The Experts below are selected from a list of 19452 Experts worldwide ranked by ideXlab platform
Avraham Raz - One of the best experts on this subject based on the ideXlab platform.
-
Galectin-3 in angiogenesis and metastasis
Glycobiology, 2014Co-Authors: Tatsuyoshi Funasaka, Avraham Raz, Pratima Nangia-makkerAbstract:Galectin-3 is a member of the family of β-galactosidebinding lectins characterized by evolutionarily conserved sequences defined by structural similarities in their carbohydrate-recognition domains. Galectin-3 is a unique, chimeric protein consisting of three distinct structural motifs: (i) a short NH2 terminal domain containing a serine phosphorylation site; (ii) a repetitive proline-rich collagen-α-like sequence cleavable by matrix metalloproteases; and (iii) a globular COOH-terminal domain containing a carbohydrate-binding motif and an NWGR anti-death motif. It is ubiquitously expressed and has diverse biological functions depending on its subcellular localization. Galectin-3 is mainly found in the cytoplasm, also seen in the nucleus and can be secreted by non-classical, secretory pathways. In general, secreted Galectin-3 mediates cell migration, cell adhesion and cell–cell interactions through the binding with high affinity to galactose-containing glycoproteins on the cell surface. Cytoplasmic Galectin-3 exhibits anti-apoptotic activity and regulates several signal transduction pathways, whereas nuclear Galectin-3 has been associated with premRNA splicing and gene expression. Its unique chimeric structure enables it to interact with a plethora of ligands and modulate diverse functions such as cell growth, adhesion, migration, invasion, angiogenesis, immune function, apoptosis and endocytosis emphasizing its significance in the process of tumor progression. In this review, we have focused on the role of Galectin-3 in tumor metastasis with special emphasis on angiogenesis.
-
Nucleoporin Nup98 mediates Galectin-3 nuclear-cytoplasmic trafficking.
Biochemical and Biophysical Research Communications, 2013Co-Authors: Tatsuyoshi Funasaka, Avraham Raz, Vitaly Balan, Richard W. WongAbstract:Nucleoporin Nup98 is a component of the nuclear pore complex, and is important in transport across the nuclear pore. Many studies implicate nucleoporin in cancer progression, but no direct mechanistic studies of its effect in cancer have been reported. We show here that Nup98 specifically regulates nucleus–cytoplasm transport of Galectin-3, which is a β-galactoside-binding protein that affects adhesion, migration, and cancer progression, and controls cell growth through the β-catenin signaling pathway in cancer cells. Nup98 interacted with Galectin-3 on the nuclear membrane, and promoted Galectin-3 cytoplasmic translocation whereas other nucleoporins did not show these functions. Inversely, silencing of Nup98 expression by siRNA technique localized Galectin-3 to the nucleus and retarded cell growth, which was rescued by Nup98 transfection. In addition, Nup98 RNA interference significantly suppressed downstream mRNA expression in the β-catenin pathway, such as cyclin D1 and FRA-1, while nuclear Galectin-3 binds to β-catenin to inhibit transcriptional activity. Reduced expression of β-catenin target genes is consistent with the Nup98 reduction and the Galectin-3–nucleus translocation rate. Overall, the results show Nup98’s involvement in nuclear–cytoplasm translocation of Galectin-3 and β-catenin signaling pathway in regulating cell proliferation, and the results depicted here suggest a novel therapeutic target/modality for cancers.
-
Galectin-3 binding and metastasis.
Methods in molecular biology (Clifton N.J.), 2012Co-Authors: Pratima Nangia-makker, Vitaly Balan, Avraham RazAbstract:Human Galectin-3 is a ~30 kDa unique chimeric gene product belonging to the family of non-integrin β-galactoside binding lectins with conserved amino acid sequences at the carbohydrate-binding motif (10). Clinical investigations have shown a correlation between expression of Galectin-3 and malignant properties of several types of cancers (11), consequently, Galectin-3 is thought to be a cancer-associated protein. It consists of three structural domains, each associated with at least one specific function: a) a N-terminal domain containing a serine phosphorylation site important to regulate its cellular signaling (12); b) a collagen-α-like sequence cleavable by matrix metalloproteinases (13); and c) a COOH terminal containing a single carbohydrate recognition domain (CRD) and the NWGR anti-death motif (14). Galectin-3 is mainly a cytosolic protein, but can easily traverse the intracellular and plasma membranes to translocate into the nucleus, mitochondria and be externalized, which suggests that Galectin-3 is a shuttling protein and may have multiple functions accordingly (15–17). Galectin-3 lacks the classical secretion signal sequence and does not pass through the standard ER/Golgi pathway (18), still it can be transported into the extra cellular milieu via a non-classical pathway (19), where it can interact with a myriad of partners regulating a number of biological functions (11) (20, 21). Many of the functions of Galectin-3 are dependent on its carbohydrate binding properties and therefore can be inhibited by a specific disaccharide inhibitor, namely lactose. The analysis of Galectin-3 properties often requires use of recombinant Galectin-3. Currently, a few methods are available to purify Galectin-3 either using affinity of Galectin-3 to the substrate or by using affinity tags fused to Galectin-3. Glutathione S-transferase (GST) is a popular affinity tag commonly used with recombinant proteins. The method is based on the affinity of GST to glutathione ligand coupled to a matrix. The binding of GST-tagged protein to matrix is reversible, and the fused protein can be eluted under mild, non-denaturating conditions by adding reduced glutathione to the elution buffer. If desired, cleavage of the protein from GST can be achieved using a site-specific protease whose recognition sequence is located immediately upstream of N-terminal of Galectin-3. GST-tagged Galectin-3 is constructed by inserting cDNA sequence encoding full length or fragment of Galectin-3 to multiple cloning site of one of the pGEX vectors or any other vector expressing GST protein under the regulation of bacterial or mammalian promoter. In case of pGEX vector the expression is under control of the tac promoter, which is induced by isopropyl β-D thiogalactoside (IPTG). All pGEX vectors also contain lacIq gene, which produce repressor protein preventing expression until induction by IPTG. Although all pGEX vectors have a range of protease cleavage recognition sites we use pGEX-6P vectors that contain unique cleavage site that is recognized by PreScission Protease. To analyze the binding of Galectin-3 to its receptors the most commonly used protocol involves labeling the protein either by biotin or by 125I (22, 23). We have discussed here the biotinylation protocol because of its relative simplicity and avoidance of radioactive reagents. After binding of biotin labeled protein to the cell surface receptors, the binding efficiency can be measured in terms of color development by using a substrate chromogen mixture. Laminin, fibronectin, or collagen type IV are the ECM proteins with affinity for Galectin-3 (24). In section 3.2a we describe the assay for binding of the cell surface proteins to ECM ligands. Since a number of surface proteins can bind to a ligand, this is generally performed as an indirect assay with a number of cell lines varying in their Galectin-3 expression that are derived from the same origin. It has been presumed that tumor cell surface lectins might play a role in cellular interactions in vivo that are important for the formation of emboli and for the arrest of circulating tumor cells (25). Homotypic aggregation is an assay that reflects on the formation of tumor cell emboli in circulation. This assay is performed using asialofetuin, which is a glycoprotein possessing several branched oligosaccharide side chains with terminal non-reducing galactosyl residues. It binds to the lectins present on the cell surface of tumor cells and induces homotypic aggregation by serving as a cross-linking bridge between adjacent cells (26). Heterotypic interactions between the tumor cells and endothelial cells can be measured by wound healing assay and the 3-dimensional co-cultures on Matrigel (27). These assays help in analyzing the interactive properties of different variants of Galectin-3, thus signifying the role of various mutations or protein fragments. One in vitro property of tumorigenic cells is their ability to grow progressively in semi-solid medium, which indicates an autonomy from growth regulatory mechanisms (28). Anchorage independent growth is an assay in which the cells are seeded on soft agar and allowed to grow. The cells, which divide and form colonies over a period of 10–15 days usually exhibit a higher metastatic potential in in vivo studies (5).
-
Galectin-3: A novel substrate for c-Abl kinase.
Biochimica et biophysica acta, 2010Co-Authors: Vitaly Balan, Pratima Nangia-makker, Yi Wang, Young Suk Jung, Avraham RazAbstract:Abstract Galectin-3, a s-galactoside-binding lectin, is found in cellular and extracellular location of the cell and has pleiotropic biological functions such as cell growth, cell adhesion and cell-cell interaction. It may exhibit anti- or pro-apoptotic activity depending on its localization and post-translational modifications. Two important post-translational modifications of Galectin-3 have been reported: its cleavage and phosphorylation. Cleavage of Galectin-3 was reported to be involved with angiogenic potential and apoptotic resistance. Phosphorylation of Galectin-3 regulates its sugar-binding ability. In this report we have identified novel tyrosine phosphorylation sites in Galectin-3 as well as the kinase responsible for its phosphorylation. Our results demonstrate that tyrosines at positions 79, 107 and 118 can be phosphorylated in vitro and in vivo by c-Abl kinase. Tyrosine 107 is the main target of c-Abl. Expression of Galectin-3 Y107F mutant in Galectin-3 null SK-Br-3 cells leads to morphological changes and increased motility compared to wild type Galectin-3. Further investigation is needed to better understand the functional significance of the novel tyrosine phosphorylated sites of Galectin-3.
