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PLATELET-DERIVED GROWTH FACTOR C
LATEST LITERATURE
1: The American journal of pathology, 2010 May 20,
PDGF-C Mediates Glomerular Capillary Repair.
[Abstract]Glomerular endothelial cell injury is a key component of a variety of diseases. Factors involved in glomerular endothelial cell repair are promising therapeutic agents for such diseases. Platelet-derived growth factor (PDGF)-C has pro-angiogenic properties; however, nothing is known about such functions in the kidney. We therefore investigated the consequences of either PDGF-C infusion or inhibition in rats with mesangioproliferative glomerulonephritis, which is accompanied by widespread glomerular endothelial cell damage. We also assessed the role of PDGF-C in a mouse model of thrombotic microangiopathy as well as in cultured glomerular endothelial cells. PDGF-C infusion in nephritic rats significantly reduced mesangiolysis and microaneurysm formation, whereas glomerular endothelial cell area and proliferation increased. PDGF-C infusion specifically up-regulated glomerular fibroblast growth factor-2 expression. In contrast, antagonism of PDGF-C in glomerulonephritis specifically reduced glomerular endothelial cell area and proliferation and increased mesangiolysis. Similarly, PDGF-C antagonism in murine thrombotic microangiopathy aggravated the disease and reduced glomerular endothelial area. In conditionally immortalized glomerular endothelial cells, PDGF-C was mitogenic and induced a 27-fold up-regulation of fibroblast growth factor-2 mRNA. PDGF-C also exerted indirect pro-angiogenic effects, since it induced endothelial cell mitogens and pro-angiogenic factors in mesangial cells and macrophages. These results identify PDGF-C as a novel, potent pro-angiogenic factor in the kidney that can accelerate capillary healing in experimental glomerulonephritis and thrombotic microangiopathy.
2: BMC cancer, 2009 Dec 8, 9(1)
Inverse correlation between PDGFC expression and lymphocyte infiltration in human papillary thyroid carcinoma.
[Abstract]ABSTRACT: BACKGROUND: Members of the PDGF family have been suggested as potential biomarkers for papillary thyroid carcinomas (PTC). However, it is known that both expression and stimulatory effect of PDGF ligands can be affected by inflammatory cytokines. We have performed a microarray study in a collection of PTCs, of which about half the biopsies contained tumour-infiltrating lymphocytes or thyroiditis. To investigate the expression level of PDGF ligands and receptors in PTC we measured the relative mRNA expression of all members of the PDGF family by qRT-PCR in 10 classical PTC, eight clinically aggressive PTC, and five non-neoplastic thyroid specimens, and integrated qRT-PCR data with microarray data to enable us to link PDGF-associated gene expression profiles into networks based on recognized interactions. Finally, we investigated potential influence on PDGF mRNA levels by the presence of tumour-infiltrating lymphocytes. METHODS: qRT-PCR was performed on PDGFA, PDGFB, PDGFC, PDGFD, PDGFRA PDGFRB and a selection of lymphocyte specific mRNA transcripts. Semiquantitative assessment of tumour-infiltrating lymphocytes was performed on the adjacent part of the biopsy used for RNA extraction for all biopsies, while direct quantitation by qRT-PCR of lymphocyte-specific mRNA transcripts were performed on RNA also subjected to expression analysis. Relative expression values of PDGF family members were combined with a cDNA microarray dataset and analyzed based on clinical findings and PDGF expression patterns. Ingenuity Pathway Analysis (IPA) was used to elucidate potential molecular interactions and networks. RESULTS: PDGF family members were differentially regulated at the mRNA level in PTC as compared to normal thyroid specimens. Expression of PDGFA (p=0.003), PDGFB (p=0.01) and PDGFC (p=0.006) were significantly up-regulated in PTCs compared to non-neoplastic thyroid tissue. In addition, expression of PDGFC was significantly up-regulated in classical PTCs as compared to clinically aggressive PTCs (p=0.006), and PDGFRB were significantly up-regulated in clinically aggressive PTCs (p=0.01) as compared to non-neoplastic tissue. Semiquantitative assessment of lymphocytes correlated well with quantitation of lymphocyte-specific gene expression. Further more, by combining TaqMan and microarray data we found a strong inverse correlation between PDGFC expression and the expression of lymphocyte specific mRNAs. CONCLUSIONS: At the mRNA level, several members of the PDGF family are differentially expressed in PTCs as compared to normal thyroid tissue. Of these, only the PDGFC mRNA expression level initially seemed to distinguish classical PTCs from the more aggressive PTCs. However, further investigation showed that PDGFC expression level correlated inversely to the expression of several lymphocyte specific genes, and to the presence of lymphocytes in the biopsies. Thus, we find that PDGFC mRNA expression were down-regulated in biopsies containing infiltrated lymphocytes or thyroiditis. No other PDGF family member could be linked to lymphocyte specific gene expression in our collection of PTCs biopsies.
