Sizing up the nucleus: nuclear shape, size and nuclear-envelope assembly. J Cell Sci

The Laboratory of Cellular and Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
Journal of Cell Science (Impact Factor: 5.43). 06/2009; 122(Pt 10):1477-86. DOI: 10.1242/jcs.037333
Source: PubMed


The nucleus is one of the most prominent cellular organelles, yet surprisingly little is known about how it is formed, what determines its shape and what defines its size. As the nuclear envelope (NE) disassembles in each and every cell cycle in metazoans, the process of rebuilding the nucleus is crucial for proper development and cell proliferation. In this Commentary, we summarize what is known about the regulation of nuclear shape and size, and highlight recent findings that shed light on the process of building a nucleus, including new discoveries related to NE assembly and the relationship between the NE and the endoplasmic reticulum (ER). Throughout our discussion, we note interesting aspects of nuclear structure that have yet to be resolved. Finally, we present an idea - which we refer to as ;the limited flat membrane hypothesis' - to explain the formation of a single nucleus that encompasses of all of the cell's chromosomes following mitosis.

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Available from: Micah T. Webster, Nov 23, 2015
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    • "This theory, however , does not explain why cells from different tissues in a given organism can have varied nuclear sizes despite having the same amount of DNA (Altman and Katz, 1976). It is likely, therefore, that a combination of cytoplasmic factors (Webster et al., 2009) and a minimum size set by DNA content (Cavalier-Smith, 2005; Gregory, 2005) determine nuclear size in the alpha and beta cells. Given the difference in endoplasmic reticulum prominence in Fig.7. "
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    • "In general, mitosis is broken down into five stages: prophase, metaphase, anaphase, telophase, and cytokinesis. When a mammalian cell enters mitosis, the cell condenses its chromosomes, undergoes nuclear envelope breakdown, reorganizes its microtubules into a spindle, and splits into two identical daughter cells (Webster et al., 2009). Two major challenges for the twenty-first century have been described in relation to mitosis: first, determining how the cell-cycle network operates dynamically and spatially within live cells (Mitchison and Salmon, 2001; Nurse, 2000; Tsien, 2003); second, determining how ordered inheritance of organelles responds to the changes in dividing cells (Mitchison and Salmon, 2001; Nurse, 2000; Tsien, 2003). "
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