A forward genetic screen in mice identifies Sema3A(K108N), which binds to neuropilin-1 but cannot signal.
We have performed a three-generation, forward genetic screen to identify recessive mutations that affect the patterning of the peripheral nervous system. Using this assay, we identified Sema3A(K108N), a novel loss-of-function allele of Sema3A. Class 3 semaphorins, which include Sema3A, are structurally conserved secreted proteins that play critical roles in the development and function of the nervous system. Sema3A(K108N) mutant mice phenocopy Sema3A-null mice, and Sema3A(K108N) protein fails to repel or collapse DRG axons in vitro. K108 is conserved among semaphorins, yet the loss-of-function effects associated with K108N are not the result of impaired expression, secretion, or binding of Sema3A to its high-affinity receptor Neuropilin-1 (Npn-1). Using in silico modeling and mutagenesis of other semaphorin family members, we predict that Sema3A(K108N) interacts poorly with the Npn-1/PlexA holoreceptor and, thus, interferes with its ability to signal at the growth cone. Therefore, through the use of a forward-genetic screen we have identified a novel allele of Sema3A that provides structural insight into the mechanism of Sema3A/Npn-1/PlexinA signaling.
Merte
Janna
J
The Solomon H. Snyder Department of Neuroscience and Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, Maryland 21205, USA.
Wang
Qiang
Q
Vander Kooi
Craig W
CW
Sarsfield
Sarah
S
Leahy
Daniel J
DJ
Kolodkin
Alex L
AL
Ginty
David D
DD
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D001216:Asparagine / Q000235:genetics; D002460:Cell Line; D005260:Female; D005808:Genes, Recessive; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D008239:Lysine / Q000235:genetics; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D039942:Neuropilin-1 / Q000235:genetics* / Q000378:metabolism*; D017354:Point Mutation; D011485:Protein Binding / Q000235:genetics; D040121:Semaphorin-3A / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics*
C488217:Sema3a protein, mouse; D040121:Semaphorin-3A; D039942:Neuropilin-1; D001216:Asparagine; D008239:Lysine
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