Cross beta-Sheet Conformation of Keratin 8 Is a Specific Feature of Mallory-Denk Bodies Compared With Other Hepatocyte Inclusions
2011 (English)In: Gastroenterology, ISSN 0016-5085, E-ISSN 1528-0012, Vol. 141, no 3, 1080-U428 p.Article in journal (Refereed) Published
BACKGROUND andamp; AIMS: Mallory-Denk bodies (MDBs) are cytoplasmic protein aggregates in hepatocytes in steato-hepatitis and other liver diseases. We investigated the molecular structure of keratin 8 (K8) and 18 (K18), sequestosome 1/p62, and ubiquitin, which are the major constituents of MDBs, to investigate their formation and role in disease pathogenesis. METHODS: Luminescent conjugated oligothiophenes (LCOs), h-HTAA, and p-FTAA are fluorescent amyloid ligands that specifically bind proteins with cross beta-sheet conformation. We used LCOs to investigate conformational changes in MDBs in situ in human and murine livers as well as in transfection studies. RESULTS: LCO analysis showed cross beta-sheet conformation in human MDBs from patients with alcoholic and nonalcoholic steatohepatitis or hepatocellular carcinoma, but not in intracellular hyaline bodies, alpha(1)-antitrypsin deficiency, or ground-glass inclusions. LCOs bound to MDBs induced by 3,5diethoxycarbonyl-1,4-dihydrocollidine feeding of mice at all developmental stages. CHO-K1 cells transfected with various combinations of SQSTM1/p62, ubi, and Krt8/Krt18 showed that K8 was more likely to have cross beta-sheet conformation than K18, whereas p62 never had cross beta-sheet conformation. The different conformational properties of K8 and K18 were also shown by circular dichroism analysis. CONCLUSIONS: K8 can undergo conformational changes from predominantly alpha-helical to cross beta-sheet, which would allow it to form MDBs. These findings might account for the observation that krt8(-/-) mice do not form MDBs, whereas its excess facilitates MDB formation. LCOs might be used in diagnosis of liver disorders; they can be applied to formalin-fixed, paraffin-embedded tissues to characterize protein aggregates in liver cells.
Place, publisher, year, edition, pages
WB Saunders , 2011. Vol. 141, no 3, 1080-U428 p.
Liver Disease, Protein Aggregation, Keratin, p62, NASH
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-70739DOI: 10.1053/j.gastro.2011.05.039ISI: 000294281200047OAI: oai:DiVA.org:liu-70739DiVA: diva2:441420
Funding Agencies|Austrian Genome Program (GEN-AU)||Medical University of Graz||Swedish Foundation for Strategic Research||Knut and Alice Wallenberg Foundation||2011-09-162011-09-162015-05-28