Plexins: axon guidance and signal transduction.
Axon guidance represents a key stage in the formation of neuronal network. Axons are guided by a variety of guidance factors, such as semaphorins, ephrins and netrin. Plexins function as receptors for the repulsive axonal guidance molecules semaphorins. Intracellular domains of plexins are responsible for initiating cellular signal transduction inducing axon repulsion. Recent advances have revealed molecular mechanisms for plexin-mediated cytoskeletal reorganization, leading to repulsive responses, and small GTPases play important roles in this signaling. Plexin-B1 activates Rho through Rho-specific guanine nucleotide exchange factors, leading to neurite retraction. Plexin-B1 possesses an intrinsic GTPase-activating protein activity for R-Ras and induces growth cone collapse through R-Ras inactivation. In this review we survey current understanding of the signaling mechanisms of plexins.
Negishi
M
M
Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. mnegishi@pharm.kyoto-u.ac.jp
Oinuma
I
I
Katoh
H
H
D000818:Animals; D001369:Axons / Q000502:physiology*; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002450:Cell Communication; D006801:Humans; D009419:Nerve Tissue Proteins / Q000502:physiology*; D039961:Semaphorins / Q000502:physiology*; D015398:Signal Transduction; D020741:rho GTP-Binding Proteins / Q000502:physiology*
D015815:Cell Adhesion Molecules; D009419:Nerve Tissue Proteins; D039961:Semaphorins; C091529:plexin; D020741:rho GTP-Binding Proteins