Hsc70 chaperone activity underlies Trio GEF function in axon growth and guidance induced by netrin-1.
During development, netrin-1 is both an attractive and repulsive axon guidance cue and mediates its attractive function through the receptor Deleted in Colorectal Cancer (DCC). The activation of Rho guanosine triphosphatases within the extending growth cone facilitates the dynamic reorganization of the cytoskeleton required to drive axon extension. The Rac1 guanine nucleotide exchange factor (GEF) Trio is essential for netrin-1-induced axon outgrowth and guidance. Here, we identify the molecular chaperone heat shock cognate protein 70 (Hsc70) as a novel Trio regulator. Hsc70 dynamically associated with the N-terminal region and Rac1 GEF domain of Trio. Whereas Hsc70 expression supported Trio-dependent Rac1 activation, adenosine triphosphatase-deficient Hsc70 (D10N) abrogated Trio Rac1 GEF activity and netrin-1-induced Rac1 activation. Hsc70 was required for netrin-1-mediated axon growth and attraction in vitro, whereas Hsc70 activity supported callosal projections and radial neuronal migration in the embryonic neocortex. These findings demonstrate that Hsc70 chaperone activity is required for Rac1 activation by Trio and this function underlies netrin-1/DCC-dependent axon outgrowth and guidance.
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada The Research Institute of McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.
Jonathan
J
DeGeer
Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 2B4, Canada.
Andrew
A
Kaplan
Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada.
Pierre
P
Mattar
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada The Research Institute of McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada.
Morgane
M
Morabito
Department of Physiology, McGill University, Montreal, Quebec H3G 1Y6, Canada.
Ursula
U
Stochaj
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 2B4, Canada.
Timothy E
TE
Kennedy
Centre de Recherche de Biochimie Macromoléculaire, Centre National de la Recherche Scientifique, UMR5237, University of Montpellier, Montpellier 34293, France.
Anne
A
Debant
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada Department of Medicine, Université de Montréal, Montreal, Quubec H3T 1J4, Canada.
Michel
M
Cayouette
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec H3A 2B4, Canada.
Alyson E
AE
Fournier
Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 0C7, Canada The Research Institute of McGill University Health Centre, Montreal, Quebec H4A 3J1, Canada nathalie.lamarche@mcgill.ca.
Nathalie
N
Lamarche-Vane
D000251:Adenosine Triphosphatases / Q000235:genetics; D000818:Animals; D001369:Axons / Q000502:physiology*; D002460:Cell Line; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D000075389:DCC Receptor; D004789:Enzyme Activation; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D057809:HEK293 Cells; D050883:HSC70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D019579:Neocortex / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D009414:Nerve Growth Factors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D000075388:Netrin-1; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
D000075389:DCC Receptor; C501912:Dcc protein, rat; D020662:Guanine Nucleotide Exchange Factors; D050883:HSC70 Heat-Shock Proteins; C494373:Hspa8 protein, rat; C000617351:NTN1 protein, human; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; C000617353:Ntn1 protein, mouse; C000617354:Ntn1 protein, rat; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C500736:Trio protein, rat; D025521:Tumor Suppressor Proteins; D000075388:Netrin-1; D000251:Adenosine Triphosphatases; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein