L1-dependent neuritogenesis involves ankyrinB that mediates L1-CAM coupling with retrograde actin flow.
The cell adhesion molecule L1 (L1-CAM) plays critical roles in neurite growth. Its cytoplasmic domain (L1CD) binds to ankyrins that associate with the spectrin-actin network. This paper demonstrates that L1-CAM interactions with ankyrinB (but not with ankyrinG) are involved in the initial formation of neurites. In the membranous protrusions surrounding the soma before neuritogenesis, filamentous actin (F-actin) and ankyrinB continuously move toward the soma (retrograde flow). Bead-tracking experiments show that ankyrinB mediates L1-CAM coupling with retrograde F-actin flow in these perisomatic structures. Ligation of the L1-CAM ectodomain by an immobile substrate induces L1CD-ankyrinB binding and the formation of stationary ankyrinB clusters. Neurite initiation preferentially occurs at the site of these clusters. In contrast, ankyrinB is involved neither in L1-CAM coupling with F-actin flow in growth cones nor in L1-based neurite elongation. Our results indicate that ankyrinB promotes neurite initiation by acting as a component of the clutch module that transmits traction force generated by F-actin flow to the extracellular substrate via L1-CAM.
Nishimura
Kazunari
K
Laboratory for Neuronal Growth Mechanisms, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
Yoshihara
Fumie
F
Tojima
Takuro
T
Ooashi
Noriko
N
Yoon
Woohyun
W
Mikoshiba
Katsuhiko
K
Bennett
Vann
V
Kamiguchi
Hiroyuki
H
D000199:Actins / Q000378:metabolism*; D000818:Animals; D017487:Ankyrins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D022081:Cell Surface Extensions / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D005727:Ganglia, Spinal / Q000166:cytology; D006801:Humans; D051379:Mice; D039842:Neural Cell Adhesion Molecule L1 / Q000737:chemistry / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism*; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism
C498994:ANK2 protein, human; D000199:Actins; C498995:Ank2 protein, mouse; D017487:Ankyrins; D039842:Neural Cell Adhesion Molecule L1; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins