IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating type V TGF-β receptor (TβR-V)-mediated tumor suppressor signaling.

The TGF-β type V receptor (TβR-V) mediates growth inhibition by IGFBP-3 and TGF-β in epithelial cells and loss of TβR-V expression in these cells leads to development of carcinoma. The mechanisms by which TβR-V mediates growth inhibition (tumor suppressor) signaling remain elusive. Previous studies revealed that IGFBP-3 and TGF-β inhibit growth in epithelial cells by stimulating TβR-V-mediated IRS-1/2-dependent activation and cytoplasm-to-nucleus translocation of IGFBP-3- or TGF-β-stimulated protein phosphatase (PPase), resulting in dephosphorylation of pRb-related proteins (p107, p130) or pRb, and growth arrest.

Development of the LYVE-1 gene with an acidic-amino-acid-rich (AAAR) domain in evolution is associated with acquisition of lymph nodes and efficient adaptive immunity.

CRSBP-1 (mammalian LYVE-1) is a membrane glycoprotein highly expressed in lymphatic endothelial cells (LECs). It has multiple ligands, including hyaluronic acid (HA) and growth factors/cytokines (e.g.

7-Dehydrocholesterol (7-DHC), But Not Cholesterol, Causes Suppression of Canonical TGF-β Signaling and Is Likely Involved in the Development of Atherosclerotic Cardiovascular Disease (ASCVD).

For several decades, cholesterol has been thought to cause ASCVD. Limiting dietary cholesterol intake has been recommended to reduce the risk of the disease. However, several recent epidemiological studies do not support a relationship between dietary cholesterol and/or blood cholesterol and ASCVD.

DMSO Enhances TGF-β Activity by Recruiting the Type II TGF-β Receptor From Intracellular Vesicles to the Plasma Membrane.

Dimethyl sulfoxide (DMSO) is used to treat many diseases/symptoms. The molecular basis of the pharmacological actions of DMSO has been unclear. We hypothesized that DMSO exerts some of these actions by enhancing TGF-β activity.

Ethanol Enhances TGF-β Activity by Recruiting TGF-β Receptors From Intracellular Vesicles/Lipid Rafts/Caveolae to Non-Lipid Raft Microdomains.

Regular consumption of moderate amounts of ethanol has important health benefits on atherosclerotic cardiovascular disease (ASCVD). Overindulgence can cause many diseases, particularly alcoholic liver disease (ALD). The mechanisms by which ethanol causes both beneficial and harmful effects on human health are poorly understood.

CRSBP-1/LYVE-1 ligands stimulate contraction of the CRSBP-1-associated ER network in lymphatic endothelial cells.

CRSBP-l/LYVE-1 ligands (PDGF-BB, VEGF-A(165) and hyaluronic acid) have been shown to induce opening of lymphatic intercellular junctions in vitro and in vivo by stimulating contraction of lymphatic endothelial cells (LECs). The mechanism by which CRSBP-1 ligands stimulate contraction of LECs is not understood. Here we demonstrate that CRSBP-1 is localized to the plasma membrane as well as intracellular fibrillar structures in LECs, including primary human dermal LECs and SVEC4-10 cells.

CRSBP-1/LYVE-1 ligands disrupt lymphatic intercellular adhesion by inducing tyrosine phosphorylation and internalization of VE-cadherin.

Cell-surface retention sequence (CRS) binding protein (CRSBP-1) is a membrane glycoprotein identified by its ability to bind PDGF-BB and VEGF-A via their CRS motifs (clusters of basic amino acid residues). CRSBP-1 is identical to LYVE-1 and exhibits dual ligand (CRS-containing proteins and hyaluronic acid) binding activity, suggesting the importance of CRSBP-1 ligands in lymphatic function. Here, we show that CRSBP-1 ligands induce disruption of VE-cadherin-mediated intercellular adhesion and opening of intercellular junctions in lymphatic endothelial cell (LEC) monolayers as determined by immunofluorescence microscopy and Transwell permeability assay.

A mechanism by which dietary trans fats cause atherosclerosis.

Dietary trans fats (TFs) have been causally linked to atherosclerosis, but the mechanism by which they cause the disease remains elusive. Suppressed transforming growth factor (TGF)-β responsiveness in aortic endothelium has been shown to play an important role in the pathogenesis of atherosclerosis in animals with hypercholesterolemia. We investigated the effects of a high TF diet on TGF-β responsiveness in aortic endothelium and integration of cholesterol in tissues.

