Soluble adenylyl cyclase mediates nerve growth factor-induced activation of Rap1.
Nerve growth factor (NGF) and the ubiquitous second messenger cyclic AMP (cAMP) are both implicated in neuronal differentiation. Multiple studies indicate that NGF signals to at least a subset of its targets via cAMP, but the link between NGF and cAMP has remained elusive. Here, we have described the use of small molecule inhibitors to differentiate between the two known sources of cAMP in mammalian cells, bicarbonate- and calcium-responsive soluble adenylyl cyclase (sAC) and G protein-regulated transmembrane adenylyl cyclases. These inhibitors, along with sAC-specific small interfering RNA, reveal that sAC is uniquely responsible for the NGF-elicited rise in cAMP and is essential for the NGF-induced activation of the small G protein Rap1 in PC12 cells. In contrast and as expected, transmembrane adenylyl cyclase-generated cAMP is responsible for Rap1 activation by the G protein-coupled receptor ligand PACAP (pituitary adenylyl cyclase-activating peptide). These results identify sAC as a mediator of NGF signaling and reveal the existence of distinct pathways leading to cAMP-dependent signal transduction.
Stessin
Alexander M
AM
Department of Pharmacology, New York, New York 10021; Tri-institutional M.D./Ph.D. Program, Weill Medical College of Cornell University, New York, New York 10021.
Zippin
Jonathan H
JH
Department of Pharmacology, New York, New York 10021; Tri-institutional M.D./Ph.D. Program, Weill Medical College of Cornell University, New York, New York 10021.
Kamenetsky
Margarita
M
Department of Pharmacology, New York, New York 10021.
Hess
Kenneth C
KC
Department of Pharmacology, New York, New York 10021.
Buck
Jochen
J
Department of Pharmacology, New York, New York 10021. Electronic address: jobuck@med.cornell.edu.
Levin
Lonny R
LR
Department of Pharmacology, New York, New York 10021.
D000262:Adenylyl Cyclases / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation; D020932:Nerve Growth Factor / Q000378:metabolism*; D016716:PC12 Cells; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D034741:RNA, Small Interfering; D020932:Nerve Growth Factor; D000242:Cyclic AMP; D020827:rap1 GTP-Binding Proteins; D018631:ras Proteins; D000262:Adenylyl Cyclases; D002118:Calcium