Nuclear matrix

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Definition

noun

plural: nuclear matrices

(cell biology) A 3-dimensional filamentous protein network that extends throughout the nucleoplasm of the cell nucleus


Details

Overview

In eukaryotic cell, the nucleus is the organelle responsible for maintaining the integrity of DNA and for controlling cellular activities such as metabolism, growth, and reproduction by regulating gene expression. It is a double-membraned organelle containing nuclear structures, such as chromatin, nuclear bodies, and nuclear matrix. Nuclear matrix is the network of fibers within the nucleus. It is the cytoskeleton of the nucleus. While the cell contains a cytoskeleton that provides structural support and a means of transport throughout the cytoplasm, the nucleus also contains fibrous scaffolding throughout in the form of nuclear matrix.


Characteristics

The nuclear matrix is the network of fibers in the nucleus as cytoskeleton is to the cell although nuclear matrix is more dynamic. Thus, similar to cytoskeleton, the nuclear matrix largely provides mechanical support. It includes the nuclear lamina, which is the dense fibrous network juxtaposes the nuclear envelope and continuous outside to the endoplasmic reticulum. There are two major components of the nuclear lamina: (1) intermediate filaments, particularly lamins and (2) nuclear lamin-associated membrane proteins.


The nuclear matrix is suggested to generally have the following components: (1) the residual elements of the nuclear envelope, i.e. the pore complex-lamina, (2) the residual nucleoli, and (3) a granular and fibrous matrix structure extending throughout the nucleus.[1] The pore complex-lamina is the residual framework that is left when the nuclear envelope is treated with buffers (such as those containing non-ionic detergents, nucleases, etc.). As for the residual nucleoli, it pertains to the residual structure (nucleolar matrix) following extraction procedures (e.g. via DNAse I treatment)[1] Different proteins are apparently associated with the nuclear matrix. Proteins referred to as SARs (Scaffold Associated Regions) are said to play a role in chromatin organization. They provide attachment sites for the DNA loops during the interphase.[2] There were also reports of the existence of actin in the nucleus. The actin in the nucleus is implicated in RNA transcription and metabolism.


Biological functions

The nuclear matrix provides structural support to the nucleus, maintaining the overall shape and size of the nucleus. Since it includes the nuclear lamina, the nuclear matrix is, thus, associated with the organizing of the genetic information since the nuclear lamina, in particular, is involved in DNA replication and cell division. The nuclear lamina also aids in the chromatin organization as well as in anchoring the nuclear pore complexes in the nuclear envelope. The association of the matrix with proteins such as SARs led to its implication in different nuclear events, such as chromosomal organization, gene localization, and regulation of DNA transcription and replication. [2]


Further reading

See also


Reference

  1. Verheijen, R., Van Venrooij, W., & Ramaekers, F. (1988). The nuclear matrix: structure and composition. Journal of Cell Science 90: 11-36. Retrieved from https://jcs.biologists.org/content/joces/90/1/11.full.pdf
  2. Nuclear Matrix. (2019). Retrieved from Celldeath.de website: http://www.celldeath.de/encyclo/misc/numatrix.htm



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