Journal of Neuroscience, Vol 16, 31-35, Copyright © 1996 by Society for Neuroscience
mRNA expression of KIF1A, KIF1B, KIF2, KIF3A, KIF3B, KIF4, KIF5, and cytoplasmic dynein during axonal regeneration
R Takemura, T Nakata, Y Okada, H Yamazaki, Z Zhang and N Hirokawa
Department of Anatomy and Cell Biology, School of Medicine, University of Tokyo, Japan.
Mouse brain expresses multiple kinesin superfamily proteins (KIFs), which
are involved in vesicle transport. The expression of KIFs is
developmentally regulated, and both the mRNA and proteins of KIF2 and KIF4
are expressed abundantly in the juvenile brain. To elucidate the role of
individual kinesin superfamily motor proteins during regenerative outgrowth
of axons, we examined the mRNA expression of KIF1A, KIF1B, KIF2, KIF3A,
KIF3B, KIF4, and KIF5 in adult mouse dorsal root ganglion cells after
sciatic nerve crush. Seven to fourteen days after the nerve crush, the mRNA
expression pattern of neurofilament and beta-tubulin isotypes suggested
that the regenerative outgrowth of axons was active. At these stages,
levels of mRNA for KIF1A, KIF1B, KIF2, KIF3A, KIF3B, KIF4, and KIF5 were
50.80% of control. The levels of mRNA for KIF4, which are detected in
juvenile brain but not in the adult, were under the detection limit in both
control and regenerating dorsal root ganglion cells. Because mRNA of
neither KIF2 nor KIF4 increased significantly, the results suggest that the
gene expression of KIFs during regeneration does not recapitulate the
embryonic development and support the hypothesis that different series of
events take place during the regenerative and embryonic outgrowths of
axons. In contrast, mRNA for cytoplasmic dynein was slightly increased, up
to 140%. This is consistent with the hypothesis that retrograde transport
plays critical roles in regeneration such as the transport of neurotrophic
factors.