記述言語：英語   出版者・発行元：FCCA(Forum: Carbohydrates Coming of Age)  

Lysosomal storage diseases (LSDs) are rare monogeneic disorders caused by mutations in over 60 lysosomal components. These mutations cause neurological and motor symptoms due to lysosomal dysfunction, and as of yet, no fundamental treatment is available. Here, a new study has unveiled a shared pathogenetic basis for various LSDs and proposed a novel treatment option (original article [Wang et al. (2024) Nat. Cell Biol. 26, 219–234]). Lysosomes hydrolyze proteins, lipids, carbohydrates, and nucleic acids that are no longer required by cells. Abnormalities in the function of hydrolases or in the mannose 6-phosphate modification of hydrolases, which is the selective transport mechanism to lysosomes, cause lysosomal dysfunction and accumulation of undigested macromolecules in lysosomes. For example, Sandhoff disease, in which Hexb gene mutations lead to the accumulation of the acidic glycolipid GM2/GD2, and Fabry’s disease, in which mutations in the Gla gene cause the accumulation of the neutral glycolipid Gb3. Therapies for the disease include enzyme replacement therapy, substrate depletion therapy, and symptom reduction therapy. However, high medical costs and lack of efficacy pose major problems. Additionally, due to its rarity, research and development targeting individual LSDs have lagged. Thus, exploring a shared pathogenetic basis for various LSDs is important for the development of novel therapies.

DOI： 10.4052/tigg.2411.6e

Scopus

CiNii Research

記述言語：日本語   出版者・発行元：FCCA(Forum: Carbohydrates Coming of Age)  

DOI： 10.4052/tigg.2411.6j

CiNii Research

記述言語：英語   出版者・発行元：FCCA(Forum: Carbohydrates Coming of Age)  

Mannose-6-phosphate (M6P) is a posttranslational modification on N-linked glycans on lysosomal hydrolases in the Golgi apparatus, which is required for selective transport of lysosomal hydrolases from the Golgi apparatus to lysosomes via M6P recep-tors. Defects in M6P modification by genetic manipulations or in hereditary genetic disorders result in abnormal extracellular secre-tion of lysosomal hydrolases and are thus the basis of the pathogenesis of lysosome storage diseases. N-acetylglucosamine (GlcNAc)-1-phosphotransferase, an enzyme catalyzing M6P modification, is synthesized as an inert form that requires proteolytic activation by the Golgi-localized protease, site-1 protease (S1P). S1P, encoded by membrane-bound transcription factor peptidase, site 1 (MBTPS1), is ubiquitously expressed and functions sequentially with the site-2 protease to proteolytically activate unique membrane-bound latent transcription factors in the Golgi apparatus. These transcription factors include sterol regulatory element-binding protein required for inducing lipogenesis, and activating transcription factor 6 required for inducing endoplasmic reticulum stress-related unfolded protein response. Since we reported the first patient with MBTPS1 pathogenic variants who has congenital skeletal dysplasia due to compound endoplasmic reticulum and lysosomal dysfunctions, there have been a few reports regarding novel MBTPS1 variants worldwide. Here we overview genotype-phenotype relationships in so far reported patients with MBTPS1 variants.

DOI： 10.4052/tigg.2309.1e

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CiNii Research

記述言語：日本語   出版者・発行元：FCCA(Forum: Carbohydrates Coming of Age)  

<p>マンノース-6-リン酸（M6P）修飾は、ゴルジ体のリソソーム酵素上の<i>N</i>-結合型糖鎖に見られる翻訳後修飾であり、M6P受容体を介してリソソームへの選択的輸送に必要である。M6P修飾の遺伝的欠損は、リソソーム酵素の細胞外分泌をもたらし、リソソーム蓄積病の発生基盤となる。M6P修飾酵素である<i>N</i>-アセチルグルコサミン（GlcNAc）-1-リン酸転移酵素は不活性型として合成され、ゴルジ体に局在するsite-1 protease （S1P）（<i>MBTPS1</i>遺伝子にコードされる）による切断活性化を必要とする。小胞体とリソソームの複合機能障害に基づく先天性骨格形成不全を有する最初のヒト<i>MBTPS1</i>変異体が報告されて以来、世界中から新たな<i>MBTPS1</i>変異体の報告が相次いでいる。そこで、これまでの<i>MBTPS1</i>変異体を概説する。</p>

DOI： 10.4052/tigg.2309.1j

CiNii Research

記述言語：英語   出版者・発行元：Molecules  

Epidermal growth factor (EGF) repeats are present in various proteins and form well-defined structures with three disulfide bonds. One representative protein is the Notch receptor. Each EGF repeat contains unique atypical O-linked glycans, such as O-linked N-acetylglucosamine (O-GlcNAc). To generate a monoclonal antibody against the O-GlcNAc moiety in mouse Notch1, we expressed the recombinant C-terminal His6-tagged Notch1 EGF14-15 protein in HEK293T cells to prepare the immunogen. Most of the proteins were not secreted and showed higher molecular weight ladders in the cell lysate, suggesting protein aggregation. To overcome this issue, we fused Sparcl1 as an extracellular escorting tag to the N-terminus of Notch1 EGF14-15. The fusion protein was efficiently secreted extracellularly without protein aggregates in the lysates. Following PreScission protease treatment, Notch1 EGF14-15 was efficiently released from the escorting tag. Notch1 EGF14-15 prepared using this method was indeed O-GlcNAcylated. The optimal length of the escorting tag was determined by generating deletion mutants to improve the extracellular secretion of EGF14-15. Hence, a large amount of EGF14-15 was successfully prepared from the culture supernatant of HEK293T cells, which were otherwise prone to aggregation.

DOI： 10.3390/molecules29051031

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