title: Cellular site and molecular mode of synapsin action in associative learning.
abstract: Synapsin is an evolutionarily conserved, presynaptic vesicular phosphoprotein. Here, we ask where and how synapsin functions in associative behavioral plasticity. Upon loss or reduction of synapsin in a deletion mutant or via RNAi, respectively, Drosophila larvae are impaired in odor-sugar associative learning. Acute global expression of synapsin and local expression in only the mushroom body, a third-order "cortical" brain region, fully restores associative ability in the mutant. No rescue is found by synapsin expression in mushroom body input neurons or by expression excluding the mushroom bodies. On the molecular level, we find that a transgenically expressed synapsin with dysfunctional PKA-consensus sites cannot rescue the defect of the mutant in associative function, thus assigning synapsin as a behaviorally relevant effector of the AC-cAMP-PKA cascade. We therefore suggest that synapsin acts in associative memory trace formation in the mushroom bodies, as a downstream element of AC-cAMP-PKA signaling. These analyses provide a comprehensive chain of explanation from the molecular level to an associative behavioral change.
authors.affiliation: Universität Würzburg, Biozentrum, Neurobiologie und Genetik, 97074 Würzburg, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Michels
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Chen
authors.forename: Timo
authors.initials: T
authors.lastname: Saumweber
authors.forename: Dushyant
authors.initials: D
authors.lastname: Mishra
authors.forename: Hiromu
authors.initials: H
authors.lastname: Tanimoto
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmid
authors.forename: Olivia
authors.initials: O
authors.lastname: Engmann
authors.forename: Bertram
authors.initials: B
authors.lastname: Gerber
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D030801:Animals, Genetically Modified; D001245:Association Learning / Q000502:physiology*; D001522:Behavior, Animal; D003216:Conditioning, Operant / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics; D018625:Microscopy, Atomic Force; D024521:Mushroom Bodies / Q000166:cytology* / Q000378:metabolism; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D034622:RNA Interference / Q000502:physiology; D017384:Sequence Deletion / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D018709:Statistics, Nonparametric; D016704:Synapsins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000199:Actins; D029721:Drosophila Proteins; D016704:Synapsins; D017868:Cyclic AMP-Dependent Protein Kinases