Biology subjects

Yonekawa, T.

Publications and source records attributed to Yonekawa, T..

3 recordsLinked to original sources

bioRxiv2023

Identification of a short, single site matriglycan that maintains neuromuscular function in the mouse

Matriglycan (-1,3-{beta}-glucuronic acid-1,3--xylose-) is a polysaccharide that is synthesized on -dystroglycan, where it functions as a high-affinity glycan receptor for extracellular proteins, such as laminin, perlecan and agrin, thus anchoring the plasma membrane to the extracellular matrix. This biological activity is closely associated with the size of matriglycan. Using high-resolution mass spectrometry and site-specific mutant mice, we show for the first time that matriglycan on the T317/T319 and T379 sites of -dystroglycan are not identical. T379-linked matriglycan is shorter than the previously characterized T317/T319-linked matriglycan, although it maintains its laminin binding capacity. Transgenic mice with only the shorter T379-linked matriglycan exhibited mild embryonic lethality, but those that survived were healthy. The shorter T379-linked matriglycan exists in multiple tissues and maintains neuromuscular function in adult mice. In addition, the genetic transfer of -dystroglycan carrying just the short matriglycan restored grip strength and protected skeletal muscle from eccentric contraction-induced damage in muscle-specific dystroglycan knock-out mice. Due to the effects that matriglycan imparts on the extracellular proteome and its ability to modulate cell-matrix interactions, our work suggests that differential regulation of matriglycan length in various tissues optimizes the extracellular environment for unique cell types.

biochemistry↗

bioRxiv2021

Large1 Gene Transfer in Older myd Mice with Severe Muscular Dystrophy Restores Muscle Function and Greatly Improves Survival

Muscular dystrophy is a progressive and ultimately lethal neuromuscular disease due to lack of therapeutic options that restore muscle function. Gene editing and gene transfer hold great promise as therapies for various neuromuscular diseases when administered prior to the onset of severe clinical symptoms. However, the efficacy of these strategies for restoring neuromuscular function and improving survival in the late stages of muscular dystrophy with severe muscle pathophysiology is unknown. Dystroglycanopathies are muscular dystrophies characterized by extensive skeletal muscle degeneration and, in many cases, are accompanied by eye and brain abnormalities. Thus far, mutations in at least eighteen human genes are known to cause dystroglycanopathies, including those in the like-acetylglucosaminyltransferase-1 (LARGE1) gene. LARGE1 encodes a xylosyl- and glucuronosyltransferase that modifies -dystroglycan (-DG) with matriglycan, a linear repeating disaccharide of alternating xylose and glucuronic acid that binds to the laminin G-like domains of extracellular matrix proteins with high affinity. Largemyd/Largemyd (myd) mice lack expression of Large1, and exhibit severe skeletal muscle pathophysiology, impaired mobility, and a drastically reduced lifespan (50% survivorship at 35 weeks of age). Here, we show that systemic delivery of AAV2/9 CMV Large1 (AAVLarge1) in >34-week-old myd mice with advanced disease restores matriglycan expression, attenuates skeletal muscle pathophysiology, improves motor and respiratory function, and normalizes systemic metabolism, which collectively and dramatically extends survival. Our results demonstrate that in a mouse model of muscular dystrophy, skeletal muscle function can be restored, illustrating its remarkable plasticity, and that survival can be greatly improved even after the onset of severe skeletal muscle pathophysiology.

physiology↗

bioRxiv2020

POMK Regulates Dystroglycan Function via LARGE-mediated Elongation of Matriglycan

Matriglycan [-GlcA-{beta}1,3-Xyl-1,3-]n serves as a scaffold in many tissues for extracellular matrix proteins containing laminin-G domains including laminin, agrin, and perlecan. Like-acetylglucosaminyltransferase-1 (LARGE) synthesizes and extends matriglycan on -dystroglycan (-DG) during skeletal muscle differentiation and regeneration; however, the mechanisms which regulate matriglycan elongation are unknown. Here, we show that Protein O-Mannose Kinase (POMK), which phosphorylates mannose of core M3 (GalNac-{beta}1,3-GlcNac-{beta}1,4-Man) preceding matriglycan synthesis, is required for LARGE-mediated generation of full-length matriglycan on -DG ([~]150 kDa). In the absence of POMK, LARGE synthesizes a very short matriglycan resulting in a [~]90 kDa -DG in mouse skeletal muscle which binds laminin but cannot prevent eccentric contraction-induced force loss or muscle pathology. Solution NMR spectroscopy studies demonstrate that LARGE directly interacts with core M3 and binds preferentially to the phosphorylated form. Collectively, our study demonstrates that phosphorylation of core M3 by POMK enables LARGE to elongate matriglycan on -DG, thereby preventing muscular dystrophy.

biochemistry↗