Open AccessM 1 muscarinic acetylcholine receptors activate zif268 gene expression via small G‐protein Rho‐dependent and λ‐independent pathways in PC12D cells
Author(s) -
Hirabayashi Toshiyuki,
Saffen David
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01258.x
Subject(s) - rhoa , muscarinic acetylcholine receptor , stimulation , acetylcholine , receptor , g protein , microbiology and biotechnology , chemistry , signal transduction , biology , endocrinology , biochemistry
We have previously shown that stimulation of M 1 muscarinic acetylcholine receptors (mAChRs) in neuronal PC12D cells rapidly induces the immediate‐early gene zif 268 [Ebihara, T. & Saffen, D. (1997) J. Neurochem. 68 , 1001–1010]. Here we show that stimulation of M 1 mAChRs in these cells activates four distal serum response elements (SREs) in the zif 268 promoter, and that this activation is strongly inhibited by Clostridium botulinum C3 exoenzyme (C3), which specifically inactivates the small G‐protein Rho. Even with high doses of C3, however, a portion of the activation remains intact, indicating that stimulation of M 1 mAChRs activates zif 268 SREs via Rho‐dependent and Rho‐independent pathways. Moreover, the Rho‐independent activation of zif 268 SREs is inhibited by the dominant‐negative form of the small G‐protein Ras, suggesting that Rho‐independent activation of zif 268 SREs is mediated by Ras. To determine if muscarinic agonists activate RhoA, we also measured the translocation of RhoA from the cytosolic fraction to the particulate fraction. Translocation of RhoA to the particulate fraction was observed within 15 min following stimulation of M 1 mAChRs, indicating that RhoA is activated with sufficient rapidity to participate in the induction of zif 268 mRNA. Together, these results suggest that RhoA is activated following stimulation of M 1 mAChRs and functions in SRE‐dependent induction of the zif 268 gene within a Ras‐independent pathway.