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Mol Neurobiol. 2019 Oct;56(10):6833-6855. doi: 10.1007/s12035-019-1551-0. Epub 2019 Mar 30.

Prominent Postsynaptic and Dendritic Exocytosis of Endogenous BDNF Vesicles in BDNF-GFP Knock-in Mice.

Author information

1
Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, D-55128, Mainz, Germany.
2
Institute of Physiology, Medical Faculty, Otto-von-Guericke University, Leipziger Str. 44, D-39120, Magdeburg, Germany.
3
Center for Behavioral Brain Sciences (CBBS), 39120, Magdeburg, Germany.
4
Institute of Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University, 39120, Magdeburg, Germany.
5
Laboratory for Electron and Laserscan Microscopy, Leibniz Institute for Neurobiology, 39118, Magdeburg, Germany.
6
Department of Informatics and Microsystem Technology, University of Applied Sciences Kaiserslautern, 66482, Zweibruecken, Germany.
7
German Resilience Center, University Medical Center of the Johannes Gutenberg University, 55128, Mainz, Germany.
8
Institute of Physiology, Medical Faculty, Otto-von-Guericke University, Leipziger Str. 44, D-39120, Magdeburg, Germany. lessmann@med.ovgu.de.
9
Center for Behavioral Brain Sciences (CBBS), 39120, Magdeburg, Germany. lessmann@med.ovgu.de.

Abstract

Brain-derived neurotrophic factor (BDNF) is a secreted messenger molecule that is crucial for neuronal function and induction of synaptic plasticity. Although altered availability of BDNF underlies many neurological deficits and neurodegenerative disorders, secretion dynamics of endogenous BDNF are unexplored. We generated a BDNF-GFP knock-in (KiBE) mouse, in which GFP-labeled BDNF is expressed under the control of the unaltered endogenous mouse BDNF gene regulatory elements. This KiBE mouse model enables for the first time live cell imaging analysis of endogenous BDNF dynamics. We show that BDNF-GFP release and biological activity in vivo are unaffected by the GFP tag, since homozygous KiBE mice, which lack wild-type BDNF, are healthy and have a normal life expectancy. STED superresolution microscopy shows that 70% of BDNF-GFP vesicles in KiBE mouse neurites are localized in dendrites, being typically 200 nm away from synaptic release sites. Live cell imaging in hippocampal slices also reveals prominent targeting of endogenous BDNF-GFP vesicles to dendrites. Fusion pore opening and cargo release of dendritic BDNF vesicles start within 30 s after a strong depolarizing stimulus and continue for > 100 s thereafter, revealing an astonishingly delayed and prolonged release of endogenous BDNF.

KEYWORDS:

BDNF; Exocytosis; GFP knock-in; Hippocampus; Neuropeptide secretion; Neurotrophin; Secretory granules

PMID:
30929164
DOI:
10.1007/s12035-019-1551-0

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