The Dunce cAMP phosphodiesterase PDE-4 negatively regulates G alpha(s)-dependent and G alpha(s)-independent cAMP pools in the Caenorhabditis elegans synaptic signaling network.
Forward genetic screens for mutations that rescue the paralysis of ric-8 (Synembryn) reduction-of-function mutations frequently reveal mutations that cause hyperactivation of one or more components of the G alpha(s) pathway. Here, we report that one of these mutations strongly reduces the function of the Dunce cAMP phosphodiesterase PDE-4 by disrupting a conserved active site residue. Loss of function and neural overexpression of PDE-4 have profound and opposite effects on locomotion rate, but drug-response assays suggest that loss of PDE-4 function does not affect steady-state acetylcholine release or reception. Our genetic analysis suggests that PDE-4 regulates both G alpha(s)-dependent and G alpha(s)-independent cAMP pools in the neurons controlling locomotion rate. By immunostaining, PDE-4 is strongly expressed throughout the nervous system, where it localizes to small regions at the outside boundaries of synaptic vesicle clusters as well as intersynaptic regions. The synaptic subregions containing PDE-4 are distinct from those containing active zones, as indicated by costaining with an antibody against the long form of UNC-13. This highly focal subsynaptic localization suggests that PDE-4 may exert its effects by spatially regulating intrasynaptic cAMP pools.
Charlie
Nicole K
NK
Program in Molecular, Cell and Developmental Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104, USA.
Thomure
Angela M
AM
Schade
Michael A
MA
Miller
Kenneth G
KG
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D000448:Aldicarb / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D002352:Carrier Proteins; D020134:Catalytic Domain / Q000235:genetics; D000242:Cyclic AMP / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D005786:Gene Expression Regulation; D017238:Genes, Helminth / Q000235:genetics; D007978:Levamisole / Q000494:pharmacology; D008124:Locomotion; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D010641:Phenotype; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017384:Sequence Deletion; D015398:Signal Transduction; D013569:Synapses / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism
D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; C083141:phorbol ester binding protein; D007978:Levamisole; D000448:Aldicarb; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D019205:GTP-Binding Protein alpha Subunits, Gs