Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis

Elizabeth A. Mills, Chung Ha O Davis, Eric A. Bushong, Daniela Boassa, Keun Young Kim, Mark H. Ellisman, Nicholas Marsh-Armstrong

Research output: Research - peer-reviewArticle

Abstract

Oligodendrocytes can adapt to increases in axon diameter through the addition of membrane wraps to myelin segments. Here, we report that myelin segments can also decrease their length in response to optic nerve (ON) shortening during Xenopus laevis metamorphic remodeling. EM-based analyses revealed that myelin segment shortening is accomplished by focal myelin-axon detachments and protrusions from otherwise intact myelin segments. Astrocyte processes remove these focal myelin dystrophies using known phagocytic machinery, including the opsonin milk fat globule-EGF factor 8 (Mfge8) and the downstream effector ras-related C3 botulinum toxin substrate 1 (Rac1). By the end of metamorphic nerve shortening, one-quarter of all myelin in the ON is enwrapped or internalized by astrocytes. As opposed to the removal of degenerating myelin by macrophages, which is usually associated with axonal pathologies, astrocytes selectively remove large amounts of myelin without damaging axons during this developmental remodeling event.

LanguageEnglish (US)
Pages10509-10514
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number33
DOIs
StatePublished - Aug 18 2015

Fingerprint

Xenopus laevis
Optic Nerve
Myelin Sheath
Phagocytosis
Astrocytes
Axons
rac1 GTP-Binding Protein
Opsonin Proteins
Oligodendroglia
Epidermal Growth Factor
Macrophages
Pathology
Membranes
milk fat globule

Keywords

  • Glia
  • Lipid droplet
  • Mfge8
  • Thyroid hormone

ASJC Scopus subject areas

  • General

Cite this

Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis. / Mills, Elizabeth A.; Davis, Chung Ha O; Bushong, Eric A.; Boassa, Daniela; Kim, Keun Young; Ellisman, Mark H.; Marsh-Armstrong, Nicholas.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 112, No. 33, 18.08.2015, p. 10509-10514.

Research output: Research - peer-reviewArticle

Mills, Elizabeth A. ; Davis, Chung Ha O ; Bushong, Eric A. ; Boassa, Daniela ; Kim, Keun Young ; Ellisman, Mark H. ; Marsh-Armstrong, Nicholas. / Astrocytes phagocytose focal dystrophies from shortening myelin segments in the optic nerve of Xenopus laevis at metamorphosis. In: Proceedings of the National Academy of Sciences of the United States of America. 2015 ; Vol. 112, No. 33. pp. 10509-10514
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