Cell
Letter to the editorGalectins: A family of animal β-galactoside-binding lectins
References (3)
- Y.D. Lobsanov et al.
J. Biol. Chem.
(1993)
Cited by (1164)
Identification of benzothiazole derived monosaccharides as potent, selective, and orally bioavailable inhibitors of human and mouse galectin-3; a rare example of using a S···O binding interaction for drug design
2024, Bioorganic and Medicinal ChemistryAs a result of our continued efforts to pursue Gal-3 inhibitors that could be used to fully evaluate the potential of Gal-3 as a therapeutic target, two novel series of benzothiazole derived monosaccharides as potent (against both human and mouse Gal-3) and orally bioavailable Gal-3 inhibitors, represented by 4 and 5, respectively, were identified. These discoveries were made based on proposals that the benzothiazole sulfur atom could interact with the carbonyl oxygen of G182/G196 in h/mGal-3, and that the anomeric triazole moiety could be modified into an N-methyl carboxamide functionality. The interaction between the benzothiazole sulfur and the carbonyl oxygen of G196 in mGal-3 was confirmed by an X-ray co-crystal structure of early lead 9, providing a rare example of using a S···O binding interaction for drug design. It was found that for both the series, methylation of 3-OH in the monosaccharides caused no loss in h & mGal-3 potencies but significantly improved permeability of the molecules.
Molecular characterization and functional analysis of galectin-1 from silver pomfret (Pampus argenteus)
2023, Fish and Shellfish ImmunologyGalectins, as members of lectin families, exhibit a high affinity for β-galactosides and play diverse roles in biological processes. They function as pattern recognition receptors (PRRs) with important roles in immune defense. In this study, galectin-1, designated as SpGal-1, was identified and characterized from silver pomfret (Pampus argenteus). The SpGal-1 comprises an open reading frame (ORF) spanning 396 base pairs (bp) and encodes a deduced amino acid (aa) sequence containing a single carbohydrate recognition domain (CRD). Sublocalization analysis revealed that SpGal-1 was mainly expressed in the cytoplasm. The mRNA transcripts of SpGal-1 were ubiquitously detected in various tissues, with a higher expression level in the intestine. In addition, when exposed to Photobacterium damselae subsp. damselae (PDD) infection, both the liver and head kidney exhibited significantly increased SpGal-1 mRNA expression. The recombinant protein of SpGal-1 (named as rSpGal-1) demonstrated hemagglutination against red blood cells (RBCs) from Larimichthys crocea and P. argenteus in a Ca2+ or β-Mercaptoethanol (β-ME)-independent manner. Notably, rSpGal-1 could bind with various pathogen-associated molecular patterns (PAMPs) including D-galactose, D-mannose, lipopolysaccharide (LPS), and peptidoglycan (PGN), with highest affinity to PGN. Moreover, rSpGal-1 effectively interacted with an array of bacterial types encompassing Gram-positive bacteria (Staphylococcus aureus and Nocardia seriolae) and Gram-negative bacteria (PDD and Escherichia coli, among others), with the most robust binding affinity towards PDD. Collectively, these findings highlight that SpGal-1 is a crucial PRR with involvement in the host immune defense of silver pomfret.
Linker remodels human Galectin-8 structure and regulates its hemagglutination and pro-apoptotic activity
2023, International Journal of Biological MacromoleculesNumerous articles have reported the involvement of linker in regulating bioactivity of tandem-repeat galectins. We hypothesize that linker interacts with N/C-CRDs to regulate the bioactivity of tandem-repeat galectins. To further investigate structural molecular mechanism of linker in regulating bioactivity of Gal-8, Gal-8LC was crystallized. Gal-8LC structure revealed formation of β-strand S1 by Asn174 to Pro176 from linker. S1-strand interacts with C-terminal of C-CRD via hydrogen bond interactions, mutually influencing their spatial structures. Our Gal-8 NL structure have demonstrated that linker region from Ser154 to Gln158 interacts with the N-terminal of Gal-8. Ser154 to Gln158 and Asn174 to Pro176 are likely involved in regulation of Gal-8's biological activity. Our preliminary experiment results revealed different hemagglutination and pro-apoptotic activities between full-length and truncated forms of Gal-8, indicating involvement of linker in regulating these activities. We generated several mutant and truncated forms of Gal-8 (Gal-8 M3, Gal-8 M5, Gal-8TL1, Gal-8TL2, Gal-8LC-M3 and Gal-8_177–317). Ser154 to Gln158 and Asn174 to Pro176 were found to be involved in regulating hemagglutination and pro-apoptotic activities of Gal-8. Ser154 to Gln158 and Asn174 to Pro176 are critical functional regulatory regions within linker. Our study holds significant importance in providing a profound understanding of how linker regulates biological activity of Gal-8.
