title: Early increases in transglutaminase activity and polyamine levels in a Mallory-Denk body mouse model.
abstract: Rodents treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) are a model of two hepatic toxic manifestations: porphyria and the appearance of hepatic cytoplasmic protein aggregates (Mallory-Denk Bodies, MDBs). MDBs are induced after long-term DDC feeding, consist primarily of keratins 8 and 18, and contain glutamine-lysine cross-links generated by transglutaminases (TGs). TGs are Ca(2+)-dependent enzymes which catalyze the formation of covalent bonds between proteins and between proteins and polyamines. The aim of the current study was to investigate the time-course of TG hepatic activity in CF1 male mice either acutely or chronically treated with DDC and to correlate this activity with polyamine and porphyrin levels. On day 3 of the treatment, statistically significant increases in TG activity (75%), porphyrin content (6740%) and spermidine levels (73%) were observed. Although not statistically significant, at this time point putrescine levels showed an increase of 52%. The highest TG activity was observed on day 30 (522%), while porphyrin levels were still gradually increasing by day 45 (37,000%). From day 7 of the treatment and until the end of the experiment, putrescine levels remained increased (781%). Spermine levels were not affected by the treatment. The DDC-induced increases in putrescine and spermidine levels herein reported seem to be an early event contributing to the stimulation of liver TG activity, and thus to the promotion of cross-linking reactions between keratin proteins. This in turn would contribute to the formation of protein aggregates, which would lead to the appearance of MDBs. Due to the pro-oxidant and antioxidant properties of polyamines, it is possible to speculate that putrescine and spermidine may also participate at several levels in the oxidative stress processes associated with MDB formation.
authors.affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina. adcris@qb.fcen.uba.ar
authors.forename: Adriana C
authors.initials: AC
authors.lastname: Cochón
authors.forename: Lelia A
authors.initials: LA
authors.lastname: Miño
authors.forename: Leonor C San Martín
authors.initials: LC
authors.lastname: de Viale
mesh_terms: D000818:Animals; D015317:Biogenic Polyamines / Q000032:analysis*; D002479:Inclusion Bodies / Q000187:drug effects / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D023421:Models, Animal; D011166:Porphyrins / Q000032:analysis; D011725:Pyridines / Q000633:toxicity; D011503:Transglutaminases / Q000378:metabolism*
chemical_list: C530773:3,5-diethoxycarbonyl-1,4-dihydrocollidine; D015317:Biogenic Polyamines; D011166:Porphyrins; D011725:Pyridines; D011503:Transglutaminases