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CD26/dipeptidyl peptidase IV does not work as an adenosine deaminase-binding protein in rat cells
S Iwaki-Egawa1, Y Watanabe, Y Fujimoto
1Department of Clinical Biochemistry, Hokkaido Institute of Pharmaceutical Sciences, Otaru, Japan.
Abstract:
In this paper, we describe further characterization of the membrane-associated molecule CD26/dipeptidyl peptidase IV (DPP IV), which is said to be adenosine deaminase-binding protein (ADA-bp) in humans, to clarify its association with ADA in rat immune cells. For this purpose, we used three types of rats: DPP IV+ rats; DPP IV- rats, which lack enzyme activity and immunological reactivity of DPP IV; and ADA- rats, which have reduced ADA activity due to continuous peritoneal injection of 2'-DCF, a potent inhibitor of ADA. ADA existed in the cells of DPP IV+ and DPP IV- rats, but it did not exist on the cell surface in either rat. ADA- rats showed a decrease in ADA activity and in the number of immune cells, but no effect on DPP IV was observed. These data suggest that in rats, in contrast to humans, DPP IV does not exist as ADA-bp.
Insights
In rats, CD26 (dipeptidyl peptidase IV) is not the adenosine deaminase-binding protein (ADA-bp), unlike in humans. This study clarifies the distinct roles of DPP IV and ADA in rat immune cells.
Area of Science:
- Immunology
- Biochemistry
Background:
- CD26, also known as dipeptidyl peptidase IV (DPP IV), is a membrane-associated molecule implicated as adenosine deaminase-binding protein (ADA-bp) in humans.
- The precise association of DPP IV with adenosine deaminase (ADA) in rat immune cells requires further clarification.
Purpose of the Study:
- To investigate the role of DPP IV and its association with ADA in rat immune cells.
- To determine if DPP IV functions as ADA-bp in rats, contrasting with its known role in humans.
Main Methods:
- Characterization of DPP IV and ADA in three rat models: DPP IV-positive (DPP IV+), DPP IV-deficient (DPP IV-), and ADA-deficient (ADA-) rats.
- DPP IV- rats lacked enzyme activity and immunological reactivity for DPP IV.
- ADA- rats were induced by 2'-deoxycoformycin (2'-DCF), a potent ADA inhibitor, to reduce ADA activity.
Main Results:
- Adenosine deaminase (ADA) was found intracellularly in both DPP IV-positive and DPP IV-deficient rats, but not on the cell surface.
- ADA-deficient rats exhibited reduced ADA activity and a lower count of immune cells.
- No significant effect on DPP IV was observed in ADA-deficient rats.
Conclusions:
- In rats, DPP IV does not appear to function as ADA-binding protein (ADA-bp), differing from its established role in humans.
- The study highlights species-specific differences in the interaction between DPP IV and ADA within immune cells.