Cytotoxic effects of recombinant proteins enhanced by momordin Ic are dependent on cholesterol and ganglioside GM1
2023, ToxiconPlant-derived triterpenoid saponins have been shown to play a powerful role in enhancing the cytotoxic activity of protein therapeutics. However, the mechanism of how saponins are acting is not clearly understood. In this study, momordin Ic (MIC), a triterpenoid saponin derived from Kochia scoparia (L.) Schrad., specifically enhance the antiproliferative effect of recombinant MAP30 (a type I ribosome inactivating protein, RIP) in breast cancer cells. Subsequently, the possible mechanism of how MIC enhanced the cytotoxicity of MAP30 was analyzed in detail. We observed the level of intracellular labeled MAP30 using fluorescence microscopy and flow cytometry. And a reporter protein, GAL9, was used to monitor the role of MIC in promoting endosomal escape. We found endosomal escape does not play a role for the enhancer effect of MIC while the effect of MIC on MAP30 is cholesterol dependent and that ganglioside GM1, a lipid raft marker, can competitively inhibit cytotoxicity of MAP30 enhanced by MIC. Finally, we provided some insights into the correlation between the sugar side chain of MIC and its role in enhancing of RIP cytotoxicity and altering of drug cell tropism.
Structure of Galectin-3 bound to a model membrane containing ganglioside GM1
2023, Biophysical JournalGalectin-3 (Gal-3) is a β-galactosidase-binding protein involved in various biological processes, including neuronal growth and adhesion. The pairing of Gal-3 with ganglioside GM1’s pentasaccharide chain at the outer leaflet of the plasma membrane, which triggers downstream cell-signaling cascades, seems to be involved in these processes. A crucial feature of Gal-3 is its ability to form oligomers and supramolecular assemblies that connect various carbohydrate-decorated molecules. Although we know the atomistic structure of Gal-3 bound to small carbohydrate ligands, it remains unclear how Gal-3 binds GM1 in a membrane. Furthermore, the influence of this interaction on Gal-3’s structure and oligomeric assembly has to be elucidated. In this study, we used X-ray reflectivity (XR) from a model membrane to determine the structure and surface coverage of Gal-3 bound to a membrane containing GM1. We observed that the carbohydrate recognition domain interacts with GM1’s pentasaccharide, while the N-terminal domain is pointed away from the membrane, likely to facilitate protein-protein interactions. In a membrane containing 20 mol % GM1, Gal-3 covered ∼50% of the membrane surface with one Gal-3 molecule bound per 2130 Å2. We used molecular dynamics simulations and Voronoi tessellation algorithms to build an atomistic model of membrane-bound Gal-3, which is supported by the XR results. Overall, this work provides structural information describing how Gal-3 can bind GM1’s pentasaccharide chain, a prerequisite for triggering regulatory processes in neuronal growth and adhesion.
Liquid-liquid phase separation: Galectin-3 in nuclear speckles and ribonucleoprotein complexes
2023, Experimental Cell ResearchNuclear speckles are subcellular structures originally characterized by punctate immunofluorescence staining of the monoclonal antibody SC35, which recognizes an epitope on SRRM2 (serine/arginine repetitive matrix protein 2) and Sfrs2, a member of the SR (serine/arginine-rich) family of splicing factors. Galectin-3 co-localizes with SC35 in nuclear speckles, which represent one group of nuclear bodies that include the nucleolus, Cajal bodies and gems, paraspeckles, etc. Although they appear to have well-delineated physical boundaries, these nuclear bodies are not membrane-bound structures but represent macromolecular assemblies arising from a phenomenon called liquid-liquid phase separation. There has been much recent interest in liquid phase condensation as a newly recognized mechanism by which a cell can organize and compartmentalize subcellular structures with distinct composition. The punctate/speckled staining of galectin-3 with SC3 demonstrates their co-localization in a phase-separated body in vivo, under conditions endogenous to the cell. The purpose of the present review is to summarize the studies that document three key features of galectin-3 for its localization in liquid phase condensates: (a) an intrinsically disordered domain; (b) oligomer formation for multivalent binding; and (c) association with RNA and ribonucleoprotein complexes.