell types.

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"The analysis performed by bioinformaticians from the Research Center of Biotechnology and MIPT showed that not only the standard double helix interactions between DNA and RNA but also those involving RNA-DNA triplexes could participate in gene regulation. Also, such interactions highlight the significance of noncoding RNA in protein targeting to particular gene loci."

Comment: Bit by bit the layers of the genome onion are being uncovered and it turns out to be complexly designed.