Dissociation Of The Nuclear Basket Triggers Chromosome Loss In Aging Yeast
As cells age, they often become more prone to errors in how they divide their genetic material, called chromosomes. These errors can lead to an abnormal number of chromosomes, a condition known as aneuploidy, which is a hallmark of aging in many organisms. Recent research using yeast, a simple model organism, has shed light on a key mechanism behind this phenomenon.
The study found that in older yeast cells, a crucial part of the cell’s internal structure, specifically a component of the nuclear pore complex called the nuclear basket, becomes detached. The nuclear pore complex acts like a gatekeeper, controlling what goes in and out of the cell’s nucleus, where the chromosomes are stored. The nuclear basket is a structure on the inner side of this gate.
When this nuclear basket detaches in aging cells, it triggers a cascade of events. Firstly, chromosomes are no longer evenly distributed during cell division; instead, they are partitioned asymmetrically, often leading to their loss. Secondly, the detachment of the nuclear basket also causes “pre-mRNAs” – which are like initial drafts of genetic instructions that need to be processed before they can be used – to leak out of the nucleus into the main body of the cell before they are ready. The researchers discovered that removing specific unprocessed sections (called introns) from three particular pre-mRNAs involved in chromosome segregation was enough to prevent chromosome loss in old cells.
This suggests that the nuclear basket plays a vital role in maintaining the quality control of these genetic instructions. When it fails, the leakage of unprocessed pre-mRNAs disrupts the delicate process of chromosome segregation, ultimately contributing to chromosome loss and the overall aging process. This discovery provides a new understanding of how cellular aging can lead to genetic instability.
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