Pm. Smith et al., SCIP/Oct-6, Krox-20, and desert hedgehog mRNA expression during CNS remyelination by transplanted olfactory ensheathing cells, GLIA, 36(3), 2001, pp. 342-353
Olfactory ensheathing cells (OECs), although having a separate developmenta
l origin to Schwann cells, are able to generate myelin sheaths following tr
ansplantation into areas of CNS demyelination that are remarkably similar t
o those made by Schwann cells. The transcriptional control of Schwann cell
myelination has been well documented, in particular the role of SCIP/Oct-6
and Krox-20. It is not known, however, whether these transcription factors
are also expressed when OECs assume a myelinating phenotype. In this study,
we addressed this question by using a transplantation approach to generate
myelinating OECs and then examined the expression of SCIP/ Oct-6 and Krox-
20 mRNA by in situ hybridization using oligonucleotide probes. We also exam
ined the expression of desert hedgehog (Dhh), a Schwann cell-derived signal
ing molecule that is responsible for regulating the development of the conn
ective tissue elements in peripheral nerve, which bear similarities to the
morphologies adopted by nonmyelinating transplanted cells. Our results indi
cate that both Krox-20 and Dhh mRNA are strongly expressed by transplanted
OECs, with SCIP mRNA present at much lower levels. The expression of Krox-2
0 relative to the expression of PO mRNA by the transplanted OECs is consist
ent with its playing a similar role in OEC myelination to that in Schwann c
ell myelination, while the expression of Dhh suggests a possible mechanism
for the diverse morphologies that cells adopt following OEC transplantation
into the damaged CNS. Taken together, our results provide further evidence
for the close similarity of OECs and Schwann cells and suggest that, despi
te their separate origins, the manner in which they generate a peripheral-t
ype myelin sheath involves similar regulatory mechanisms. (C) 2001 Wiley-Li
ss, Inc.