3: Biology of reproduction, 2009 Oct, 81(4)
Platelet-derived growth factor C is upregulated in human uterine fibroids and regulates uterine smooth muscle cell growth.
[Abstract]Leiomyomata uteri (i.e., uterine fibroids) are benign tumors arising from the abnormal growth of uterine smooth muscle cells (SMCs). We show here that the expression of platelet-derived growth factor C (PDGFC) is higher in approximately 80% of uterine fibroids than in adjacent myometrial tissues examined. Increased expression of PDGFC is also observed in fibroid-derived SMCs (fSMCs) relative to myometrial-derived SMCs (mSMCs). Recombinant bioactive PDGFCC homodimer stimulates the growth of fSMCs and mSMCs in ex vivo cultures and prolongs the survival of fSMCs in Matrigel plugs implemented subcutaneously in immunocompromised mice. The knockdown of PDGF receptor-alpha (PDGFRA) through lentiviral-mediated RNA interference reduces the growth of fSMCs and mSMCs in ex vivo cultures and in Matrigel implants. Furthermore, two small molecule inhibitors of the PDGFR tyrosine kinase (i.e., imatinib and dasatinib) exerted negative effects on fSMC and mSMC growth in ex vivo cultures, albeit at concentrations that cannot be achieved in vivo. These results suggest that the PDGFCC/PDGFRA signaling module plays an important role in fSMC and mSMC growth, and that the upregulation of PDGFC expression may contribute to the clonal expansion of fSMCs in the development of uterine fibroids.
4: PloS one, 2009, 4(4)
PDGF-C induces maturation of blood vessels in a model of glioblastoma and attenuates the response to anti-VEGF treatment.
[Abstract]BACKGROUND: Recent clinical trials of VEGF inhibitors have shown promise in the treatment of recurrent glioblastomas (GBM). However, the survival benefit is usually short-lived as tumors escape anti-VEGF therapies. Here we tested the hypothesis that Platelet Derived Growth Factor-C (PDGF-C), an isoform of the PDGF family, affects GBM progression independent of VEGF pathway and hinders anti-VEGF therapy. PRINCIPAL FINDINGS: We first showed that PDGF-C is present in human GBMs. Then, we overexpressed or downregulated PDGF-C in a human GBM cell line, U87MG, and grew them in cranial windows in nude mice to assess vessel structure and function using intravital microscopy. PDGF-C overexpressing tumors had smaller vessel diameters and lower vascular permeability compared to the parental or siRNA-transfected tumors. Furthermore, vessels in PDGF-C overexpressing tumors had more extensive coverage with NG2 positive perivascular cells and a thicker collagen IV basement membrane than the controls. Treatment with DC101, an anti-VEGFR-2 antibody, induced decreases in vessel density in the parental tumors, but had no effect on the PDGF-C overexpressing tumors. CONCLUSION: These results suggest that PDGF-C plays an important role in glioma vessel maturation and stabilization, and that it can attenuate the response to anti-VEGF therapy, potentially contributing to escape from vascular normalization.
5: European journal of clinical investigation, 2009 Apr, 39(4)
PDGF-C and -D and their receptors PDGFR-alpha and PDGFR-beta in atherosclerotic human arteries.
