Structural plasticity of actin-spectrin membrane skeleton and functional role of actin and spectrin in axon degeneration

ABSTRACT: Axon degeneration sculpts precise patterns of connectivity in the developing nervous system and is an early pathological hallmark of several adult-onset neurodegenerative disorders. Substantial progress has been made in identifying effector mechanisms that drive axon fragmentation, but far less is known about the upstream signaling pathways that initiate this process. Here we describe a role for the newly discovered axonal Membrane-associated Periodic Skeleton (MPS) –a quasi-1D periodic ultrastructure composed of actin, spectrin and associated molecules– during sensory axon degeneration. We find that trophic deprivation (TD) of sensory axons causes a rapid breakdown in the periodicity of the MPS in distal axons. These structural changes occur prior to and independently of caspase-driven axon fragmentation. We further show that acute actin destabilization to break down the MPS can initiate TD-related retrograde signaling. Actin stabilization prevents MPS breakdown during TD and blocks this signal. Moreover, deletion of βII-spectrin (Sptbn1), an obligate component of the MPS, suppresses this retrograde signaling and protects axons against degeneration. Together our data suggest that ultrastructural plasticity of the MPS underlies the earliest steps of axon degeneration.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Neuron, Sensory Neuron Of Dorsal Root Ganglion

SUBMITTER: henrik molina  

LAB HEAD: David J. Simon

PROVIDER: PXD009854 | Pride | 2019-03-14

REPOSITORIES: Pride