-
Regulation of Prostate Cancer Progression by Galectin-3
The American journal of pathology, 2009Co-Authors: Yi Wang, Kenneth J. Pienta, Victor Hogan, Pratima Nangia-makker, Vitaly Balan, Larry Tait, Avraham RazAbstract:Galectin-3, a β-galactoside-binding protein, has been implicated in a variety of biological functions including cell proliferation, apoptosis, angiogenesis, tumor progression, and metastasis. The present study was undertaken to understand the role of Galectin-3 in the progression of prostate cancer. Immunohistochemical analysis of Galectin-3 expression revealed that Galectin-3 was cleaved during the progression of prostate cancer. Galectin-3 knockdown by small interfering RNA (siRNA) was associated with reduced cell migration, invasion, cell proliferation, anchorage-independent colony formation, and tumor growth in the prostates of nude mice. Galectin-3 knockdown in human prostate cancer PC3 cells led to cell-cycle arrest at G1 phase, up-regulation of nuclear p21, and hypophosphorylation of the retinoblastoma tumor suppressor protein (pRb), with no effect on cyclin D1, cyclin E, cyclin-dependent kinases (CDK2 and CDK4), and p27 protein expression levels. The data obtained here implicate Galectin-3 in prostate cancer progression and suggest that Galectin-3 may serve as both a diagnostic marker and therapeutic target for future disease treatments.
Fu-tong Liu - One of the best experts on this subject based on the ideXlab platform.
-
Galectin-3 and Inflammation
2016Co-Authors: Lei Wan, Fu-tong LiuAbstract:Galectins are a family of β-galactoside-binding proteins that share a consensus sequence in the carbohydrate recognition domain (CRD). Galectin-3 is the most widely studied family member and can be found in the cellular cytoplasm and nucleus, as well as extracellularly in various tissues. The 30-kDa molecule contains an N-terminal proline-rich domain that is important for its oligomerization and a C-terminal CRD for carbohydrate-binding activity. Many studies have shown that Galectin-3 may regulate inflammation through a variety of mechanisms. Endogenous Galectin-3 has been shown to be involved in the pathogenesis of various diseases, such as fibrosis in the lung, liver, and heart, diabetes mellitus, coronary artery disease, and allergic diseases. In this review, we briefly discuss the pro- or anti-inflammatory roles, as well as potential clinical implications of Galectin-3 in these disorders.
-
Galectin-3 regulates the innate immune response of human monocytes.
The Journal of Infectious Diseases, 2012Co-Authors: Andrew W. Chung, Peter A. Sieling, Mirjam Schenk, Rosane M. B. Teles, Stephan R. Krutzik, Daniel K. Hsu, Fu-tong Liu, Euzenir Nunes Sarno, Thomas H. Rea, Steffen StengerAbstract:Galectin-3 is a β-galactoside-binding lectin widely expressed on epithelial and hematopoietic cells, and its expression is frequently associated with a poor prognosis in cancer. Because it has not been well-studied in human infectious disease, we examined Galectin-3 expression in mycobacterial infection by studying leprosy, an intracellular infection caused by Mycobacterium leprae. Galectin-3 was highly expressed on macrophages in lesions of patients with the clinically progressive lepromatous form of leprosy; in contrast, Galectin-3 was almost undetectable in self-limited tuberculoid lesions. We investigated the potential function of Galectin-3 in cell-mediated immunity using peripheral blood monocytes. Galectin-3 enhanced monocyte interleukin 10 production to a TLR2/1 ligand, whereas interleukin 12p40 secretion was unaffected. Furthermore, Galectin-3 diminished monocyte to dendritic cell differentiation and T-cell antigen presentation. These data demonstrate an association of Galectin-3 with unfavorable host response in leprosy and a potential mechanism for impaired host defense in humans.
-
Galectin-3 and the skin.