[Abstract]BACKGROUND: Platelet derived growth factors (PDGFs) are mitogens for fibroblasts and smooth muscle cells. This growth factor family contains four members PDGF-A, PDGF-B, PDGF-C and PDGF-D. Biology of recently discovered PDGF-C and PDGF-D is not well-established. Here we studied the expression of PDGF-C and PDGF-D and their receptors PDGFR-alpha and PDGFR-beta in normal and atherosclerotic human arteries. MATERIALS AND METHODS: Human arterial samples from amputations and autopsies were classified according to the atherosclerotic stage and the expression of PDGF-C and PDGF-D proteins and their receptors was studied by immunohistochemistry. In situ hybridization and reverse transcriptase-PCR were used to study mRNA expression. RESULTS: Both growth factors were expressed in medial smooth muscle cells (SMCs) in normal arteries and atherosclerotic lesions. However, clear differences were found in the expression profiles in endothelium: PDGF-C was strongly expressed in endothelial cells in both normal arteries and lesions whereas PDGF-D was only weakly expressed in endothelium. PDGF-C expression was very prominent in lesion macrophages. PDGF-D was expressed throughout the artery wall in lesions. PDGFR-alpha expression was strong in endothelium and in lesion macrophage-rich areas, whereas PDGFR-beta was mostly expressed in SMCs. CONCLUSIONS: Our results suggest that PDGF-C may play an important role in endothelium in normal and atherosclerotic arteries and in macrophages in lesions. PDGF-D was expressed in all types of lesions with the same intensity and thus differs from the expression of PDGF-C.
6: Cancer cell, 2009 Jan 6, 15(1)
PDGF-C mediates the angiogenic and tumorigenic properties of fibroblasts associated with tumors refractory to anti-VEGF treatment.
[Abstract]Tumor- or cancer-associated fibroblasts (TAFs or CAFs) from different tumors exhibit distinct angiogenic and tumorigenic properties. Unlike normal skin fibroblasts or TAFs from TIB6 tumors that are sensitive to anti-VEGF treatment (TAF-TIB6), TAFs from resistant EL4 tumors (TAF-EL4) can stimulate TIB6 tumor growth even when VEGF is inhibited. We show that platelet-derived growth factor C (PDGF-C) is upregulated in TAFs from resistant tumors. PDGF-C-neutralizing antibodies blocked the angiogenesis induced by such TAFs in vivo, slowed the growth of EL4 and admixture (TAF-EL4 + TIB6) tumors, and exhibited additive effects with anti-VEGF-A antibodies. Hence, our data reveal an additional mechanism for TAF-mediated tumorigenesis and suggest that some tumors may overcome inhibition of VEGF-mediated angiogenesis through upregulation of PDGF-C.
7: European journal of human genetics : EJHG, 2008 Dec 17, 15(1)
The PDGF-C regulatory region SNP rs28999109 decreases promoter transcriptional activity and is associated with CL/P.
[Abstract]Human linkage and association studies suggest a gene(s) for nonsyndromic cleft lip with or without cleft palate (CL/P) on chromosome 4q31-q32 at or near the platelet-derived growth factor-C (PDGF-C) locus. The mouse Pdgfc(-/-) knockout shows that PDGF-C is essential for palatogenesis. To evaluate the role of PDGF-C in human clefting, we performed sequence analysis and SNP genotyping using 1048 multiplex CL/P families and 1000 case-control samples from multiple geographic origins. No coding region mutations were identified, but a novel -986 C>T SNP (rs28999109) was significantly associated with CL/P (P=0.01) in cases from Chinese families yielding evidence of linkage to 4q31-q32. Significant or near-significant association was also seen for this and several other PDGF-C SNPs in families from the United States, Spain, India, Turkey, China, and Colombia, whereas no association was seen in families from the Philippines, and Guatemala, and case-controls from Brazil. The -986T allele abolished six overlapping potential transcription regulatory motifs. Transfection assays of PDGF-C promoter reporter constructs show that the -986T allele is associated with a significant decrease (up to 80%) of PDGF-C gene promoter activity. This functional polymorphism acting on a susceptible genetic background may represent a component of human CL/P etiology.European Journal of Human Genetics advance online publication, 17 December 2008; doi:10.1038/ejhg.2008.245.
