Language：English  

DOI： 10.3390/molecules29051031

PubMed

Language：English  

DOI： 10.1182/bloodadvances.2023011490

PubMed

Language：English   Publisher：Science  

Influenza viruses escape immunity owing to rapid antigenic evolution, which requires vaccination strategies that allow for broadly protective antibody responses. We found that the lipid globotriaosylceramide (Gb3) expressed on germinal center (GC) B cells is essential for the production of high-affinity antibodies. Mechanistically, Gb3 bound and disengaged CD19 from its chaperone CD81, permitting CD19 to translocate to the B cell receptor complex to trigger signaling. Moreover, Gb3 regulated major histocompatibility complex class II expression to increase diversity of T follicular helper and GC B cells reactive with subdominant epitopes. In influenza infection, elevating Gb3, either endogenously or exogenously, promoted broadly reactive antibody responses and cross-protection. These data demonstrate that Gb3 determines the affinity and breadth of B cell immunity and has potential as a vaccine adjuvant.

DOI： 10.1126/science.adg0564

Scopus

PubMed

Language：English   Publisher：Journal of Biochemistry  

Dystroglycan (DG), a muscular transmembrane protein, plays a critical role in transducing extracellular matrix-derived signals to the cytoskeleton and provides physical strength to skeletal muscle cell membranes. The extracellular domain of DG, α-DG, displays unique glycosylation patterns. Fully functional glycosylation is required for this domain to interact with components of extracellular matrices, including laminin. One of the unique sugar compositions found in such functional glycans on DG is two ribitol phosphates that are transferred by the sequential actions of fukutin (FKTN) and fukutin-related protein (FKRP), which use CDP-ribitol as a donor substrate. These are then further primed for matriglycan biosynthesis. A recent in vitro study reported that glycerol phosphate could be similarly added to α-DG by FKTN and FKRP if they used CDP-glycerol (CDP-Gro) as a donor substrate. However, the physiological relevance of these findings remains elusive. Imae et al. addressed the knowledge gap regarding whether CDP-Gro is present in mammals and how CDP-Gro is synthesized and functions in mammals.

DOI： 10.1093/jb/mvad003

Web of Science

Scopus

PubMed

Language：English   Publisher：Glycoconjugate Journal  

Immunotherapy of malignant cancers is now becoming one of representative approaches to overcome cancers. To construct strategies for immunotherapy, presence of tumor-specific antigens should be a major promise. A number of cancer specific- or cancer-associated antigens have been reported based on various experimental sets and various animal systems. The most reasonable strategy to define tumor-specific antigens might be “autologous typing” performed by Old’s group, proposing three classes of tumor-antigens recognized by host immune systems of cancer patients. Namely, class 1, individual antigens that is present only in the patient’s sample analyzed; class 2, shared antigens that can be found only in some group of cancers in some patients, but not in normal cells and tissues; class 3, universal antigens that are present in some cancers but also in normal cells and tissues with different densities. Sen Hakomori reported there were novel carbohydrates in cancers that could not be detected in normal cells mainly by biochemical approaches. Consequently, many of class 2 cancer-specific antigens have been revealed to be carbohydrate antigens, and been used for cancer diagnosis and treatment. Not only as cancer markers, but roles of those cancer-associated carbohydrates have also been recognized as functional molecules in cancer cells. In particular, roles of complex carbohydrates in the regulation of cell signaling on the cell surface microdomains, glycolipid-enriched microdomain (GEM)/rafts have been reported by Hakomori and many other researchers including us. The processes and present status of these studies on cancer-associated glycolipids were summarized.

DOI： 10.1007/s10719-022-10051-1

Web of Science

Scopus

PubMed

Since cDNAs of glycosyltransferase genes were isolated, and become applicable for genetic engineering of glycosylation patterns, biological functions of glycolsphingolipids have been largely elucidated via glyco-remodeling cells and animals. The progress in these glycobiology techniques has enabled us to understand the roles of “tumor-specific” carbohydrates during these 3 decades. Tumor antigens recognized by host immune systems of cancer patients were classified into three classes based on “autologous typing”, that is, class 1: individual antigens present only in the patient’s tumors, class 2: shared antigens among some group of cancers, but not in normal cells, class 3: universal antigens that are present in not only some cancers but also in normal cells. Many of class 2 antigens have been elucidated to be carbohydrate antigens, and are considered to be differentiation antigens. Many of them have been used for cancer diagnosis and treatment. Functional analyses of those cancer-associated glycosphingolipids based on the genetic engineering of glyco-genes have revealed that disialylated glycolipids generally enhance malignant properties such as cell growth, invasion, and motility. On the other hand, monosialylated glycolipids rather suppress those phenotypes. As a regulatory platform for cell signaling, cell surface microdomains, glycolipid-enriched microdomain (GEM)/rafts have been proposed. Interestingly, cancer-associated glycosphingolipids play critical roles in the composition of GEM/rafts, and in the regulation of signal transduction. Molecular complex formation of glycolipids with membrane molecules that are defined by enzyme-mediated activation of radical sources/mass spectrometry should be a key factor to regulate cell signals and to determine the cell fates. They are also expected to be targets of the cancer treatment.

DOI： 10.1007/978-981-19-7732-9_8

Scopus