A Uniform and Isotropic Cytoskeletal Tiling Fills Dendritic Spines

• Dendritic spines are submicron, subcellular compartments whose shape is defined by actin filaments and associated proteins. Accurately mapping the cytoskeleton is a challenge, given the small size of its components. It remains unclear whether the actin-associated structures analyzed in dendritic spines of neurons in vitro apply to dendritic spines of intact, mature neurons in situ. Here, we combined advanced preparative methods with multitilt serial section electron microscopy (EM) tomography and computational analysis to reveal the full three-dimensional (3D) internal architecture of spines in the intact brains of male mice at nanometer resolution. We compared hippocampal (CA1) pyramidal cells and cerebellar Purkinje cells in terms of the length distribution and connectivity of filaments, their branching-angles and absolute orientations, and the elementary loops formed by the network. Despite differences in shape and size across spines and between spine heads and necks, the internal organization was remarkably similar in both neuron types and largely homogeneous throughout the spine volume. In the tortuous mesh of highly branched and interconnected filaments, branches exhibited no preferred orientation except in the immediate vicinity of the cell membrane. We found that new filaments preferentially split off from the convex side of a bending filament, consistent with the behavior of Arp2/3-mediated branching of actin under mechanical deformation. Based on the quantitative analysis, the spine cytoskeleton is likely subject to considerable mechanical force in situ. 

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

Nyckelord

actin cytoskeleton

cerebellar Purkinje cell

dendritic spines in situ

EM tomography

hippocampal pyramidal cell

image segmentation

Actins

Animals

Cytoskeleton

Dendritic Spines

Hippocampus

Male

Mice

Neurons

ketamine

xylazine

actin

actin filament

animal cell

animal experiment

animal model

animal tissue

Article

brain tissue

C57BL/6N mouse

cell membrane

controlled study

dendritic spine

electron microscopy

electron tomography

endoplasmic reticulum

image reconstruction

machine learning

molecular dynamics

morphometry

mouse

nonhuman

postsynaptic density

Purkinje cell

pyramidal nerve cell

quantitative analysis

synapse

three dimensional echography

animal

metabolism

nerve cell

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)