Journal of dermatological science, 2011Co-Authors: Larissa N Larsen, Huan Yuan Chen, Jun Saegusa, Fu-tong LiuAbstract:Galectin-3 is highly expressed in epithelial cells including keratinocytes and is involved in the pathogenesis of inflammatory skin diseases by affecting the functions of immune cells. For example, Galectin-3 can contribute to atopic dermatitis (AD) by promoting polarization toward a Th2 immune response by regulating dendritic cell (DC) and T cell functions. In addition, Galectin-3 may be involved in the development of contact hypersensitivity by regulating the migratory capacity of antigen presenting cells. Galectin-3 may act as a regulator of epithelial tumor progression and development through various signaling pathways, such as inhibiting keratinocyte apoptosis through regulation of the activation status of extracellular signal-regulated kinase (ERK) and activated protein kinase B (AKT). Galectin-3 is detected at different stages of melanoma development. In contrast, a marked decrease in the expression of Galectin-3 is observed in non-melanoma skin cancers, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Galectin-3 may play an important role in tumor cell growth, apoptosis, cell motility, invasion, and metastasis. Galectin-3 may be a novel therapeutic target for a variety of skin diseases.
-
Role of Galectin-3 in prion infections of the CNS
Biochemical and biophysical research communications, 2007Co-Authors: Simon W. F. Mok, Daniel K. Hsu, Fu-tong Liu, Constanze Riemer, Kazimierz Madela, Sandra Gültner, Ines Heise, Michael BaierAbstract:Galectin-3 is a multi-functional protein and participates in mediating inflammatory reactions. The pronounced overexpression of Galectin-3 in prion-infected brain tissue prompted us to study the role of this protein in a murine prion model. Immunofluorescence double-labelling identified microglia as the major cell type expressing Galectin-3. Ablation of Galectin-3 did not affect PrP(Sc)-deposition and development of gliosis. However, Galectin-3(-/-)-mice showed prolonged survival times upon intracerebral and peripheral scrapie infections. Moreover, protein levels of the lysosomal activation marker LAMP-2 were markedly reduced in prion-infected Galectin-3(-/-)-mice suggesting a role of Galectin-3 in regulation of lysosomal functions. Lower mRNA levels of Beclin-1 and Atg5 in prion-infected wild-type and Galectin-3(-/-)-mice indicated an impairment of autophagy although autophagosome formation was unchanged. The results point towards a detrimental role of Galectin-3 in prion infections of the CNS and suggest that endo-/lysosomal dysfunction in combination with reduced autophagy may contribute to disease development.
-
Roles of Galectin-3 in immune responses.
Archivum immunologiae et therapiae experimentalis, 2005Co-Authors: Huan Yuan Chen, Fu-tong Liu, Ri Yao YangAbstract:Galectins are a family of animal lectins with conserved carbohydrate-recognition domains for beta-galactoside. Galectin-3 is the only family member that is composed of a glycine/prolinerich N-terminal repeated sequence and a C-terminal carbohydrate-binding domain.Multiple functions of Galectin-3 have been reported, depending on its location. Extracellular Galectin-3 can bind to cell surface through glycosylated proteins and thereby trigger or modulate cellular responses such as mediator release or apoptosis. Intracellular Galectin-3 has been reported to inhibit apoptosis, regulate the cell cycle, and participate in the nuclear splicing of pre-mRNA. Recent studies have revealed that Galectin-3 is expressed in a variety of cell types in the immune system, constitutively or in response to microbial invasion. These studies implicate Galectin-3 in both innate and adaptive immune responses, where it participates in the activation or differentiation of immune cells. This review summarizes the roles of Galectin-3 in the immune system and discusses the possible underlying mechanisms.
Giuseppe Pugliese - One of the best experts on this subject based on the ideXlab platform.
-
Role of Galectin-3 in Obesity and Impaired Glucose Homeostasis.
Oxidative medicine and cellular longevity, 2015Co-Authors: Stefano Menini, Claudia Blasetti Fantauzzi, Carla Iacobini, Carlo Pesce, Giuseppe PuglieseAbstract:Galectin-3 is an important modulator of several biological functions. It has been implicated in numerous disease conditions, particularly in the long-term complications of diabetes because of its ability to bind the advanced glycation/lipoxidation end products that accumulate in target organs and exert their toxic effects by triggering proinflammatory and prooxidant pathways. Recent evidence suggests that Galectin-3 may also participate in the development of obesity and type 2 diabetes. It has been shown that Galectin-3 levels are higher in obese and diabetic individuals and parallel deterioration of glucose homeostasis. Two studies in Galectin-3 knockout mice fed a high-fat diet (HFD) have shown increased adiposity and adipose tissue and systemic inflammation associated with altered glucose homeostasis, suggesting that Galectin-3 negatively modulates the responsiveness of innate and adaptive immunity to overnutrition. However, these studies have also shown that impaired glucose homeostasis occurs in Galectin-3 knockout animals independently of obesity. Moreover, another study reported decreased weight and fat mass in HFD-fed Galectin-3 knockout mice. In vitro, Galectin-3 was found to stimulate differentiation of preadipocytes into mature adipocytes. Altogether, these data indicate that Galectin-3 deserves further attention in order to clarify its role as a potential player and therapeutic target in obesity and type 2 diabetes.
