RT Journal Article
SR Electronic
T1 Chick PTPς Regulates the Targeting of Retinal Axons within the Optic Tectum
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 5024
OP 5033
DO 10.1523/JNEUROSCI.22-12-05024.2002
VO 22
IS 12
A1 Fiza Rashid-Doubell
A1 Iain McKinnell
A1 A. Radu Aricescu
A1 Gustavo Sajnani
A1 Andrew Stoker
YR 2002
UL http://www.jneurosci.org/content/22/12/5024.abstract
AB Chick PTPς (cPTPς), also known as CRYPα, is a receptor-like protein tyrosine phosphatase found on axons and growth cones. Putative ligands for cPTPς are distributed within basement membranes and on glial end feet of the retina, optic nerve, and optic tectum, suggesting that cPTPς signaling is occurring along the whole retinotectal pathway. We have shown previously that cPTPς plays a role in supporting the retinal phase of axon outgrowth. Here we have now addressed the role of cPTPς within retinal axons as they undergo growth and topographic targeting in the optic tectum. With the use of retroviruses, a secretable cPTPς ectodomain was ectopically expressedin ovo in the developing chick optic tectum, with the aim of directly disrupting the function of endogenous cPTPς.In ovo, the secreted ectodomains accumulated at tectal sites in which cPTPς ligands are also specifically found, suggesting that they are binding to these endogenous ligands. Anterograde labeling of retinal axons entering these optic tecta revealed abnormal axonal phenotypes. These included the premature stalling and arborization of fibers, excessive pretectal arbor formation, and diffuse termination zones. Most of the defects were rostral of the predicted termination zone, indicating that cPTPς function is necessary for sustaining the growth of retinal axons over the optic tectum and for directing axons to their correct sites of termination. This demonstrates that regulation of cPTPς signaling in retinal axons is required for their topographic mapping, the first evidence of this function for a receptor-like protein tyrosine phosphatase in the retinotectal projection.