8: Cellular and molecular neurobiology, 2009 Mar, 29(2)
The molecular cloning of platelet-derived growth factor-C (PDGF-C) gene of Gekko japonicus and its expression change in the spinal cord after tail amputation.
[Abstract]The platelet-derived growth factor-C (PDGF-C) gene of Gekko japonicus was obtained from a brain and spinal cord cDNA library. The results of Northern blot showed that transcript of PDGF-C gene of gecko is 2.8 kb in length, and it was abundantly expressed in tissues of heart, lung, kidney, and ovary. In situ hybridization (ISH) revealed that positive hybridization signals were present in both gray matter and white matter of the spinal cord. The change of PDGF-C expression in the spinal cord after tail amputation was examined by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. The expression of PDGF-C in the spinal cord showed highest level at 1 day after tail amputation, and gradually decreased until 2 weeks, which indicated that the expression level of PDGF-C might be associated with the process of spinal cord injury and regeneration.
9: Experimental cell research, 2008 Aug 15, 314(14)
Identification and expression analysis of an N-terminally truncated isoform of human PDGF-C.
[Abstract]Platelet-derived growth factor C (PDGF-C) is a member of the PDGF family that plays an important role in developmental and physiological processes, and in human diseases. Here, we report a novel splice variant of human PDGF-C (PDGF-Cb), which encodes an N-terminally truncated protein, lacking the signal peptide and CUB domain. This variant is coexpressed with PDGF-C in all normal tissues analyzed. PDGF-Cb is produced as a cytoplasmic protein, and has a similar intracellular localization to PDGF-C, but is not secreted from transfected cells. Further, we show that PDGF-Cb can form heterodimers (PDGF-CCb) with PDGF-C, which is thereby retained and degraded within cells. In primary renal cell carcinoma (RCC), expression of the two alternatively spliced transcripts was different. Generally, expression of the full-length PDGF-C transcript was increased in RCC tumors, whereas expression of PDGF-Cb was not in the 30 analyzed cases with paired RCC tumor tissues and normal renal tissues. Based on these findings, we suggest that PDGF-Cb might act as a dominant negative molecule regulating the secretion of PDGF-C, and that deregulation of full-length PDGF-C is involved in RCC tumorigenesis.
10: Atherosclerosis, 2009 Feb, 202(2)
Effects of PDGF-C and PDGF-D on monocyte migration and MMP-2 and MMP-9 expression.
[Abstract]BACKGROUND AND AIMS: Atherosclerosis is a chronic inflammatory process involving the activity of several cytokines and growth factors. Platelet-derived growth factor-A (PDGF-A) and PDGF-B are important mitogens and chemoattractants for monocytes as well as smooth muscle cells. We sought to identify the role of PDGF-C and PDGF-D, two new members of the PDGF family, in monocyte migration and differentiation. We also assessed their effects in regulating matrix metalloproteinase-2 (MMP-2) and MMP-9, which are important for cell migration. METHODS AND RESULTS: PDGF-C and PDGF-D were expressed in macrophages, smooth muscle cells, and endothelial cells in human atherosclerotic plaques, as shown by immunohistochemical analysis. PDGF-C and PDGF-D mRNA and protein expression was induced after differentiation of THP-1 monocytes to macrophages, and both PDGF-C and PDGF-D induced MMP-9 mRNA expression in a concentration-dependent manner. Treatment of cells with PDGF-C or PDGF-D enhanced the secretion of MMP-2 and MMP-9 in a cell-dependent manner. In a migration assay using a Boyden chamber with 8 microm pore size, PDGF-C and PDGF-D attracted THP-1 monocytes in a concentration-dependent manner. CONCLUSIONS: Our data suggest that PDGF-C and PDGF-D, like PDGF-A and PDGF-B, play important roles in atherosclerosis by stimulating MMP activity and influencing monocyte migration.
11: Nucleic acids research, 2008 Apr, 36(6)
Angiotensin II induction of PDGF-C expression is mediated by AT1 receptor-dependent Egr-1 transactivation.
