Modulation of a Glycoprotein Recognition System on Rat Hepatic Endothelial Cells by Glucose and Diabetes Mellitus

Summerfield, John A.; Vergalla, John; Jones, E. Anthony

doi:10.1172/jci110573

Cited by 80 publications

(25 citation statements)

References 50 publications

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“…Cell Culture-Adult rat hepatocytes and HSC were prepared by collagenase perfusion (16) and Pronase-collagenase perfusion (17), respectively. They were maintained in Dulbecco's modified Eagle's medium supplemented with 10% (for hepatocytes) or 20% (for HSC) fetal bovine serum (FBS).…”

Section: Methodsmentioning

confidence: 99%

Interaction between GC Box Binding Factors and Smad Proteins Modulates Cell Lineage-specific α2(I) Collagen Gene Transcription

Inagaki

Nemoto²,

Nakao

et al. 2001

Journal of Biological Chemistry

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Type I collagen is produced predominantly in mesenchymal cells, but molecular mechanisms responsible for cell type-specific expression are virtually unknown. During fibrogenic process in the liver, activated hepatic stellate cells (HSC) are the main producers of type I collagen, whereas parenchymal hepatocytes produce little, if any, of this protein. We have previously reported that Sp1 and an interacting unknown factor(s) bind to the ؊313 to ؊255 sequence of the ␣2(I) collagen gene (COL1A2) and play essential roles for basal and TGF-␤-stimulated transcription in skin fibroblasts and HSC. Recently, Smad3 has been shown to bind to this region, and its interaction with Sp1 has been implicated in TGF-␤-elicited COL1A2 stimulation. The present study demonstrates predominant binding of Sp3 rather than Sp1 to this regulatory element in parenchymal hepatocytes. In these cells, this region did not exhibit strong enhancer activity or mediate the effect of TGF-␤. Transfection of HSC with an Sp3 expression plasmid abolished the COL1A2 response to TGF-␤, whereas overexpression of Sp1 in hepatocytes increased basal COL1A2 transcription and conferred TGF-␤ responsiveness. Functional and physical interactions between Sp1 and Smad3, but not between Sp3 and Smad3, were demonstrated using the bacterial GAL4 system and immunoprecipitationWestern blot analyses. These results indicate that cell lineage-specific interactions between GC box binding factors and Smad protein(s) may account, at least in part, for differential COL1A2 transcription and TGF-␤ responsiveness in HSC and parenchymal hepatocytes.Type I collagen, the major component of extracellular matrix in various organs, is produced predominantly in mesenchymal cells such as fibroblasts, osteoblasts, and myofibroblasts. It is composed of two ␣1 chains and one ␣2 chain, which are coordinately expressed but encoded by the distinct genes, COL1A1 1 and COL1A2, respectively. Transforming growth factor-␤1 (TGF-␤1, henceforth referred to as TGF-␤) plays important roles in stimulating type I collagen gene expression mainly at the levels of transcription (1). In the liver, it has been widely accepted that activated hepatic stellate cells (HSC) showing the morphological and functional features of myofibroblasts are the main producers of type I collagen (2, 3). By contrast, parenchymal hepatocytes produce little, if any, collagen during hepatic fibrogenesis (4, 5). Recent studies by us and others have indicated that both COL1A1 (6) and COL1A2 (7) transgenes are expressed in mesenchymal cells, but not in parenchymal hepatocytes, after carbon tetrachloride administration into transgenic mice harboring collagen promoter-reporter gene constructs. These results further confirmed the minor contribution of hepatocytes to collagen production. However, very little is known regarding the molecular mechanisms determining differential type I collagen gene expression in activated HSC and parenchymal hepatocytes.We have previously shown that similar regulatory mechanisms control COL1A2 transcription...

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Section: Methodsmentioning

confidence: 99%

Interaction between GC Box Binding Factors and Smad Proteins Modulates Cell Lineage-specific α2(I) Collagen Gene Transcription

Inagaki

Nemoto²,

Nakao

et al. 2001

Journal of Biological Chemistry

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“…Mannosylrich enzymes such as lysosomal hydrolases including Hex (11), myeloperoxidase (13), and plasminogen activator (14) are also taken up by MR that has been found in liver reticuloendothelial (Kupffer) cells (15)(16)(17), mononuclear phagocytes (18), retinal pigment epithelium (19), placenta (20), and recently in lymphoid dendritic cells (21). However, it is not known whether MR is expressed in ASM.…”

mentioning

confidence: 99%

A mannose receptor mediates mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth muscle cells.

