Comparative expression analysis and characterization of 20S proteasomes in human intestinal tissues: The proteasome pattern as diagnostic tool for IBD patients.
BACKGROUND
The diagnostic differentiation between Crohn's disease (CD) and ulcerative colitis (UC) is sometimes difficult. To date, there are no serological markers that are specific and sensitive enough to differentiate between these 2 diseases. Early and safe prediction of the inflammatory bowel disease (IBD) type is of great importance for the specific treatment of IBD patients. We thus analyzed and compared the expression of catalytic proteasome subunits in the gut of mice and in the normal and inflamed intestines of CD and UC patients and assessed whether the subunit pattern is suitable for diagnostic differentiation.


METHODS
The 20S proteasomes were isolated from surgical tissue specimens derived from terminal ileum and colon of IBD patients and controls. Spots of 20S proteasomes separated by 2D electrophoresis were analyzed by mass spectrometry. Quick detection of catalytic beta2, beta2i, and beta5i subunits was performed by incubating proteasomes with a biotinylated inhibitor (AdaK(Bio)Ahx3L3VS) and subsequently by streptavidin-horseradish peroxide.


RESULTS
20S proteasomes were isolated from the human liver, colon, and terminal ileum. Low expression of the immunosubunits beta1i and beta2i was found in the liver and colon but high amounts in the small intestine. In colon and liver beta5i was found to be associated with the constitutive beta1, beta2 subunits, indicating the existence of mixed proteasomes. Further, inflammation in CD but not UC patients induced massive upregulation of beta1i and beta2i in the colon and terminal ileum, indicating the importance of this protein complex as a disease marker.


CONCLUSIONS
We here show that CD and UC patients display a characteristic pattern of proteasome subunit composition which can be used as diagnostic tool to differentiate between CD and UC.
Visekruna
Alexander
A
Department of Surgery I, Charité-Medical School, Campus Benjamin Franklin, Berlin, Germany.
Joeris
Thorsten
T
Schmidt
Nicole
N
Lawrenz
Maria
M
Ritz
Jörg-P
JP
Buhr
Heinz J
HJ
Steinhoff
Ulrich
U
D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D003093:Colitis, Ulcerative / Q000175:diagnosis* / Q000378:metabolism*; D003424:Crohn Disease / Q000175:diagnosis* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008875:Middle Aged; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013045:Species Specificity; D055815:Young Adult
D015415:Biomarkers; D046988:Proteasome Endopeptidase Complex