[Abstract]Platelet-derived growth factors are a family of mitogens and chemoattractants comprising of four ligand genes (A-, B-, C-, D-chains) implicated in many physiologic and pathophysiologic processes, including atherosclerosis, fibrosis and tumorigenesis. Our understanding of the molecular mechanisms, which regulate PDGF-C transcription remains incomplete. Transient transfection analysis, conventional and quantitative real-time PCR revealed the induction of PDGF-C transcription and mRNA expression in smooth muscle cells (SMCs) exposed to the peptide hormone angiotensin (ATII), which induces Egr-1. Occupancy of a G + C-rich element in the proximal region of the PDGF-C promoter was unaffected by ATII. Instead we discovered, using both nuclear extracts and recombinant proteins with EMSA and ChIP analyses, the existence of a second Egr-1-binding element located 500 bp upstream. ATII induction of PDGF-C transcription is mediated by the angiotensin type 1 receptor (AT1R) and Egr-1 activation through this upstream element. DNAzyme ED5 targeting Egr-1 blocked ATII-inducible PDGF-C expression. Moreover, increased PDGF-C expression after exposure to ATII depends upon the differentiation state of the SMCs. This study demonstrates the existence of this novel ATII-AT1R-Egr-1-PDGF-C axis in SMCs of neonatal origin, but not in adult SMCs, where ATII induces Egr-1 but not PDGF-C.
12: Investigative ophthalmology & visual science, 2008 Jan, 49(1)
Plasmin is the major protease responsible for processing PDGF-C in the vitreous of patients with proliferative vitreoretinopathy.
[Abstract]PURPOSE: Proliferative vitreoretinopathy (PVR) is the primary cause of failure of retinal reattachment surgery. Growth factors such as platelet-derived growth factor (PDGF) are strongly associated with PVR. Of the five PDGF family members, PDGF-C predominates in the vitreous of experimental and clinical PVR. PDGF-C is secreted as a latent protein that requires proteolytic processing for activation. Although tissue plasminogen activator (tPA) is primarily responsible for processing PDGF-C in cultured cells, it constitutes a minority of the processing activity in the vitreous of experimental animals and in patients with PVR. Identifying the major PDGF-C processing protease was the purpose of this study. METHODS: The presence of serum proteins in the vitreous was detected by Coomassie blue staining and Western blotting. PDGF-C processing activity was detected in an in vitro processing assay using either native or recombinant PDGF-C as the substrate. Plasmin activity was blocked using alpha(2)-plasmin inhibitor. Phosphorylation of the PDGF receptor (PDGFR) was monitored by antiphosphotyrosine Western blotting. Vitreous specimens were collected from experimental rabbits or from patients undergoing vitrectomy to repair retinal detachment or for other reasons. RESULTS: A number of prominent serum proteins (albumin and IgG) were detected in the vitreous of all patients undergoing retinal surgery. The level of these proteins markedly increased in the vitreous of rabbits as they developed PVR. These observations suggested that serum-borne proteases are also likely to be present in the vitreous. Indeed, plasmin (a protease capable of processing PDGF-C) was present in the vitreous from PVR rabbits and retinal surgery patients. Plasmin was dramatically more effective than tPA in processing PDGF-C in an in vitro assay. Blocking plasmin activity eliminated most of the processing activity in the vitreous of patients and rabbits with PVR. CONCLUSIONS: Plasmin was the major PDGF-C processing protease in the vitreous of PVR rabbits and patients undergoing retinal surgery. Blocking plasmin prevented the generation of active PDGF-C, which is the major PDGF isoform relevant for PVR. These observations are the first report of an in vivo protease responsible for processing PDGF-C. In addition, plasmin was identified as a novel therapeutic target for patients with PVR.
