RT Journal Article
SR Electronic
T1 The roles of microtubules and membrane tension in axonal beading, retraction, and atrophy
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 575258
DO 10.1101/575258
A1 Anagha Datar
A1 Jaishabanu Ameeramja
A1 Alka Bhat
A1 Roli Srivastava
A1 Roberto Bernal
A1 Jacques Prost
A1 Andrew Callan-Jones
A1 Pramod A Pullarkat
YR 2019
UL http://biorxiv.org/content/early/2019/03/12/575258.abstract
AB Axonal beading—formation of a series of swellings along the axon—and retraction are commonly observed shape transformations that precede axonal atrophy in Alzheimer’s, Parkinson, and other neurodegenerative conditions. The mechanisms driving these morphological transformations are poorly understood. Here we report controlled experiments which can induce either beading or retraction and follow the time evolution of these responses. By making quantitative analysis of the shape modes under different conditions, measurement of membrane tension, and using theoretical considerations, we argue that membrane tension is the main driving force that pushes cytosol out of the axon when microtubules are degraded, causing axonal thinning. Under pharmacological perturbation, atrophy is always retrograde and this is set by a gradient in the microtubule stability. The nature of microtubule depolymerization dictates the type of shape transformation vis à vis beading or retraction. Elucidating the mechanisms of these shape transformations will facilitate development of strategies to prevent or arrest axonal atrophy due to neurodegenerative conditions.