Keratin 7 Is a Constituent of the Keratin Network in Mouse Pancreatic Islets and Is Upregulated in Experimental Diabetes

Catharina M Alam*, Sarah Baghestani, Ada Pajari, M Bishr Omary, Diana M Toivola*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)


Keratin (K) 7 is an intermediate filament protein expressed in ducts and glands of simple epithelial organs and in urothelial tissues. In the pancreas, K7 is expressed in exocrine ducts, and apico-laterally in acinar cells. Here, we report K7 expression with K8 and K18 in the endocrine islets of Langerhans in mice. K7 filament formation in islet and MIN6 β-cells is dependent on the presence and levels of K18. K18-knockout (K18‒/‒) mice have undetectable islet K7 and K8 proteins, while K7 and K18 are downregulated in K8‒/‒ islets. K7, akin to F-actin, is concentrated at the apical vertex of β-cells in wild-type mice and along the lateral membrane, in addition to forming a fine cytoplasmic network. In K8‒/‒ β-cells, apical K7 remains, but lateral keratin bundles are displaced and cytoplasmic filaments are scarce. Islet K7, rather than K8, is increased in K18 over-expressing mice and the K18-R90C mutation disrupts K7 filaments in mouse β-cells and in MIN6 cells. Notably, islet K7 filament networks significantly increase and expand in the perinuclear regions when examined in the streptozotocin diabetes model. Hence, K7 represents a significant component of the murine islet keratin network and becomes markedly upregulated during experimental diabetes.

Original languageEnglish
Pages (from-to)1-16
Number of pages16
JournalInternational Journal of Molecular Sciences
Issue number15
Publication statusPublished - 21 Jul 2021
MoE publication typeA1 Journal article-refereed


  • Animals
  • Diabetes Mellitus, Experimental/genetics
  • Gene Expression Regulation
  • Insulin-Secreting Cells/metabolism
  • Keratin-18/genetics
  • Keratin-7/genetics
  • Keratin-8/genetics
  • Mice
  • Mice, Knockout
  • Up-Regulation


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