In biology, the nuclear matrix is the network of fibres found throughout the inside of a cell nucleus and is somewhat analogous to the cell cytoskeleton. However, in contrast to the cytoskeleton, the nuclear matrix has been proposed to be a highly dynamic structure, perhaps more like a dynamic sponge with open compartments for free diffusion of molecules in the nucleus. The exact function of this matrix is still disputed, and its very existence has recently been called into question.^[1] There is evidence that the nuclear matrix is involved in regulation of gene expression in Arabidopsis thaliana. ^[2]

[edit] Justification of the Nuclear Matrix Hypothesis

For a long time the question whether a polymer meshwork, a “nuclear matrix” or “nuclear-scaffold” is an essential component of the in vivo nuclear architecture has remained a matter of debate. While there are arguments that the relative position of chromosome territories (CTs), the equivalent of condensed metaphase chromosomes at interphase, may be maintained due to steric hindrance or electrostatic repulsion forces between the apparently highly structured CT surfaces, this concept has to be reconciled with observations according to which cells treated with the classical matrix-extraction procedures maintain defined territories up to the point where a minor subset of acidic nuclear matrix proteins is released – very likely those proteins that governed their association with the nuclear skeleton.

S/MARs (scaffold/matrix attachment elements), the DNA regions that are thought to attach genomic DNA to the nuclear skeleton, show an ever increasing spectrum of established biological activities. All these activities are in agreement with (or most easily explained by) the nuclear matrix hypothesis. This is one justification for maintaining this concept before equally plausible alternative models emerge.

In this context it should be noted that S/MARs find increasing use for the rational design of vectors with widespread use in gene therapy and biotechnology. Nowadays S/MAR functions can be modulated, improved and custom-tailored to the specific needs of novel vector systems.

• See also: minicircle

[edit] Nuclear Matrix and Cancer

The nuclear matrix composition on human cells has been proven to be cell type and tumor specific. It has been clearly demonstrated that the nuclear matrix composition in a tumor is different from its normal counterparts. This fact has been useful to characterize cancer markers and to predict the disease even earlier. These markers have been found in urine and blood and could potentially be used in early detection and prognosis of human cancers.

[edit] References

• Nickerson J (February 2001). "Experimental observations of a nuclear matrix". J. Cell. Sci. 114 (Pt 3): 463–74. PMID 11171316. http://jcs.biologists.org/cgi/content/abstract/114/3/463. 
• Dynamic view of the nuclear matrix
• Miller TE, Beausang LA, Winchell LF, Lidgard GP (January 1992). "Detection of nuclear matrix proteins in serum from cancer patients". Cancer Res. 52 (2): 422–7. PMID 1728414. http://cancerres.aacrjournals.org/cgi/reprint/52/2/422. 
• Girod P, Nguyen D, Calabrese D, et al. (2007). "Genome-wide prediction of matrix attachment regions that increase gene expression in mammalian cells". Nature Methods 4: 747–53. doi:10.1038/nmeth1076. http://www.nature.com/nmeth/journal/v4/n9/abs/nmeth1076.html.