Inhibitors of clathrin-dependent endocytosis enhance TGFbeta signaling and responses.

Clathrin-dependent endocytosis is believed to be involved in TGFbeta-stimulated cellular responses, but the subcellular locus at which TGFbeta induces signaling remains unclear. Here, we demonstrate that inhibitors of clathrin-dependent endocytosis, which are known to arrest the progression of endocytosis at coated-pit stages, inhibit internalization of cell-surface-bound TGFbeta and promote colocalization and accumulation of TbetaR-I and SARA at the plasma membrane. These inhibitors enhance TGFbeta-induced signaling and cellular responses (Smad2 phosphorylation/nuclear localization and expression of PAI-1).

A novel TGF-beta antagonist speeds reepithelialization and reduces scarring of partial thickness porcine burns.

Scar formation after thermal injury is common and results in significant aesthetic and functional impairment. Transforming growth factor beta (TGF-beta) plays a significant role in scar formation. We tested the hypothesis that a novel TGF-beta peptantagonist would reduce scar formation and wound contraction in partial thickness burns by using a randomized controlled experiment.

Cholesterol modulates cellular TGF-beta responsiveness by altering TGF-beta binding to TGF-beta receptors.

Transforming growth factor-beta (TGF-beta) responsiveness in cultured cells can be modulated by TGF-beta partitioning between lipid raft/caveolae- and clathrin-mediated endocytosis pathways. The TbetaR-II/TbetaR-I binding ratio of TGF-beta on the cell surface has recently been found to be a signal that controls TGF-beta partitioning between these pathways. Since cholesterol is a structural component in lipid rafts/caveolae, we have studied the effects of cholesterol on TGF-beta binding to TGF-beta receptors and TGF-beta responsiveness in cultured cells and in animals.

Cholesterol suppresses cellular TGF-beta responsiveness: implications in atherogenesis.

Hypercholesterolemia is a major causative factor for atherosclerotic cardiovascular disease. The molecular mechanisms by which cholesterol initiates and facilitates the process of atherosclerosis are not well understood. Here, we demonstrate that cholesterol treatment suppresses or attenuates TGF-beta responsiveness in all cell types studied as determined by measuring TGF-beta-induced Smad2 phosphorylation and nuclear translocation, TGF-beta-induced PAI-1 expression, TGF-beta-induced luciferase reporter gene expression and TGF-beta-induced growth inhibition.

Cellular heparan sulfate negatively modulates transforming growth factor-beta1 (TGF-beta1) responsiveness in epithelial cells.

Cell-surface proteoglycans have been shown to modulate transforming growth factor (TGF)-beta responsiveness in epithelial cells and other cell types. However, the proteoglycan (heparan sulfate or chondroitin sulfate) involved in modulation of TGF-beta responsiveness and the mechanism by which it modulates TGF-beta responsiveness remain unknown. Here we demonstrate that TGF-beta1 induces transcriptional activation of plasminogen activator inhibitor-1 (PAI-1) and growth inhibition more potently in CHO cell mutants deficient in heparan sulfate (CHO-677 cells) than in wild-type CHO-K1 cells.

TGF-beta control of cell proliferation.

This article focuses on recent findings that the type V TGF-beta receptor (TbetaR-V), which co-expresses with other TGF-beta receptors (TbetaR-I, TbetaR-II, and TbetaR-III) in all normal cell types studied, is involved in growth inhibition by IGFBP-3 and TGF-beta and that TGF-beta activity is regulated by two distinct endocytic pathways (clathrin- and caveolar/lipid-raft-mediated). TGF-beta is a potent growth inhibitor for most cell types, including epithelial and endothelial cells. The signaling by which TGF-beta controls cell proliferation is not well understood.

Identification of insulin receptor substrate proteins as key molecules for the TbetaR-V/LRP-1-mediated growth inhibitory signaling cascade in epithelial and myeloid cells.

The type V TGF-beta receptor (TbetaR-V) mediates IGF-independent growth inhibition by IGFBP-3 and mediates growth inhibition by TGF-beta1 in concert with the other TGF-beta receptor types. TbetaR-V was recently found to be identical to LRP-1. Here we find that insulin and (Q3A4Y15L16) IGF-I (an IGF-I analog that has a low affinity for IGFBP-3) antagonize growth inhibition by IGFBP-3 in mink lung epithelial cells (Mv1Lu cells) stimulated by serum.

