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Molecular Analysis of Endothelial-mesenchymal Transition Induced by Transforming Growth Factor-β Signaling
Published on: August 3, 2018
Differential expression of transforming growth factor-beta isoforms and receptors in experimental membranous
S J Shankland1, J Pippin, R H Pichler
1Division of Nephrology, University of Washington, Seattle, USA.
Abstract:
In membranous nephropathy (MN) overproduction of matrix by glomerular epithelial cells (GEC) is believed to be responsible for glomerular basement membrane thickening and spikes. We studied experimental MN in rats (passive Heymann nephritis, PHN) at 5, 10 and 30 days. PHN rats exhibited a marked increase in GEC immunostaining for TGF-beta 2 at all time points. TGF-beta 3 staining was increased at day 10 only, and TGF-beta 1 was unchanged. Glomerular mRNA for TGF-beta 2 and -beta 3 was increased by day 5 when urine protein increased, whereas TGF-beta 1 was not. TGF-beta 2 bioactivity was increased at day 5. There was also a marked increase in GEC immunostaining for TGF-beta receptor type I (T beta IR) and TGF-beta receptor type II (T beta IIR) at all time points in PHN. mRNA levels for both receptors increased at day 5. Increases in protein expression and mRNA levels for the TGF-beta 2 and -beta 3 isoforms, and T beta IR and T beta RII were prevented by complement depletion. We conclude that complement-mediated injury to the GEC in vivo is associated with the up-regulation of TGF-beta 2 and -beta 3 isoforms, an increase in TGF-beta 2 bioactivity, and an increase in T beta RI and T beta RII expression. This contrasts with changes in TGF-beta 1 reported in mesangial disease, suggesting that TGF-beta 2 and -beta 3 may be important in diseases of the GEC. The differential expression of TGF-beta isoforms and receptors may be important determinants of the GEC response to injury.
Insights
Complement-mediated injury in membranous nephropathy (MN) upregulates TGF-beta 2 and TGF-beta 3 in glomerular epithelial cells (GEC). This study highlights the role of these TGF-beta isoforms in GEC response to injury.
Area of Science:
- Nephrology
- Cell Biology
- Molecular Biology
Background:
- Membranous nephropathy (MN) involves matrix overproduction by glomerular epithelial cells (GEC), leading to glomerular basement membrane thickening.
- The specific molecular mechanisms driving GEC matrix production in MN require further elucidation.
Purpose of the Study:
- To investigate the role of transforming growth factor-beta (TGF-beta) isoforms and their receptors in experimental membranous nephropathy (MN).
- To determine if complement-mediated injury influences TGF-beta signaling in glomerular epithelial cells (GEC).
Main Methods:
- Studied passive Heymann nephritis (PHN) in rats at 5, 10, and 30 days.
- Assessed immunostaining and glomerular mRNA levels for TGF-beta isoforms (1, 2, 3) and their receptors (T beta RI, T beta RII).
- Evaluated TGF-beta 2 bioactivity and the effect of complement depletion.
Main Results:
- PHN rats showed increased GEC immunostaining for TGF-beta 2 at all time points and TGF-beta 3 at day 10.
- Glomerular mRNA for TGF-beta 2 and -beta 3 increased by day 5, coinciding with increased urine protein.
- Increased expression and mRNA levels of TGF-beta 2, TGF-beta 3, T beta RI, and T beta RII were prevented by complement depletion.
Conclusions:
- Complement-mediated GEC injury in vivo upregulates TGF-beta 2 and -beta 3 isoforms and their receptors.
- Increased TGF-beta 2 bioactivity suggests a functional role in experimental MN.
- TGF-beta 2 and -beta 3, rather than TGF-beta 1, appear critical in GEC-specific responses to injury in MN.
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