Lew

Songu-Mize²,

Pontow³

et al. 1994

J. Clin. Invest.

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IntroductionThe putative mannose receptor (MR), previously implicated in mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth muscle (ASM) cells, was studied to determine its properties. (7). The mitogenic effect is blocked by yeast mannan, a mannose receptor (MR) blocker (8), but not by mannose-6-phosphate, a specific blocker of the cation independent mannose-6-phosphate/insulin-like growth factor II receptor (9), suggesting the involvement of a mannose-recognizing moiety (7).The well-studied mannose receptor of macrophages (M0MR) is involved in receptor-mediated endocytosis and molecular scavenging of ManGP as well as phagocytosis and host defense against mannosyl-rich pathogens (10-12). Mannosylrich enzymes such as lysosomal hydrolases including Hex (11), myeloperoxidase (13), and plasminogen activator (14)

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“…It is not surprising that it has been difficult to purify the Man-R from liver using affinity chromatography on immobilized ligands containing terminal mannose, procedures that are effective for isolation of the Man-R from lung (24), macrophage lines (26), and placenta (25), in light of the properties of the S4GGnM-R. It now seems likely that the S4GGnM-R we have isolated from liver accounts for a major fraction of binding and internalization of ligands containing terminal Man, Fuc, or GlcNAc by hepatic endothelial cells and Kupffer cells (41)(42)(43). The characteristics of binding and internalization of Man-BSA by the S4GGnM-R are likely to differ from those encountered with the Man-R of alveolar macrophages.…”

Section: Source Of Peptidementioning

confidence: 99%

Isolation of the SO4-4-GalNAcβ1,4GlcNAcβ1,2Manα-specific Receptor from Rat Liver

Fiete

Baenziger

1997

Journal of Biological Chemistry

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Glycoproteins, such as the glycoprotein hormone lutropin (LH), bear oligosaccharides terminating with the sequence SO 4 -4GalNAc␤1,4GlcNAc␤1,2Man␣ (S4GGnM) and are rapidly removed from the circulation by a receptor present in hepatic endothelial cells and Kupffer cells. Rapid removal from the circulation is essential for attaining maximal hormone activity in vivo. We have isolated a protein from rat liver which has the properties expected for the S4GGnM-specific receptor (S4GGnM-R). The S4GGnM-R is closely related to the macrophage mannose receptor (Man-R) both antigenically and structurally. At least 12 peptides prepared from the S4GGnM-R have amino acid sequences that are identical to those of the Man-R. Nonetheless, the ligand binding properties of the S4GGnM-R and the Man-R differ in a number of respects. The S4GGnM-R binds to immobilized LH but not to immobilized mannose, whereas the Man-R binds to immobilized mannose but not to immobilized LH. When analyzed using a binding assay that precipitates receptor ligand complexes with polyethylene glycol, the S4GGnM-R is able to bind S4GGnM-bovine serum albumin (S4GGnM-BSA) conjugates whereas the Man-R is not. In contrast both the S4GGnM-R and the Man-R are able to bind Man-BSA. Monosaccharides that inhibit binding of Man-BSA by the Man-R enhance binding by the S4GGnM-R. Oligosaccharides terminating with S4GGnM and those terminating with Man are bound at independent sites on the S4GGnM-R. The S4GGnM-R present in hepatic endothelial cells may account for clearance of glycoproteins bearing oligosaccharides terminating with S4GGnM and glycoproteins bearing oligosaccharides terminating with either mannose, fucose, or N-acetylglucosamine.Asn-linked oligosaccharides present on the glycoprotein hormones lutropin (LH) 1 and thyrotropin (TSH) terminate with the sequence SO 4 -4GalNAc␤1,4GlcNAc␤1,2Man␣ (S4GGnM), whereas those on follitropin and chorionic gonadotropin (CG) terminate with the sequence Sia␣2,3/6Gal␤1,4GlcNAc␤1, 2Man␣ (1-5). We have proposed that the sulfated oligosaccharides present on LH and TSH are critical for the expression of full biologic function by these hormones (6 -9). Terminal GalNAc-4-SO 4 does not influence binding to or activation of the LH/CG receptor itself (10) but does have a marked impact on the circulatory half-life of LH following secretion (7, 11) due to recognition of the sulfated oligosaccharides by a receptor expressed at the surface of hepatic endothelial cells and Kupffer cells (11,12). The rapid removal of LH from the circulation in conjunction with its release from granules in response to gonadotropin releasing hormone accounts for the episodic rise and fall in hormone levels seen in the circulation. Since the LH/CG receptor is a G-protein-coupled receptor, which rapidly becomes refractory to further stimulation following ligand binding (13-15), episodic stimulation may provide for maximal activation during the preovulatory surge in circulating LH levels. TSH shows similar properties with respect to half-life and receptor activatio...

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Modulation of a Glycoprotein Recognition System on Rat Hepatic Endothelial Cells by Glucose and Diabetes Mellitus

Cited by 80 publications

References 50 publications

Interaction between GC Box Binding Factors and Smad Proteins Modulates Cell Lineage-specific α2(I) Collagen Gene Transcription

Interaction between GC Box Binding Factors and Smad Proteins Modulates Cell Lineage-specific α2(I) Collagen Gene Transcription

A mannose receptor mediates mannosyl-rich glycoprotein-induced mitogenesis in bovine airway smooth muscle cells.

Isolation of the SO4-4-GalNAcβ1,4GlcNAcβ1,2Manα-specific Receptor from Rat Liver

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