Keratinocyte transglutaminase in proliferative vitreoretinopathy.
OBJECTIVE
Proliferative vitreoretinopathy (PVR) is an excessive wound-healing process and the major complication in rhegmatogenous retinal detachment. The present study was designed to investigate the expression of keratinocyte transglutaminase (kTgase) in PVR membranes and retinal pigment epithelial (RPE) cells and to evaluate its expression in response to growth factors known to be increased in PVR disease.


METHODS
Distribution of kTgase and its relation to fibronectin have been investigated immunohistochemically. PVR membranes and native and cultured RPE cells were analyzed by RT-PCR for the presence of kTgase mRNA. In vitro, RPE cells were treated with transforming growth factor (TGF)-beta2, basic fibroblast growth factor, interleukin-6, and interleukin-1beta. Expression of kTgase was studied by Northern and Western blot analysis. The effect of connective tissue growth factor (CTGF) silencing on the TGF-beta2-modulated expression of kTgase was investigated by transfection with CTGF small interfering (si)RNA before TGF-beta2 treatment.


RESULTS
mRNA expression of kTgase was present in all PVR membranes. Immunohistochemical staining for kTgase showed an inhomogeneous pattern with localized accumulation and little colocalization with fibronectin. Although native RPE cells contained only a basal level of kTgase mRNA, the expression of kTgase was increased under culture conditions and was further enhanced by TGF-beta2 treatment. Silencing of CTGF expression did not attenuate the TGF-beta2-mediated induction of kTgase.


CONCLUSIONS
The findings demonstrate that kTgase is present in PVR membranes. Its amount is related to the differentiation state of RPE cells and stimulation by TGF-beta2. TGF-beta2-mediated increase seems to be independent of CTGF.
Priglinger
Siegfried G
SG
Department of Ophthalmology, Ludwig-Maximilians-University Munich, Mathildenstrasse 8, 80336 Munich, Germany. siegfried.priglinger@med.uni-muenchen.de
Alge
Claudia S
CS
Kreutzer
Thomas C
TC
Neubauer
Aljoscha S
AS
Haritoglou
Christos
C
Kampik
Anselm
A
Welge-Luessen
Ulrich
U
D000293:Adolescent; D000328:Adult; D000368:Aged; D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor; D005353:Fibronectins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008875:Middle Aged; D010857:Pigment Epithelium of Eye / Q000187:drug effects / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology; D011503:Transglutaminases / Q000235:genetics* / Q000378:metabolism; D018630:Vitreoretinopathy, Proliferative / Q000201:enzymology*
C526317:CCN2 protein, human; D005353:Fibronectins; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D053781:Transforming Growth Factor beta2; D055513:Connective Tissue Growth Factor; D011503:Transglutaminases; C105804:transglutaminase 1