Expression of transforming growth factor-beta s and their receptors by human retinal glial cells.
OBJECTIVE
To help test the hypothesis that transforming growth factor beta (TGF-beta) may serve an autocrine function in the retina, we asked whether human Müller (glial) cells in culture express TGF-beta receptors, contain transcripts for various isoforms of this cytokine, and release TGF-beta s into the medium.


METHODS
Using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique with specific primers for TGF-beta 1, -beta 2 and -beta 3 precursors and for TGF-beta type I and type II receptors, we searched for mRNA transcripts expressed by cultured human Müller cells. Also, an ELISA assay allowed quantification of the levels of various TGF-beta s in medium exposed to these glial cells.


RESULTS
Human Müller cells in culture express transcripts for both type I and type II TGF-beta receptors and also for TGF-beta 1 and TGF-beta 2. In conditioned medium, the concentration of TGF-beta 1 in the mature form was below detectable levels, and the total TGF-beta 1 was relatively low (mean = 252 pg/ml in confluent cultures). In contrast, the mean levels of mature (55 pg/ml) and total (2530 pg/ml) TGF-beta 2 were markedly higher.


CONCLUSIONS
Our observations that cultured Müller cells contain mRNA coding for the TGF-beta 2 precursor, release TGF-beta 2 into the medium and express transcripts for both type I and type II TGF-beta receptors are consistent with the idea that this cytokine serves an autocrine function for these glia in the retina.
Ikeda
T
T
Department of Ophthalmology, Kyoto Prefectual University of Medicine, Japan. tikeda@eyeeye.ophth.kpu-m.ac.jp
Homma
Y
Y
Nisida
K
K
Hirase
K
K
Sotozono
C
C
Kinoshita
S
S
Puro
D G
DG
D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004587:Electrophoresis, Agar Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D009457:Neuroglia / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta