Localization of Phospholipid Synthesis to Schwann Cells and Axons

Robert M. Gould, John Holshek, Wayne Silverman, Warren D. Spivack

Research output: Contribution to journalArticlepeer-review

Abstract

Abstract: Quantitative electron microscopic autoradiography was used to detect and characterize endoneurial sites of lipid synthesis in mouse sciatic nerve. Six tritiated phospholipid precursors (choline, serine, methionine, inositol, glyc‐erol, and ethanolamine) and a protein precursor (proline) were individually injected into exposed nerves and after 2 h the mice were perfused with buffered aldehyde. The labeled segments of nerve were prepared for autoradiography with procedures that selectively remove nonincorporated precursors and other aqueous metabolites, while preserving nerve lipids (and proteins). At both the light and electron microscope levels, the major site of phospholipid and protein synthesis was the crescent‐shaped perinuclear cytoplasm of my‐elinating Schwann cells. Other internodal Schwann cell cytoplasm, including that in surface channels, Schmidt‐Lanterman incisures, and paranodal regions, was less well labeled than the perinuclear region. Newly formed proteins were selectively located in the Schwann cell nucleus. Lipid and protein formation was also detected in unmyelinated fiber bundles and in endoneurial and perineurial cells. Tritiated inositol was selectively incorporated into phospholip‐ids in both myelinated axons and unmyelinated fibers. Like inositol, glycerol incorporation appeared particularly active in unmyelinated fibers. Quantitative autoradiographic analyses substantiated the following points: (1) myelinating Schwann cells dominate phospholipid and protein synthesis, (2) myelinated axons selectively incorporate tritiated inositol, (3) phospholipid precursors label myelin sheaths and myelinated axons better than proline.

Original languageEnglish (US)
Pages (from-to)1121-1131
Number of pages11
JournalJournal of Neurochemistry
Volume48
Issue number4
DOIs
StatePublished - Apr 1987

Keywords

  • Axons
  • Electron microscope autoradiography
  • Peripheral nerve
  • Phosphatidylinositol
  • Phospholipid metabolism
  • Schwann cells

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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