J. Eichberg et al., RECEPTOR-MEDIATED PHOSPHOINOSITIDE METABOLISM IN PERIPHERAL-NERVE ANDCULTURED SCHWANN-CELLS, Journal of lipid mediators and cell signalling, 14(1-3), 1996, pp. 187-195
Peripheral nerve possesses muscarinic cholinergic receptors, predomina
ntly of the M(3) subtype, that stimulate phosphoinositide metabolism.
Evidence suggests that one site of this response is the myelin sheath.
Purified peripheral nerve myelin contains several heterotrimeric GTP-
binding proteins. Furthermore, carbachol and guanosine-5'-(3-O-thio)tr
iphosphate-stimulated hydrolysis of exogenous phosphatidylinositol-4,5
-bis-phosphate that is blocked by atropine can be reconstituted in a p
urified peripheral myelin-rich fraction. Nerve phosphoinositide turnov
er is also stimulated by adenosine analogs and blocked by adenosine re
ceptor antagonists in a pattern consistent with the presence of adenos
ine A(2) receptors in the tissue. Receptor-mediated phosphoinositide m
etabolism has also been studied in a human tumor-derived Schwann cell
line (NF1T) derived from a neurofibromatosis-1 patient. By the same ex
perimental criteria, NF1T cells also appear to contain adenosine A(2)
receptors which upon activation stimulate phosphoinositide turnover. H
owever, phosphoinositide metabolism in these cells is not increased by
either carbachol or ATP. Our findings taken together with other repor
ts suggest that Schwann cells may possess a variety of receptors which
regulate phosphoinositide metabolism.