Project description:Mice overexpressing galectin-8 (gal-8 Tg), a secreted mammalian lectin, exhibit enhanced bone turnover and reduced bone mass, similar to cases of post-menopausal osteoporosis. Gal-8 knockout (KO) mice have increased bone mass accrual at young age, but exhibit accelerated bone loss during adulthood. These phenotypes can be attributed to gal-8-mediated increase in RANKL expression that promotes osteoclastogenesis, combined with direct inhibition of osteoblasts differentiation, evident by reduced BMP signaling, SMAD phosphorylation, and reduced expression of osteoblasts differentiation markers OSX, OCN, RUNX2, DMP-1 and ALP. Gal-8 mRNA positively correlates with the mRNA levels of osteoclastogenic markers RANKL, TRAP and CTSK in human femurs. Collectively, these findings identify gal-8 as a new physiological player in the regulation of bone mass.
Project description:Herein, we constructed a human lectin microarray with 60 human lectin and lectin-like proteins. All of the lectins and lectin-like proteins were purified from yeast, and most showed binding to human glycans. To demonstrate the applicability of the human lectin microarray, human sperm were probed on the microarray and strong bindings were observed for several lectins, including galectin-1, 7, 8, GalNAc-T6, and ERGIC-53 (LMAN1). These bindings were validated by flow cytometry and fluorescence immunostaining. Further, mass spectrometry analysis showed that galectin-1 binds several membrane proteins including HSP90. Finally, functional assays showed that binding of galectin-8 could significantly enhance the acrosome reaction within human sperms. To our knowledge, this is the first construction of a human lectin microarray, and we anticipate it will find wide use for a range of human or mammalian studies, alone or in combination with plant lectin microarrays.
Project description:Galectin-1 is a prototype member of the galectin family of b-galactoside-binding proteins with several immunoregulatory activities (Sundblad et al., 2017). Although this lectin exerts extracellular activities by cross-linking cell surface glycoconjugates, the mechanisms and molecular machinery involved in its secretion are uncertain as it lacks the classical signal sequence required for ER-Golgi release (Camby, 2006; Croci et al., 2014). To assess the global impact of galectin-1 on LPS-induced transcriptomic response, we performed RNAseq analysis of total RNAs from the spleen and the lungs of wild-type and Lgals1-/- mice injected with LPS.
Project description:Inflammatory chemo- and cytokines and matrix-degrading proteases underlie the progression of osteoarthritis (OA). Aiming to define upstream regulators for these disease markers, we pursued initial evidence for an upregulation of members of the adhesion/growth-regulatory galectin family. Immunohistochemical localization of galectin-3 (Gal-3) in sections of human cartilage with increasing levels of degeneration revealed a linear correlation reaching a chondrocyte positivity of 60%. Presence in situ was cytoplasmic, in OA chondrocyte cultures the lectin was secreted and binding of Gal-3 yielded lactose-inhibitable surface staining. Exposure of cells to the lectin led to enhanced gene expression and secretion of functional disease markers. Genome-wide transcriptomic analysis broadened this insight to reveal a pro-degradative/inflammatory gene signature under the control of NF-κB. Fittingly, targeting this route of activation by inhibitors impaired the unfavourable response to Gal-3 binding, as also seen by shortening the lectin’s collagen-like repeat region. Gal-3’s activation profile overlaps with that of homodimeric galectin-1 (Gal-1) and also has distinctive (supplementing) features. Tested at subsaturating concentrations in a mixture, we found cooperation between the two galectins, apparently able to team up as driving forces in OA pathogenesis. In summary, our results suggest that a network of endogenous lectins acts as upstream master regulator in OA.
