Expression Profile of Cationic Amino Acid Transporters in Rats with Endotoxin-Induced Uveitis

Purpose. The transcellular arginine transportation via cationic amino acid transporter (CAT) is the rate-limiting step in nitric oxide (NO) synthesis, which is crucial in intraocular inflammation. In this study, CAT isoforms and inducible nitric oxide synthase (iNOS) expression was investigated in endotoxin-induced uveitis (EIU).Methods.EIU was induced in Lewis rats by lipopolysaccharide (LPS) injection. In the treatment group, the rats were injected intraperitoneally with the proteasome inhibitor bortezomib before EIU induction. After 24 hours, leukocyte quantification, NO measurement of the aqueous humor, and histopathological examination were evaluated. The expression of CAT isoforms and iNOS was determined by reverse transcription-polymerase chain reaction, western blotting, and immunofluorescence staining. Nuclear factor-kappa B (NF-κB) binding activity was evaluated by electrophoretic mobility shift assay. The mouse macrophage cell line RAW 264.7 was used to validate thein vivofindings.Results. LPS significantly stimulated iNOS, CAT-2A, and CAT-2B mRNA and protein expression but did not affect CAT-1 in EIU rats and RAW 264.7 cells. Bortezomib attenuated inflammation and inhibited iNOS, CAT-2A, and CAT-2B expression through NF-κB inhibition.Conclusions.CAT-2 and iNOS, but not CAT-1, are specifically involved in EIU. NF-κB is essential in the induction of CAT-2 and iNOS in EIU.

Developmental changes of catalase and superoxide dismutase isoenzymes in zygotic and somatic embryos of horse chestnut

Catalase (CAT) and superoxide dismutase (SOD), two of the major antioxidant enzyme systems, were examined by native PAGE at different stages of zygotic and somatic embryogenesis of horse chestnut (Aesculus hippocastanum L.). During both zygotic and somatic embryogenesis, CAT and SOD specific activities increased, but electrophoretic analysis revealed remarkable differences in the isoenzyme patterns. Two CAT isoforms were differentially present during zygotic embryogenesis. The transition from the fast to the slow migrating form occurred in July, approximately 2 months after pollination. In contrast to zygotic, the two isoforms were continuously detectable during somatic embryo-genesis. In fact, with the exception of the callus stage, in which only one form was present, both of the CAT isoforms are equally active during the somatic embryo development. Unlike CAT, all SOD isoenzymes, one Mn-SOD and five Cu/Zn-SODs, were present during all the stages of zygotic embryo formation, but only Mn-SOD and an Fe-SOD were detected during somatic embryogenesis. These results suggest the occurrence of oxidative stress conditions during in vitro culture which, in horse chestnut, could account for the difficulties observed in the development of the somatic embryo into a plantlet.