-
Galectin-3 in diabetic patients
Clinical chemistry and laboratory medicine, 2014Co-Authors: Giuseppe Pugliese, Carla Iacobini, Carlo Ricci, Claudia Blasetti Fantauzzi, Stefano MeniniAbstract:Galectin-3 is a versatile molecule which exerts several and sometimes opposite functions in various pathophysiological processes. Recently, Galectin-3 has gained attention as a powerful predictor of heart fail- ure and mortality, thus becoming a useful prognostic marker in clinical practice. Moreover, though not spe- cifically investigated in diabetic cohorts, plasma levels of Galectin-3 correlated with the prevalence of diabetes and related metabolic conditions, thus suggesting that phar- macological blockade of this lectin might be successful for treating heart failure especially in subjects suffering from these disorders. Indeed, Galectin-3 is considered not only as a marker of heart failure, but also as a mediator of the disease, due to its pro-fibrotic action, though evidence comes mainly from studies in Galectin-3 deficient mice. However, these studies have provided contrasting results, with either attenuation or acceleration of organ fibrosis and inflammation, depending on the experimental set- ting and particularly on the levels of advanced glycation endproducts (AGEs)/advanced lipoxidation endprod- ucts (ALEs), of which Galectin-3 is a scavenging receptor. In fact, under conditions of increased AGE/ALE levels, Galectin-3 ablation was associated with tissue-specific outcomes, reflecting the AGE/ALE-receptor function of this lectin. Conversely, in experimental models of acute inflammation and fibrosis, Galectin-3 deficiency resulted in attenuation of tissue injury. There is a need for prospec- tive studies in diabetic patients specifically investigating the relation of Galectin-3 levels with complications and for further animal studies in order to establish the effective role of this lectin in organ damage before considering its pharmacological blockade in the clinical setting.
-
Role of Galectin-3 in Diabetic Nephropathy
Journal of the American Society of Nephrology, 2003Co-Authors: Carla Iacobini, Carlo Ricci, Lorena Amadio, Giovanna Oddi, Paola Barsotti, Serena Missori, Mariella Sorcini, Umberto Di Mario, Flavia Pricci, Giuseppe PuglieseAbstract:ABSTRACT. The advanced glycosylation end products (AGE) participate in the pathogenesis of nephropathy and other diabetic complications through several mechanisms, including their binding to cell surface receptors. The AGE receptors include RAGE, the macrophage scavenger receptors, OST-48 (AGE-R1), 80K-H (AGE-R2), and Galectin-3 (AGE-R3). Galectin-3 interacts with the β-galactoside residues of cell surface and matrix glycoproteins via the carbohydrate recognition domain and with intracellular proteins via peptide–peptide associations mediated by its N-terminus domain. These structural properties enable Galectin-3 to exert multiple functions, including the mRNA splicing activity, the control of cell cycle, the regulation of cell adhesion, the modulation of allergic reactions, and the binding of AGE. The lack of transmembrane anchor sequence or signal peptide suggests that it is associated with other AGE receptors, possibly AGE-R1 and AGE-R2, to form an AGE-receptor complex, rather than playing an independent role. In target tissues of diabetic vascular complications, such as the endothelium and mesangium, Galectin-3 is weakly expressed under basal conditions and is markedly upregulated by the diabetic milieu (and to a lesser extent by aging). Galectin-3–deficient mice were found to develop accelerated diabetic glomerulopathy versus the wild-type animals, as evidenced by the more pronounced increase in proteinuria, mesangial expansion, and matrix gene expression. This was associated with a more marked renal/glomerular AGE accumulation, suggesting that it was attributable to the lack of Galectin-3 AGE-receptor function. These data indicate that Galectin-3 is upregulated under diabetic conditions and is operating in vivo to provide protection toward AGE-induced tissue injury, as opposed to RAGE. E-mail: giuseppe.pugliese@uniroma1.it
-
Role of Galectin-3 in diabetic nephropathy.
