Local Accumulation of Axonal Mitochondria in the Optic Nerve Glial Lamina Precedes Myelination

Mitochondria are essential for neurons and must be optimally distributed along their axon to fulfill local functions. A high density of mitochondria has been observed in retinal ganglion cell (RGC) axons of an unmyelinated region of the optic nerve, called the glial lamina (GL) in mouse (lamina crib...

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Bibliographic Details
Published in:Frontiers in neuroanatomy 2021-05, Vol.15, p.678501-678501
Main Authors: Wilkison, Samantha J, Bright, Cora L, Vancini, Ricardo, Song, Daniel J, Bomze, Howard M, Cartoni, Romain
Format: Article
Language:English
Subjects:
Axons
Blindness
Chloride
Degeneration
Glaucoma
Laboratory animals
Mitochondria
Myelination
Neuronal-glial interactions
Neuroscience
Optic nerve
retina
Retinal ganglion cells
Scanning electron microscopy
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Summary:Mitochondria are essential for neurons and must be optimally distributed along their axon to fulfill local functions. A high density of mitochondria has been observed in retinal ganglion cell (RGC) axons of an unmyelinated region of the optic nerve, called the glial lamina (GL) in mouse (lamina cribrosa in human). In glaucoma, the world's leading cause of irreversible blindness, the GL is the epicenter of RGC degeneration and is connected to mitochondrial dysfunction. It is generally accepted that the local accumulation of mitochondria in the GL is established due to the higher energy requirement of unmyelinated axons. Here we revisit the connection between mitochondrial positioning and myelin in RGC axons. We show that the high density of mitochondria in the GL is restricted to larger axons and is established before myelination. Thus, contrary to a longstanding belief in the field, the myelination pattern is not responsible for the establishment of the local accumulation of mitochondria in GL axons. Our findings open new research avenues likely critical to understanding the pathophysiology of glaucoma.
ISSN:1662-5129
1662-5129
DOI:10.3389/fnana.2021.678501