2013 Group 5 Project

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2013 Projects: Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6 | Group 7

The Nuclear Envelope During Cell Division

Introduction

The nuclear envelope is a highly specialised membrane that outlines the nucleus [1] and is a key physical compartment that defines eukaryotic cells. Hetzer’s review (2010) describes it as a highly organised and regulated double membrane that compartmentalises the cell’s genome. [2]

It is composed of two concentric membranes, the outer nuclear membrane and the inner nuclear membrane, which are joined by Nuclear Pore Complexes (NPC) that span both membranes. [3] The outer membrane is continuous with the membrane of the Rough Endoplasmic Reticulum (rER), [4] while the inner membrane is attached to the lamina (directly beneath the inner membrane) and chromatin of the nucleus. [5]

The nuclear envelope serves to maintain the structure of the nucleus and its position in the cell by providing anchoring sites for its attachment to the cell’s cytoskeleton. [6] More importantly it serves to separate nuclear and cytoplasmic activities, [7] including transcription from translation, protecting genetic material from the highly metabolic environment of the cytoplasm. [8] It acts as a selective barrier between the cytoplasm and nuclear contents, with the NPCs contributing to this diffusion barrier by regulating the passage of proteins, RNA and ribonuleoprotein complexes in and out of the nucleus. [9] In addition, Hetzer’s has pointed out in his review article (2010) that more recent studies have shown the inner membrane proteins to play various important roles in the function of the nucleus including chromatin organization, gene expression and DNA metabolism.

Changes to the nuclear envelope’s structure occur at the onset of mitosis, these changes are very slight in lower eukaryotes and in vertebrate cells result in the complete disassembly of the nuclear membrane, [10] this complete or partial breakdown is necessary in order to form the mitotic spindle on condensed chromosomes. [11] In higher eukaryotes must consequently reassemble the nuclear envelope each time a cell divides in order to re-establish the nuclear compartment. [12] This page aims to explore the process of the breakdown and reassembly of the nuclear envelope and its role in cell division.

Historical Background

Structure of the Nuclear Envelope

The Nuclear Envelope At the Onset of Mitosis

Breakdown of the Nuclear Envelope

Mitotic Functions of Nuclear Envelope Components

Reformation of the Nuclear Envelope

Remodeling of the Nuclear Envelope During Interphase

Open vs. Closed/Semi-closed Mitosis

Abnormalities in Nuclear Envelope Breakdown and Reformation

Current and Future Research

Glossary

Images

References

  1. <pubmed>16389459</pubmed>
  2. <pubmed>PMC2829960</pubmed>
  3. <pubmed>16212499</pubmed>
  4. <pubmed>PMC2223813</pubmed>
  5. <pubmed>16212499</pubmed>
  6. <pubmed>16212499</pubmed>
  7. <pubmed>PMC3501164</pubmed>
  8. Evans D, Hutchison C & Bryant J (2004) The Nuclear Envelope, Garland Science/BIOS Scientific Publishers, New York
  9. <pubmed>PMC35011640</pubmed>
  10. <pubmed>PMC2713602</pubmed>
  11. <pubmed>PMC3501164</pubmed>
  12. <pubmed>PMC2829960</pubmed>



2013 Projects: Group 1 | Group 2 | Group 3 | Group 4 | Group 5 | Group 6 | Group 7

Dr Mark Hill 2013, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G