Journal of the American Society of Nephrology : JASN, 2003Co-Authors: Carla Iacobini, Carlo Ricci, Lorena Amadio, Giovanna Oddi, Paola Barsotti, Serena Missori, Mariella Sorcini, Umberto Di Mario, Flavia Pricci, Giuseppe PuglieseAbstract:The advanced glycosylation end products (AGE) participate in the pathogenesis of nephropathy and other diabetic complications through several mechanisms, including their binding to cell surface receptors. The AGE receptors include RAGE, the macrophage scavenger receptors, OST-48 (AGE-R1), 80K-H (AGE-R2), and Galectin-3 (AGE-R3). Galectin-3 interacts with the beta-galactoside residues of cell surface and matrix glycoproteins via the carbohydrate recognition domain and with intracellular proteins via peptide-peptide associations mediated by its N-terminus domain. These structural properties enable Galectin-3 to exert multiple functions, including the mRNA splicing activity, the control of cell cycle, the regulation of cell adhesion, the modulation of allergic reactions, and the binding of AGE. The lack of transmembrane anchor sequence or signal peptide suggests that it is associated with other AGE receptors, possibly AGE-R1 and AGE-R2, to form an AGE-receptor complex, rather than playing an independent role. In target tissues of diabetic vascular complications, such as the endothelium and mesangium, Galectin-3 is weakly expressed under basal conditions and is markedly upregulated by the diabetic milieu (and to a lesser extent by aging). Galectin-3-deficient mice were found to develop accelerated diabetic glomerulopathy versus the wild-type animals, as evidenced by the more pronounced increase in proteinuria, mesangial expansion, and matrix gene expression. This was associated with a more marked renal/glomerular AGE accumulation, suggesting that it was attributable to the lack of Galectin-3 AGE-receptor function. These data indicate that Galectin-3 is upregulated under diabetic conditions and is operating in vivo to provide protection toward AGE-induced tissue injury, as opposed to RAGE.
Tariq Sethi - One of the best experts on this subject based on the ideXlab platform.
-
the regulation of inflammation by Galectin 3
Immunological Reviews, 2009Co-Authors: Neil C. Henderson, Tariq SethiAbstract:Abstract Galectin-3 is a beta-galactoside-binding animal lectin of approximately 30 kDa and is evolutionarily highly conserved. Galectin-3 is promiscuous, its localization within the tissue micro-environment may be extracellular, cytoplasmic, or nuclear, and it has a concentration-dependent ability to be monomeric or form oligomers. These properties impart great flexibility on Galectin-3 as a specific regulator of many biological systems including inflammation. For example, in acute tissue damage Galectin-3 is a key component in the host defense against microbes such as Streptococcus pneumoniae. However, if tissue injury becomes repetitive Galectin-3 also appears to be intimately involved in the transition to chronic inflammation, facilitating the walling off of tissue injury with fibrogenesis and organ scarring. Therefore Galectin-3 can be viewed as a regulatory molecule acting at various stages along the continuum from acute inflammation to chronic inflammation and tissue fibrogenesis. In this review, we examine the role of Galectin-3 in inflammation, and discuss the manipulation of Galectin-3 expression as a potentially novel therapeutic strategy in the treatment of a broad range of inflammatory diseases.
-
The regulation of inflammation by Galectin‐3
Immunological reviews, 2009Co-Authors: Neil C. Henderson, Tariq SethiAbstract:Abstract Galectin-3 is a beta-galactoside-binding animal lectin of approximately 30 kDa and is evolutionarily highly conserved. Galectin-3 is promiscuous, its localization within the tissue micro-environment may be extracellular, cytoplasmic, or nuclear, and it has a concentration-dependent ability to be monomeric or form oligomers. These properties impart great flexibility on Galectin-3 as a specific regulator of many biological systems including inflammation. For example, in acute tissue damage Galectin-3 is a key component in the host defense against microbes such as Streptococcus pneumoniae. However, if tissue injury becomes repetitive Galectin-3 also appears to be intimately involved in the transition to chronic inflammation, facilitating the walling off of tissue injury with fibrogenesis and organ scarring. Therefore Galectin-3 can be viewed as a regulatory molecule acting at various stages along the continuum from acute inflammation to chronic inflammation and tissue fibrogenesis. In this review, we examine the role of Galectin-3 in inflammation, and discuss the manipulation of Galectin-3 expression as a potentially novel therapeutic strategy in the treatment of a broad range of inflammatory diseases.
