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Glial transcytosis of a photoreceptor‐secreted signaling protein, retinoschisin
Author(s) -
Reid Silvia N.M.,
Farber Debora B.
Publication year - 2005
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.20131
Subject(s) - retina , biology , microbiology and biotechnology , transcytosis , retinal , signal transduction , muller glia , cell signaling , cell , neuroscience , biochemistry , stem cell , progenitor cell , endocytosis
In vitro studies have clearly shown that signaling/guidance proteins can diffuse to their targets. However, it is unclear whether they can travel by diffusion in vivo , or if they are distributed in the tissue by an active mechanism. Retinoschisin, a signaling molecule related to neuropilins, is synthesized and secreted by photoreceptor cells in the outer retina; then it interacts with inner retinal cells contributing to synaptic organization and optic nerve fiber integrity. We developed an assay to examine how retinoschisin, which is secreted a distance away, reaches its inner retinal targets. We found that retinoschisin is preferentially taken up and carried into the inner retina from the retinal outer border (the photoreceptor side) by Müller cells (the main glial cells of the vertebrate retina). This transcytosis is disrupted by DL ‐α‐aminoadipic acid, a Müller cell/glia‐specific toxin. Our results suggest that glial uptake/transcytosis can provide an effective and precise alternative for distributing signaling molecules in the nervous system. © 2004 Wiley‐Liss, Inc.