Prosaposin gene expression in normal and dystrophic RCS rat retina.
OBJECTIVE
To identify proteins secreted by the retinal pigment epithelium (RPE) and to analyze their cellular distribution in normal and pathologic rat retinas at various stages of eye development.


METHODS
A cDNA library was constructed with RNA isolated from porcine RPE sheets and screened by using the yeast signal sequence trap system. In situ hybridization, immunohistochemistry, and semiquantitative RT-PCR analysis were performed on rat retinas.


RESULTS
The cDNA encoding prosaposin was isolated. This is the first time this gene has been shown to be expressed in the retina. Prosaposin mRNA was detected in the rat RPE cell monolayer and in ganglion cells 14, 21, and 45 days after birth. The amount of prosaposin mRNA increased between days 14 and 45 after birth in normal retinas (rdy+), but not in the pathologic retinas (rdy-) of RCS rats.


CONCLUSIONS
Several techniques were used to determine the localization of prosaposin in rat retinas. The increase in the amount of prosaposin mRNA in normal retinas coincided with the maturation of photoreceptor cells and the beginning of the phagocytosis process. In addition, the RCS rdy- RPE cells, characterized by the abrogation of the ingestion phase of the photoreceptor outer segments, are deficient in prosaposin expression.
Van Den Berghe
Loïc
L
Centre de Recherche Thérapeutique en Ophthalmologie (CERTO), Faculté de Médecine Necker Enfants Malades, Paris, France.
Sainton
Karine
K
Gogat
Karïn
K
Marchant
Dominique
D
Dufour
Eric
E
Bonnel
Sébastien
S
Gadin
Stéphanie
S
Menasche
Maurice
M
Abitbol
Marc
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015870:Gene Expression; D015723:Gene Library; D006023:Glycoproteins / Q000235:genetics*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011922:Rats, Mutant Strains; D012160:Retina / Q000378:metabolism*; D012162:Retinal Degeneration / Q000378:metabolism* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D049231:Saposins; D013552:Swine
D006023:Glycoproteins; C483347:Psap protein, rat; D012333:RNA, Messenger; D049231:Saposins