RNA binding protein with multiple splicing: a new marker for retinal ganglion cells.
OBJECTIVE
To characterize expression of the RNA binding protein (RBPMS) in the retina as a specific marker for retinal ganglion cells (RGCs).


METHODS
Optic nerve transection (ONT) was performed on adult male Wistar rats. Retrograde RGC labeling was performed with FluoroGold (FG) applied to the cut surface of the optic nerve. RBPMS mRNA and protein expression in the retina was analyzed by in situ hybridization and immunohistochemistry, respectively. The expression of RBPMS in various rat tissues was analyzed with semiquantitative RT-PCR.


RESULTS
RBPMS mRNA and protein expression was localized primarily to irregularly shaped cells in the ganglion cell layer of the retina. Quantitative analysis showed that almost 100% of RGCs labeled by FG were also RBPMS-positive, irrespective of their location relative to the optic nerve head. Approximately 94% to 97% of RBPMS-positive cells were also positive for Thy-1, neurofilament H, and III beta-tubulin. In 2-week ONT retinas, the remaining few RGCs were weakly stained with RBPMS compared with intact RGCs in control retinas. Outside the retina, expression of RBPMS was observed in the heart, kidney, liver, and lungs. No expression was detected in any neuronal tissues except the retina.


CONCLUSIONS
The data indicate that in the retina RBPMS is selectively expressed in RGCs and therefore could serve as a marker for RGC quantification in normal retinas and for estimation of RGC loss in ocular neuropathies.
Kwong
Jacky M K
JM
Jules Stein Eye Institute, University of California Los Angeles, Los Angeles, California 90095, USA.
Caprioli
Joseph
J
Piri
Natik
N
D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008969:Molecular Sequence Data; D016900:Neurofilament Proteins / Q000378:metabolism; D020221:Optic Nerve Injuries / Q000378:metabolism; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013266:Stilbamidines; D018800:Thy-1 Antigens / Q000378:metabolism
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D015415:Biomarkers; D016900:Neurofilament Proteins; C101827:RBPMS protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013266:Stilbamidines; D018800:Thy-1 Antigens; C051774:neurofilament protein H