Sequence of events in the assembly of Mallory body components in mouse liver: clues to the pathogenesis and significance of Mallory body formation.
OBJECTIVE
Chronic intoxication of mice with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) or griseofulvin (GF) results in appearance of Mallory bodies (MBs) and alterations of the keratin cytoskeleton, which are reversible upon drug withdrawal but recur after readministration within 2-3 days.


METHODS
DDC- or GF-treated and recovered mice were reintoxicated with the original drugs but also colchicine and lumicolchicine. Cytoskeletal alterations of hepatocytes and MB formation were monitored by immunofluorescence microscopy using keratin, MB-specific antibodies, antibodies to phosphoepitopes and to HSP70. Keratin 8/18 mRNA expression and protein levels were determined by competitive reverse transcription-polymerase chain reaction, in situ-hybridization and western blotting.


RESULTS
Duration of pretreatment was important for the efficiency of MB triggering. Rapid increase of keratin 8/18 mRNA and proteins was found in all reintoxicated mice concomitant with MB formation, whereby keratin 8 prevailed over keratin 18. Keratins and a protein with heat shock characteristics (M(M) 120-1 antigen) were the earliest detectable MB components, whereas ubiquitination and phosphorylation followed later.


CONCLUSIONS
Overproduction of keratins is a major but not the only step responsible for MB formation. Additional components (e.g. M(M) 120-1 antigen) and excess of keratin 8 over keratin 18 are essential.
Stumptner
C
C
Department of Pathology, University of Graz, School of Medicine, Austria.
Fuchsbichler
A
A
Lehner
M
M
Zatloukal
K
K
Denk
H
H
D000818:Animals; D000954:Antigens, Surface / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D003997:Dicarbethoxydihydrocollidine / Q000506:poisoning; D006118:Griseofulvin / Q000506:poisoning; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000502:physiology*; D053533:Keratin-8; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008162:Lumicolchicines / Q000494:pharmacology; D008297:Male; D051379:Mice; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism
D000954:Antigens, Surface; D053533:Keratin-8; C486595:Krt8 protein, mouse; D008162:Lumicolchicines; C439523:M(M)120-1 antigen, mouse; D012333:RNA, Messenger; D025801:Ubiquitin; D006118:Griseofulvin; C042109:lumicolchicine; D003997:Dicarbethoxydihydrocollidine; D007633:Keratins; D003078:Colchicine