Kinetic Investigation of Chemokine Truncation by CD26/Dipeptidyl Peptidase IV Reveals a Striking Selectivity within the Chemokine Family

Abstract

Chemokines coordinate many aspects of leukocyte migration. As chemoattractants they play an important role in the innate and acquired immune response. There is good experimental evidence that N-terminal truncation by secreted or cell surface proteases is a way of modulating chemokine action. The localization of CD26/ dipeptidyl peptidase IV on cell surfaces and in biological fluids, its primary specificity, and the type of naturally occurring truncated chemokines are consistent with such a function.We determined the steady-state catalytic parameters for a relevant selection of chemokines (CCL3b, CCL5, CCL11, CCL22, CXCL9, CXCL10, CXCL11, and CXCL12) previously reported to alter their chemotactic behavior due to CD26/dipeptidyl peptidase IV-catalyzed truncation. The results reveal a striking selectivity for stromal cell-derived factor-1␣ (CXCL12) and macrophage-derived chemokine (CCL22). The kinetic parameters support the hypothesis that CD26/dipeptidyl peptidase IV contributes to the degradation of certain chemokines in vivo. The data not only provide insight into the selectivity of the enzyme for specific chemokines, but they also contribute to the general understanding of CD26/dipeptidyl peptidase IV secondary substrate specificity.

One Site Mutation Disrupts Dimer Formation in Human DPP-IV Proteins

“…3B, lane 1). By measuring its kinetic constants (k cat and K m values), we confirmed that purified sDPP-IV was as active as reported previously (Table I) (31). On a native gel, sDPP-IV runs predominantly as a dimer of about 200 kDa with the presence of minor but higher molecular mass species (Fig.…”

Regulation of Fibroblast Migration on Collagenous Matrix by a Cell Surface Peptidase Complex

“…4). In some studies on the chemokine truncation by DPPIV (30) and gelatin degradation by seprase (10,11), the cleavage of prolyl dipeptides required a large amount of enzyme and inordinately long incubation times. This raises the possibility that formation of the seprase-DPPIV complex enhanced gelatin degradation by migratory cells.…”

The chemokine system: tuning and shaping by regulation of receptor expression and coupling in polarized responses

“…However, some of them, like CCL2/MCP-1, CCL7/MCP-3, CCL8/MCP-2 and CCL13/MCP-4 are protected from CD26 degradation by a pyroglutamate at the N-terminus that protects the protein by degradation. On the contrary, other chemokines can be effectively processed by the enzyme (27), and the biological output of this cleavage is unpredictable. Cleavage of CXCL6/GCP-2 does not modify its biological activity, but for most chemokines (CCL5/RANTES, CXCL12/SDF-1, CCL22/MDC, and CCL11/eotaxin) truncation by CD26 is accompanied by reduced, or somewhat altered, receptor binding and signaling.…”