Myosin IIA is required for neurite outgrowth inhibition produced by repulsive guidance molecule.
Although myelin-associated neurite outgrowth inhibitors express their effects through RhoA/Rho-kinase, the downstream targets of Rho-kinase remain unknown. We examined the involvement of myosin II, which is one of the downstream targets of Rho-kinase, by using blebbistatin - a specific myosin II inhibitor - and small interfering RNA targeting two myosin II isoforms, namely, MIIA and MIIB. We found that neurite outgrowth inhibition by repulsive guidance molecule (RGMa) was mediated via myosin II, particularly MIIA, in cerebellar granule neurons. RGMa induced myosin light chain (MLC) phosphorylation by a Rho-kinase-dependent mechanism. After spinal cord injury in rats, phosphorylated MLC in axons around the lesion site was up-regulated, and this effect depends on Rho-kinase activity. Further, RGMa-induced F-actin reduction in growth cones and growth cone collapse were mediated by MIIA. We conclude that Rho-kinase-dependent activation of MIIA via MLC phosphorylation induces F-actin reduction and growth cone collapse and the subsequent neurite retraction/outgrowth inhibition triggered by RGMa.
Kubo
Takekazu
T
Department of Neurobiology, Graduate School of Medicine, Chiba University, Chuo-ku, Chiba, Japan, and BioClues Inc., Nihonbashi, Chuo-ku, Tokyo, Japan. kubo@restaff.chiba-u.jp
Endo
Mitsuharu
M
Hata
Katsuhiko
K
Taniguchi
Junko
J
Kitajo
Keiko
K
Tomura
Sayaka
S
Yamaguchi
Atsushi
A
Mueller
Bernhard K
BK
Yamashita
Toshihide
T
D000199:Actins / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D005260:Female; D058851:GPI-Linked Proteins; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D047468:Immunoprecipitation / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D007796:Laminectomy / Q000379:methods; D008562:Membrane Glycoproteins / Q000494:pharmacology; D018994:Myosin Light Chains / Q000378:metabolism; D024462:Myosin Type II / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection / Q000379:methods; D054460:rho-Associated Kinases / Q000378:metabolism
D000199:Actins; D058851:GPI-Linked Proteins; D006576:Heterocyclic Compounds, 4 or More Rings; D008562:Membrane Glycoproteins; D018994:Myosin Light Chains; D009419:Nerve Tissue Proteins; C502259:RGM protein, rat; D034741:RNA, Small Interfering; C472645:blebbistatin; D054460:rho-Associated Kinases; D024462:Myosin Type II