Heparan Sulfate/Heparin Oligosaccharides Protect Stromal Cell-derived Factor-1 (SDF-1)/CXCL12 against Proteolysis Induced by CD26/Dipeptidyl Peptidase IV

Abstract

Stromal cell-derived factor-1 (SDF-1) is a CXC chemokine that is constitutively expressed in most tissues and displayed on the cell surface in association with heparan sulfate (HS). Its numerous biological effects are mediated by a specific G protein-coupled receptor, CXCR4. A number of cells inactivate SDF-1 by specific processing of the N-terminal domain of the chemokine. In particular, CD26/dipeptidyl peptidase IV (DPP IV), a serine protease that co-distributes with CXCR4 at the cell surface, mediates the selective removal of the N-terminal dipeptide of SDF-1. We report here that heparin and HS specifically prevent the processing of SDF-1 by DPP IV expressed by Caco-2 cells. The level of processing increases with the level of differentiation of these cells, which correlates with an increase of DPP IV activity. A mutant SDF-1 that does not interact with HS is readily cleaved by DPP IV, a process that is not inhibited by HS, demonstrating that a productive interaction between HS and SDF-1 is required for the protection to take place. Moreover, we found that protection depends on the degree of polymerization of the HS sulfated S-domains. Finally a structural model of SDF-1, in complex with HS oligosaccharides of defined length, rationalizes the experimental data. The mechanisms by which HS regulates SDF-1 may thus include, in addition to its ability to locally concentrate the chemokine at the cell surface, a control of selective protease cleavage events that directly affect the chemokine activity.

Altered SDF-1/CXCR4 axis in patients with primary myelofibrosis and in the Gata1low mouse model of the disease

“…Since production of SDF-1 in the marrow of Gata1 low mice is not higher than normal (Figure 1), entrapment of SDF-1 within the increased number of mutant megakaryocytes reduces the amount of SDF-1 available for other cells in the marrow. Furthermore, since SDF-1 is very sensitive to protease degradation [27][28][29][30] and both the full length and its proteolytic products 58 are recognized by immunostaining, it is possible that the high levels of SDF-1 observed in the marrow both of Gata1 low mice and PV patients represent proteolytically cleaved SDF-1. In summary, it is possible that, in spite of high levels of SDF-1 immunostaining, the marrow of the animal model and of the PMF patients is deprived of functional SDF-1 because of increased SDF-1 uptake by the high numbers of defective megakaryocytes and presence of inactive degradation products of SDF-1 bound to the extracellular matrix.…”

“…In fact, under steady-state conditions, the levels of soluble SDF-1 present in the blood of younger animals are low. SDF-1 is very sensitive to protease degradation [27][28][29][30] .…”

Electron detachment dissociation of dermatan sulfate oligosaccharides

“…The doubly-charged peak at m/z 440.056 has also been assigned as a B 4 product. However, no product ion is present that differs from the doubly-charged B 4 product by the exact mass of SO 3 . The relationship of charge state to SO 3 loss has been previously observed by°Zaia°and°coworkers°for°heparin-like°molecules° [18].…”

“…GAGs participate in a number of important biological activities, such as binding growth factors and chemokines [2,3], inhibiting proteolysis [4], affecting angiogenesis [5], and acting as signaling molecules in response to cellular damage [6]. GAGs also play an important role in pathogenic infections [7][8][9], and have been shown to undergo alteration in certain types of cancer [10].…”

Prolonged transendothelial migration of human haematopoietic stem and progenitor cells (HSPCs) towards hydrogel-released SDF1

“…It is also known that heparin is a natural protector of SDF1 [31] that prevents the protein from degradation. Therefore, sulphated polysaccacharides define a promising starting point for the design of biomimetic matrices capable of modulating SDF1 gradients.…”