Project description:The goal of this study was to examine differences in gene expression of tumor specific CD8 T cells in an in vivo tumor mouse model after inhibition of galectin-3 protein expression by genetic knockout. Galectin-3 is thought to modulate CD8 T cell response by cross-linking cell surface glycoproteins Galectin-3 is a 31 kD carbohydrate-binding lectin that is over-expressed by many human malignancies. It also modulates T cell responses through a diverse array of mechanisms including induction of apoptosis, TCR cross linking in CD8+ T cells, and T cell receptor (TCR) down regulation in CD4+ T cells. We found that patients responding to a granulocyte-macrophage colony-stimulating factor (GM-CSF) secreting allogeneic pancreatic tumor vaccine developed post immunization antibody responses to galectin-3 on a proteomic screen. We used the HER-2/neu (neu-N) transgenic mouse model to study galectin-3 binding on adoptively transferred high avidity neu-specific CD8+ T cells derived from TCR transgenic mice. Here, we show that galectin-3 binds preferentially to activated antigen-committed CD8+ T cells only in the tumor microenvironment (TME). Galectin-3 deficient mice exhibit improved CD8+ T cell effector function and increased expression of several inflammatory genes when compared with wild type (WT) mice. We also show that galectin-3 binds to LAG-3, and LAG-3 expression is necessary for galectin-3 mediated suppression of CD8+ T cells in vitro. Lastly, galectin-3 deficient mice have significantly elevated levels of circulating plasmacytoid dendritic cells (pDCs), which are superior to conventional dendritic cells (cDCs) in activating CD8+ T cells. Binding of galectin-3 to cell-surface glycoproteins on immune cells suppresses a pro-inflammatory immune response. Thus, inhibiting galectin-3 in conjunction with CD8+ T cell directed immunotherapies should enhance the tumor specific immune response.
Project description:The goal of this study was to examine differences in gene expression of tumor specific CD8 T cells in an in vivo tumor mouse model after inhibition of galectin-3 protein expression by genetic knockout. Galectin-3 is thought to modulate CD8 T cell response by cross-linking cell surface glycoproteins Galectin-3 is a 31 kD carbohydrate-binding lectin that is over-expressed by many human malignancies. It also modulates T cell responses through a diverse array of mechanisms including induction of apoptosis, TCR cross linking in CD8+ T cells, and T cell receptor (TCR) down regulation in CD4+ T cells. We found that patients responding to a granulocyte-macrophage colony-stimulating factor (GM-CSF) secreting allogeneic pancreatic tumor vaccine developed post immunization antibody responses to galectin-3 on a proteomic screen. We used the HER-2/neu (neu-N) transgenic mouse model to study galectin-3 binding on adoptively transferred high avidity neu-specific CD8+ T cells derived from TCR transgenic mice. Here, we show that galectin-3 binds preferentially to activated antigen-committed CD8+ T cells only in the tumor microenvironment (TME). Galectin-3 deficient mice exhibit improved CD8+ T cell effector function and increased expression of several inflammatory genes when compared with wild type (WT) mice. We also show that galectin-3 binds to LAG-3, and LAG-3 expression is necessary for galectin-3 mediated suppression of CD8+ T cells in vitro. Lastly, galectin-3 deficient mice have significantly elevated levels of circulating plasmacytoid dendritic cells (pDCs), which are superior to conventional dendritic cells (cDCs) in activating CD8+ T cells. Binding of galectin-3 to cell-surface glycoproteins on immune cells suppresses a pro-inflammatory immune response. Thus, inhibiting galectin-3 in conjunction with CD8+ T cell directed immunotherapies should enhance the tumor specific immune response. 3 different experimental groups were studied. Galectin-3 WT CD8 T cells adoptively transferred into Galectin-3 WT mice, galectin-3 WT CD8 T cells transferred into galectin-3 KO mice, and finally galectin-3 KO CD8 T cells transferred into galectin-3 KO mice. Galectin-3 WT CD8 T cells transferred into Galectin-3 WT mice were used as the reference group. Four biological replicates were submitted for each group, and adoptively transfered CD8 T cells were isolated 5 days post-adoptive transfer into tumor-bearing mice treated with a whole cell GM-CSF secreting vaccine. Cells were purified by cell sorting on the Thy1.2 surface marker.
Project description:Galectins are lectin-binding proteins expressed both at the plasma membrane and intracellularly. Our research focuses on identifyingthe role of these proteins (mostly galectin-9) on dendritic cell function. For this, we wanted to run an unbiased approach to identify the galectin-9 binding partners in primary dendritic cells.
