Down syndrome cell adhesion molecule (DSCAM) associates with uncoordinated-5C (UNC5C) in netrin-1-mediated growth cone collapse.
In the developing nervous system, neuronal growth cones explore the extracellular environment for guidance cues, which can guide them along specific trajectories toward their targets. Netrin-1, a bifunctional guidance cue, binds to deleted in colorectal cancer (DCC) and DSCAM mediating axon attraction, and UNC5 mediating axon repulsion. Here, we show that DSCAM interacts with UNC5C and this interaction is stimulated by netrin-1 in primary cortical neurons and postnatal cerebellar granule cells. DSCAM partially co-localized with UNC5C in primary neurons and brain tissues. Netrin-1 induces axon growth cone collapse of mouse cerebellum external granule layer (EGL) cells, and the knockdown of DSCAM or UNC5C by specific shRNAs or blocking their signaling by overexpressing dominant negative mutants suppresses netrin-1-induced growth cone collapse. Similarly, the simultaneous knockdown of DSCAM and UNC5C also blocks netrin-1-induced growth cone collapse in EGL cells. Netrin-1 increases tyrosine phosphorylation of endogenous DSCAM, UNC5C, FAK, Fyn, and PAK1, and promotes complex formation of DSCAM with these signaling molecules in primary postnatal cerebellar neurons. Inhibition of Src family kinases efficiently reduces the interaction of DSCAM with UNC5C, FAK, Fyn, and PAK1 and tyrosine phosphorylation of these proteins as well as growth cone collapse of mouse EGL cells induced by netrin-1. The knockdown of DSCAM inhibits netrin-induced tyrosine phosphorylation of UNC5C and Fyn as well as the interaction of UNC5C with Fyn. The double knockdown of both receptors abolishes the induction of Fyn tyrosine phosphorylation by netrin-1. Our study reveals the first evidence that DSCAM coordinates with UNC5C in netrin-1 repulsion.
Department of Biological Sciences, University of Toledo, Toledo, Ohio 43606, USA.
Anish A
AA
Purohit
Weiquan
W
Li
Chao
C
Qu
Trisha
T
Dwyer
Qiangqiang
Q
Shao
Kun-Liang
KL
Guan
Guofa
G
Liu
D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002478:Cells, Cultured; D017931:DNA Primers; D020439:Growth Cones / Q000473:pathology*; D051379:Mice; D009414:Nerve Growth Factors / Q000378:metabolism*; D000075386:Netrin Receptors; D000075388:Netrin-1; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
D015815:Cell Adhesion Molecules; D017931:DNA Primers; C110833:DSCAM protein, human; C000617351:NTN1 protein, human; D009414:Nerve Growth Factors; D000075386:Netrin Receptors; C000617353:Ntn1 protein, mouse; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; C115727:UNC5C protein, human; D000075388:Netrin-1; D019061:src-Family Kinases