Purification and analysis of proteinase-resistant mutants of recombinant platelet-derived growth factor-BB exhibiting improved biological activity.
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ABSTRACT:
SUBMITTER: Cook AL
PROVIDER: S-EPMC1130640 | biostudies-other | 1992 Jan
REPOSITORIES: biostudies-other
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Project description:A detailed biophysical study of the secondary and tertiary structures of recombinant platelet-derived growth factor (PDGF)-BB produced in yeast has been carried out. The secondary structure of the molecule is composed of 54% beta-sheet with less than 5% ordered helix. The single tryptophan residue has been shown to be solvent-accessible; however, the ability of the side chain to rotate is severely restricted. The fluorescence emission is quenched at pH 7.0 and in the presence of high salt, but dequenched by titration to lower pH with a pK of 5.8. Two proteinase-resistant mutants of PDGF [( Ser28]- and [Pro32]-PDGF-BB) have also been characterized and shown to have secondary and tertiary structures indistinguishable from wild-type PDGF-BB. These are, therefore, suitable stable background molecules in which to carry out structure-activity-relationship studies on PDGF-BB.
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Project description:Osteoarthritis (OA) arises from imbalance of cartilage metabolism between the synthesis and degradation of type II collagen by the chondrocyte. Collagen type II degradation is characterized by increase in the biomarker of C-telopeptide fragment of type II collagen (CTX-II), while the anabolic process of cartilage is characterized by an increase in the biosynthesis of procollagen amino terminal N-propeptide type IIA (PIIANP). Platelet derived growth factor (PDGF) with Hyaluronic Acid (HA) as a potent growth factor can be used to stimulate the higher formation of chondrocyte and PIIANP levels and lower CTX-II levels in mouse knee osteoarthritis model.
| S-EPMC6411620 | biostudies-literature
Project description:Yeast Pichia pastoris is a widely used system for heterologous protein expression. However, post-translational modifications, especially glycosylation, usually impede pharmaceutical application of recombinant proteins because of unexpected alterations in protein structure and function. The aim of this study was to identify glycosylation sites on recombinant human platelet-derived growth factor-BB (rhPDGF-BB) secreted by P. pastoris, and investigate possible effects of O-linked glycans on PDGF-BB functional activity. PDGF-BB secreted by P. pastoris is very heterogeneous and contains multiple isoforms. We demonstrated that PDGF-BB was O-glycosylated during the secretion process and detected putative O-glycosylation sites using glycosylation staining and immunoblotting. By site-directed mutagenesis and high-resolution LC/MS analysis, we, for the first time, identified two threonine residues at the C-terminus as the major O-glycosylation sites on rhPDGF-BB produced in P. pastoris. Although O-glycosylation resulted in heterogeneous protein expression, the removal of glycosylation sites did not affect rhPDGF-BB mitogenic activity. In addition, the unglycosylated PDGF-BB?Gly mutant exhibited the immunogenicity comparable to that of the wild-type form. Furthermore, antiserum against PDGF-BB?Gly also recognized glycosylated PDGF-BB, indicating that protein immunogenicity was unaltered by glycosylation. These findings elucidate the effect of glycosylation on PDGF-BB structure and biological activity, and can potentially contribute to the design and production of homogeneously expressed unglycosylated or human-type glycosylated PDGF-BB in P. pastoris for pharmaceutical applications.
| S-EPMC4689512 | biostudies-literature
Project description:Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.
| S-EPMC8881622 | biostudies-literature
Project description:Brain pericytes not only maintain the anatomical, biochemical and immune blood-brain barrier, but display features of mesenchymal stem cells (MSCs) in vitro. MSCs have pro-regenerative properties attributed to their secretome. However, whether also brain pericytes possess such pro-regenerative capacities is largely unknown. Here we characterize the secretome and microvesicle (MV) release of human brain pericytes mediated by platelet-derived growth factor-BB (PDGF-BB)/PDGF receptor beta (PDGFRβ) signalling. Upon PDGF-BB, pericytes release not only a plethora of growth factors and a panel of cytokines, but also MVs containing BDNF, FGFb, βNGF, VEGF and PLGF, a response that is specific for PDGFRβ signalling and activation of the ERK 1/2 pathway. In contrast, lipopolysaccharide (LPS), an activator of the innate immune system, stimulates the secretion of much higher amounts of mainly inflammatory cytokines and activates the NFκB pathway. Pericytes change their morphology and undergo opposite changes in surface marker expression, respectively. Our findings provide evidence that the secretome of human brain pericytes varies greatly depending on the exogenous stimulus. The differential secretory functions of pericytes may play an important role in either regulating neuroinflammation or contributing to neurorestoration and identify a possible new target cell for neuroregeneration.
| S-EPMC5757443 | biostudies-literature
Project description:Tissue engineering using mesenchymal stem cells (MSCs) holds great promise for regenerating critically sized bone defects. While the bone marrow-derived MSC is the most widely studied stromal/stem cell type for this application, its rarity within bone marrow and painful isolation procedure have motivated investigation of alternative cell sources. Adipose-derived stromal/stem cells (ASCs) are more abundant and more easily procured; furthermore, they also possess robust osteogenic potency. While these two cell types are widely considered very similar, there is a growing appreciation of possible innate differences in their biology and response to growth factors. In particular, reports indicate that their osteogenic response to platelet-derived growth factor BB (PDGF-BB) is markedly different: MSCs responded negatively or not at all to PDGF-BB while ASCs exhibited enhanced mineralization in response to physiological concentrations of PDGF-BB. In this study, we directly tested whether a fundamental difference existed between the osteogenic responses of MSCs and ASCs to PDGF-BB. MSCs and ASCs cultured under identical osteogenic conditions responded disparately to 20 ng/ml of PDGF-BB: MSCs exhibited no difference in mineralization while ASCs produced more calcium per cell. siRNA-mediated knockdown of PDGFRβ within ASCs abolished their ability to respond to PDGF-BB. Gene expression was also different; MSCs generally downregulated and ASCs generally upregulated osteogenic genes in response to PDGF-BB. ASCs transduced to produce PDGF-BB resulted in more regenerated bone within a critically sized murine calvarial defect compared to control ASCs, indicating PDGF-BB used specifically in conjunction with ASCs might enhance tissue engineering approaches for bone regeneration.
| S-EPMC4549224 | biostudies-literature
Project description:We showed previously that proliferating human islet-derived de-differentiated cells (DIDs) exhibit many characteristics of mesenchymal stem cells. Dispersed DIDs can be induced by serum deprivation to undergo mesenchymal-to-epithelial transition and aggregate into epithelial cell clusters (ECCs). Conversely, ECCs can be induced to disperse and undergo epithelial-to-mesenchymal transition (EMT) by re-addition of mammalian sera. In this study, we show that platelet-derived growth factor BB (PDGF-BB) mimics and mediates serum-induced ECCs' dispersal accompanied by accumulation of cytoplasmic ?-catenin and a decrease in the levels of insulin and glucagon mRNAs. Moreover, we show that PDGF-BB-induced dispersal of ECCs is a more general phenomenon that occurs also with bone marrow mesenchymal stem cells (BM-MSCs) and dermal fibroblasts (DFs). In DIDs, BM-MSCs, and DFs, PDGF decreased the levels of DKK1 mRNA, suggesting involvement of the Wnt signaling pathway. PDGF-BB stimulated a significant increase in S473 phosphorylation of Akt and the PI3K specific inhibitor (PIP828) partially inhibited PDGF-BB-induced ECC dispersal. Lastly, the PDGF-receptor (PDGF-R) antagonist JNJ-10198409 inhibited both PDGF-BB--and serum-induced ECC dispersal. Epidermal growth factor (EGF), which shares most of the PDGF signaling pathway, did not induce dispersal and only weakly stimulated Akt phosphorylation. Our data suggest that PDGF-BB mediates serum-induced DIDs dispersal, correlated with the activation of the PI3K-Akt pathway.
| S-EPMC6295663 | biostudies-literature
Project description:The field of tissue engineering is severely limited by a lack of microvascularization in tissue engineered constructs. Biomimetic poly(ethylene glycol) hydrogels containing covalently immobilized platelet-derived growth factor BB (PDGF-BB) were developed to promote angiogenesis. Poly(ethylene glycol) hydrogels resist protein absorption and subsequent non-specific cell adhesion, thus providing a "blank slate", which can be modified through the incorporation of cell adhesive ligands and growth factors. PDGF-BB is a key angiogenic protein able to support neovessel stabilization by inducing functional anastomoses and recruiting pericytes. Due to the widespread effects of PDGF in the body and a half-life of only 30 min in circulating blood, immobilization of PDGF-BB may be necessary. In this work bioactive, covalently immobilized PDGF-BB was shown to induce tubulogenesis on two-dimensional modified surfaces, migration in three-dimensional (3D) degradable hydrogels and angiogenesis in a mouse cornea micropocket angiogenesis assay. Covalently immobilized PDGF-BB was also used in combination with covalently immobilized fibroblast growth factor-2, which led to significantly increased endothelial cell migration in 3D degradable hydrogels compared with the presentation of each factor alone. When a co-culture of endothelial cells and mouse pericyte precursor 10T1/2 cells was seeded onto modified surfaces tubule formation was independent of surface modifications with covalently immobilized growth factors. Furthermore, the combination of soluble PDGF-BB and immobilized PDGF-BB induced a more robust vascular response compared with soluble PDGF-BB alone when implanted into an in vivo mouse cornea micropocket angiogenesis assay. Based on these results, we believe bioactive hydrogels can be tailored to improve the formation of functional microvasculature for tissue engineering.
| S-EPMC3049810 | biostudies-literature
Project description:Previously we have demonstrated that the phosphoinositide 3-kinase (PI-3K) signal-transduction pathway mediates platelet-derived growth factor (PDGF)-BB-induced glycosaminoglycan (GAG) synthesis in fetal lung fibroblasts. In the present study we further investigated the signal-transduction pathway(s) that results in PDGF-BB-induced GAG synthesis. Over-expression of a soluble PDGF beta-receptor as well as a mutated form of the beta-receptor, unable to bind PI-3K, diminished GAG synthesis in fetal lung fibroblasts subsequent to PDGF-BB stimulation. The PI-3K inhibitor wortmannin blocked PDGF-BB-induced Akt activity as well as significantly diminishing PDGF-BB-mediated GAG synthesis. Expression of dominant-negative PI-3K also abrogated Akt activity and GAG synthesis. Furthermore, expression of dominant-negative Akt abrogated endogenous Akt activity, Rab3D phosphorylation and GAG synthesis, whereas expression of constitutively activated Akt stimulated Rab3D phosphorylation and GAG synthesis in the absence of PDGF-BB. Over-expression of wild-type PTEN (phosphatase and tensin homologue deleted in chromosome 10) inhibited Akt activity and concomitantly attenuated GAG synthesis in fibroblasts stimulated with PDGF-BB. These data suggest that Akt is an integral protein involved in PDGF-BB-mediated GAG regulation in fetal lung fibroblasts.
| S-EPMC1222446 | biostudies-other
Project description:ObjectiveOsteoarthritis is caused by cartilage degeneration arising from cartilage degradation of type II collagen which synthesis also deteriorated. Nowadays, osteoarthritis is still difficult to handle because of the irreversibility and progressivity of the disease. Regenerative therapy offers a great challenge and better result for osteoarthritis treatment. This study aims to prove that the administration of recombinant platelet-derived growth factor-BB (rrPDGF-BB) with hyaluronic acid (HA) can stimulate the higher forms of chondrocyte and lower the YKL-40 levels as a specific marker of cartilage degradation in mouse knee osteoarthritis model.MethodThis was an experimental study, post-test only control group design using white Wistar rats as subjects that were induced by monosodium iodoacetate (MIA) to create osteoarthritis (OA). The treatment group was given treatment group was given rrPDGF-BB and HA, while no such treatment was given to the control group. The chondrocyte cell count was examined with routine histopathology, and YKL-40 levels were calculated by ELISA.ResultStatistical analysis using independent t-test showed that the mean difference in the number of cell counts of chondrocytes was significantly higher than the control group. While the mean difference of YKL-40 level in the treatment group was significantly lower compared to the control group with.ConclusionWe conclude that the administration of rrPDGF-BB and HA in mouse knee joint osteoarthritis model have a regenerative effect on knee joint cartilage characterized by a higher number of chondrocytes and lower YKL-40 levels.
| S-EPMC6978183 | biostudies-literature