Transcriptional and post-translational regulation of Flip, an inhibitor of Fas-mediated apoptosis, in human gut inflammation.
Gut
; 57(12): 1674-80, 2008 Dec.
Article
in En
| MEDLINE
| ID: mdl-18625693
ABSTRACT
OBJECTIVE:
Defects in Fas-mediated apoptosis are supposed to contribute to the accumulation of T lymphocytes in the gut of patients with Crohn's disease (CD). This phenomenon has been functionally linked with the elevated expression of Flip, an inhibitor of Fas-mediated apoptosis. In this study, the molecular mechanisms that control Flip in CD were examined.METHODS:
Paired colonic biopsies of patients with CD, patients with ulcerative colitis (UC) and normal controls were analysed for Flip by real-time PCR and western blotting. Flip was also evaluated in CD3(+) lamina propria lymphocytes (T-LPLs) cultured with tosyl phenylalanyl chloromethyl ketone (TPCK; a nuclear factor-kappaB (NF-kappaB) inhibitor), AG490 (a Janus kinase 2 (Jak2)/signal transducer and activator of transcription (Stat) inhibitor) or 17-desmethoxy-17-N,N-dimethylamino-geldanamycin (DMAG; an inhibitor of heat shock protein 90). The rate of apoptosis was examined by flow cytometry.RESULTS:
In CD, upregulation of Flip occurred at both the RNA and protein level. Treatment of CD CD3(+) T-LPLs with TPCK or AG490 markedly reduced Flip RNA, suggesting a role for NF-kappaB and Jak/Stat pathways in the transcriptional control of Flip in this condition. Consistently, both TPCK and AG490 sensitised CD T-LPLs to Fas-mediated apoptosis. Flip protein in cells from normal gut was rapidly degraded by the proteasome pathway. In contrast, in inflamed gut of both CD and UC patients, there was a reduced degradation of Flip via the ubiquitin-proteasome-dependent pathway, but Flip expression can be decreased by DMAG.CONCLUSIONS:
The data demonstrate that Flip is regulated at both the transcriptional and post-translational level in CD, and indicate that in the normal but not inflamed gut Flip is degraded via the ubiquitin-proteasome-dependent pathway.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
T-Lymphocytes
/
Colitis, Ulcerative
/
Crohn Disease
/
Apoptosis
/
Caspases
/
Fas Ligand Protein
Limits:
Female
/
Humans
/
Male
Language:
En
Journal:
Gut
Year:
2008
Document type:
Article
Affiliation country:
Italia