Irradiation of rat tubule epithelial cells alters the expression of gene products associated with the synthesis and degradation of extracellular matrix.
OBJECTIVE
To determine the ability of radiation to modulate kidney tubule epithelial cell expression of various molecules involved in regulating extracellular matrix accumulation (collagen types I and III, fibronectin, plasminogen activator-inhibitor 1 (PAI-1), TGF-beta and tissue inhibitor of metalloproteinases-2 (TIMP-2)) and degradation (plasminogen activators u-PA or t-PA, MMP-2 and MMP-9).


METHODS
NRK52E rat tubule epithelial cells were placed in serum-free medium 24 h prior to irradiation with single doses of 1.0-10.0 Gy 137Cs gamma-rays. After irradiation, cells were maintained in serum-free medium for up to 48 h.


RESULTS
Irradiation of NRK52E cells was associated with significant dose-dependent increases in collagen I (p<0.05) and PAI-1 (p< or =0.002) mRNA. Collagen III mRNA levels also exhibited a dose-dependent increase; however, this increase failed to reach levels that were statistically significant. Fibronectin mRNA levels were unaltered following irradiation. Radiation also led to an isoform-specific alteration in TGF-beta expression; TGF-beta1 mRNA increased, TGF-beta3 mRNA decreased. The amount of TGF-beta protein secreted into the medium was unchanged following irradiation; however, there was a fivefold increase in the relative amount of active TGF-beta. Irradiation was also associated with differential changes in MMP expression: active MMP-2 levels increased, while MMP-9 levels were unaltered; PA secretion into the medium was unchanged following irradiation.


CONCLUSIONS
Irradiation of rat kidney tubule epithelial cells leads to altered production of various molecules associated with extracellular matrix accumulation and degradation.
Zhao
W
W
Department of Radiology, The University of Iowa, Iowa City 52242, USA.
O'Malley
Y
Y
Wei
S
S
Robbins
M E
ME
D000818:Animals; D002460:Cell Line; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation / Q000528:radiation effects; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D005109:Extracellular Matrix / Q000378:metabolism* / Q000528:radiation effects; D005353:Fibronectins / Q000096:biosynthesis / Q000235:genetics; D005720:Gamma Rays; D005780:Gelatin / Q000378:metabolism; D005786:Gene Expression Regulation / Q000528:radiation effects*; D007684:Kidney Tubules / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000096:biosynthesis / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation / Q000528:radiation effects
D005353:Fibronectins; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D019716:Tissue Inhibitor of Metalloproteinase-2; D005780:Gelatin; D003094:Collagen; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9