On the Role of Galectin-3 in Cancer Metastasis : From the Bench to the Clinic and Back

C-type lectins (CTLs) play an important role in innate immune defense. In this study, we identified and characterized two CTLs (Lec1 and Lec2) from the tubeworm Alaysia sp. collected from a hydrothermal vent in Pacmanus. Lec1 and Lec2 possess the typical CTL domain but share low sequence identities (10.8%–20.4%) with known CTLs. Recombinant (r) of Lec1 and Lec2 bound to various PAMPs and a wide arrange of bacteria from neritic and deep-sea environments in a Ca2+-independent manner, but only rLec1 caused agglutination of the bound bacteria. The activities of rLec1 and rLec2 were most stable and highest at 4 °C, the ambient temperature of the hydrothermal vent, and decreased at higher temperatures. Both lectins inhibited bacterial growth in a highly selective manner and agglutinated the erythrocytes of fish, rabbit, and chicken in a Ca2+-dependent manner. These results provided the first insights into the functional properties of CTLs in deep-sea Alaysia sp.

First characterization of two C-type lectins of the tubeworm Alaysia sp. from a deep-sea hydrothermal vent.

Due to their high biodiversity and adaptation to a mutable and challenging environment, aquatic lophotrochozoan animals are regarded as a virtually unlimited source of bioactive molecules. Among these, lectins, i.e., proteins with remarkable carbohydrate-recognition properties involved in immunity, reproduction, self/nonself recognition and several other biological processes, are particularly attractive targets for biotechnological research. To date, lectin research in the Lophotrochozoa has been restricted to the most widespread phyla, which are the usual targets of comparative immunology studies, such as Mollusca and Annelida. Here we provide the first overview of the repertoire of the secretory lectin-like molecules encoded by the genomes of six target rotifer species: Brachionus calyciflorus, Brachionus plicatilis, Proales similis (class Monogononta), Adineta ricciae, Didymodactylos carnosus and Rotaria sordida (class Bdelloidea). Overall, while rotifer secretory lectins display a high molecular diversity and belong to nine different structural classes, their total number is significantly lower than for other groups of lophotrochozoans, with no evidence of lineage-specific expansion events. Considering the high evolutionary divergence between rotifers and the other major sister phyla, their widespread distribution in aquatic environments and the ease of their collection and rearing in laboratory conditions, these organisms may represent interesting targets for glycobiological studies, which may allow the identification of novel carbohydrate-binding proteins with peculiar biological properties.

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First Insights into the Repertoire of Secretory Lectins in Rotifers

The invention relates to a recombinant protein induced expression method for human Gal (galectin)-3 and belongs to the technical field of peptide obtaining genetic engineering methods. A codon of an open reading frame of human Gal-3 is optimized and synthesized chemically, prokaryotic expression recombinant plasmid pET-25b-Gal3-Homo is established successfully, and induced expression conditions of the plasmid are optimized.

Codon optimization and recombinant protein induced expression method for human Gal (galectin)-3

The invention discloses an artificially-synthesized Galectin-3 gene sequence, Galectin-3 protein and a preparation method. The Galectin-3 gene sequence comprises SEQ ID NO: 1. The stable Galectin-3 protein can be obtained, has high expression quantity and solubleness, and is easy to purify.

Galectin-3 gene sequence, Galectin-3 protein and preparation method

Lectins are sugar-specific binding proteins or glycoproteins that play important physiological roles in cellular recognition and regulation. And they are also valuable in medicine and pharmacy. Tubeworm is the representative species around the hydrothermal vent in the deep sea. They have developed unique mechanisms to adapt to the harsh environment. In this study, a 1 092 bp cDNA, designed as rpgal, was first cloned and characterized from the tubeworm Ridgeia piscesae. Sequence analysis showed that RPGAL had low homology with the known galectin. And it had two homologous carbohydrate-recognition domains, which is the characteristic of the tandem-repeat type galectins. The RPGAL was successfully recombinant expressed in Escherichia coli and purified. Analysis of biological activity revealed that RPGAL was metal ion independent and it could agglutinate all the vertebrate erythrocytes tested. It was stable at 10–50°C and pH 5–10. And the hemagglutinating activity of RPGAL was strongly inhibited by D-Lactose and lipopolysaccharide. Although RPGAL had no effect on the microorganisms tested, it showed anti-tumor activity towards HeLa cells and HT1080 cells, which was accomplished by apoptosis. The study demonstrated that RPGAL was a novel galectin and provided a potential candidate for therapy of anti-tumor.

A novel beta-galactose-specific lectin of the tubeworm, Ridgeia piscesae, from the hydrothermal vent

The invention discloses tubular worm galactose lectin and a preparing method of the tubular worm galactose lectin and relates to nucleotide sequences of tubular worm galactose lectin genes and amino acid sequences coded by the nucleotide sequences. By extracting the general RNA of tubular worm Ridgeia piscesae, reverse transcription is performed, and galactose lectin genes rpgal are augmented and identified through primers. Recombination pronucleus expression vectors are constructed through pET-His, recombination protein expression is performed in escherichia coli BL21. Purified protein is high in purity and good in vigor, and a foundation is provided for practical use of the protein. Galactose lectin is expressed through homologous recombination, the defects that the separation and purification processes are complex and tedious and the yield is low are overcome, and a foundation is laid for wide application of protein in the fields of biology, foods, medicine, agriculture and the like.

Haipeng Xu

Papers

A novel beta-galactose-specific lectin of the tubeworm, Ridgeia piscesae, from the hydrothermal vent

Tubular worm galactose lectin and preparing method thereof