Absence of the mid-sized neurofilament subunit decreases axonal calibers, levels of light neurofilament (NF-L), and neurofilament content.
Neurofilaments (NFs) are prominent components of large myelinated axons and probably the most abundant of neuronal intermediate filament proteins. Here we show that mice with a null mutation in the mid-sized NF (NF-M) subunit have dramatically decreased levels of light NF (NF-L) and increased levels of heavy NF (NF-H). The calibers of both large and small diameter axons in the central and peripheral nervous systems are diminished. Axons of mutant animals contain fewer neurofilaments and increased numbers of microtubules. Yet the mice lack any overt behavioral phenotype or gross structural defects in the nervous system. These studies suggest that the NF-M subunit is a major regulator of the level of NF-L and that its presence is required to achieve maximal axonal diameter in all size classes of myelinated axons.
Elder
G A
GA
Department of Psychiatry, Mount Sinai School of Medicine, New York 10029, USA.
Friedrich
V L
VL
Bosco
P
P
Kang
C
C
Gourov
A
A
Tu
P H
PH
Lee
V M
VM
Lazzarini
R A
RA
D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D002460:Cell Line; D017353:Gene Deletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016900:Neurofilament Proteins / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype
D016900:Neurofilament Proteins; C044882:neurofilament protein L; C051774:neurofilament protein H; C061195:neurofilament protein M