Mesangial cell gelatinase A synthesis is attenuated by oscillating hyperbaric pressure.
Glomerular hypertension has been established as a major factor contributing to glomerular scarring. Underlying cellular mechanisms leading to matrix accumulation are largely unknown. The isolated effect of oscillating hyperbaric pressure [OP; P(max) 50 mmHg (1 mmHg=0.133 kPa), P(mean) 24 mmHg, with a fixed oscillation of 60/min] on matrix-degrading protease secretion by rat mesangial cells (MCs) was analysed using a pressure chamber model described previously [Mertens, Espenkott, Venjakob, Heintz, Handt and Sieberth (1998) Hypertension 32, 945-952]. MCs were grown under atmospheric pressure (AP) or a controlled OP, and protease synthesis and gene transcription were analysed. A distinct biphasic cellular response to OP with stimulated gelatinase A protein expression and enzyme activity during the initial 24 h, and subsequent inhibition, was apparent, as shown by gelatin zymography. Gelatinase B activity remained unchanged. The abundance of gelatinase A transcripts, determined by reverse transcriptase-PCR, indicated a concordant regulation of gene transcription. To elucidate underlying regulatory events, reporter constructs were transfected. In these experiments, a recently identified response element, RE-1, conferred a significant stimulatory effect within the initial 4 h of OP. Nuclear protein/RE-1 binding studies revealed additional complexes from 5 min up to 3 h after OP exposure, with intensities dependent on P(max). STAT3 was identified as a component of these novel complexes. Down-regulation of cis-activity after 48 h of OP exposure was not transferred via the proximal 1686 bp of the gelatinase A regulatory sequence. In conclusion, hyperbaric OP elicits time-dependent changes in rat MC gelatinase A gene transcription.
En-Nia
Abdelaziz
A
Division of Nephrology and Immunology, Medical Clinic II, RWTH Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany.
Reisdorff
Julia
J
Stefanidis
Ioannis
I
Floege
Juergen
J
Heinrich
Peter C
PC
Mertens
Peter R
PR
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology; D002478:Cells, Cultured; D017931:DNA Primers; D015971:Gene Expression Regulation, Enzymologic; D005920:Glomerular Mesangium / Q000201:enzymology*; D006977:Hypertension, Renal / Q000201:enzymology; D007700:Kinetics; D020778:Matrix Metalloproteinase 2 / Q000235:genetics*; D061965:Matrix Metalloproteinase Inhibitors; D009991:Oscillometry; D016133:Polymerase Chain Reaction; D011312:Pressure; D051381:Rats; D013997:Time Factors; D014158:Transcription, Genetic
D017931:DNA Primers; D061965:Matrix Metalloproteinase Inhibitors; D020778:Matrix Metalloproteinase 2