Synaptopodin regulates denervation-induced plasticity at hippocampal mossy fiber synapses

Neurological diseases can lead to the denervation of brain regions caused by demyelination, traumatic injury or cell death. The molecular and structural mechanisms underlying lesion-induced reorganization of denervated brain regions, however, are a matter of ongoing investigation. In order to address this issue, we performed an entorhinal cortex lesion (ECL) in mouse organotypic entorhino-hippocampal tissue cultures of both sexes and studied denervation-induced plasticity of mossy fiber synapses, which connect dentate granule cells (dGCs) with CA3 pyramidal cells (CA3-PCs) and play important roles in learning and memory formation. Partial denervation caused a strengthening of excitatory neurotransmission in dGCs, CA3-PCs and their direct synaptic connections, as revealed by paired recordings (dGC-to-CA3-PC). These functional changes were accompanied by ultrastructural reorganization of mossy fiber synapses, which regularly contain the plasticity-regulating protein synaptopodin and the s..., Ethics statement
Mice were maintained in a 12 h light/dark cycle with food and water available ad libitum. Every effort was made to minimize distress and pain of animals. All experimental procedures were performed according to German animal welfare legislation and approved by the appropriate animal welfare committee and the animal welfare officer of Albert-Ludwigs-University Freiburg, Faculty of Medicine (X-17/07K, X-17/09K, X-21/01B) and Hannover Medical School (2022/308).
Preparation of tissue cultures
Entorhino-hippocampal tissue cultures were prepared at postnatal day 3-5 from C57BL/6J (wildtype, Synpo+/+) and B6.129-Synpotm1Mndl/Dllr (Synpo-/-) mice of either sex. Synpo-/- strain was back crossed for at least 10 times to establish C57BL/6J genetic background. Cultivation medium contained 50% (v/v) MEM, 25% (v/v) basal medium eagle, 25% (v/v) heat-inactivated normal horse serum, 25 mM HEPES buffer solution, 0.15% (w/v) bicarbonate, 0.65% (w/v) glucose, 0.1 mg/ml streptomycin, 100 U/..., Experimental Design and Statistical Analysis
Electrophysiological data were analyzed using pClamp 10.7 (Axon Instruments) and MiniAnalysis (Synaptosoft) software. The fraction of action potentials followed by time-locked excitatory postsynaptic current responses was considered as synaptic response rate. uEPSC amplitude was assessed in uEPSCs from successfully transmitted action potentials as well as the mean amplitude of all successfully evoked postsynaptic responses. In order to ensure analysis of time-locked unitary responses, events were included if > 5% of presynaptic pulses were successfully transmitted for each pulse respectively. For individual pulses in pulse trains that caused ≤ 5% successfully transmitted events, response rate was set to ‘0’. sEPSC properties were analyzed using the automated template search tool for event detection. Since sEPSC kinetics might contain information on their synaptic origin (in CA3-PCs, large EPSCs have been identified to originate from hippo..., # README for Synaptopodin regulates denervation-induced plasticity at hippocampal mossy fiber synapses

Pia Kruse1, Gudrun Brandes2, Hanna Hemeling1, Zhong Huang2, Christoph Wrede3,4, Jan Hegermann3,4, Andreas Vlachos1,5,6, and Maximilian Lenz1,2,

1    Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

2    Hannover Medical School, Institute of Neuroanatomy and Cell Biology, Hannover, Germany.

3    Hannover Medical School, Institute of Functional and Applied Anatomy, Hannover, Germany.

4    Hannover Medical School, Research Core Unit Electron Microscopy, Hannover, Germany.

5    Center for Basics in Neuromodulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany.

6    Center BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany.

Correspondence: and

## Description of the data and file structure

#### General information

Source Data for statistical analys...