TY - JOUR

T1 - Natural carboxyterminal truncation of human CXCL10 attenuates glycosaminoglycan binding, CXCR3A signaling and lymphocyte chemotaxis, while retaining angiostatic activity

AU - Dillemans, Luna

AU - Yu, Karen

AU - De Zutter, Alexandra

AU - Noppen, Sam

AU - Gouwy, Mieke

AU - Berghmans, Nele

AU - Verhallen, Lisa

AU - De Bondt, Mirre

AU - Vanbrabant, Lotte

AU - Brusselmans, Stef

AU - Martens, Erik

AU - Schols, Dominique

AU - Verschueren, Patrick

AU - Rosenkilde, Mette M.

AU - Marques, Pedro Elias

AU - Struyf, Sofie

AU - Proost, Paul

PY - 2024

Y1 - 2024

N2 - Background: Interferon-γ-inducible protein of 10 kDa (IP-10/CXCL10) is a dual-function CXC chemokine that coordinates chemotaxis of activated T cells and natural killer (NK) cells via interaction with its G protein-coupled receptor (GPCR), CXC chemokine receptor 3 (CXCR3). As a consequence of natural posttranslational modifications, human CXCL10 exhibits a high degree of structural and functional heterogeneity. However, the biological effect of natural posttranslational processing of CXCL10 at the carboxy (C)-terminus has remained partially elusive. We studied CXCL10(1–73), lacking the four endmost C-terminal amino acids, which was previously identified in supernatant of cultured human fibroblasts and keratinocytes. Methods: Relative levels of CXCL10(1–73) and intact CXCL10(1–77) were determined in synovial fluids of patients with rheumatoid arthritis (RA) through tandem mass spectrometry. The production of CXCL10(1–73) was optimized through Fmoc-based solid phase peptide synthesis (SPPS) and a strategy to efficiently generate human CXCL10 proteoforms was introduced. CXCL10(1–73) was compared to intact CXCL10(1–77) using surface plasmon resonance for glycosaminoglycan (GAG) binding affinity, assays for cell migration, second messenger signaling downstream of CXCR3, and flow cytometry of CHO cells and primary human T lymphocytes and endothelial cells. Leukocyte recruitment in vivo upon intraperitoneal injection of CXCL10(1–73) was also evaluated. Results: Natural CXCL10(1–73) was more abundantly present compared to intact CXCL10(1–77) in synovial fluids of patients with RA. CXCL10(1–73) had diminished affinity for GAG including heparin, heparan sulfate and chondroitin sulfate A. Moreover, CXCL10(1–73) exhibited an attenuated capacity to induce CXCR3A-mediated signaling, as evidenced in calcium mobilization assays and through quantification of phosphorylated extracellular signal-regulated kinase-1/2 (ERK1/2) and protein kinase B/Akt. Furthermore, CXCL10(1–73) incited significantly less primary human T lymphocyte chemotaxis in vitro and peritoneal ingress of CXCR3+ T lymphocytes in mice. In contrast, loss of the four endmost C-terminal residues did not affect the inhibitory properties of CXCL10 on migration, proliferation, wound closure, phosphorylation of ERK1/2, and sprouting of human microvascular endothelial cells. Conclusion: Our study shows that the C-terminal residues Lys74-Pro77 of CXCL10 are important for GAG binding, signaling through CXCR3A, T lymphocyte chemotaxis, but dispensable for angiostasis. Graphical Abstract: (Figure presented.).

AB - Background: Interferon-γ-inducible protein of 10 kDa (IP-10/CXCL10) is a dual-function CXC chemokine that coordinates chemotaxis of activated T cells and natural killer (NK) cells via interaction with its G protein-coupled receptor (GPCR), CXC chemokine receptor 3 (CXCR3). As a consequence of natural posttranslational modifications, human CXCL10 exhibits a high degree of structural and functional heterogeneity. However, the biological effect of natural posttranslational processing of CXCL10 at the carboxy (C)-terminus has remained partially elusive. We studied CXCL10(1–73), lacking the four endmost C-terminal amino acids, which was previously identified in supernatant of cultured human fibroblasts and keratinocytes. Methods: Relative levels of CXCL10(1–73) and intact CXCL10(1–77) were determined in synovial fluids of patients with rheumatoid arthritis (RA) through tandem mass spectrometry. The production of CXCL10(1–73) was optimized through Fmoc-based solid phase peptide synthesis (SPPS) and a strategy to efficiently generate human CXCL10 proteoforms was introduced. CXCL10(1–73) was compared to intact CXCL10(1–77) using surface plasmon resonance for glycosaminoglycan (GAG) binding affinity, assays for cell migration, second messenger signaling downstream of CXCR3, and flow cytometry of CHO cells and primary human T lymphocytes and endothelial cells. Leukocyte recruitment in vivo upon intraperitoneal injection of CXCL10(1–73) was also evaluated. Results: Natural CXCL10(1–73) was more abundantly present compared to intact CXCL10(1–77) in synovial fluids of patients with RA. CXCL10(1–73) had diminished affinity for GAG including heparin, heparan sulfate and chondroitin sulfate A. Moreover, CXCL10(1–73) exhibited an attenuated capacity to induce CXCR3A-mediated signaling, as evidenced in calcium mobilization assays and through quantification of phosphorylated extracellular signal-regulated kinase-1/2 (ERK1/2) and protein kinase B/Akt. Furthermore, CXCL10(1–73) incited significantly less primary human T lymphocyte chemotaxis in vitro and peritoneal ingress of CXCR3+ T lymphocytes in mice. In contrast, loss of the four endmost C-terminal residues did not affect the inhibitory properties of CXCL10 on migration, proliferation, wound closure, phosphorylation of ERK1/2, and sprouting of human microvascular endothelial cells. Conclusion: Our study shows that the C-terminal residues Lys74-Pro77 of CXCL10 are important for GAG binding, signaling through CXCR3A, T lymphocyte chemotaxis, but dispensable for angiostasis. Graphical Abstract: (Figure presented.).

KW - Angiogenesis

KW - Chemokine

KW - CXCL10

KW - Lymphocytes

KW - Posttranslational modifications

KW - Proteolysis

KW - Solid phase peptide synthesis

U2 - 10.1186/s12964-023-01453-1

DO - 10.1186/s12964-023-01453-1

M3 - Journal article

C2 - 38308278

AN - SCOPUS:85183822767

VL - 22

JO - Cell Communication and Signaling

JF - Cell Communication and Signaling

SN - 1478-811X

IS - 1

M1 - 94

ER -