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Role of Rho kinase pathway in chondroitin sulfate proteoglycan‐mediated inhibition of neurite outgrowth in PC12 cells
Author(s) -
Gopalakrishnan Sujatha M.,
Teusch Nicole,
Imhof Christiane,
Bakker Margot H. M.,
Schurdak Mark,
Burns David J.,
Warrior Usha
Publication year - 2008
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.21671
Subject(s) - neurite , rho associated protein kinase , fasudil , microbiology and biotechnology , chondroitin sulfate proteoglycan , cofilin , growth cone , phosphorylation , chemistry , chondroitin sulfate , phosphatase , myosin , proteoglycan , biology , biochemistry , actin cytoskeleton , axon , cell , cytoskeleton , in vitro , extracellular matrix , glycosaminoglycan
Activation of the Rho kinase (ROCK) pathway has been associated with inhibition of neurite regeneration and outgrowth in spinal cord injury. Growth‐inhibitory substances present in the glial scar such as chondroitin sulfate proteoglycans (CSPGs) have been shown to create a nonpermissive environment for axon regeneration that results in growth cone collapse. In this study, an in vitro model was developed in nerve growth factor‐differentiated PC12 cells where the Rho/ROCK pathway was modulated by CSPG. CSPG elicited concentration‐dependent inhibition of neurite outgrowth in PC12 cells, which was reversed by ROCK inhibitors such as fasudil, dimethylfasudil, and Y27632. Further studies on the interactions of CSPG with ROCK inhibitors revealed that the modulation of ROCK by CSPG is noncompetitive in nature. It was also observed that ROCK inhibitors increased neurite outgrowth in undifferentiated PC12 cells, indicating constitutive ROCK activity in the cells. Analysis of signaling pathways demonstrated that the effect of CSPG increases the phosphorylation of myosin phosphatase, a substrate immediately downstream of ROCK activation. Fasudil, dimethylfasudil, and Y27632 inhibited the phosphorylation of myosin phosphatase induced by CSPG with rank order potencies comparable to those observed in the neurite outgrowth assay. In addition, ROCK inhibitors reversed cofilin phosphorylation induced by CSPG with similar rank order potencies. Taken together, our data demonstrate that the interaction of CSPG with the ROCK pathway involves downstream effectors of ROCK such as myosin phosphatase and cofilin. © 2008 Wiley‐Liss, Inc.