Showing papers by "Raghu Kalluri published in 2003"
TL;DR: This review highlights recent advances in the process of EMT signaling in health and disease and how it may be attenuated or reversed by selective cytokines and growth factors.
Abstract: Epithelial to mesenchymal transition (EMT) is a central mechanism for diversifying the cells found in complex tissues. This dynamic process helps organize the formation of the body plan, and while EMT is well studied in the context of embryonic development, it also plays a role in the genesis of fibroblasts during organ fibrosis in adult tissues. Emerging evidence from studies of renal fibrosis suggests that more than a third of all disease-related fibroblasts originate from tubular epithelia at the site of injury. This review highlights recent advances in the process of EMT signaling in health and disease and how it may be attenuated or reversed by selective cytokines and growth factors.
2,426 citations
TL;DR: The basement membrane (BM) as mentioned in this paper is a specialized form of extracellular matrix (ECM) which mediates tissue compartmentalization and sends signals to epithelial cells about the external microenvironment.
Abstract: In recent years, the basement membrane (BM)--a specialized form of extracellular matrix (ECM)--has been recognized as an important regulator of cell behaviour, rather than just a structural feature of tissues. The BM mediates tissue compartmentalization and sends signals to epithelial cells about the external microenvironment. The BM is also an important structural and functional component of blood vessels, constituting an extracellular microenvironment sensor for endothelial cells and pericytes. Vascular BM components have recently been found to be involved in the regulation of tumour angiogenesis, making them attractive candidate targets for potential cancer therapies.
1,560 citations
TL;DR: It is reported that BMP-7 reverses TGF-β1–induced epithelial-to-mesenchymal transition (EMT) by reinduction of E-cadherin, a key epithelial cell adhesion molecule, which provides evidence of cross talk between B MP-7 and TGF -β1 in the regulation of EMT in health and disease.
Abstract: Bone morphogenic protein (BMP)-7 is a 35-kDa homodimeric protein and a member of the transforming growth factor (TGF)-beta superfamily. BMP-7 expression is highest in the kidney, and its genetic deletion in mice leads to severe impairment of eye, skeletal and kidney development. Here we report that BMP-7 reverses TGF-beta1-induced epithelial-to-mesenchymal transition (EMT) by reinduction of E-cadherin, a key epithelial cell adhesion molecule. Additionally, we provide molecular evidence for Smad-dependent reversal of TGF-beta1-induced EMT by BMP-7 in renal tubular epithelial cells and mammary ductal epithelial cells. In the kidney, EMT-induced accumulation of myofibroblasts and subsequent tubular atrophy are considered key determinants of renal fibrosis during chronic renal injury. We therefore tested the potential of BMP-7 to reverse TGF-beta1-induced de novo EMT in a mouse model of chronic renal injury. Our results show that systemic administration of recombinant human BMP-7 leads to repair of severely damaged renal tubular epithelial cells, in association with reversal of chronic renal injury. Collectively, these results provide evidence of cross talk between BMP-7 and TGF-beta1 in the regulation of EMT in health and disease.
1,321 citations
TL;DR: It is demonstrated that anti-VEGF antibodies and sFlt-1 cause rapid glomerular endothelial cell detachment and hypertrophy, in association with down-regulation of nephrin, a key epithelial protein in the glomersular filtration apparatus, suggesting that down- regulation or neutralization of circulating VEGF may play an important role in the induction of proteinuria in various kidney diseases, some forms of cancer therapy and also in women with preeclampsia.
540 citations
TL;DR: Results indicate that MMP-generated fragments of basement membrane collagen can have endogenous function as integrin-mediated suppressors of pathologic angiogenesis and tumor growth.
522 citations
TL;DR: Collectively, such distinct properties of human tumstatin and human endostatin provide the first insight into their diverse antiangiogenic actions and argue for combining them for targeting tumor angiogenesis.
Abstract: Tumstatin and endostatin are two inhibitors of angiogenesis derived from precursor human collagen molecules known as α3 chain of type IV collagen and α1 chain of type XVIII collagen, respectively. Although both these inhibitors are noncollagenous (NC1) domain fragments of collagens, they only share a 14% amino acid homology. In the present study we evaluated the functional receptors, mechanism of action, and intracellular signaling induced by these two collagen-derived inhibitors. Human tumstatin prevents angiogenesis via inhibition of endothelial cell proliferation and promotion of apoptosis with no effect on migration, whereas human endostatin prevents endothelial cell migration with no effect on proliferation. We demonstrate that human tumstatin binds to αvβ3 integrin in a vitronectin/fibronectin/RGD cyclic peptide independent manner, whereas human endostatin competes with fibronectin/RGD cyclic peptide to bind α5β1 integrin. The activity of human tumstatin is mediated by αvβ3 integrin, whereas the activity of human endostatin is mediated by α5β1 integrin. Additionally, although human tumstatin binding to αvβ3 integrin leads to the inhibition of Cap-dependent translation (protein synthesis) mediated by focal adhesion kinase/phosphatidylinositol 3-kinase/Akt/mTOR/4E-BP1 pathway, human endostatin binding to α5β1 integrin leads to the inhibition of focal adhesion kinase/c-Raf/MEK1/2/p38/ERK1 mitogen-activated protein kinase pathway, with no effect on phosphatidylinositol 3-kinase/Akt/mTOR/4E-BP1 and Cap-dependent translation. Collectively, such distinct properties of human tumstatin and human endostatin provide the first insight into their diverse antiangiogenic actions and argue for combining them for targeting tumor angiogenesis.