13: Zhonghua gan zang bing za zhi = Zhonghua ganzangbing zazhi = Chinese journal of hepatology, 2007 Nov, 15(11)
[Dynamic characteristics of PDGF-C during liver lipoid degeneration and fibrogenesis processes in rats]
[Abstract]Non-invasive therapies for the treatment of hepatocellular carcinoma (HCC) would be of great benefit to public health. To this end, we have developed a platelet-derived growth factor-C (PDGF-C) transgenic (Tg) mouse model, which mimics many aspects of human liver carcinogenesis. Specifically, overexpression of PDGF-C results in liver fibrosis, which is preceded by activation and proliferation of hepatic stellate cells, and is followed by the development of dysplastic lesions and angiogenesis, and progression to HCCs by 8 months of age. Here, we show that PDGF-C overexpression induces the proliferation of endothelial-like cells that are present in tumors and adjacent non-neoplastic parenchyma. The protein tyrosine kinase inhibitor, imatinib (Gleevec), decreases the proliferation of non-parenchymal cells (NPC) in vitro and in vivo, with concomitant inhibition of Akt. In vivo treatment with imatinib also blocks the expression of CD34 in PDGF-C Tg mice. Decreased NPC proliferation and CD34 expression correlated with lower levels of active ERK1/2 and total levels of PDGF receptor alpha (PDGFRalpha). In summary, the small molecule inhibitor imatinib attenuates stromal cell proliferation in PDGF-C-induced HCC, which coincides with decreased expression of both CD34 and PDGFRalpha, and activated Akt. Our findings suggest that imatinib may be efficacious in the treatment of hepatocarcinogenesis, particularly when neovascularization is present.
14: Investigative ophthalmology & visual science, 2007 Dec, 48(12)
PDGF-C and -D induced proliferation/migration of human RPE is abolished by inflammatory cytokines.
[Abstract]PURPOSE: The role of growth factors and inflammation in regulating retinal pigment epithelial (RPE) function is complex and still poorly understood. The present study investigated human RPE cell proliferation and migration mediated by platelet-derived growth factor (PDGF) and inflammatory cytokines. METHODS: Human fetal RPE (hfRPE) cells were obtained as previously described. Gene expressions of PDGF isoforms and their receptors were detected using real-time PCR. Protein expression, activity, and localization of PDGFR-alpha and -beta were analyzed by Western blot and immunohistochemistry. BrdU incorporation and wound healing assays were used to test the effects of different PDGF isoforms and inflammatory cytokines on hfRPE proliferation and migration. Annexin-V and phalloidin staining were used to detect apoptosis and the actin cytoskeleton, respectively. RESULTS: PDGF-C and PDGF-D proteins are expressed in native human adult RPE, and mRNA levels are up to 100-fold higher than PDGF-A and -B. PDGFR-alpha and -beta proteins are expressed in native adult RPE and hfRPE (mainly localized to the apical membrane). In hfRPE, these receptors can be activated by PDGF-CC and -DD. PDGF-CC, -DD, and -BB significantly increased hfRPE proliferation, whereas PDGF-DD, -BB, and -AB significantly increased cell migration. An inflammatory cytokine mixture (TNF-alpha/IL-1beta/IFN-gamma) completely inhibited the stimulatory effect of PDGF-BB, -CC, and -DD; in contrast, this mixture stimulated the proliferation of choroidal cells. This inflammatory cytokine mixture also induced apoptosis, significant disruption of actin filaments and zonula occludens (ZO-1), and a decrease in transepithelial resistance. CONCLUSIONS: These results suggest that proinflammatory cytokines in vivo can inhibit the proliferative effect of PDGF on human RPE and, at the same time, stimulate the proliferation of choroidal cells. They also suggest an important role of proinflammatory cytokines in overcoming local proliferative/wound-healing responses, thereby controlling the development of disease processes at the retina/RPE/choroid interface.
15: Differentiation; research in biological diversity, 2007 Nov, 75(9)
Targeting stromal cells for the treatment of platelet-derived growth factor C-induced hepatocellular carcinogenesis.
