A. Haidan et al., Expression of adrenocortical steroidogenic acute regulatory (StAR) proteinis influenced by chromaffin cells, MOL C ENDOC, 165(1-2), 2000, pp. 25-32
Cell-cell interactions are crucial role for the proper functioning of endoc
rine glands. We recently demonstrated that interactions of chromaffin and c
ortical cells are important for adrenocortical steroidogenesis. However, th
e molecular mechanisms have not been elucidated and it is unclear if this i
nvolves acute and/or chronic processes. By Northern analysis and the quanti
tative technique of TaqMan PCR we investigated whether chromaffin cells inf
luence the regulation of StAR and the peripheral benzodiazepine receptor (P
BR), both required for the rate-limiting step, the delivery of cholesterol
to the inner mitochondrial membrane. StAR mRNA levels in bovine adrenocorti
cal cells were increased by incubation with chromaffin cell-conditioned med
ium (CCM). Short-term treatment for 4 h resulted in a greater stimulation (
229 +/- 29% of basal, mean +/- SEM) than did longer incubation times of 8 h
and 5 days (159 +/- 13 and 177 +/- 24%). Neither short nor a long-term tre
atment affected PER expression. Consistently, the major secretion of chroma
ffin cells, epinephrine dose-dependently stimulated StAR expression with no
effect on PER mRNA. In conclusion, adrenomedullary secretory products are
not necessary for the maintenance of PER expression but facilitate steroid
biosynthesis by increasing StAR mRNA expression and therefore can account f
or an ACTH-independent regulation of the rate-limiting step in steroidogene
sis. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserve
d.