A quantitative analysis of an average cultured neuron
von Sebastian Jähne
Datum der mündl. Prüfung:2019-05-20
Betreuer:Prof. Dr. Silvio O. Rizzoli
Gutachter:Prof. Dr. Silvio O. Rizzoli
Gutachter:Prof. Dr. Nils Brose
EnglischNeurons are the functional unit of the brain. They have been extensively studied, from a molecular perspective up to brain wide levels. Nonetheless, we are still missing a quantitative description of the neuronal components. I present here a comprehensive description of cultured hippocampal neurons and their compartments and organelles. I used a combination of fluorescence microscopy, super-resolution microscopy, and electron microscopy to determine the distributions, volumes, and compartment specific differences of 32 organelle markers. I found that organelles occupy almost 90% of the neuronal cell body, which implicated diffusional constraints. Comparing organelle sizes across axons, dendrites, and cell bodies, I could show that most organelles are significantly different when located in different compartments. Finally, I was able to show that the number of pre- and postsynapses per cultured neuron is tightly correlated despite a strong disparity between the axonal and dendritic volumes. The dataset provided here is the basis for a quantitative molecular nanomap of a cultured hippocampal neuron, which in addition to the organelle composition will contain the molecular composition. Furthermore, I used correlated optical and isotopic imaging to study the protein turnover at synapses. I found that the presynaptic protein turnover is correlated to synaptic activity at the single synapse level. This is interesting as it shows for the first time a direct coupling of synaptic activity to protein turnover. Chronically inhibiting synaptic activity produced a homeostatic scaling effect with increased protein turnover.
Keywords: hippocampal neuron; neuron nanomap; organelle; synapse turnover; quantitative neurobiology