Myelin Gene Expression in Cultured Rat Schwann Cells

Morrison, Sylvia A (1993) Myelin Gene Expression in Cultured Rat Schwann Cells. PhD thesis, University of Glasgow.

Abstract

This thesis examines expression of myelin protein genes, in particular, the major myelin protein Po, in cultured rat Schwann cells. Schwann cells from various sources, sciatic nerve, dorsal root ganglia, cervical sympathetic trunk, stellate ganglia and superior cervical ganglia, were studied with respect to their ability to form myelin, and their expression of Po. Schwann cell gene expression was studied in the presence and absence of neuronal influences, and in the presence and absence of serum components. Freshly dissociated myelinating Schwann cells from neonatal sciatic nerve express Po mRNA, however signal intensity falls markedly in the absence of neurons such that by day 7 in vitro only basal levels are detectable, and are negligible compared to the level in vivo. Dorsal root ganglia from day 16 embryos (E16) display no significant levels of Po mRNA. When cultured in full myelinating medium containing serum and chick embryo extract increasing expression is observed from 4 to 5 days and myelination occurs at about day 14 in vitro. Schwann cells in dorsal root ganglia maintained in serum-free defined medium express Po mRNA in similar levels to those observed in myelinating medium prior to myelin formation. However, no Po protein is detected and the Schwann cells do not assemble a basal lamina or ensheath or myelinate axons. Schwann cells in the presence of sensory neurons in myelinating medium and defined medium also express galactocerebroside and the sulphatide recognised by the O4 antibody. Neurons from sympathetic ganglia also induce expression of Po mRNA in associated Schwann cells, although myelination does not occur in these cultures. Axonal signals appear to induce Po mRNA expression to a certain extent in defined medium and in myelinating medium, however several criteria appear to be required to initiate myelin formation. PC12 cells may also be capable of inducing Po mRNA in Schwann cells extracted from sciatic nerve. Induction of Po mRNA synthesis appears to be mediated through axonal contact signals since no expression was detected in Schwann cells exposed to DRG-conditioned medium. The results in chapters 3 - 9 suggest that Po gene expression may be regulated at several stages of synthesis.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Ian R Griffiths
• Keywords: Genetics
• Date of Award: 1993
• Depositing User: Enlighten Team
• Unique ID: glathesis:1993-75289
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 21:19
• Last Modified: 19 Nov 2019 21:19
• URI: https://theses.gla.ac.uk/id/eprint/75289