Changes in the amount of nucleotide sugars in aged mouse tissues.

Aging affects tissue glycan profiles, which may alter cellular functions and increase the risk of age-related diseases. Glycans are biosynthesized by glycosyltransferases using the corresponding nucleotide sugar, and the availability of nucleotide sugars affects glycosylation efficiency. However, the effects of aging on nucleotide sugar profiles and contents are yet to be elucidated.

An endomembrane zinc transporter negatively regulates systemic RNAi in .

Double-stranded RNA (dsRNA) regulates gene expression in a sequence-dependent manner. In , dsRNA spreads through the body and leads to systemic RNA silencing. Although several genes involved in systemic RNAi have been genetically identified, molecules that mediate systemic RNAi remain largely unknown.

Chemical and Chemo-Enzymatic Syntheses of Glycans Containing Ribitol Phosphate Scaffolding of Matriglycan.

Ribitol phosphate modifications to the core M3 -mannosyl glycan are important for the functional maturation of α-dystroglycan. Three sequentially extended partial structures of the core M3 -mannosyl glycan including a tandem ribitol phosphate were regio- and stereo-selectively synthesized: Rbo5P-3GalNAcβ, Rbo5P-1Rbo5P-3GalNAcβ, and Xylβ1-4Rbo5P-1Rbo5P-3GalNAcβ (Rbo5P, d-ribitol-5-phosphate; GalNAc, -acetyl-d-galactosamine; Xyl, d-xylose). Rbo5P-3GalNAcβ with -nitrophenyl at the aglycon part served as a substrate for ribitol phosphate transferase (FKRP, fukutin-related protein), and its product was glycosylated by the actions of a series of glycosyltransferases, namely, ribitol xylosyltransferase 1 (RXYLT1), β1,4-glucuronyltransferase 1 (B4GAT1), and like-acetyl-glucosaminyltransferase (LARGE).

CDP-ribitol prodrug treatment ameliorates ISPD-deficient muscular dystrophy mouse model.

Ribitol-phosphate modification is crucial for the functional maturation of α-dystroglycan. Its dysfunction is associated with muscular dystrophy, cardiomyopathy, and central nervous system abnormalities; however, no effective treatments are currently available for diseases caused by ribitol-phosphate defects. In this study, we demonstrate that prodrug treatments can ameliorate muscular dystrophy caused by defects in isoprenoid synthase domain containing (ISPD), which encodes an enzyme that synthesizes CDP-ribitol, a donor substrate for ribitol-phosphate modification.

Biosynthetic Mechanisms and Biological Significance of Glycerol Phosphate-Containing Glycan in Mammals.

Bacteria contain glycerol phosphate (GroP)-containing glycans, which are important constituents of cell-surface glycopolymers such as the teichoic acids of Gram-positive bacterial cell walls. These glycopolymers comprising GroP play crucial roles in bacterial physiology and virulence. Recently, the first identification of a GroP-containing glycan in mammals was reported as a variant form of -mannosyl glycan on α-dystroglycan (α-DG).

The structure of POMGNT2 provides new insights into the mechanism to determine the functional O-mannosylation site on α-dystroglycan.

Defects in the O-mannosyl glycan of α-dystroglycan (α-DG) are associated with α-dystroglycanopathy, a group of congenital muscular dystrophies. While α-DG has many O-mannosylation sites, only the specific positions can be modified with the functional O-mannosyl glycan, namely, core M3-type glycan. POMGNT2 is a glycosyltransferase which adds β1,4-linked GlcNAc to the O-mannose (Man) residue to acquire core M3-type glycan.

Crystal structures of fukutin-related protein (FKRP), a ribitol-phosphate transferase related to muscular dystrophy.

α-Dystroglycan (α-DG) is a highly-glycosylated surface membrane protein. Defects in the O-mannosyl glycan of α-DG cause dystroglycanopathy, a group of congenital muscular dystrophies. The core M3 O-mannosyl glycan contains tandem ribitol-phosphate (RboP), a characteristic feature first found in mammals.

CDP-glycerol inhibits the synthesis of the functional -mannosyl glycan of α-dystroglycan.

α-Dystroglycan (α-DG) is a highly glycosylated cell-surface laminin receptor. Defects in the -mannosyl glycan of an α-DG with laminin-binding activity can cause α-dystroglycanopathy, a group of congenital muscular dystrophies. In the biosynthetic pathway of functional -mannosyl glycan, fukutin (FKTN) and fukutin-related protein (FKRP), whose mutated genes underlie α-dystroglycanopathy, sequentially transfer ribitol phosphate (RboP) from CDP-Rbo to form a tandem RboP unit (RboP-RboP) required for the synthesis of the laminin-binding epitope on -mannosyl glycan.

Cell endogenous activities of fukutin and FKRP coexist with the ribitol xylosyltransferase, TMEM5.

