HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Kurumada, S. Articles by Sato, S. B. Search for Related Content PubMed PubMed Citation Articles by Kurumada, S. Articles by Sato, S. B.

Stage-Specific Association of Apolipoprotein A-I and E in Developing Mouse Retina

¹From the Department of Biophysics, Graduate School of Science and the ³Primate Research Institute, Kyoto University, Kyoto, Japan; and the ⁴Sphingolipid Functions Laboratory, Supra-Biomolecular System Research Group, Riken Frontier Research System, Hirosawa, Wako, Saitama, Japan.

PURPOSE. To characterize the intercellular lipid transport systems in differentiating retina.

METHODS. Developing mouse retinas were evaluated for the expression of apolipoproteins (apoE, apoA-I) by Western blot analysis and reverse transcription–polymerase chain reaction (RT-PCR). They were compared with changes in the lipid content and association of retinal proteins, such as postsynaptic density protein 95, glial fibrillary acidic protein, and cellular retinaldehyde-binding protein. Intraretinal distribution of apolipoproteins and their receptors was examined by immunofluorescence and in situ hybridization of prenatal and postnatal retinal sections. In vitro culture of dissociated cells was also examined.

RESULTS. Although apoE is known to be present in the mature retina, the neonatal retina remarkably expressed apoA-I mRNA and protein. This protein was present until postnatal day (P)3, and its putative receptor, scavenger receptor class B-I, was present until P5 to P7. This state subsequently exhibited a dramatic switchover to an apoE-rich one, in parallel with the stratification. Whereas apoE was synthesized at low levels until P7, apoE mRNA was clearly concentrated in Müller glia cells, which extended long apoE-bound processes to the plexuses and contours of photoreceptor cells. These acceptor cells expressed LDL receptor–related protein 1 as a putative receptor. ApoE genes were not transcribed in ganglion cells, though they were associated with a high level of the protein throughout the development. ApoE protein in ganglion cells initially appeared to be synthesized by astrocytes but later were observed to be supplied from an extraretinal space.

CONCLUSIONS. The present results document several new aspects of apoA-I and apoE in the developing retina. The switchover of the lipoprotein systems runs a parallel course with the differentiation.