Cell endocytosis in AIS is essential for maintaining dendritic protein polarity.
a, morphology nervous cells (A neuron, or neuron, is an passive cell that forms the functional unit…) PVD in C. elegans. The dendrites are very long and branched, while the axon does not branch. In AIS, marked with various signs, dots denote protein (A protein is a biological macromolecule consisting of one or more…) Dendritic (DMA-1) habitat.
b, in a neuron of Mouse (The word “rat” means in French, colloquially…)dendritic protein-containing endocytosis events occur in dendrites and soma (trans blue (Blue (from Old German “blao” = shiny) is one of the three colors…) clear) and SIA (yellow crosses) but very little in the axon.
C, In human neurons, after inhibiting endocytosis, dendritic proteins, which are not normally found in the axon, become detectable in the axon.
D, Schematic of the three cellular mechanisms that maintain polarity in neurons. The third mechanism, endocytosis in AIS, was revealed in the study by Eichel et al.
© David Pires
Neurons, the main cells in brain (The brain is the main organ of the central nervous system of animals. Brain processes…)are highly polarized cells, that is, they consist of two completely different parts: on the one hand, the axon, which is a very fine tubular segment (less than 1 μm in diameter) that can reach some neurons height (The length of an object is the distance between its farthest ends…) From several centimeters or even about one meter (The meter (symbol m, from the Greek metronome, measure) is the basic unit of length…). The axon allows electrical signals to be transmitted to target neurons through the synapses. On the other hand, the cell body and the dendrites that make up the “receptive” part of the neuron, in which there are many synapses formed with other neurons, are located. The electrical signals from the synapses are combined, and then, if they are large enough, they will cause the generation of an action potential at the level of an intermediate compartment between the axon and the soma called the axon initial segment (AIS).
In addition to its role in generating action potentials, SIA game (The cheek is the part that covers and closes the oral cavity of the face…) A very important role in preserving polarization (polarization of electromagnetic waves; polarization due to moments…) nervous cells. In fact, the constituent elements of the axon or dendrites/soma, in particular the proteins, differ greatly. Neurons, at the level of the AIS, possess mechanisms that allow the sorting of cellular elements in order to ensure this polarity. So far, scientists have been able to prove two cellular mechanisms for maintaining polarity. First, vesicles Transportation (Transportation is the process of moving something, or someone, from one place to another, and more…) Cells are sorted at the SIA level: those that transport hub proteins pass through filtered (The filter is a system for separating the elements in the flow.) It is located in the AIS while vesicles carrying dendritic proteins enter the AIS but cannot pass (The genus Passer was created by the French zoologist Mathurin Jacques…) Filter and turn around. Second, the proteins on plasma membrane (The plasma membrane, or plasma membrane, is the membrane that defines the cell, it is…) in space (Surface generally refers to the surface layer of an object. The term A…) Neurons diffuse into the membrane but AIS also has a barrier identification (In everyday parlance, the term diffusion refers to an idea…) This makes it possible to filter out dendritic surface proteins by preventing them from diffusion into the axon.
As part of the cooperation withUniversity (The university is an institution of higher education whose goal is…) From Stanford in California, scientists from CNRS (The National Center for Scientific Research, better known by the acronym CNRS, is the largest…) identified a third mechanism for maintaining neuronal polarity: internalization of dendritic surface proteins by endocytosis and their degradation in AIS. To reach this conclusion, they used three biological models. everybody (All is understood as all that exists most often as the world or …) First, they studied some neurons in worm (Worms are a heterogeneous group of invertebrate animals…) nematodes Certain types are eleganta millimeter-long worm is one of the most model systems studied by biologists.
By focusing their study on one of the worm’s 302 neurons, the scientists showed that this neuron has AIS and that specifically blocking endocytosis in this neuron causes a redistribution of a dendritic surface protein called DMA-1 to the axon. Moreover, this protein, which is responsible for the formation of dendritic branches, causes the formation of ectopic branches that are normally absent in the axon when present in the axon. They also showed that endocytosis plays the same role for dendritic surface proteins in human neurons, as well as in rodent neurons.
The scientists also directly visualized the cellular endocytosis of AIS using the . methodphotographer (Images are basically the making and circulation of physical images that…) by optical (Fluorescence is a light emission resulting from the excitation of a molecule…) To detect the formation of internal vesicles in time (Time is a concept developed by humans to understand…) real (see Sposini et al. 2020) to show that dendritic surface proteins are indeed internalized into the AIS of neurons, and that repeat (In physics, frequency generally refers to a measure of how many times…) The composition of the internal vesicle is the same as that of the dendrites.
These findings constitute an important advance in understanding the cellular mechanisms of neuronal polarity formation and maintenance. It will also make it possible to study this new form of cellular endocytosis and identify its specific mechanisms, which could lead to a better understanding of the functioning of AIS, an essential part of neuronal function.
To find out more:
Endocytosis in the initial segment of the axon is a depolarizing mechanism for maintaining neuronal polarity.
Eichel K, Uenaka T, Belapurkar V, Lu R, Cheng S, Pak JS, Taylor CA, Südhof TC, Malenka RC, Wernig M, Özkan E, Perrais D, Shen K.
Nature August 17, 2022. https://doi.org/10.1038 / s41586-022-05074-5
Imaging of inner vesicle formation at high spatio-temporal resolution with a pulsed pH-pH protocol.
Spozzini, M. Roosendaal, El Claverie, Van TNN, De Jolly, De Pireas.
Nature Protocols September 2020 DOI: 10.1038 / s41596-020-0371-z
institute interdisciplinary (Interdisciplinary work includes concepts from different disciplines.) From Neurology (Neuroscience corresponds to the range of all biological disciplines and …) (CNRS/Purdue University). Broca New Aquitaine Building. 146 Street (The street is a trading space in the city that serves housing and places…) Leo Senat.
French version (674.92 KB)
David Perez- Researcher (Researcher (researcher) refers to a person whose job it is to conduct research…) CNRS ininstitute (An institute is a permanent organization created for a specific purpose. It is…) Interdisciplinary Neurosciences (CNRS / Bordeaux University) – david.perrais at u-bordeaux.fr
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