Dipeptidyl peptidase 8/9-like activity in human leukocytes.
The proline-specific dipeptidyl peptidases (DPPs) are emerging as a protease family with important roles in the regulation of signaling by peptide hormones. Inhibitors of DPPs have an intriguing, therapeutic potential, with clinical efficacy seen in patients with diabetes. Until now, only recombinant forms of DPP8 and DPP9 have been characterized. Their enzymatic activities have not been demonstrated in or purified from any natural source. Using several selective DPP inhibitors, we show that DPP activity, attributable to DPP8/9 is present in human PBMC. All leukocyte types tested (lymphocytes, monocytes, Jurkat, and U937 cells) were shown to contain similar DPP8/9-specific activities, and DPPII- and DPPIV-specific activities varied considerably. The results were confirmed by DPPIV/CD26 immunocapture experiments. Subcellular fractionation localized the preponderance of DPP8/9 activity to the cytosol and DPPIV in the membrane fractions. Using Jurkat cell cytosol as a source, a 30-fold, enriched DPP preparation was obtained, which had enzymatic characteristics closely related to the ones of DPP8 and/or -9, including inhibition by allo-Ile-isoindoline and affinity for immobilized Lys-isoindoline.
Maes
Marie-Berthe
MB
Laboratory of Medical Biochemistry, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
Dubois
Véronique
V
Brandt
Inger
I
Lambeir
Anne-Marie
AM
Van der Veken
Pieter
P
Augustyns
Koen
K
Cheng
Jonathan D
JD
Chen
Xin
X
Scharpé
Simon
S
De Meester
Ingrid
I
D000218:Adamantane / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000378:metabolism; D004150:Dipeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018819:Dipeptidyl Peptidase 4 / Q000276:immunology; D054873:Dipeptidyl-Peptidase IV Inhibitors; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology; D007532:Isoleucine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D007962:Leukocytes / Q000276:immunology*; D008968:Molecular Conformation; D009570:Nitriles / Q000737:chemistry / Q000494:pharmacology; D063065:Organophosphonates / Q000737:chemistry / Q000494:pharmacology; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology; D011392:Proline / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D011480:Protease Inhibitors / Q000737:chemistry / Q000494:pharmacology; D011759:Pyrrolidines / Q000737:chemistry / Q000494:pharmacology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D000077597:Vildagliptin
D000911:Antibodies, Monoclonal; D054873:Dipeptidyl-Peptidase IV Inhibitors; D007211:Indoles; D009570:Nitriles; D063065:Organophosphonates; D010880:Piperidines; D011480:Protease Inhibitors; D011759:Pyrrolidines; C512119:UAMC00039; C524159:UAMC00132; C118220:bis(4-acetamidophenyl) 1-prolylpyrrolidine-2-phosphonate; D007532:Isoleucine; D011392:Proline; D004150:Dipeptidases; C471241:DPP9 protein, human; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C487997:DPP8 protein, human; D018819:Dipeptidyl Peptidase 4; D000077597:Vildagliptin; D000218:Adamantane