Galectin-3 is one of the most extensively studied members of the galectin family along with galectin-1. Galectin-3 is involved in a wide variety of functions and places, in vitro in both intracellular and extracellular spaces and in vivo in various organs. As mentioned in Part 1, galectin-3 contains an “intrinsically disordered peptide region” with repeated peptide sequences, and the total length of these peptides is almost the same as the carbohydrate-binding domain (CBD) at the C-terminus (Figure 3) . Notably, this region is not found in other animal lectins. Most of the reported activities of galectin-3 require this intrinsically disordered region. Galectin-3, which usually exists as a monomer, oligomerizes in a manner that is dependent on this region after binding to its glycan ligand. Therefore, the activity of galectin-3 is thought to be regulated primarily by intrinsically disordered region-dependent oligomerization. In Part 2, I would first like to delve deeper into the mechanism by which the unique intrinsically disordered region is involved in the oligomerization of galectin-3 by referring to the latest reports. Then, I will explore the relationship between the oligomerization of galectin-3 and its diverse functions. ...and more
An increasing body of work has shown that the gut microbiota plays an important role in human health and disease, and the microbial colonization of the infant gut that occurs postpartum is a critical period for gut microbiota development. Furthermore, the gut microbiota that forms during infancy can have long-term effects that last into adulthood5. As a result, therapeutic interventions aimed at regulating the gut microbiota, such as probiotics (microorganisms administered exogenously) and prebiotics (indigestible compounds that promote the growth of specific gut microbes), have become increasingly popular. For example, probiotic taxa such as bifidobacteria and prebiotics like human milk oligosaccharides (HMOs) are administered to encourage the development of a healthy gut microbiota in preterm infants. Despite increasing use, studies report conflicting results and host response to microbiota-based therapies are highly variable. Based on recent in vitro and in vivo studies, I discuss how ecological processes like priority effects (i.e. the effect of species arrival order on community structure) and the presence of prebiotic HMOs can alter the structure of the infant gut microbiota and influence the effectiveness of such microbiota-based therapies. ...and more
Sialic acid is a “uronic acid”, sugar with a carboxyl group as an acidic functional group. While many monosaccharides in glycans in the body are pentoses and hexoses, sialic acid is a nonose and plays various and important physiological roles. In the author’s opinion, sialic acid must be a distinguished from other sugars. Regarding the chemical synthesis of glycans, the presence of sialic acid in a glycan dramatically increases the difficulty of its synthesis. Because of its unique structure, sialic acid markedly decreases the success rate of glycosidation. A fundamental solution to this problem has been sought for more than half a century. Recently, our group successfully developed one approach to solving this problem. In this article, I will outline this approach. ...and more
We have focused on a molecule named podoplanin (PDPN) as a therapeutic target of malignant brain tumors. PDPN is a type I transmembrane mucin-like glycoprotein that is abundant in several solid tumors including squamous cell carcinoma, malignant mesothelioma, Kaposi sarcoma, angiosarcoma, testicular seminoma, and brain tumors. The expression level of PDPN is reported to increase as tumor malignancy increases. The side effects of currently available treatments can be avoided or mitigated if new measures are developed that only kill PDPN-expressing tumor cells. ...and more
