Cytoplasmic keratins couple with and maintain nuclear envelope integrity in colonic epithelial cells

Carl-Gustaf A Stenvall, Joel H Nyström, Ciarán Butler-Hallissey, Theresia Jansson, Taina R H Heikkilä, Stephen A Adam, Roland Foisner, Robert D Goldman, Karen M Ridge, Diana M Toivola

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Keratin intermediate filaments convey mechanical stability and protection against stress to epithelial cells. Keratins are essential for colon health, as seen in keratin 8 knockout (K8-/-) mice exhibiting a colitis phenotype. We hypothesized that keratins support the nuclear envelope and lamina in colonocytes. K8-/- colonocytes in vivo exhibit significantly decreased levels of lamins A/C, B1, and B2 in a colon-specific and cell-intrinsic manner. CRISPR/Cas9- or siRNA-mediated K8 knockdown in Caco-2 cells similarly decreased lamin levels, which recovered after reexpression of K8 following siRNA treatment. Nuclear area was not decreased, and roundness was only marginally increased in cells without K8. Down-regulation of K8 in adult K8flox/flox;Villin-CreERt2 mice following tamoxifen administration significantly decreased lamin levels at day 4 when K8 levels had reduced to 40%. K8 loss also led to reduced levels of plectin, LINC complex, and lamin-associated proteins. While keratins were not seen in the nucleoplasm without or with leptomycin B treatment, keratins were found intimately located at the nuclear envelope and complexed with SUN2 and lamin A. Furthermore, K8 loss in Caco-2 cells compromised nuclear membrane integrity basally and after shear stress. In conclusion, colonocyte K8 helps maintain nuclear envelope and lamina composition and contributes to nuclear integrity.

Original languageEnglish
Article numberar121
Number of pages14
JournalMolecular biology of the cell
Volume33
Issue number13
DOIs
Publication statusPublished - Nov 2022
MoE publication typeA1 Journal article-refereed

Keywords

  • Animals
  • Caco-2 Cells
  • Colon/metabolism
  • Cytoskeletal Proteins/metabolism
  • Epithelial Cells/metabolism
  • Humans
  • Keratin-8/genetics
  • Keratins/metabolism
  • Lamin Type A/metabolism
  • Mice
  • Nuclear Envelope/metabolism
  • Plectin/metabolism
  • RNA, Small Interfering/metabolism
  • Tamoxifen

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