-
Regulation of Alternative Macrophage Activation by Galectin-3
Journal of immunology (Baltimore Md. : 1950), 2008Co-Authors: Alison C. Mackinnon, Neil C. Henderson, Ulf J. Nilsson, Hakon Leffler, Sarah L. Farnworth, Philip S. Hodkinson, Kirsten M. Atkinson, Christopher Haslett, Stuart J. Forbes, Tariq SethiAbstract:Alternative macrophage activation is implicated in diverse disease pathologies such as asthma, organ fibrosis, and granulomatous diseases, but the mechanisms underlying macrophage programming are not fully understood. Galectin-3 is a carbohydrate-binding lectin present on macrophages. We show that disruption of the Galectin-3 gene in 129sv mice specifically restrains IL-4/IL-13-induced alternative macrophage activation in bone marrow-derived macrophages in vitro and in resident lung and recruited peritoneal macrophages in vivo without affecting IFN-gamma/LPS-induced classical activation or IL-10-induced deactivation. IL-4-mediated alternative macrophage activation is inhibited by siRNA-targeted deletion of Galectin-3 or its membrane receptor CD98 and by inhibition of PI3K. Increased Galectin-3 expression and secretion is a feature of alternative macrophage activation. IL-4 stimulates Galectin-3 expression and release in parallel with other phenotypic markers of alternative macrophage activation. By contrast, classical macrophage activation with LPS inhibits Galectin-3 expression and release. Galectin-3 binds to CD98, and exogenous Galectin-3 or cross-linking CD98 with the mAb 4F2 stimulates PI3K activation and alternative activation. IL-4-induced alternative activation is blocked by bis-(3-deoxy-3-(3-methoxybenzamido)-beta-D-galactopyranosyl) sulfane, a specific inhibitor of extracellular Galectin-3 carbohydrate binding. These results demonstrate that a Galectin-3 feedback loop drives alternative macrophage activation. Pharmacological modulation of Galectin-3 function represents a novel therapeutic strategy in pathologies associated with alternatively activated macrophages.
-
Galectin 3 regulates myofibroblast activation and hepatic fibrosis
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Neil C. Henderson, Alison C. Mackinnon, Sarah L. Farnworth, Christopher Haslett, Françoise Poirier, Francesco P. Russo, John P. Iredale, Kenneth J. Simpson, Tariq SethiAbstract:Central to fibrogenesis and the scarring of organs is the activation of fibroblasts into matrix-secreting myofibroblasts. We demonstrate that Galectin-3 expression is up-regulated in established human fibrotic liver disease and is temporally and spatially related to the induction and resolution of experimental hepatic fibrosis. Disruption of the Galectin-3 gene blocks myofibroblast activation and procollagen (I) expression in vitro and in vivo, markedly attenuating liver fibrosis. Addition of exogenous recombinant Galectin-3 in vitro reversed this abnormality. The reduction in hepatic fibrosis observed in the Galectin-3−/− mouse occurred despite equivalent liver injury and inflammation, and similar tissue expression of TGF-β. TGF-β failed to transactivate Galectin-3−/− hepatic stellate cells, in contrast with WT hepatic stellate cells; however, TGF-β-stimulated Smad-2 and -3 activation was equivalent. These data suggest that Galectin-3 is required for TGF-β mediated myofibroblast activation and matrix production. Finally, in vivo siRNA knockdown of Galectin-3 inhibited myofibroblast activation after hepatic injury and may therefore provide an alternative therapeutic approach to the prevention and treatment of liver fibrosis.
-
Galectin-3 regulates myofibroblast activation and hepatic fibrosis.
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Neil C. Henderson, Alison C. Mackinnon, Christopher Haslett, Françoise Poirier, Sarah L. Farnworth, Francesco P. Russo, John P. Iredale, Kenneth J. Simpson, Tariq SethiAbstract:Central to fibrogenesis and the scarring of organs is the activation of fibroblasts into matrix-secreting myofibroblasts. We demonstrate that Galectin-3 expression is up-regulated in established human fibrotic liver disease and is temporally and spatially related to the induction and resolution of experimental hepatic fibrosis. Disruption of the Galectin-3 gene blocks myofibroblast activation and procollagen (I) expression in vitro and in vivo, markedly attenuating liver fibrosis. Addition of exogenous recombinant Galectin-3 in vitro reversed this abnormality. The reduction in hepatic fibrosis observed in the Galectin-3-/- mouse occurred despite equivalent liver injury and inflammation, and similar tissue expression of TGF-{beta}. TGF-{beta} failed to transactivate Galectin-3-/- hepatic stellate cells, in contrast with WT hepatic stellate cells; however, TGF-{beta}-stimulated Smad-2 and -3 activation was equivalent. These data suggest that Galectin-3 is required for TGF-{beta} mediated myofibroblast activation and matrix production. Finally, in vivo siRNA knockdown of Galectin-3 inhibited myofibroblast activation after hepatic injury and may therefore provide an alternative therapeutic approach to the prevention and treatment of liver fibrosis.
