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Keratin 8 overexpression promotes mouse Mallory body formation.

Abstract
Keratins 8 and 18 (K8/18) are major constituents of Mallory bodies (MBs), which are hepatocyte cytoplasmic inclusions seen in several liver diseases. K18-null but not K8-null or heterozygous mice form MBs, which indicates that K8 is important for MB formation. Early stages in MB genesis include K8/18 hyperphosphorylation and overexpression. We used transgenic mice that overexpress K8, K18, or K8/18 to test the importance of K8 and/or K18 in MB formation. MBs were induced by feeding 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). Livers of young K8 or K8/K18 overexpressors had no histological abnormalities despite increased keratin protein and phosphorylation. In aging mice, only K8-overexpressing livers spontaneously developed small "pre-MB" aggregates. Only K8-overexpressing young mice are highly susceptible to MB formation after short-term DDC feeding. Thus, the K8 to K18 ratio, rather than K8/18 overexpression by itself, plays an essential role in MB formation. K8 overexpression is sufficient to form pre-MB and primes animals to accumulate MBs upon DDC challenge, which may help explain MB formation in human liver diseases.
AuthorsIkuo Nakamichi, Diana M Toivola, Pavel Strnad, Sara A Michie, Robert G Oshima, Hélène Baribault, M Bishr Omary
JournalThe Journal of cell biology (J Cell Biol) Vol. 171 Issue 6 Pg. 931-7 (Dec 19 2005) ISSN: 0021-9525 [Print] United States
PMID16365160 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
Chemical References
  • KRT18 protein, human
  • Keratin-18
  • Keratin-8
  • Krt8 protein, mouse
  • Mallory body protein, mouse
  • Proteins
  • RNA, Messenger
  • Keratins
Topics
  • Animals
  • Gene Expression Regulation (physiology)
  • Hepatocytes (ultrastructure)
  • Humans
  • Inclusion Bodies (ultrastructure)
  • Keratin-18
  • Keratin-8
  • Keratins (metabolism)
  • Liver (enzymology, metabolism)
  • Mice
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • Models, Biological
  • Proteins (metabolism)
  • RNA, Messenger (metabolism)

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