[Abstract]Non-invasive therapies for the treatment of hepatocellular carcinoma (HCC) would be of great benefit to public health. To this end, we have developed a platelet-derived growth factor-C (PDGF-C) transgenic (Tg) mouse model, which mimics many aspects of human liver carcinogenesis. Specifically, overexpression of PDGF-C results in liver fibrosis, which is preceded by activation and proliferation of hepatic stellate cells, and is followed by the development of dysplastic lesions and angiogenesis, and progression to HCCs by 8 months of age. Here, we show that PDGF-C overexpression induces the proliferation of endothelial-like cells that are present in tumors and adjacent non-neoplastic parenchyma. The protein tyrosine kinase inhibitor, imatinib (Gleevec), decreases the proliferation of non-parenchymal cells (NPC) in vitro and in vivo, with concomitant inhibition of Akt. In vivo treatment with imatinib also blocks the expression of CD34 in PDGF-C Tg mice. Decreased NPC proliferation and CD34 expression correlated with lower levels of active ERK1/2 and total levels of PDGF receptor alpha (PDGFRalpha). In summary, the small molecule inhibitor imatinib attenuates stromal cell proliferation in PDGF-C-induced HCC, which coincides with decreased expression of both CD34 and PDGFRalpha, and activated Akt. Our findings suggest that imatinib may be efficacious in the treatment of hepatocarcinogenesis, particularly when neovascularization is present.
16: Genesis (New York, N.Y. : 2000), 2007 Oct, 45(10)
Generation of conditional knockout alleles for PDGF-C.
[Abstract]PDGF-C is a newly identified member of the platelet-derived growth factor (PDGF) family, which is involved in multiple cellular functions by signaling through PDGF receptor (PDGFR)-alphaalpha and alphabeta dimers. PDGF-C deficiency is perinatal lethal due to the formation of cleft palate. To further characterize the cellular function of PDGF-C during both embryonic and postnatal development, we have generated two conditional alleles of the Pdgf-c gene in which two loxP sites flank exon 5. Global Cre-mediated excision of the floxed exon 5 in these alleles resulted in a complete loss of PDGF-C expression and caused embryonic defects identical to those previously described for the PDGF-C null embryos. These conditional alleles will therefore be the important genetic tools for dissecting the spatial and temporal roles of PDGF-C during development and in adult tissues. Furthermore, from this work, we have also described a simple approach for creating mouse conditional alleles in an efficient manner.
17: Experimental eye research, 2008 May, 86(5)
Focus on molecules: platelet-derived growth factor C, PDGF-C.
[Abstract]Platelet-derived growth factor C (PDGF-C) is a member of the PDGF family that plays an important role in developmental and physiological processes, and in human diseases. Here, we report a novel splice variant of human PDGF-C (PDGF-Cb), which encodes an N-terminally truncated protein, lacking the signal peptide and CUB domain. This variant is coexpressed with PDGF-C in all normal tissues analyzed. PDGF-Cb is produced as a cytoplasmic protein, and has a similar intracellular localization to PDGF-C, but is not secreted from transfected cells. Further, we show that PDGF-Cb can form heterodimers (PDGF-CCb) with PDGF-C, which is thereby retained and degraded within cells. In primary renal cell carcinoma (RCC), expression of the two alternatively spliced transcripts was different. Generally, expression of the full-length PDGF-C transcript was increased in RCC tumors, whereas expression of PDGF-Cb was not in the 30 analyzed cases with paired RCC tumor tissues and normal renal tissues. Based on these findings, we suggest that PDGF-Cb might act as a dominant negative molecule regulating the secretion of PDGF-C, and that deregulation of full-length PDGF-C is involved in RCC tumorigenesis.
18: Investigative ophthalmology & visual science, 2007 May, 48(5)
A potential role for PDGF-C in experimental and clinical proliferative vitreoretinopathy.
