Upon destruction of the protein components of cells by free oxygen radicals, these cellular proteins can be marked or more accurately, “tagged,” for expulsion from the cell. In spite of this, however, some cellular proteins can circumnavigate rigid protocols and be expelled from the cell even in the absence of prior tagging. The second process is known as the emergency pathway.
Proteasomes. Image Courtesy of Nature Communications
The Study
The discovery of an alternate method for the expulsion of destroyed cellular proteins that have been affected by oxygen radicals was brought about by a team of researchers, under the direction of Technoin scientists. The expulsion of destroyed cellular proteins can occur in such instances as the occurrence of human heart failure. When this happens, cellular respiration becomes sub-optimal, and this causes more rapid depletion of oxygen stores. This is clinically known as hypoxia and is caused by poor inhalation of oxygen.
Another important thing discovered by researchers is that a shift can take place from a tightly controlled method of expelling the cellular proteins to a more flexible method, which happens when cells initiate an emergency protocol. This shift occurs to take care of the toxic cellular proteins in order to prevent heightened levels of toxicity of the cellular proteins.
The research study was published in the journal of Natural communications on 26th October 2021. During the research process, the team, in a bid to carry out their studies, investigated a number of proteasome complexes (proteins that function by using chemical reactions to break down unnecessary or injured cellular proteins). The result of the research is that increased levels of a particular group of proteasomes- the 20S- were shown to be important to cell survival. This was even the same for cells that were undergoing stress caused by injured cellular proteins.
Human cells undergo a continuous process where the cells are continuously being recycled. This process occurs in both functional and injured cells, and the purpose of recycling the cells is to “tag” and target the injured cells for their expulsion in the event that they are subjected to stress by the Ubiquitin system.
In the exact same process, some of the proteins that still retain their full functionality and remain unaffected can go through the 20S proteasome’s molecular disposal unit in addition to other highly toxic proteins that have already been marked for destruction.
However, instead of harming the cells, the method of action of the 20S proteasome can help cells to eliminate toxic cellular proteins more quickly.
The authors of the study concluded by bringing up interesting speculation about how the emergency pathway might shield injured cellular proteins from the negative effects of stress, also help in handling the stress, and even create an avenue where the cells are allowed to ‘age gracefully’ afterward.
Clinical Significance
The clinical significance of the study is the fact that the 20S proteasomes can facilitate the elimination of toxic cellular proteins, thereby increasing the chances of cell survival.
Conclusion
The 20S proteasomes are useful for increasing the chances of cell survival via the emergency pathway.
References
Sahu, I., Mali, S.M., Sulkshane, P. et al. The 20S as a stand-alone proteasome in cells can degrade the ubiquitin tag. Nat Commun 12, 6173 (2021). https://doi.org/10.1038/s41467-021-26427-0
