Structure and Characteristics of a Lectin named ”Cvill” isolated from Canavalia villosa seeds

A group from Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Belgium, etc. has reported about a ConA-like mannose-specific lectin, Cvill, isolated from Canavalia villosa seeds.

Cvill is a ConA-like mannose-specific lectin isolated from Canavalia villosa seeds.

The lectin structure is composed of 237 amino acid residues, similar to other ConA-like lectins .

Cvill exhibits the typical legume lectin fold, also known as a β-sandwich, characterized by the presence of two superimposed beta sheets, resembling a sandwich. These beta sheets consist of antiparallel strands, with one beta sheet formed by six long, flat beta strands and the other by seven curved strands.The arrangement of dimers and tetramers in the quaternary structure was predicted.

Glycan array experiments indicated that Cvill exhibits affinity for terminal α-mannosyl residues and the tri-mannosidic core of N-glycans.

Cvill demonstrated dose-dependent cytotoxicity against all tested cell lines and this toxicity was carbohydrate-mediated. Cvill presented IC50 values of 97.0 μg/mL after 48 h incubation period for HeLa ells. Cvill also affected the viability of the fibrosarcoma (HT1080 cells) and the NHDF cells with IC50 values of 116.08 μg/mL and 108.34 μg/mL after a 48 h incubation period.

Gal modification of laminin receptor integrin α6β1 is reduced in hepatocellular carcinoma, and thereby accelerates cancer cell invasion

A group from Graduate Institute of Anatomy and Cell Biology, College of Medicine, National Taiwan University, Taipei, Taiwan, etc. has reported that Beta1,4-galactosyltransferases (B4GALTs) downregulation upregurates agalacto N-glycans and enhances the laminin-binding activity of integrin α6 and integrin β1 to promote invasiveness of Hepatocellular carcinoma (HCC) cells.

Increase in high mannosylation prevents decidualization of the endometrium and causes pregnancy failure

A group from Liaoning Provincial Core Lab of Glycobiology and Glycoengineering, Department of Biochemistry and Molecular Biology, Dalian Medical University, China, etc. has found increased high-mannose glycans and concomitant reduction of mannosidase MAN1A1 in the decidual tissues of miscarriage patients compared with early pregnant women using lectin microarrays. Among lectins, mannose binding lerctins, NPA, HHL, LCHA, CALSEPA, and GNA, showed significant changes.

The abnormally elevated high mannosylation by MAN1A1 downregulation inhibited decidualization.
Screening of Long noncoding RNAs (LncRNAs) revealed that LncNEAT1 was increased in the decidual tissues of miscarriage patients.
Furthermore, it was found that LncNEAT1 interacted with NPM1-SP1 transcription complex and inhibited MAN1A1 expression, thereby hampering endometrial decidualization and embryo implantation.

SARS-CoV-2 suppresses TLR4 expressed on human DCs

A group from Department of Experimental Immunology, Amsterdam UMC location University of Amsterdam, The Netherlands, etc. has identified a novel pathway activated by SARS-CoV-2 that suppresses TLR4, the major bacterial TLR on human dendritic cells (DCs).

It was strongly suggested that SARS-CoV-2 interacts with the C-type lectin receptor DC-SIGN leading to Raf-1-mediated suppression of TLR4 signaling. As a result, SARS-CoV-2 actively suppresses DC function via DC-SIGN, and causes the higher mortality rates observed in patients with COVID-19 and bacterial superinfections.