RT Journal Article
SR Electronic
T1 Expression of TrkB receptor isoforms in the developing avian visual system
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1740
OP 1752
DO 10.1523/JNEUROSCI.16-05-01740.1996
VO 16
IS 5
A1 AS Garner
A1 HJ Menegay
A1 KL Boeshore
A1 XY Xie
A1 JM Voci
A1 JE Johnson
A1 TH Large
YR 1996
UL http://www.jneurosci.org/content/16/5/1740.abstract
AB The expression of novel TrkB receptor transcripts has been characterized to understand the potentially diverse roles of brain- derived neurotrophic factor (BDNF) in the developing avian visual system. In situ localization with an extracellular domain probe common to all TrkB transcripts labeled a sub-population of large retinal ganglion cells as well as many associated visual nuclei, including the neuronal layers within the tectum that receive retinal innervation. Because of the potential for structurally and functionally distinct receptors derived from the TrkB gene locus, cDNA cloning and reverse transcription-PCR analysis were used to further analyze receptor isoform expression in the retina and tectum. Receptor isoforms were sequenced that contained a deletion of the N terminus, a deletion in the putative ligand-binding domain, or a deletion in the cytoplasmic juxtamembrane (JM) domain. Two novel JM insertion sequences also were identified, one of which exhibits weak homology to beta-actin and was found in both kinase-containing (TK+) and kinase deletion (KD) receptor isoforms. In the developing retina, TK+ receptor mRNA is upregulated during the period of retinal ganglion cell (RGC) death, consistent with the proposed role of BDNF as a tectal-derived survival factor for RGCs. However, the expression of TK+ transcripts in the tectum indicates that this structure also contains cells responsive to BDNF throughout development. Because BDNF is expressed in both the retina and tectum, it is conceivable that TrkB also mediates autocrine/paracrine signaling within these structures or anterograde retinotectal trophic support.