Hyaluronan‐binding properties of human serum hemopexin

Hrkal, Zbyněk; Kuželová, Kateřina; Müller‐Eberhard, Ursula; Stern, Robert

doi:10.1016/0014-5793(96)00225-6

Cited by 25 publications

(20 citation statements)

References 18 publications

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“…In particular, PRG4 has a hemopexin-like domain near the C-terminus. Purified hemopexin interacts with hyaluronan (HA), 12 suggesting that the hemopexin-like domain could also mediate PRG4 binding to HA present at or near the articular surface. In addition, lubrication studies have shown that HA and PRG4 act in concert to reduce friction, 13 supporting the possibility of molecular interaction between the two at the articular surface.…”

Section: Introductionmentioning

confidence: 99%

PRG4 exchange between the articular cartilage surface and synovial fluid

Nugent-Derfus

Chan

Schumacher

et al. 2007

Journal Orthopaedic Research

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ABSTRACT:The boundary lubrication function of articular cartilage is mediated in part by proteoglycan 4 (PRG4) molecules, found both in synovial fluid (SF) and bound to the articular cartilage surface. Currently the mechanism by which PRG4 binds to the articular surface is not well understood. The objectives of this study were to determine (1) the effect of bathing fluid contents on PRG4 concentration at the articular surface ([PRG4] cart ), and (2) whether native PRG4 can be removed from the surface and subsequently repleted with PRG4 from synovial fluid. In one experiment, cylindrical cartilage disks were stored in solutions of various PRG4 concentrations, either in phosphate-buffered saline (PBS) or SF as the carrier fluid. In a separate experiment, cartilage disks were stored in solutions expected to remove native PRG4 from the articular surface and allow subsequent repletion with PRG4 from SF. [PRG4] cart was independent of PRG4 concentration of the bathing fluid, and was similar for both carrier fluids. PRG4 was removed from cartilage by treatment with hyaluronidase, reduction/alkylation, and sodium dodecyl sulphate, and was repleted fully by subsequent bathing in SF. These results suggest that the articular surface is normally saturated with tightly bound PRG4, but this PRG4 can exchange with the PRG4 in SF under certain conditions. This finding suggests that all tissues surrounding the joint cavity that secrete PRG4 into the SF may help to maintain lubrication function at the articular surface. ß

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Section: Introductionmentioning

confidence: 99%

PRG4 exchange between the articular cartilage surface and synovial fluid

Nugent-Derfus

Chan

Schumacher

et al. 2007

Journal Orthopaedic Research

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“…71 This finding was based on cloned complementary DNA corresponding to an abundant protein in a purified porcine liver fraction that exhibited hyaluronidase activity. Hrkal et al determined later 73 that human hemopexin does not possess hyaluronidase activity but that hyaluronidase, which is electrophoretically distinct from hemopexin, contaminated nearly half of their hemopexin preparations. Nevertheless, these authors found that a portion (10-60%) of their purified hemopexin could bind hyaluronic acid.…”

Section: Hemopexin As a Hyaluronidasementioning

confidence: 99%

“…Nevertheless, these authors found that a portion (10-60%) of their purified hemopexin could bind hyaluronic acid. In an agarose matrix, 73 the pattern of hemopexin-hyaluronic acid interaction exhibited microheterogeneity that varied from one serum sample to another as well as from one hemopexin preparation to another. Subsequently, however, purified hemopexin was found to be unable to bind hyaluronic acid in solution.…”

Section: Hemopexin As a Hyaluronidasementioning

confidence: 99%

“…Initial studies concerned the 100KF material that contained hemopexin and impurities as described above, and subsequent studies involved purified hemopexin preparations that SDS-PAGE analysis showed to contain various amounts of protein contaminants when stained with Ponceau S, 44 a protein stain that is less sensitive than Coomassie Blue. 81 A protocol for further fractionation of the 100KF fraction 44 used Blue-Sepharose chromatography, 11 a procedure shown to produce hemopexin contaminated with hyaluronidase, 73 to obtain samples containing hemopexin as well as multiple protein bands of >85 kDa. An alternative approach was also taken to fractionate a human 100KF preparation further by chromatography on a rabbit anti-hemopexin antibody affinity column, but the resulting product exhibited substantial cleavage following this treatment [Ref.…”

Section: Hemopexin As a Serine Proteasementioning

confidence: 99%

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An alternative view of the proposed alternative activities of hemopexin

2011

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Hemopexin is a plasma protein that plays a well-established biological role in sequestering heme that is released into the plasma from hemoglobin and myoglobin as the result of intravascular or extravascular hemolysis as well as from skeletal muscle trauma or neuromuscular disease. In recent years, a variety of additional biological activities have been attributed to hemopexin, for example, hyaluronidase activity, serine protease activity, proinflammatory and anti-inflammatory activity as well as suppression of lymphocyte necrosis, inhibition of cellular adhesion, and binding of divalent metal ions. This review examines the challenges involved in the purification of hemopexin from plasma and in the recombinant expression of hemopexin and evaluates the questions that these challenges and the characteristics of hemopexin raise concerning the validity of many of the new activities proposed for this protein. As well, an homology model of the three-dimensional structure of human hemopexin is used to reveal that the protein lacks the catalytic triad that is characteristic of many serine proteases but that hemopexin possesses two highly exposed Arg-Gly-Glu sequences that may promote interaction with cell surfaces.

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“…25,38 The final solution was made in Tris buffer (pH 7.4). Heat-inactivated Hx was used as an inactive control as described previously.…”

Section: Reagentsmentioning

confidence: 99%

Hemopexin Induces Nephrin-Dependent Reorganization of the Actin Cytoskeleton in Podocytes

Lennon

Singh

Welsh

et al. 2008

Journal of the American Society of Nephrology

108

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Hemopexin is an abundant plasma protein that effectively scavenges heme. When infused into rats, hemopexin induces reversible proteinuria, and activated hemopexin is increased in children with minimal change nephrotic syndrome. These observations suggest a role for hemopexin in glomerular disease; in this study, the effects of active hemopexin on human podocytes and glomerular endothelial cells, the two cell types that compose the glomerular filtration barrier, were investigated. Within 30 min of treatment with hemopexin, actin reorganized from stress fibers to cytoplasmic aggregates and membrane ruffles in wild-type podocytes. This did not occur in nephrin-deficient podocytes unless they were transfected with nephrin-expressing plasmids. Furthermore, hemopexin did not affect actin organization in cells that do not express nephrin, specifically human glomerular endothelial cells, fibroblasts, and HEK293 cells. The effects of hemopexin on wild-type podocytes reversed within 4 h and were inhibited by preincubation with human plasma. Treatment with hemopexin activated protein kinase B in both wild-type and nephrin-deficient podocytes but activated RhoA only in wild-type cells. In addition, hemopexin led to a selective increase in the passage of albumin across monolayers of glomerular endothelial cells and to a reduction in glycocalyx. In summary, active hemopexin causes nephrindependent remodeling of podocytes and affects permeability of the glomerular filtration barrier by degrading the glycocalyx.

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Hyaluronan‐binding properties of human serum hemopexin

Cited by 25 publications

References 18 publications

PRG4 exchange between the articular cartilage surface and synovial fluid

PRG4 exchange between the articular cartilage surface and synovial fluid

An alternative view of the proposed alternative activities of hemopexin

Hemopexin Induces Nephrin-Dependent Reorganization of the Actin Cytoskeleton in Podocytes

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