Identification and characterization of the acidic pH binding sites for growth regulatory ligands of low density lipoprotein receptor-related protein-1.

The type V TGF-beta receptor (TbetaR-V) plays an important role in growth inhibition by IGFBP-3 and TGF-beta in responsive cells. Unexpectedly, TbetaR-V was recently found to be identical to the LRP-1/alpha(2)M receptor; this has disclosed previously unreported growth regulatory functions of LRP-1. Here we demonstrate that, in addition to expressing LRP-1, all cells examined exhibit low affinity but high density acidic pH binding sites for LRP-1 growth regulatory ligands (TGF-beta(1), IGFBP-3, and alpha(2)M(*)).

Cellular growth inhibition by TGF-beta1 involves IRS proteins.

In Mv1Lu cells, insulin partially reverses transforming growth factor-beta1 (TGF-beta1) growth inhibition in the presence of alpha5beta1 integrin antagonists. TGF-beta1 appears to induce phosphorylation of IRS-2 in these cells; this is inhibited by a TGF-beta antagonist known to reverse TGF-beta growth inhibition. Stable transfection of 32D myeloid cells (which lack endogenous IRS proteins and are insensitive to growth inhibition by TGF-beta1) with IRS-1 or IRS-2 cDNA confers sensitivity to growth inhibition by TGF-beta1; this IRS-mediated growth inhibition can be partially reversed by insulin in 32D cells stably expressing IRS-2 and the insulin receptor (IR).

LRP-1/TbetaR-V mediates TGF-beta1-induced growth inhibition in CHO cells.

The type V transforming growth factor-beta (TGF-beta) receptor (TbetaR-V) is hypothesized to be involved in cellular growth inhibition by TGF-beta(1). Recently, TbetaR-V was found to be identical to low density lipoprotein receptor-related protein-1 (LRP-1). Here we demonstrate that TGF-beta(1) inhibits growth of wild-type CHO cells but not LRP-1-deficient mutant cells (CHO-LRP-1(-) cells).

Cellular growth inhibition by IGFBP-3 and TGF-beta1 requires LRP-1.

The type V TGF-beta receptor (TbetaR-V)/IGFBP-3 receptor mediates the IGF-independent growth inhibition induced by IGFBP-3. It also mediates the growth inhibitory response to TGF-beta1 in concert with other TGF-beta receptor types, and its loss may contribute to the malignant phenotype of human carcinoma cells. Here we demonstrate that TbetaR-V is identical to LRP-1/alpha2M receptor as shown by MALDI-TOF analysis of tryptic peptides of TbetaR-V purified from bovine liver.

Cloning, expression, characterization, and role in autocrine cell growth of cell surface retention sequence binding protein-1.

Cell surface retention sequence binding protein-1 (CRSBP-1) is a cell surface binding protein for the cell surface retention sequence (CRS) motif of the v-sis gene product (platelet-derived growth factor-BB). It has been shown to be responsible for cell surface retention of the v-sis gene product in v-sis-transformed cells (fibroblasts) and has been hypothesized to play a role in autocrine growth and transformation of these cells. Here we demonstrate that the CRSBP-1 cDNA cloned from bovine liver libraries encodes a 322-residue type I membrane protein containing a 23-residue signal peptide, a 215-residue cell surface domain, a 21-residue transmembrane domain, and a 63-residue cytoplasmic domain.

Fatty acids modulate transforming growth factor-beta activity and plasma clearance.

The activity and plasma clearance of transforming growth factor (TGF)-beta are known to be regulated by activated alpha2-macroglobulin (alpha2M*). This has been implicated in pathophysiological processes, but no small molecule compounds have been reported to modulate TGF-beta activity by affecting the interaction of TGF-beta and alpha2M*. Here, we demonstrate that fatty acids are capable of inhibiting complex formation of TGF-beta isoforms and alpha2M* as demonstrated by nondenaturing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Synthetic TGF-beta antagonist accelerates wound healing and reduces scarring.

Wound healing consists of re-epithelialization, contraction and formation of granulation and scar tissue. TGF-b is involved in these events, but its exact roles are not well understood. Here we demonstrate that topical application of a synthetic TGF-b antagonist accelerates re-epithelialization in pig burn wounds (100% re-epithelialization in antagonist-treated wounds vs.