How nucleus cleans itself

The Nucleus

The nucleus is a membrane-bound organelle that contains the genetic material of a eukaryotic organism (as prokaryotes lack a well-defined nucleus). It serves as the ‘Brain’ of the cell by maintaining the integrity of the cell by facilitating transcription and replication processes. It is a crucial part of a cell and thus an integral part of the study of cell biology.

While textbooks often illustrate the nucleus as a static structure suspended in the cell’s milieu, the nucleus is highly responsive to external and cell internal forces. The nucleus is responsive to the environment outside it, and this affects processes that occur within it. It happens due to the presence of structures such as KASH and SUN domain proteins, within the nuclear envelope that helps to transduce mechanical signals.

Likewise, components of the nucleus are also dynamic, but not more than the nuclear envelope itself. During mitosis, the nuclear envelope disassembles to various degrees and reassembles (Vietri et al.) depending on cell type. The notion that the nucleus, once reformed, is merely a sack of randomly organized DNA has long been dispelled.

How nucleus cleans itself

The first transcription phase is inescapable and it produces a large number of surplus RNAs, however, theses RNAs do not accumulate, because they are degraded shortly after their production. This prevents the deleterious accumulation of non-functional transcripts that would otherwise be detrimental to cell health.

Most of the RNA decay is achieved by the nuclear RNA exosome complex, an RNA 3'-5' exonuclease, which is called up to RNA by specific adapters, like the so-called NEXT complex and the PAXT (poly (A) tail exosome targeting) connection.

The decay systems co-operate sometimes and help cells to degrade NEXT substrates, even in the potentially hazardous situation. In this case, NEXT targets (which are normally produced without a poly(A) tail and swiftly removed) acquire poly(A) tails -- a hallmark of PAXT targets -- which subject them to PAX -mediated decay. These systems provide a two-layered targeting mechanism for the efficient nuclear sorting of the human transcriptome.