title: Microtubule-associated protein 1B (MAP1B)-deficient neurons show structural presynaptic deficiencies in vitro and altered presynaptic physiology.
abstract: Microtubule-associated protein 1B (MAP1B) is expressed predominantly during the early stages of development of the nervous system, where it regulates processes such as axonal guidance and elongation. Nevertheless, MAP1B expression in the brain persists in adult stages, where it participates in the regulation of the structure and physiology of dendritic spines in glutamatergic synapses. Moreover, MAP1B expression is also found in presynaptic synaptosomal preparations. In this work, we describe a presynaptic phenotype in mature neurons derived from MAP1B knockout (MAP1B KO) mice. Mature neurons express MAP1B, and its deficiency does not alter the expression levels of a subgroup of other synaptic proteins. MAP1B KO neurons display a decrease in the density of presynaptic and postsynaptic terminals, which involves a reduction in the density of synaptic contacts, and an increased proportion of orphan presynaptic terminals. Accordingly, MAP1B KO neurons present altered synaptic vesicle fusion events, as shown by FM4-64 release assay, and a decrease in the density of both synaptic vesicles and dense core vesicles at presynaptic terminals. Finally, an increased proportion of excitatory immature symmetrical synaptic contacts in MAP1B KO neurons was detected. Altogether these results suggest a novel role for MAP1B in presynaptic structure and physiology regulation in vitro.
authors.affiliation: Laboratory of Cell and Neuronal Dynamics (CENEDYN), Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.|Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
authors.forename: Felipe J
authors.initials: FJ
authors.lastname: Bodaleo
authors.affiliation: Laboratory of Cell and Neuronal Dynamics (CENEDYN), Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.
authors.forename: Carolina
authors.initials: C
authors.lastname: Montenegro-Venegas
authors.affiliation: Laboratory of Cell and Neuronal Dynamics (CENEDYN), Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.|Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Henríquez
authors.affiliation: Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.|Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Catolica de Chile, Santiago, Chile.
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Court
authors.affiliation: Laboratory of Cell and Neuronal Dynamics (CENEDYN), Department of Biology, Faculty of Sciences, Universidad de Chile, Santiago, Chile.|Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.|The Buck Institute for Research on Ageing, Novato, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Gonzalez-Billault
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology; D002478:Cells, Cultured; D018920:Coculture Techniques; D049229:Dendritic Spines / Q000378:metabolism / Q000502:physiology*; D018846:Excitatory Amino Acids / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D009474:Neurons / Q000166:cytology*; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D022142:Secretory Vesicles / Q000378:metabolism; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism
chemical_list: D018846:Excitatory Amino Acids; C092350:FM 4-64; D008869:Microtubule-Associated Proteins; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D034741:RNA, Small Interfering; C085284:microtubule-associated protein 1B