Adenylyl cyclases 1 and 8 initiate a presynaptic homeostatic response to ethanol treatment.
BACKGROUND
Although ethanol exerts widespread action in the brain, only recently has progress been made in understanding the specific events occurring at the synapse during ethanol exposure. Mice deficient in the calcium-stimulated adenylyl cyclases, AC1 and AC8 (DKO), demonstrate increased sedation duration and impaired phosphorylation by protein kinase A (PKA) following acute ethanol treatment. While not direct targets for ethanol, we hypothesize that these cyclases initiate a homeostatic presynaptic response by PKA to reactivate neurons from ethanol-mediated inhibition.


RESULTS
Here, we have used phosphoproteomic techniques and identified several presynaptic proteins that are phosphorylated in the brains of wild type mice (WT) after ethanol exposure, including synapsin, a known PKA target. Phosphorylation of synapsins I and II, as well as phosphorylation of non-PKA targets, such as, eukaryotic elongation factor-2 (eEF-2) and dynamin is significantly impaired in the brains of DKO mice. This deficit is primarily driven by AC1, as AC1-deficient, but not AC8-deficient mice also demonstrate significant reductions in phosphorylation of synapsin and eEF-2 in cortical and hippocampal tissues. DKO mice have a reduced pool of functional recycling vesicles and fewer active terminals as measured by FM1-43 uptake compared to WT controls, which may be a contributing factor to the impaired presynaptic response to ethanol treatment.


CONCLUSIONS
These data demonstrate that calcium-stimulated AC-dependent PKA activation in the presynaptic terminal, primarily driven by AC1, is a critical event in the reactivation of neurons following ethanol-induced activity blockade.
Conti
Alana C
AC
Department of Pediatrics, Washington University in St. Louis, St. Louis, Missouri, United States of America. contia@psychiatry.wustl.edu
Maas
James W
JW
Moulder
Krista L
KL
Jiang
Xiaoping
X
Dave
Bhumy A
BA
Mennerick
Steven
S
Muglia
Louis J
LJ
D000262:Adenylyl Cyclases / Q000172:deficiency / Q000378:metabolism*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D034281:Dynamins / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D054736:Elongation Factor 2 Kinase / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects / Q000201:enzymology; D006706:Homeostasis / Q000187:drug effects*; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000201:enzymology*; D040901:Proteomics; D016704:Synapsins / Q000378:metabolism; D013572:Synaptic Vesicles / Q000187:drug effects / Q000201:enzymology
D010750:Phosphoproteins; D016704:Synapsins; D000431:Ethanol; D017868:Cyclic AMP-Dependent Protein Kinases; D054736:Elongation Factor 2 Kinase; D034281:Dynamins; D000262:Adenylyl Cyclases; C106670:adenylyl cyclase 1; C118292:adenylyl cyclase 8