Effect of deoxycoformycin and Val-boroPro on the associated catalytic activities of lymphocyte CD26 and ecto-adenosine deaminase

• Published in: Biochemical pharmacology 1996-12, Vol.52 (11), p.1757-1765
• Main Authors: Jeanfavre, Deborah D., Woska, Joseph R., Pargellis, Christopher A., Kennedy, Charles A., Prendergast, Jay, Stearns, Carol, Reilly, Patricia L., Barton, Randall W., Bormann, Barbara-Jean
• Format: Article
• Language: English
• Subjects: adenosine; adenosine deaminase; Adenosine Deaminase - metabolism; Adenosine Deaminase Inhibitors; Allosteric Regulation; Animals; Biological and medical sciences; boronic acid inhibitors; Boronic Acids - pharmacology; Cell Line; CHO Cells; Cricetinae; deoxycoformycin; Dipeptidyl Peptidase 4 - metabolism; dipeptidylpeptidase IV; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Immunobiology; lymphocyte activation; Lymphocytes - enzymology; Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation; Pentostatin - pharmacology
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/S0006-2952(96)00597-7

CD26 and ecto-adenosine deaminase (ADA) are found associated on the plasma membrane of T lymphocytes and each possess distinct catalytic activities. CD26 has a proteolytic activity identical to dipep-tidylpeptidase IV (DPPIV; E.C. 3.4.14.5), and ecto-ADA (E.C. 3.5.4-4) degrades extracellular adenosine. The cell surface expression of CD26 and ecto-adenosine deaminase (ecto-ADA) is regulated on stimulated T lymphocytes, and ADA binding to CD26 produces a synergistic costimulatory response with T cell receptor activation. This study addresses the potential regulation by allosteric interactions of the catalytic activities of CD26 associated with ecto-ADA, which could define the mechanism of the synergism observed in T cell signaling. Cell lines genetically deficient in ADA, ligands for ADA such as adenosine, and a specific inhibitor of ADA, deoxycoformycin, were used to define the effect of ADA activity on CD26 DPPIV activity and affinity for dipeptide substrate. Conversely, a recombinant Chinese hamster ovary cell line expressing human CD26 with or without a mutation in the DPPIV catalytic domain, and the boronic acid inhibitor Val-boroPro, were used to determine the effect of DPPIV activity on ecto-ADA activity and association with CD26. These studies found no significant allosteric interaction between the catalytic activities of CD26 and ecto-ADA when associated. Therefore, signaling events in T cells involving costimulation with CD26 and ecto-ADA and the synergism observed upon ADA binding to CD26 occur independently of the catalytic activities of these cell surface molecules.