Deep nuclear invaginations are linked to cytoskeletal filaments - integrated bioimaging of epithelial cells in 3D culture

J Cell Sci. 2017 Jan 1;130(1):177-189. doi: 10.1242/jcs.190967. Epub 2016 Aug 5.

Abstract

The importance of context in regulation of gene expression is now an accepted principle; yet the mechanism by which the microenvironment communicates with the nucleus and chromatin in healthy tissues is poorly understood. A functional role for nuclear and cytoskeletal architecture is suggested by the phenotypic differences observed between epithelial and mesenchymal cells. Capitalizing on recent advances in cryogenic techniques, volume electron microscopy and super-resolution light microscopy, we studied human mammary epithelial cells in three-dimensional (3D) cultures forming growth-arrested acini. Intriguingly, we found deep nuclear invaginations and tunnels traversing the nucleus, encasing cytoskeletal actin and/or intermediate filaments, which connect to the outer nuclear envelope. The cytoskeleton is also connected both to other cells through desmosome adhesion complexes and to the extracellular matrix through hemidesmosomes. This finding supports a physical and/or mechanical link from the desmosomes and hemidesmosomes to the nucleus, which had previously been hypothesized but now is visualized for the first time. These unique structures, including the nuclear invaginations and the cytoskeletal connectivity to the cell nucleus, are consistent with a dynamic reciprocity between the nucleus and the outside of epithelial cells and tissues.

Keywords: Cytoskeleton; Extracellular matrix; Human mammary epithelial cells; Integrated bioimaging; Mechanotransduction; Nucleoplasmic reticulum.

Publication types

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

MeSH terms

  • Actins / metabolism
  • Biomimetics
  • Breast / cytology
  • Cell Adhesion
  • Cell Communication
  • Cell Culture Techniques / methods*
  • Cell Cycle Checkpoints
  • Cell Nucleus Structures / metabolism*
  • Cell Nucleus Structures / ultrastructure
  • Cytoskeleton / metabolism*
  • Cytoskeleton / ultrastructure
  • Desmosomes / metabolism
  • Desmosomes / ultrastructure
  • Epithelial Cells / cytology*
  • Epithelial Cells / metabolism*
  • Epithelial Cells / ultrastructure
  • Extracellular Space / metabolism
  • Female
  • Humans
  • Imaging, Three-Dimensional*
  • Keratins / metabolism
  • Microscopy, Fluorescence
  • Nuclear Envelope / metabolism
  • Nuclear Envelope / ultrastructure

Substances

  • Actins
  • Keratins

Associated data

  • figshare/10.6084/m9.figshare.c.2864557