On the cell-free association of lamins A and C with metaphase chromosomes

Exp Cell Res. 1990 Jan;186(1):169-76. doi: 10.1016/0014-4827(90)90223-w.

Abstract

Nuclear envelopes have previously been shown to assemble spontaneously around endogenous chromosomes in cell-free homogenates of mitotic Chinese hamster ovary cells. In order to further analyze the mechanisms underlying nuclear envelope reformation and the functions of the individual nuclear lamin polypeptides, a fractionated cell-free nuclear envelope reassembly system involving purified chromosomes and either a postchromosomal supernatant or a cytosol fraction from mitotic cells has been devised. Results obtained with this fractionated system show that lamins A and C will associate with the surfaces of chromosomes in the absence of lamin B and membranes, this association being inhibitable by ATP-gamma-S. However, in the absence of membranes chromatin decondensation never occurs. Using the reversible swelling of chromosomes in low ionic strength buffers lacking divalent cations as the basis of a simple assay, it is demonstrated that the association of lamins A and C with the surfaces of chromosomes has a pronounced and easily observable effect on chromatin organization.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Communication
  • Chromosomes / metabolism*
  • Chromosomes / ultrastructure
  • Cricetinae
  • Cricetulus
  • Female
  • Lamin Type B
  • Lamins
  • Metaphase*
  • Microscopy, Electron
  • Mitosis
  • Nuclear Proteins / metabolism*
  • Nuclear Proteins / physiology
  • Ovary / cytology*
  • Ovary / metabolism
  • Ovary / ultrastructure

Substances

  • Lamin Type B
  • Lamins
  • Nuclear Proteins