Oligodendrocytes express different isoforms of β-amyloid precursor protein in chemically defined cell culture conditions: In situ hybridization and immunocytochemical detection
✍ Scribed by F.J. Garcia-Ladona; Y. Huss; P. Frey; M.S. Ghandour
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 616 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0360-4012
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✦ Synopsis
The expression of -amyloid precursor protein (APP) by astrocytes is well documented; however, data concerning oligodendrocytes remain controversial. The main goal of the present study was to determine whether or not oligodendrocytes in culture constitutively express the different APP isoforms.
Oligodendrocytes were cultured in a chemically defined medium that avoids putative effects of unknown serum factors on oligodendrocyte development. We have employed immunocytochemistry and in situ hybridization with antibodies and synthetic oligonucleotides recognizing, respectively, specific protein epitopes and mRNA transcripts of rat APP isoforms. Oligodendrocytes, in both mixed primary cultures in the presence of serum or in secondary cultures in defined medium, were clearly labeled by antibodies directed to different APP sequences. Antibodies against the serine protease inhibitor domain of APP, also strongly labelled oligodendrocytes.
Immunohistochemistry and in situ hybridization were combined to determine precisely the expression of different isoforms of APP. In situ hybridization revealed the presence in oligodendrocytes of mRNA transcripts coding not only for APP 695 but also for APP 770 and APP 751 . This indicates that APP immunoreactivity found in oligodendrocytes corresponds to constitutive expression of APP.
Oligodendrocyte cultured in chemically defined medium are able to express not only APP 695 but also APP 770 , APP 751 isoforms containing the Kunitz protease inhibitor domain. Although the role of APP in the pathological processes of Alzheimer's disease (AD) remains unknown, possible disturbances of APP processing and/or synthesis in oligodendrocytes may account for some myelin disorders observed in AD and other senile dementias.