Biology subjects

Motohashi, N.

Publications and source records attributed to Motohashi, N..

3 recordsLinked to original sources

bioRxiv2026

Biomechanical regulation of Ca2+ dynamics during muscle stem cell activation

Muscle satellite cells (MuSCs) are muscle-resident stem cells that are responsible for myofiber regeneration. Although the importance of calcium ions (Ca2+) in muscle physiology has been well established, the mechanism by which Ca2+ mobilization governs MuSC function remains poorly understood. In this study, we aimed to systematically characterize Ca2+ dynamics in MuSCs and to define the mechanisms regulating these signals during muscle regeneration. By employing modified protocols for mouse MuSC isolation and Ca2+ measurement, we observed spontaneous Ca2+ fluctuations in MuSCs isolated from regenerating muscle after cardiotoxin-induced myofiber injury. Our detailed analysis using chemical Ca2+ indicators and a genetically encoded Ca2+ indicator revealed that the frequency and amplitude of Ca2+ fluctuations increased significantly during the activated and proliferative stages of MuSCs in muscle regeneration. This effect was more pronounced in MuSCs isolated from dystrophic and aged mice. Mechanistically, these Ca2+ fluctuations were at least partially mediated by mechanosensitive ion channels, including PIEZO1 and TRPM7, which promote MuSC migration. Collectively, our findings demonstrate that Ca2+ fluctuations through mechanosensitive ion channels act as a key regulator of MuSC activation during muscle regeneration and may provide new insights into the role of Ca2+ influx in muscle biology and the pathogenesis of muscle diseases.

cell biology↗

bioRxiv2025

MBOAT2 limits the amounts of PUFA in phosphatidylcholine of neonatal and dystrophic skeletal muscle and promotes muscle regeneration

Skeletal muscle regeneration is critically shaped by lipid remodeling, yet regulatory mechanisms involved remain unexplored. We identify MBOAT2, a lysophospholipid acyltransferase highly induced in activated satellite cells, as a key enzyme that limits the amounts of polyunsaturated fatty acids (PUFAs) in phosphatidylcholine (PC). Lipidomic profiling reveals a characteristic PC signature--high in monounsaturated fatty acids (MUFAs) and low in PUFAs--in dystrophic, injured, and neonatal muscle, paralleling elevated Mboat2 expression. Given the susceptibility of PUFAs to oxidative damage and the emerging role of lipid peroxidation in driving muscle atrophy during denervation, disuse, and aging, MBOAT2-mediated enrichment of MUFA-PC may represent a protective and pro-regenerative lipid environment. Loss- and gain-of-function approaches confirm that MBOAT2 remodels PC and promotes myogenic repair. Our findings uncover a lipid remodeling circuit in muscle stem cells that buffers oxidative stress and highlight that MBOAT2 may improve regenerative capacity in muscular dystrophy, sarcopenia, and other muscle-wasting conditions. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/686003v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@e9acddorg.highwire.dtl.DTLVardef@1541b14org.highwire.dtl.DTLVardef@bdfe54org.highwire.dtl.DTLVardef@1844b89_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2023

Exon 44 skipping in Duchenne muscular dystrophy: NS-089/NCNP-02, a dual-targeting antisense oligonucleotide

Exon-skipping therapy mediated by antisense oligonucleotides (ASOs) is expected to provide a therapeutic option for Duchenne muscular dystrophy (DMD). ASOs for exon skipping reported so far target a single continuous sequence in or around the target exon. In the present study, we investigated ASOs for exon 44 skipping (applicable to approximately 6% of all DMD patients) to improve activity by using a novel ASO design incorporating two connected sequences. Phosphorodiamidate morpholino oligomers targeting two separate sequences in exon 44 were created to simultaneously target two splicing regulators in exon 44, and their exon 44 skipping was measured. NS-089/NCNP-02 showed the highest skipping activity among the oligomers. NS-089/NCNP-02 also induced exon 44 skipping and dystrophin protein expression in cells from a DMD patient to whom exon 44 skipping is applicable. We also assessed the in vivo activity of NS-089/NCNP-02 by intravenous administration to cynomolgus monkeys. NS-089/NCNP-02 induced exon 44 skipping in skeletal and cardiac muscle of cynomolgus monkeys. In conclusion, NS-089/NCNP-02, an ASO with a novel connected-sequence design, showed both in vitro and in vivo exon-skipping activity.

cell biology↗