Mechanism that prevents damage caused by shortened proteins

Human cells are made up of the following: a cell nucleus, which contains the genetic material in the form of DNA; and the cytoplasm, where proteins are built. In the cell nucleus, the DNA that contains the blueprint for the organism is rewritten into another form, messenger RNA, in order to transport the information so that these instructions can be used for protein production. Separated from the original transcript, the proteins can then be produced in the cytoplasm. The separation is important because the messenger RNA is not immediately usable; rather, a precursor (pre-messenger RNA) has to be produced that still contains areas that have to be removed before the messenger RNA reaches the cytoplasm. If these areas are not removed beforehand, then shortened or dysfunctional proteins are produced, which is dangerous for the cell.

The molecular machinery that cuts these areas out of the messenger RNA are the spliceosomes. They contain proteins and another type of transcripts of the DNA, the snRNA. The snRNA is not translated into proteins like messenger RNA, but together with the proteins, forms the molecular machinery: the spliceosome. In human cells, the snRNA of the spliceosomes also moves into the cytoplasm. In other organisms, such as baker's yeast, which is often used as a model organism in research, scientists had thought that the snRNA of the spliceosomes never left the cell nucleus. The reason for the evolutionary development to export snRNA before incorporation into the spliceosomes of human cells was also a mystery.

See:

Daniel Becker, Anna Greta Hirsch, Lysann Bender, Thomas Lingner, Gabriela Salinas, Heike Krebber. Nuclear Pre-snRNA Export Is an Essential Quality Assurance Mechanism for Functional Spliceosomes. Cell Reports, 2019; 27 (11): 3199 DOI: 10.1016/j.celrep.2019.05.031

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology