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Regulation of the receptor specificity and function of the chemokine RANTES (regulated on activation, normal T cell expressed and secreted) by dipeptidyl peptidase IV (CD26)-mediated cleavage.

Oravecz T, Pall M, Roderiquez G, Gorrell MD, Ditto M, Nguyen NY, Boykins R, Unsworth E, Norcross MA - J. Exp. Med. (1997)

Bottom Line: The truncated RANTES(3-68) lacked the ability of native RANTES(1-68) to increase the cytosolic calcium concentration in human monocytes, but still induced this response in macrophages activated with macrophage colony-stimulating factor.Analysis of chemokine receptor messenger RNAs and patterns of desensitization of chemokine responses showed that the differential activity of the truncated molecule results from an altered receptor specificity.Our results indicate that CD26-mediated processing together with cell activation-induced changes in receptor expression provides an integrated mechanism for differential cell recruitment and for the regulation of target cell specificity of RANTES, and possibly other chemokines.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematologic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. tamas@helix.nih.gov

ABSTRACT
CD26 is a leukocyte activation marker that possesses dipeptidyl peptidase IV activity but whose natural substrates and immunological functions have not been clearly defined. Several chemo-kines, including RANTES (regulated on activation, normal T cell expressed and secreted), have now been shown to be substrates for recombinant soluble human CD26. The truncated RANTES(3-68) lacked the ability of native RANTES(1-68) to increase the cytosolic calcium concentration in human monocytes, but still induced this response in macrophages activated with macrophage colony-stimulating factor. Analysis of chemokine receptor messenger RNAs and patterns of desensitization of chemokine responses showed that the differential activity of the truncated molecule results from an altered receptor specificity. RANTES(3-68) showed a reduced activity, relative to that of RANTES(1-68), with cells expressing the recombinant CCR1 chemokine receptor, but retained the ability to stimulate CCR5 receptors and to inhibit the cytopathic effects of HIV-1. Our results indicate that CD26-mediated processing together with cell activation-induced changes in receptor expression provides an integrated mechanism for differential cell recruitment and for the regulation of target cell specificity of RANTES, and possibly other chemokines.

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Activity of full-length  and truncated RANTES in cells  expressing recombinant CCR5  or CCR1 receptors. The [Ca2+]i  was measured in HEK-293 cells  expressing CCR5 (A and C) and  HOS-CD4 cells expressing CCR1  (B and D). (A and B) Cells were  stimulated with various concentrations of the two RANTES  variants as indicated and maximal  fluorescence values were calculated from the peaks of the Ca2+  response curves. (C and D) Homologous and heterologous desensitization of the responses induced by RANTES(1–68) and  RANTES(3–68) was measured  in transfectants as described in  Fig. 5.
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Figure 6: Activity of full-length and truncated RANTES in cells expressing recombinant CCR5 or CCR1 receptors. The [Ca2+]i was measured in HEK-293 cells expressing CCR5 (A and C) and HOS-CD4 cells expressing CCR1 (B and D). (A and B) Cells were stimulated with various concentrations of the two RANTES variants as indicated and maximal fluorescence values were calculated from the peaks of the Ca2+ response curves. (C and D) Homologous and heterologous desensitization of the responses induced by RANTES(1–68) and RANTES(3–68) was measured in transfectants as described in Fig. 5.

Mentions: HEK-293 cells expressing CCR5 and HOS-CD4 cells expressing CCR1 were loaded with Fura-2 and exposed to various concentrations of RANTES(1–68) or RANTES(3–68). The two RANTES variants showed similar abilities to increase [Ca2+]i in the CCR5 transfectant (Fig. 6 A); the responses were dose dependent, with 10 nM of each variant sufficient to induce a maximal Ca2+ response. In contrast, in the cells expressing CCR1, the amount of RANTES(3–68) required to produce a detectable Ca2+ response was ∼100 times that for RANTES(1–68) (Fig. 6 B); the effect of RANTES(1–68) saturated at 50 nM, whereas that of RANTES(3–68) appeared not to have achieved saturation at 200 nM. Furthermore, bidirectional cross-desensitization between the two RANTES variants was evident only with the cells expressing CCR5 (Fig. 6 C); in the CCR1 transfectant, cross-desensitization was induced by full-length RANTES but not by the truncated form, which also did not exhibit self-desensitization (Fig. 6 D). Control cells transfected with vector alone or with vectors encoding CCR2b, CCR3, or CXCR4 did not respond to these ligands (data not shown). These results thus confirm that the native and CD26-truncated RANTES variants exhibit markedly different activities at the CCR1 receptor.


Regulation of the receptor specificity and function of the chemokine RANTES (regulated on activation, normal T cell expressed and secreted) by dipeptidyl peptidase IV (CD26)-mediated cleavage.

Oravecz T, Pall M, Roderiquez G, Gorrell MD, Ditto M, Nguyen NY, Boykins R, Unsworth E, Norcross MA - J. Exp. Med. (1997)

Activity of full-length  and truncated RANTES in cells  expressing recombinant CCR5  or CCR1 receptors. The [Ca2+]i  was measured in HEK-293 cells  expressing CCR5 (A and C) and  HOS-CD4 cells expressing CCR1  (B and D). (A and B) Cells were  stimulated with various concentrations of the two RANTES  variants as indicated and maximal  fluorescence values were calculated from the peaks of the Ca2+  response curves. (C and D) Homologous and heterologous desensitization of the responses induced by RANTES(1–68) and  RANTES(3–68) was measured  in transfectants as described in  Fig. 5.
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Related In: Results  -  Collection

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Figure 6: Activity of full-length and truncated RANTES in cells expressing recombinant CCR5 or CCR1 receptors. The [Ca2+]i was measured in HEK-293 cells expressing CCR5 (A and C) and HOS-CD4 cells expressing CCR1 (B and D). (A and B) Cells were stimulated with various concentrations of the two RANTES variants as indicated and maximal fluorescence values were calculated from the peaks of the Ca2+ response curves. (C and D) Homologous and heterologous desensitization of the responses induced by RANTES(1–68) and RANTES(3–68) was measured in transfectants as described in Fig. 5.
Mentions: HEK-293 cells expressing CCR5 and HOS-CD4 cells expressing CCR1 were loaded with Fura-2 and exposed to various concentrations of RANTES(1–68) or RANTES(3–68). The two RANTES variants showed similar abilities to increase [Ca2+]i in the CCR5 transfectant (Fig. 6 A); the responses were dose dependent, with 10 nM of each variant sufficient to induce a maximal Ca2+ response. In contrast, in the cells expressing CCR1, the amount of RANTES(3–68) required to produce a detectable Ca2+ response was ∼100 times that for RANTES(1–68) (Fig. 6 B); the effect of RANTES(1–68) saturated at 50 nM, whereas that of RANTES(3–68) appeared not to have achieved saturation at 200 nM. Furthermore, bidirectional cross-desensitization between the two RANTES variants was evident only with the cells expressing CCR5 (Fig. 6 C); in the CCR1 transfectant, cross-desensitization was induced by full-length RANTES but not by the truncated form, which also did not exhibit self-desensitization (Fig. 6 D). Control cells transfected with vector alone or with vectors encoding CCR2b, CCR3, or CXCR4 did not respond to these ligands (data not shown). These results thus confirm that the native and CD26-truncated RANTES variants exhibit markedly different activities at the CCR1 receptor.

Bottom Line: The truncated RANTES(3-68) lacked the ability of native RANTES(1-68) to increase the cytosolic calcium concentration in human monocytes, but still induced this response in macrophages activated with macrophage colony-stimulating factor.Analysis of chemokine receptor messenger RNAs and patterns of desensitization of chemokine responses showed that the differential activity of the truncated molecule results from an altered receptor specificity.Our results indicate that CD26-mediated processing together with cell activation-induced changes in receptor expression provides an integrated mechanism for differential cell recruitment and for the regulation of target cell specificity of RANTES, and possibly other chemokines.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematologic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA. tamas@helix.nih.gov

ABSTRACT
CD26 is a leukocyte activation marker that possesses dipeptidyl peptidase IV activity but whose natural substrates and immunological functions have not been clearly defined. Several chemo-kines, including RANTES (regulated on activation, normal T cell expressed and secreted), have now been shown to be substrates for recombinant soluble human CD26. The truncated RANTES(3-68) lacked the ability of native RANTES(1-68) to increase the cytosolic calcium concentration in human monocytes, but still induced this response in macrophages activated with macrophage colony-stimulating factor. Analysis of chemokine receptor messenger RNAs and patterns of desensitization of chemokine responses showed that the differential activity of the truncated molecule results from an altered receptor specificity. RANTES(3-68) showed a reduced activity, relative to that of RANTES(1-68), with cells expressing the recombinant CCR1 chemokine receptor, but retained the ability to stimulate CCR5 receptors and to inhibit the cytopathic effects of HIV-1. Our results indicate that CD26-mediated processing together with cell activation-induced changes in receptor expression provides an integrated mechanism for differential cell recruitment and for the regulation of target cell specificity of RANTES, and possibly other chemokines.

Show MeSH
Related in: MedlinePlus