457 citations
TL;DR: Treatment with rhBMP-7 leads to improved renal function, histology, and survival in mice deficient in the alpha3-chain of type IV collagen and MRL/MpJlpr/lpr lupus mice, two genetic models for chronic renal injury and fibrosis.
Abstract: Tubulointerstitial fibrosis is a hallmark feature of chronic renal injury. Specific therapies to control the progression of renal fibrosis toward end-stage renal failure are limited. Previous studi...
306 citations
TL;DR: Basement membrane matrix integrity, composition, and cell-matrix interactions play an important role in anchoring HSCs and preventing them from spreading within the space of Disse and potentially elsewhere in the liver.
269 citations
TL;DR: It is concluded that α-actinin-4 is required for normal glomerular function and the nonsarcomeric forms of α-Actininin (α-act inin-1 and α- actin in-4) are not functionally redundant, and these genetic studies demonstrate that the nonsArcomeric α- Actn4 is involved in the regulation of cell movement.
Abstract: Dominantly inherited mutations in ACTN4, which encodes α-actinin-4, cause a form of human focal and segmental glomerulosclerosis (FSGS). By homologous recombination in ES cells, we developed a mouse model deficient in Actn4. Mice homozygous for the targeted allele have no detectable α-actinin-4 protein expression. The number of homozygous mice observed was lower than expected under mendelian inheritance. Surviving mice homozygous for the targeted allele show progressive proteinuria, glomerular disease, and typically death by several months of age. Light microscopic analysis shows extensive glomerular disease and proteinaceous casts. Electron microscopic examination shows focal areas of podocyte foot-process effacement in young mice, and diffuse effacement and globally disrupted podocyte morphology in older mice. Despite the widespread distribution of α-actinin-4, histologic examination of mice showed abnormalities only in the kidneys. In contrast to the dominantly inherited human form of ACTN4-associated FSGS, here we show that the absence of α-actinin-4 causes a recessive form of disease in mice. Cell motility, as measured by lymphocyte chemotaxis assays, was increased in the absence of α-actinin-4. We conclude that α-actinin-4 is required for normal glomerular function. We further conclude that the nonsarcomeric forms of α-actinin (α-actinin-1 and α-actinin-4) are not functionally redundant. In addition, these genetic studies demonstrate that the nonsarcomeric α-actinin-4 is involved in the regulation of cell movement.
238 citations
Journal Article•
TL;DR: Inhibition of cell-ECM interactions with blocking antibodies to α1 and α2 integrins were sufficient to inhibit both haptotactic and chemotactic migration induced by individual growth factors, strongly suggesting that targeting these integRins to abrogate pathogenic cell- ECM interactions might be a promising tool for inhibiting growth factor-induced invasion and metastasis of HCC.
Abstract: As with many types of cancer, cell motility is an important factor in the progression and metastasis of hepatocellular carcinomas (HCC). HCC is associated with significant fibrosis in the liver. The fibrotic microenvironment in the liver is characterized by an altered composition of the extracellular matrix (ECM) and an abundance of growth factors that are likely conducive to migration of HCC cells. The purpose of this study was to delineate promigratory stimuli within the fibrotic microenvironment and to identify specific targets for prevention of HCC cell migration. We used a modified Boyden chamber system that allowed distinction between chemotactic (indirect stimulation) and haptotactic (direct stimulation) migration of two distinct HCC cell lines across the ECM-coated membrane. Fibrotic microenvironment-associated growth factors, such as transforming growth factor beta1 (TGF-beta1), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF), induced chemotactic and haptotactic migration of HepG2 and Chang cells. Neutralizing antibodies to individual growth factors significantly decreased chemotactic and haptotactic migration. Haptotactic stimulation, but not chemotactic stimulation of HCC cell lines with TGF-beta1, bFGF, and EGF, induced production of matrix metalloproteinase (MMP) 2, a potential mediator of migration. Inhibition of MMPs significantly decreased haptotactic migration induced by individual growth factors but had an insignificant effect on chemotactic migration, suggesting an MMP-independent migration in this setting. Inhibition of cell-ECM interactions with blocking antibodies to alpha1 and alpha2 integrins were sufficient to inhibit both haptotactic and chemotactic migration induced by individual growth factors, strongly suggesting that targeting these integrins to abrogate pathogenic cell-ECM interactions might be a promising tool for inhibiting growth factor-induced invasion and metastasis of HCC.