Project description:Human monocyte derived dendritic cells matured via galectin-1 or LPS. Experiment Overall Design: 4 conditions with 3 replicates of each include control or intreated immature MDDCS, galectin-1 treated MDDCs, LPS treated MDDCs, and vehicle control MDDCs. (each replicate is from a distinct DONOR). Dendritic cells (DCs) are potent mediators of the immune response, and can be activated by exogenous pathogen components. Galectin-1 is a member of the conserved beta-galactoside-binding lectin family that binds galactoside residues on cell surface glycoconjugates. Galectin-1 is known to play a role in immune regulation via action on multiple immune cells. However, its effects on human DCs are unknown. In this study, we show that galectin-1 induces a phenotypic and functional maturation in human monocyte-derived DCs (MDDCs) similar to but distinct from the activity of the exogenous pathogen stimuli, LPS. Immature human MDDCs exposed to galectin-1 up-regulated cell surface markers characteristic of DC maturation (CD40, CD83, CD86, and HLA-DR), secreted high levels of IL-6 and TNF-alpha, stimulated T cell proliferation, and showed reduced endocytic capacity, similar to LPS-matured MDDCs. However, unlike LPS-matured DCs, galectin-1-treated MDDCs did not produce the Th1-polarizing cytokine IL-12. Microarray analysis revealed that in addition to modulating many of the same DC maturation genes as LPS, galectin-1 also uniquely up-regulated a significant subset of genes related to cell migration through the extracellular matrix (ECM). Indeed, compared with LPS, galectin-1-treated human MDDCs exhibited significantly better chemotactic migration through Matrigel, an in vitro ECM model. Our findings show that galectin-1 is a novel endogenous activator of human MDDCs that up-regulates a significant subset of genes distinct from those regulated by a model exogenous stimulus (LPS). One unique effect of galectin-1 is to increase DC migration through the ECM, suggesting that galectin-1 may be an important component in initiating an immune response.
Project description:The reading of glycan-encoded signals by tissue lectins is considered a major route of the flow of biological information in many (patho)physiological processes. The arising challenge for current research is to proceed from work on a distinct protein to family-wide testing of lectin function. Having previously identified homodimeric galectin-1 and chimera-type galectin-3 as molecular switches in osteoarthritis progression, we here provide proof-of-principle evidence for an intra-network cooperation of galectins with three types of modular architecture. We show that the presence of tandem-repeat-type galectin-8 significantly correlated with cartilage degeneration and that it is secreted by osteoarthritic chondrocytes. Glycan-inhibitable surface binding of galectin-8 to these cells increased gene transcription and the secretion of functional disease markers. The natural variant galectin-8 (F19Y) was less active than the prevalent form. Genome-wide array analysis revealed induction of a pro-degradative/inflammatory gene signature, largely under control of NF-κB signaling. This signature overlapped with respective gene-expression patterns elicited by galectins-1 and -3, but also presented supplementary features. Functional assays with mixtures of galectins that mimic the pathophysiological status unveiled cooperation between the three galectins. Our findings shape the novel concept to consider individual galectins as part of a so far not realized teamwork in osteoarthritis pathogenesis, with relevance beyond this disease.
Project description:Disruption of skin homeostasis by environmental insults activates pathologic circuitries leading to inflammation and carcinogenesis. Galectin-7 (Gal-7), a lectin preferentially expressed in keratinocytes, has been implicated in wound healing and defective skin repair. Here we report using genetically-engineered mouse models and human samples, essential roles for Gal-7 during skin carcinogenesis via coordinated intracellular and extracellular mechanisms. Heightened Gal-7 expression delineated malignant lesions in non-melanoma skin cancer (NMSC) patients and shaped the course of skin carcinogenesis in mice. Intracellularly, increased Gal-7 conferred genomic instability to skin lesions and favored transcription of inflammation-related genes reprogramming the immune landscape toward a myeloid immunoregulatory profile. Extracellularly, Gal-7 accelerated skin carcinogenesis through glycan-dependent induction of monocytic myeloid-derived suppressor cells with enhanced immune regulatory activity. Our findings identify a lectin-driven molecular circuitry that promotes skin carcinogenesis by coupling genomic instability, transcriptional regulation and myeloid immunosuppressive programs, suggesting a potential therapeutic target for the treatment of NMSC.