[Abstract]PURPOSE: Proliferative vitreoretinopathy (PVR) is a disorder characterized by the formation of cellular membranes on both surfaces of the retina and within the vitreous cavity. It occurs in 5% to 10% of patients who undergo retinal reattachment surgery. In the rabbit model of the disease, the platelet-derived growth factor alpha receptor (PDGFRalpha) is dramatically more capable of promoting PVR than is closely related PDGFRbeta. To test the ligand hypothesis (i.e., that this phenomenon can be explained by a predominance of PDGFRalpha-specific ligands) this study was conducted to determine the profile of PDGF ligands expressed by cells that induce PVR and in the vitreous of rabbits that have PVR. In addition, we examined which PDGF isoforms were present in the vitreous of patients with PVR, to assess the relevance of the rabbit model to the clinical setting. METHODS: PDGF isoforms were detected and quantified by Western blot analysis and ELISA. An assay was performed of conditioned medium from mouse embryo fibroblasts expressing the PDGFRalpha (Falpha) and rabbit conjunctival fibroblasts (RCFs), both of which cause PVR in the experimental model, and from human retinal pigment epithelial cells (ARPE-19). Because PDGF-C is secreted in a latent form and must be proteolytically processed to become biologically active, a PDGF-C processing assay was established, and conditioned medium was tested from these cells lines, for processing activity. Vitreous specimens, from control and PVR rabbits and from patients undergoing vitrectomy surgery, either to repair retinal detachment or for other reasons, were also tested for PDGF isoforms and for PDGF-C processing activity. RESULTS: PDGF isoforms that activate PDGFRbeta (PDGF-B and -D) were either undetectable or were present at very low levels in all the samples tested. Relatively low levels of PDGF-A and -AB were detected, whereas PDGF-C was the predominant isoform. Falpha, RCFs, and ARPE-19 cells accumulated PDGF-C in the conditioned medium at an average rate of 2.0 +/- 0.2, 2.9 +/- 0.3, and 71.3 +/- 6.0 ng/mL per day, respectively. Although there was no detectable PDGF-C in the vitreous of control rabbits (n = 8), there was an average of 1784 +/- 1150 ng/mL latent PDGF-C in the vitreous from rabbits with PVR (n= 14). Of the patients with PVR, eight of nine contained PDGF-C (range, 50-1000 ng/mL). In contrast, PDGF-C was detected in only 1 of 16 of the patients without PVR. In both conditioned medium and vitreous samples, the latent (instead of the active) form of PDGF-C was detected, even though processing activity was present in all the samples tested. CONCLUSIONS: The predominance of PDGF isoforms that activate PDGFRalpha support the ligand hypothesis as an explanation of why PDGFRalpha is more capable of inducing PVR than is PDGFRbeta. Furthermore, the profile of PDGF isoforms observed in the rabbit model accurately reflected the clinical specimens from patients with PVR. Finally, these findings implicate one of the new PDGF family members as an important contributor to experimental and clinical PVR.
19: Birth defects research. Part A, Clinical and molecular teratology, 2007 Mar, 79(3)
Platelet-derived growth factor C plays a role in the branchial arch malformations induced by retinoic acid.
[Abstract]BACKGROUND: All-trans-retinoic acid (RA) can produce branchial arch abnormalities in postimplantation rodent embryos cultured in vitro. Platelet-derived growth factor C (PDGF-C) was recently identified as a member of the PDGF ligand family. Many members of the PDGF family are essential for branchial arch morphogenesis and can be regulated by RA. The roles of PDGF-C in branchial arch malformations induced by RA and possible mechanisms were investigated. METHODS: In whole embryo culture (WEC), mouse embryos were exposed to RA at 0, 0.1, 0.4, 1.0, or 10.0 microM, PDGF-C at 25, 50, or 75 ng/mL, or PDGF-C at 25, 50, or 75 ng/mL containing 0.4 microM RA. After 48 h of culture, mouse embryos were examined for dysmorphogenesis, and whole-mount immunohistochemistry was applied to PDGF-C. In explant cultures, explants were exposed to the same doses of RA and PDGF-C as WEC. Semiquantitative RT-PCR, zymography, and reverse zymography were used to evaluate the expressions and activities of matrix metalloproteinase (MMP)-2, MMP-14, and tissue inhibitor of metalloproteinase (TIMP)-2. RESULTS: PDGF-C was reduced by RA, and exogenous PDGF-C rescued the branchial arch malformations induced by RA. Moreover, PDGF-C prevented RA-induced inhibition of the migratory ability of mesenchymal cells in the first branchial arch, by regulating the expressions of MMP-2, MMP-14, and TIPM-2. CONCLUSIONS: Our results suggest that RA exposure reduces the expression of PDGF-C. The branchial arch malformations resulting from fetal RA exposure are caused at least partially by loss of PDGF-C and subsequent misregulations of the expressions of MMP-2, MMP-14, and TIMP-2.