129 citations
TL;DR: Data demonstrate that, in Goodpasture's disease, regulatory CD25+ T cells play a role in inhibiting the autoimmune response, which may underlie the "single hit" nature of this condition.
TL;DR: In vivo and in vitro results provide direct evidence that the balance between Th1 and Th2 responses associates with the outcome ofAnti‐GBM disease in mice and show the importance of cell‐mediated immunity in the course and severity of autoimmune anti‐glomerular basement membrane disease in dogs.
Abstract: Anti-glomerular basement membrane (GBM) disease is a rapidly progressive glomerulonephritis (GN) resulting from autoimmunity against the Goodpasture antigen alpha3(IV)NC1. In addition to the well-characterized antibody contribution, a T helper 1 (Th1) response has been suspected as the culprit for glomerular injury. We induced anti-GBM disease in DBA/1, C57BL/6, AKR, and NOD mice with recombinant human alpha3(IV)NC1 to investigate the involvement of humoral and cellular autoimmunity. DBA/1 mice had crescentic GN 11 wk postimmunization with alpha3(IV)NC1. C57BL/6 and AKR mice developed a chronic disease course resulting in comparable kidney injury to DBA/1 mice within 6 months. NOD revealed only minor glomerular changes. The rapid course and the severity of the disease in DBA/1 mice can be explained by our immunological findings in their sera and splenocytes: 1) high antibody titers specific for the putative clinically relevant epitope of alpha3(IV)NC1 with Th1-type isotypes, and 2) a strong proliferative response and high amounts of the inflammatory cytokine IFN-gamma, secreted by splenocytes stimulated in vitro with alpha3(IV)NC1, with only low amounts of the anti-inflammatory cytokine IL-10. Our in vivo and in vitro results provide direct evidence that the balance between Th1 and Th2 responses associates with the outcome of anti-GBM disease in mice.
TL;DR: It is concluded that relaxin might be developed as a useful agent for the treatment of renal fibrosis by demonstrating that fibronectin is a target protein substrate for ubiquitin-dependent degradation.
Abstract: Fibronectin, a large adhesive glycoprotein, is a prominent constituent of the extracellular matrix. Abnormalities in fibronectin homeostasis occur in numerous disease states, ranging from primary fibrosing conditions to neoplastic transformation. We demonstrate that fibronectin is a target protein substrate for ubiquitin-dependent degradation. Coimmunoprecipitation experiments and confocal microscopy demonstrated ubiquitin-fibronectin interaction. In an in vitro model of renal fibrosis, relaxin, an insulin-like growth factor, increased ubiquitin-dependent fibronectin degradation. Relaxin also was evaluated in an anti-glomerular basement membrane model of renal fibrosis. Animals treated with relaxin experienced renoprotection, manifested by decreased serum creatinine and proteinuria. Histological evaluation of kidney sections from animals treated with relaxin showed decreased glomerulosclerosis and interstitial fibrosis. We conclude that relaxin might be developed as a useful agent for the treatment of renal fibrosis.
TL;DR: The results indicate that the ultrastructure of the filtration slit diaphragm is altered in patients with IgA nephropathy as a consequence of targeted downregulation of extracellular nephrin.
Abstract: Background: The identification of nephrin and CD2AP, podocyte proteins which modulate the properties of glomerular barrier selectivity, has made it possible to unravel the mechanisms undergoing foot process effacement and proteinuria. Here we explored the role of nephrin and CD2AP together with the integrity of the slit diaphragm in the pathogenesis of proteinuria in patients with acquired glomerular diseases. Methods: Nephrin mRNA and protein expression were systematically evaluated in 28 renal biopsy samples from adult patients with primary glomerular disease and proteinuria by in situ hybridization and immunohistochemistry using antibodies directed against extra- and intracellular nephrin and compared with biopsy samples from normal controls. CD2AP protein expression by immunohistochemistry was also assessed. Morphometrical analysis of the filtration slit was performed by transmission electron microscopy. Results: Nephrin mRNA and expression of the extracellular nephrin were markedly reduced in IgA nephropathy. No changes were found in patients with minimal change nephrosis and focal segmental glomerulosclerosis. The staining of intracellular nephrin and CD2AP did not change among patients. A comparable frequency of the filtration slits was observed in all patient groups, except in minimal change disease patients, due to extensive foot process effacement. The percentage of slit diaphragms with a filamentous image was markedly reduced in IgA nephropathy, but was comparable to controls in minimal change disease. Slit pore width showed a tendency to decrease both in patients with minimal change disease and IgA nephropathy. Conclusions: These results indicate that the ultrastructure of the filtration slit diaphragm is altered in patients with IgA nephropathy as a consequence of targeted downregulation of extracellular nephrin. Further studies are needed to evaluate the pathophysiological meaning of nephrin abnormality in IgA nephropathy and how these changes can be modulated by antiproteinuric therapy.