Ib. Walter et al., DIFFERENTIAL EXPRESSION OF TRIIODOTHYRONINE RECEPTORS IN SCHWANNOMA AND NEUROFIBROMA - ROLE OF SCHWANN CELL-AXON INTERACTION, Acta Neuropathologica, 90(2), 1995, pp. 142-149
Regulation of gene expression in Schwann cells may be determined, at l
east in part, by the interaction of these cells with axons. Two periph
eral nerve tumors, neurofibroma and schwannoma, represent good tools f
or studying Schwann cell activity in the presence or absence of axon a
ction. In the present work we studied the expression of triiodothyroni
ne receptors (T(3)R) by Schwann cells in these two tumors and also in
adult normal sciatic nerve. Confirming the results of the histological
examination, immunostaining of the neurofilaments showed the presence
of fascicles of scattered axons in all neurofibroma sections studied.
In these neurofibromas, Schwann cells did not express T(3)R immunorea
ctivity. Furthermore, in adult normal sciatic nerve, Schwann cells whi
ch ensheathed axons were devoid of any T(3)R expression. In contrast,
in schwannoma, the complete absence of axons was demonstrated by the l
ack of neurofilament immunostaining. Here, Schwann cells deprived of a
xonal interaction displayed clear T(3)R immunoreactivity. In schwannom
a cell cultures, Schwann cells continued to express T(3)R, even in cul
tures treated with medium that had been conditioned with rat sensory n
eurons. On the basis of these results, we suggest that, beside the pos
sible regulatory mechanisms for T(3)R, the synthesis of T(3)R is regul
ated, at least in part, by Schwann cell-axon interaction.