Tension Sensor Based on Fluorescence Resonance Energy Transfer Reveals Fiber Diameter-Dependent Mechanical Factors During Myelination

Oligodendrocytes (OLs) form a myelin sheath around neuronal axons to increase conduction velocity of action potential. Although both large and small diameter axons are intermingled in the central nervous system (CNS), the number of myelin wrapping is related to the axon diameter, such that the ratio...

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Bibliographic Details
Published in:Frontiers in cellular neuroscience 2021-08, Vol.15, p.685044-685044
Main Authors: Shimizu, Takeshi, Murakoshi, Hideji, Matsumoto, Hidetoshi, Ichino, Kota, Hattori, Atsunori, Ueno, Shinya, Ishida, Akimasa, Tajiri, Naoki, Hida, Hideki
Format: Article
Language:English
Subjects:
Action potential
Adhesion
Axons
Central nervous system
Cytoskeleton
Fibers
Fluorescence resonance energy transfer
Kinases
mechanical factor
Mechanical properties
Mechanotransduction
Mutation
Myelination
Neuroscience
oligodendrocyte
Oligodendrocytes
Polystyrene
Proteins
Sensors
Signal transduction
Spinal cord
tension sensor
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Summary:Oligodendrocytes (OLs) form a myelin sheath around neuronal axons to increase conduction velocity of action potential. Although both large and small diameter axons are intermingled in the central nervous system (CNS), the number of myelin wrapping is related to the axon diameter, such that the ratio of the diameter of the axon to that of the entire myelinated-axon unit is optimal for each axon, which is required for exerting higher brain functions. This indicates there are unknown axon diameter-dependent factors that control myelination. We tried to investigate physical factors to clarify the mechanisms underlying axon diameter-dependent myelination. To visualize OL-generating forces during myelination, a tension sensor based on fluorescence resonance energy transfer (FRET) was used. Polystyrene nanofibers with varying diameters similar to neuronal axons were prepared to investigate biophysical factors regulating the OL-axon interactions. We found that higher tension was generated at OL processes contacting larger diameter fibers compared with smaller diameter fibers. Additionally, OLs formed longer focal adhesions (FAs) on larger diameter axons and shorter FAs on smaller diameter axons. These results suggest that OLs respond to the fiber diameter and activate mechanotransduction initiated at FAs, which controls their cytoskeletal organization and myelin formation. This study leads to the novel and interesting idea that physical factors are involved in myelin formation in response to axon diameter.
ISSN:1662-5102
1662-5102
DOI:10.3389/fncel.2021.685044