Galectin

About: Galectin is a research topic. Over the lifetime, 2076 publications have been published within this topic receiving 103409 citations. The topic is also known as: IPR001079 & Galectin.

Human galectins as sensors for apoptosis/necrosis‐associated surface changes of granulocytes and lymphocytes

Abstract: Changes in the glycomic profile can significantly affect the cells' communication with the environment. Plant lectins have so far been used to address the issue as to whether the courses of apoptosis or necrosis are associated with such alterations. We, here, initiate the study of members of the family of functionally pleiotropic human galectins in this respect. Established protocols for the induction of apoptosis/necrosis of blood cells and for flow cytometry using annexin V/propidium iodide were combined with cell surface staining using biotinylated galectins at a nontoxic concentration. The galectin panel covered members from all three subfamilies. Flow cytometry revealed specific binding of galectins to viable control cells and conspicuous staining differences when testing apoptotic or necrotic cells. Onset and especially progression of cell death led to pronounced reactivity with the proto-type galectins-1, -2, and -7 and tandem-repeat-type galectin-4. Extent of staining depended on the nature and stage of cell death, type of dying cell, and type of galectin. Galectins act as sensors for cell-death-associated surface changes. Staining of late-apoptotic polymorphonuclear cells was particularly strong. Examining the functional significance of this result may reveal a new aspect within the surveillance system to protect against autoinflammation. © 2008 International Society for Analytical Cytology

Galectin-1 and -3 gene silencing in immature and mature dendritic cells enhances T cell activation and interferon-γ production

Abstract: DCs are specialized APCs capable of inducing T cell activation as well as promoting tolerance. Although Gal, a family of β-galactoside-binding proteins, were found to affect immunity, little is known about the contribution of DC-expressed Gal on T cell activation. Here, we show that human imDCs and mDCs constitutively express Gal-1, Gal-3, Gal-8, and Gal-9 at mRNA and protein levels. Two of the most abundant Gal-Gal-1 and Gal-3-were highly expressed and detected on the cell surface of DCs. In contrast to Gal-8, knockdown of Gal-1 or Gal-3 in DCs enhanced allogeneic T cell responses. This was observed with imDCs and mDCs, but the effects were more pronounced with imDCs. Furthermore, allogeneic CD4(+) T cells incubated with Gal-1 or Gal-3 knockdown DCs produced more IFN-γ and less IL-10 than did control cells. The percentage of apoptotic T cells was significantly higher in cultures with control DCs than that with Gal-1 or Gal-3 knockdown DCs. Collectively, the data indicate that DC-expressed Gal-1 and Gal-3 are regulatory molecules that favor the inhibition of T cell activation. Furthermore, the data provide a new mechanism for the poor capacity of imDCs to stimulate T cells.

Galectin-1 signaling in leukocytes requires expression of complex-type N-glycans

Abstract: Dimeric galectin-1 (dGal-1) is a homodimeric lectin with multiple proposed functions. Although dGal-1 binds to diverse glycans, it is unclear whether dGal-1 preferentially binds to specific subsets of glycans on cell surfaces to transmit signals. To explore this question, we selectively inhibited major glycan biosynthetic pathways in human HL60, Molt-4, and Jurkat cells. Inhibition of N-glycan processing blocked surface binding of dGal-1 and prevented dGal-1-induced Ca2+ mobilization and phosphatidylserine exposure. By contrast, inhibition of O-glycan or glycosphingolipid biosynthesis did not affect dGal-1 binding or dGal-1-induced Ca2+ mobilization and phosphatidylserine exposure. These results demonstrate that dGal-1 preferentially binds to and signals through glycoproteins containing complex-type N-glycans in at least some leukocyte subsets.

Marker profiling of normal keratinocytes identifies the stroma from squamous cell carcinoma of the oral cavity as a modulatory microenvironment in co-culture.

Abstract: Purpose: The microenvironment established by stromal cells may or may not influence phenotypic aspects of epithelial cells and may be relevant for tumor and stem cell biology. We address this issue for keratinocytes using tumor-derived stromal cells in a co-culture system.Materials and methods: We isolated stromal cells from human squamous cell carcinoma tissue and studied their effect on phenotypic characteristics of normal human interfollicular keratinocytes in vitro.Results: Stromal fibroblasts significantly influence immuno- and lectin cytochemical properties of co-cultured normal keratinocytes. Expression of keratins 8 and 19, the nucleolar protein nucleostemin, parameters related to adhesion/growth-regulatory galectins and the epithelial-mesenchymal transition were altered. This biological activity of tumor-derived stromal cells, which did not require cell contact, appeared to be stable, because it was maintained during passaging of keratinocytes in the absence of cancer cells.Conclusions: Tumor-der...

Galectin-7 in Epithelial Homeostasis and Carcinomas

Abstract: Galectins are small unglycosylated soluble lectins distributed both inside and outside the cells. They share a conserved domain for the recognition of carbohydrates (CRD). Although galectins have a common affinity for β-galatosides, they exhibit different binding preferences for complex glycans. First described twenty years ago, galectin-7 is a prototypic galectin, with a single CRD, able to form divalent homodimers. This lectin, which is mainly expressed in stratified epithelia, has been described in epithelial tissues as being involved in apoptotic responses, in proliferation and differentiation but also in cell adhesion and migration. Most members of the galectins family have been associated with cancer biology. One of the main functions of galectins in cancer is their immunomodulating potential and anti-angiogenic activity. Indeed, galectin-1 and -3, are already targeted in clinical trials. Another relevant function of galectins in tumour progression is their ability to regulate cell migration and cell adhesion. Among these galectins, galectin-7 is abnormally expressed in various cancers, most prominently in carcinomas, and is involved in cancer progression and metastasis but its precise functions in tumour biology remain poorly understood. In this issue, we will focus on the physiological functions of galectin-7 in epithelia and present the alterations of galectin-7 expression in carcinomas with the aim to describe its possible functions in tumour progression.