Integrin-linked kinase links dynactin-1/dynactin-2 with cortical integrin receptors to orient the mitotic spindle relative to the substratum

Sci Rep. 2015 Feb 11;5:8389. doi: 10.1038/srep08389.

Abstract

Cells must divide strictly along a plane to form an epithelial layer parallel to the basal lamina. The axis of cell division is primarily governed by the orientation of the mitotic spindle and spindle misorientation pathways have been implicated in cancer initiation. While β1-Integrin and the Dynein/Dynactin complex are known to be involved, the pathways linking these complexes in positioning mitotic spindles relative to the basal cortex and extracellular matrix remain to be elucidated. Here, we show that Integrin-Linked Kinase (ILK) and α-Parvin regulate mitotic spindle orientation by linking Dynactin-1 and Dynactin-2 subunits of the Dynein/Dynactin complex to Integrin receptors at the basal cortex of mitotic cells. ILK and α-Parvin are required for spindle orientation. ILK interacts with Dynactin-1 and Dynactin-2 and ILK siRNA attenuates Dynactin-2 localization to the basal cortex. Furthermore we show that Dynactin-2 can no longer colocalize or interact with Integrins when ILK is absent, suggesting mechanistically that ILK is acting as a linking protein. Finally we demonstrate that spindle orientation and cell proliferation are disrupted in intestinal epithelial cells in vivo using tissue-specific ILK knockout mice. These data demonstrate that ILK is a linker between Integrin receptors and the Dynactin complex to regulate mitotic spindle orientation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cerebral Cortex / metabolism*
  • Dynactin Complex
  • Humans
  • Integrins / metabolism*
  • Intestinal Mucosa / metabolism
  • Mice
  • Mice, Knockout
  • Microfilament Proteins / metabolism
  • Microtubule-Associated Proteins / metabolism*
  • Mitosis
  • Protein Binding
  • Protein Transport
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Spindle Apparatus / metabolism*

Substances

  • DCTN1 protein, human
  • DCTN2 protein, human
  • Dctn1 protein, mouse
  • Dctn2 protein, mouse
  • Dynactin Complex
  • Integrins
  • Microfilament Proteins
  • Microtubule-Associated Proteins
  • Parva protein, mouse
  • integrin-linked kinase
  • Protein-Serine-Threonine Kinases