Dissociation of Axonal Neurofilament Content from Its Transport Rate

TY - JOUR

T1 - Dissociation of Axonal Neurofilament Content from Its Transport Rate

AU - Yuan, Aidong

AU - Hassinger, Linda

AU - Rao, Mala V.

AU - Julien, Jean-Pierre

AU - Miller, Christopher C. J.

AU - Nixon, Ralph A.

PY - 2015/7/24

Y1 - 2015/7/24

N2 - The axonal cytoskeleton of neurofilament (NF) is a long-lived network of fibrous elements believed to be a stationary structure maintained by a small pool of transported cytoskeletal precursors. Accordingly, it may be predicted that NF content in axons can vary independently from the transport rate of NF. In the present report, we confirm this prediction by showing that human NFH transgenic mice and transgenic mice expressing human NFL Ser55 (Asp) develop nearly identical abnormal patterns of NF accumulation and distribution in association with opposite changes in NF slow transport rates. We also show that the rate of NF transport in wild-type mice remains constant along a length of the optic axon where NF content varies 3-fold. Moreover, knockout mice lacking NFH develop even more extreme (6-fold) proximal to distal variation in NF number, which is associated with a normal wild-type rate of NF transport. The independence of regional NF content and NF transport is consistent with previous evidence suggesting that the rate of incorporation of transported NF precursors into a metabolically stable stationary cytoskeletal network is the major determinant of axonal NF content, enabling the generation of the striking local variations in NF number seen along axons.

AB - The axonal cytoskeleton of neurofilament (NF) is a long-lived network of fibrous elements believed to be a stationary structure maintained by a small pool of transported cytoskeletal precursors. Accordingly, it may be predicted that NF content in axons can vary independently from the transport rate of NF. In the present report, we confirm this prediction by showing that human NFH transgenic mice and transgenic mice expressing human NFL Ser55 (Asp) develop nearly identical abnormal patterns of NF accumulation and distribution in association with opposite changes in NF slow transport rates. We also show that the rate of NF transport in wild-type mice remains constant along a length of the optic axon where NF content varies 3-fold. Moreover, knockout mice lacking NFH develop even more extreme (6-fold) proximal to distal variation in NF number, which is associated with a normal wild-type rate of NF transport. The independence of regional NF content and NF transport is consistent with previous evidence suggesting that the rate of incorporation of transported NF precursors into a metabolically stable stationary cytoskeletal network is the major determinant of axonal NF content, enabling the generation of the striking local variations in NF number seen along axons.

KW - AMYOTROPHIC-LATERAL-SCLEROSIS

KW - MOLECULAR-MASS SUBUNIT

KW - GANGLION-CELL NEURONS

KW - IN-VIVO

KW - INITIAL SEGMENT

KW - RADIAL GROWTH

KW - HEAVY SUBUNIT

KW - CHICKEN MOTONEURONS

KW - PHOSPHORYLATED TAIL

KW - ALPHA-INTERNEXIN

U2 - 10.1371/journal.pone.0133848

DO - 10.1371/journal.pone.0133848

M3 - Article

SN - 1932-6203

VL - 10

JO - PL o S One

JF - PL o S One

IS - 7

M1 - 0133848

ER -