title: Preserved morphology and physiology of excitatory synapses in profilin1-deficient mice.
abstract: Profilins are important regulators of actin dynamics and have been implicated in activity-dependent morphological changes of dendritic spines and synaptic plasticity. Recently, defective presynaptic excitability and neurotransmitter release of glutamatergic synapses were described for profilin2-deficient mice. Both dendritic spine morphology and synaptic plasticity were fully preserved in these mutants, bringing forward the hypothesis that profilin1 is mainly involved in postsynaptic mechanisms, complementary to the presynaptic role of profilin2. To test the hypothesis and to elucidate the synaptic function of profilin1, we here specifically deleted profilin1 in neurons of the adult forebrain by using conditional knockout mice on a CaMKII-cre-expressing background. Analysis of Golgi-stained hippocampal pyramidal cells and electron micrographs from the CA1 stratum radiatum revealed normal synapse density, spine morphology, and synapse ultrastructure in the absence of profilin1. Moreover, electrophysiological recordings showed that basal synaptic transmission, presynaptic physiology, as well as postsynaptic plasticity were unchanged in profilin1 mutants. Hence, loss of profilin1 had no adverse effects on the morphology and function of excitatory synapses. Our data are in agreement with two different scenarios: i) profilins are not relevant for actin regulation in postsynaptic structures, activity-dependent morphological changes of dendritic spines, and synaptic plasticity or ii) profilin1 and profilin2 have overlapping functions particularly in the postsynaptic compartment. Future analysis of double mutant mice will ultimately unravel whether profilins are relevant for dendritic spine morphology and synaptic plasticity.
authors.affiliation: Neurobiology/Neurophysiology Group, University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Görlich
authors.forename: Anika-Maria
authors.initials: AM
authors.lastname: Zimmermann
authors.forename: Doreen
authors.initials: D
authors.lastname: Schober
authors.forename: Ralph T
authors.initials: RT
authors.lastname: Böttcher
authors.forename: Marco
authors.initials: M
authors.lastname: Sassoè-Pognetto
authors.forename: Eckhard
authors.initials: E
authors.lastname: Friauf
authors.forename: Walter
authors.initials: W
authors.lastname: Witke
authors.forename: Marco B
authors.initials: MB
authors.lastname: Rust
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000502:physiology; D049229:Dendritic Spines / Q000378:metabolism / Q000648:ultrastructure; D017353:Gene Deletion; D051379:Mice; D008822:Mice, Transgenic; D009473:Neuronal Plasticity / Q000502:physiology; D009928:Organ Specificity; D051304:Profilins / Q000172:deficiency* / Q000378:metabolism; D016548:Prosencephalon / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
chemical_list: C495739:Pfn1 protein, mouse; C495742:Pfn2 protein, mouse; D051304:Profilins