Dystroglycanopathies are a group of muscular dystrophies that are caused by abnormal glycosylation of dystroglycan; currently 18 causative genes are known. Functions of the dystroglycanopathy genes fukutin, fukutin-related protein (FKRP), and transmembrane protein 5 (TMEM5) were most recently identified; fukutin and FKRP are ribitol-phosphate transferases and TMEM5 is a ribitol xylosyltransferase. In this study, we show that fukutin, FKRP, and TMEM5 form a complex while maintaining each of their enzyme activities.

Endomembrane-associated RSD-3 is important for RNAi induced by extracellular silencing RNA in both somatic and germ cells of Caenorhabditis elegans.

RNA silencing signals in C. elegans spread among cells, leading to RNAi throughout the body. During systemic spread of RNAi, membrane trafficking is thought to play important roles.

The Tumor Suppressor BCL7B Functions in the Wnt Signaling Pathway.

Human BCL7 gene family consists of BCL7A, BCL7B, and BCL7C. A number of clinical studies have reported that BCL7 family is involved in cancer incidence, progression, and development. Among them, BCL7B, located on chromosome 7q11.

A conditional knockout toolkit for Caenorhabditis elegans based on the Cre/loxP recombination.

Conditional knockout (cKO) based on site-specific recombination (SSR) technology is a powerful approach for estimating gene functions in a spatially and temporally specific manner in many model animals. In Caenorhabditis elegans (C. elegans), spatial- and temporal-specific gene functions have been largely determined by mosaic analyses, rescue experiments and feeding RNAi methods.

Methods for single/low-copy integration by ultraviolet and trimethylpsoralen treatment in Caenorhabditis elegans.

Single/low-copy transgene integration is essential for avoiding overexpression, ectopic expression and gene silencing in the germline. Here, we present an overview of a method that uses ultraviolet and trimethylpsoralen (UV/TMP) to generate single/low-copy gene integrations in Caenorhabditis elegans. Single/low-copy transgenes from extrachromosomal arrays are integrated into the genome using positive selection based on temperature sensitivity with a vps-45 rescue fragment and negative selection based on benzimidazole sensitivity with a ben-1 rescue fragment.

Mitochondria-type GPAT is required for mitochondrial fusion.

Glycerol-3-phosphate acyltransferase (GPAT) is involved in the first step in glycerolipid synthesis and is localized in both the endoplasmic reticulum (ER) and mitochondria. To clarify the functional differences between ER-GPAT and mitochondrial (Mt)-GPAT, we generated both GPAT mutants in C. elegans and demonstrated that Mt-GPAT is essential for mitochondrial fusion.

Ablation of ALCAT1 mitigates hypertrophic cardiomyopathy through effects on oxidative stress and mitophagy.

Oxidative stress causes mitochondrial dysfunction and heart failure through unknown mechanisms. Cardiolipin (CL), a mitochondrial membrane phospholipid required for oxidative phosphorylation, plays a pivotal role in cardiac function. The onset of age-related heart diseases is characterized by aberrant CL acyl composition that is highly sensitive to oxidative damage, leading to CL peroxidation and mitochondrial dysfunction.

LYCAT, a homologue of C. elegans acl-8, acl-9, and acl-10, determines the fatty acid composition of phosphatidylinositol in mice.

Mammalian phosphatidylinositol (PI) has a unique fatty acid composition in that 1-stearoyl-2-arachidonoyl species is predominant. This fatty acid composition is formed through fatty acid remodeling by sequential deacylation and reacylation. We recently identified three Caenorhabditis elegans acyltransferases (ACL-8, ACL-9, and ACL-10) that incorporate stearic acid into the sn-1 position of PI.

Intracellular phospholipase A1 and acyltransferase, which are involved in Caenorhabditis elegans stem cell divisions, determine the sn-1 fatty acyl chain of phosphatidylinositol.

Phosphatidylinositol (PI), an important constituent of membranes, contains stearic acid as the major fatty acid at the sn-1 position. This fatty acid is thought to be incorporated into PI through fatty acid remodeling by sequential deacylation and reacylation. However, the genes responsible for the reaction are unknown, and consequently, the physiological significance of the sn-1 fatty acid remains to be elucidated.

Caenorhabditis elegans mboa-7, a member of the MBOAT family, is required for selective incorporation of polyunsaturated fatty acids into phosphatidylinositol.

Phosphatidylinositol (PI) is a component of membrane phospholipids, and it functions both as a signaling molecule and as a compartment-specific localization signal in the form of polyphosphoinositides. Arachidonic acid (AA) is the predominant fatty acid in the sn-2 position of PI in mammals. LysoPI acyltransferase (LPIAT) is thought to catalyze formation of AA-containing PI; however, the gene that encodes this enzyme has not yet been identified.