Transforming growth factor-beta: a growth factor inducing alpha B-crystallin expression in ciliary muscle cells.
BACKGROUND
In a recent study we showed that, in vitro, transforming growth factor-beta 2 (TGF-beta 2) induces alpha B-crystallin expression in cultured trabecular meshwork (TM) cells, but not in cultured fibroblasts. We assumed that alpha B-crystallin can be induced by TGF-beta 2 only if the cells are already expressing a basal level of the protein. In the present study we therefore treated cultured ciliary muscle (CM) cells constitutively expressing alpha B-crystallin and investigated the effect of TGF-beta on expression of alpha B-crystallin and the corresponding mRNA in these cells.


METHODS
Monolayer cultures of third-passage CM cells from eyes of five human donors (12-73 years), being confluent for 7 days, were treated with 1.0 ng/ml TGF-beta 1 or TGF-beta 2. Induction of alpha B-crystallin and the related mRNA was investigated by immunofluorescence and by western and northern blot analysis.


RESULTS
An increase in alpha B-crystallin mRNA was observed following treatment with TGF-beta. Actinomycin blocked the induction of alpha B-crystallin by the cytokine TGF-beta. Using western blotting the increase in alpha B-crystallin expression in CM cells was only small.


CONCLUSIONS
These results confirm our assumption that induction of alpha B-crystallin by the cytokine TGF-beta depends on basal levels of the protein and its mRNA constitutively present within the cells. Comparison of the increase in alpha B-crystallin mRNA and protein expression indicate that post-transcriptional regulation mechanisms are responsible for these findings in CM cells.
Welge-Lüssen
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Department of Anatomy II, University of Erlangen-Nürnberg, Universitätsstrasse 19, 91054 Erlangen/Germany. anat2.gl@anatomie.uni-erlangen.de
Bloemendal
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Lütjen-Drecoll
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D000368:Aged; D015153:Blotting, Western; D002478:Cells, Cultured; D002648:Child; D002924:Ciliary Body / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D003459:Crystallins / Q000096:biosynthesis* / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006801:Humans; D008875:Middle Aged; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2
D003459:Crystallins; D012333:RNA, Messenger; C508960:TGFB1 protein, human; C509041:TGFB2 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2