Alan B. Diekman - One of the best experts on this subject based on the ideXlab platform.
-
Proteomic identification of Galectin-3 binding ligands and characterization of Galectin-3 proteolytic cleavage in human prostasomes.
Andrology, 2013Co-Authors: Matthew R. Kovak, Sarika Saraswati, Sabrina Goddard, Alan B. DiekmanAbstract:Summary Galectin-3 is a multifunctional carbohydrate-binding protein that was previously characterized as a proteolytic substrate for prostate-specific antigen (PSA) and was shown to be associated with prostasomes in human semen. Prostasomes are exosome-like vesicles that are secreted by the prostatic epithelium and have multiple proposed functions in normal reproduction and prostate cancer. In the current study, Galectin-3 binding ligands in human prostasomes were identified and characterized with the goal to investigate Galectin-3 function in prostasomes. Galectin-3 binding proteins were isolated by affinity column chromatography. Candidate ligands identified by MS/MS were PSA, prostatic acid phosphatase (PAP), zinc alpha-2-glycoprotein (ZAG), dipeptidyl peptidase-4 (CD26), aminopeptidase N (CD13), neprilysin, clusterin, antibacterial protein (FALL-39) and alpha-1-acid glycoprotein (ORM1). Biochemical methods were used to characterize the ability of Galectin-3 to bind to selected ligands, and Galectin-3 cleavage assays were utilized to investigate the protease(s) in prostasomes that cleaves Galectin-3. CD26, CD13, PSA, PAP and ZAG immunoreactivity were detected in extracts of purified prostasomes. One-dimensional electroblot analysis of prostasomes demonstrated that CD26, PAP and CD13 immunoreactivity co-migrated with Galectin-3-reactive protein bands. PSA and ZAG were found to be associated with the surface of prostasomes. Both intact and cleaved Galectin-3 were detected in prostate and prostasome extracts. Cleavage and inhibition assays indicated that PSA in prostasomes proteolytically cleaves Galectin-3. The identification of these glycoproteins as Galectin-3 ligands lays the groundwork for future studies of Galectin-3 and prostasome function in reproduction and prostate cancer.
-
Galectin-3 is associated with prostasomes in human semen
Glycoconjugate journal, 2009Co-Authors: Jennifer L. Jones, Sarika Saraswati, Ashley S. Block, Cheryl F. Lichti, Maha M. Mahadevan, Alan B. DiekmanAbstract:Galectin-3 is a β-galactoside-binding protein involved in immunomodulation, cell interactions, cancer progression, and pathogenesis of infectious organisms. We report the identification and characterization of Galectin-3 in human semen. In the male reproductive tract, the ~30 kDa Galectin-3 protein was identified in testis, epididymis, vas deferens, prostate, seminal vesicle, and sperm protein extracts. In seminal plasma, Galectin-3 was identified in the soluble fraction and in prostasomes, cholesterol-rich, membranous vesicles that are secreted by the prostate and incorporated into seminal plasma during ejaculation. Two-dimensional immunoblot analysis of purified prostasomes identified five Galectin-3 isoelectric variants with a pI range of 7.0 to 9.2. Affinity purification and tandem mass spectrometry of β-galactoside-binding proteins from prostasomes confirmed the presence of Galectin-3 in prostasomes and identified a truncated Galectin-3 variant. The intact Galectin-3 molecule contains a carbohydrate recognition domain and a non-lectin domain that interacts with protein and lipid moieties. The identification of a monovalent Galectin-3 fragment with conserved carbohydrate-binding activity indicates the functional relevance of this truncation and suggests a regulatory mechanism for Galectin-3 in prostasomes. Surface biotinylation studies suggested that Galectin-3 and the truncated Galectin-3 variant are localized to the prostasome surface. Prostasomes are proposed to function in immunosuppression and regulation of sperm function in the female reproductive tract, are implicated in facilitating sexually-transmitted infections, and are indicated in prostate cancer progression. Given the overlap in functional significance, the identification of Galectin-3 in prostasomes lays the groundwork for future studies of prostasomes in reproduction, disease transmission, and cancer progression.
