Chromatin Position in Human HepG2 Cells: Although Being Non-Random, Significantly Changed in Daughter Cells

J Struct Biol. 2009 Feb;165(2):107-17. doi: 10.1016/j.jsb.2008.10.007. Epub 2008 Nov 12.

Abstract

Mammalian chromosomes occupy chromosome territories within nuclear space the positions of which are generally accepted as non-random. However, it is still controversial whether position of chromosome territories/chromatin is maintained in daughter cells. We addressed this issue and investigated maintenance of various chromatin regions of unknown composition as well as nucleolus-associated chromatin, a significant part of which is composed of nucleolus organizer region-bearing chromosomes. The photoconvertible histone H4-Dendra2 was used to label such regions in transfected HepG2 cells, and its position was followed up to next interphase. The distribution of labeled chromatin in daughter cells exhibited a non-random character. However, its distribution in a vast majority of daughter cells extensively differed from the original ones and the labeled nucleolus-associated chromatin differently located into the vicinity of different nucleoli. Therefore, our results were not consistent with a concept of preservation chromatin position. This conclusion was supported by the finding that the numbers of nucleoli significantly differed between the two daughter cells. Our results support a view that while the transfected daughter HepG2 cells maintain some features of the parental cell chromosome organization, there is also a significant stochastic component associated with reassortment of chromosome territories/chromatin that results in their positional rearrangements.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cell Nucleolus / metabolism
  • Cell Nucleus / metabolism
  • Chromatin / chemistry*
  • Chromatin / metabolism
  • Chromosomes / ultrastructure
  • Fibroblasts / metabolism
  • Histones / metabolism
  • Humans
  • Image Processing, Computer-Assisted
  • Microscopy, Fluorescence / methods
  • Time Factors

Substances

  • Chromatin
  • Histones