Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2013 May;24(6):897-905.
doi: 10.1681/ASN.2012070759. Epub 2013 Mar 28.

Kielin/chordin-like protein attenuates both acute and chronic renal injury

Abdul Soofi  1 , Peng Zhang, Gregory R Dressler
Affiliations

Kielin/chordin-like protein attenuates both acute and chronic renal injury

Abdul Soofi et al. J Am Soc Nephrol. 2013 May.

Abstract

The secreted kielin/chordin-like (KCP) protein, one of a family of cysteine-rich proteins, suppresses TGF-β signaling by sequestering the ligand from its receptor, but it enhances bone morphogenetic protein (BMP) signaling by promoting ligand-receptor interactions. Given the critical roles for TGF-β and BMP proteins in enhancing or suppressing renal interstitial fibrosis, respectively, we examined whether secreted KCP could attenuate renal fibrosis in mouse models of chronic and acute disease. Transgenic mice that express KCP in adult kidneys showed significantly less expression of collagen IV, α-smooth muscle actin, and other markers of disease progression in the unilateral ureteral obstruction model of renal interstitial fibrosis. In the folic acid nephrotoxicity model of acute tubular necrosis, mice expressing KCP survived high doses of folic acid that were lethal for wild-type mice. With a lower dose of folic acid, mice expressing KCP exhibited improved renal recovery compared with wild-type mice. Thus, these data suggest that extracellular regulation of the TGF-β/BMP signaling axis by KCP, and by extension possibly other cysteine-rich domain proteins, can attenuate both acute and chronic renal injury.

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Expression of the KCP transgene in proximal tubules. (A) A schematic of the transgene is shown. A 570 bp Pepck promoter fragment is fused to the Igk secretory signal peptide followed by 1250 amino acids of the KCP coding region (red) and a myc epitope tag (blue). (B) Western blots from adult tissue lysates show mycKCP expression in kidney (K) and liver (L) but not other tissues tested, including brain (B), heart (H), lung (Lu), pancreas (P), spleen (S), and testis (T). (C) Immunostaining for mycKCP (red) and Laminin (green) in an adult kidney section through a glomerulus and surrounding tubules shows transgene expression in presumptive proximal tubules and parietal epithelia. (D) Double labeling for mycKCP (green) and villin (red) shows that most all proximal tubules with brush borders (arrow) also express the transgene.
Figure 2.
Figure 2.
KCP primary renal epithelial cells exhibit altered signaling. (A) Primary renal epithelial cells, isolated from 6- to 8-week-old KCP transgenic mice, are passaged twice on plastic and stained with the indicated antibodies. Nuclei are counterstained with 4',6-diamidino-2-phenylindole (blue). (B) The responses of WT and KCP expressing primary renal epithelial cells to increasing doses of TGF-β are assayed by Western blotting with the indicated antibodies 1 hour after addition. Note the decreased levels of P-Smad3 in KCP expressing cells at 0 and 0.5 ng/ml of TGF-β. Protein levels are quantified by Licor imaging and expressed as relative units of P-Smad3:Smad3 (right panel; *P<0.01). (C) The responses of WT and KCP expressing primary cells to increasing doses of BMP7 are assayed by Western blotting with the indicated antibodies 1 hour after addition. Note the increased levels of P-Smad1/5/8 in KCP expressing cells at 10 and 100 ng/ml of BMP7. Protein levels are quantified by Licor imaging and expressed as relative units of P-Smad1/5/8:Smad1 (right panel; *P<0.01).
Figure 3.
Figure 3.
KCP transgenic kidneys show altered signaling and SMA levels in the UUO model. (A) Proteins from WT and KCP transgenic kidneys are isolated before UUO (0) or from obstructed kidneys at 7 and 14 days after UUO and assayed by Western blotting with the indicated antibodies. Four independent kidneys are assayed at each time point. Note that KCP transgenics show higher Kim1 expression levels at 7 and 14 days after UUO relative to WT controls. (B) Quantitation of protein levels by Licor imaging. Relative protein levels compared with control Gapdh are shown on the y axis. KCP transgenic mice show increased P-Smad1 at 7 days after UUO compared with WT controls at similar time points. KCP transgenic kidneys show decreased P-Smad3 levels relative to WT controls at all time points and less αSMA at 7 and 14 days after UUO compared with WT controls. Values are the mean from four samples, with error bars representing 1 SD (*P<0.01).
Figure 4.
Figure 4.
Attenuation of fibrosis in KCP transgenic kidneys after UUO. Representative sections are shown from control, 7 day UUO, and 14 day UUO kidneys for WT and KCP transgenics. (A) Kim1 (green) and αSMA (red) staining show decreased interstitial αSMA and increased epithelial Kim1 expression in KCP transgenic kidneys. (B) Collagen IV (red) and Kim (green) staining shows increased and more diffuse collagen IV staining in WT kidneys at 7 and 14 days after UUO and persistent Kim1 expression in KCP transgenic kidneys.
Figure 5.
Figure 5.
Reduced expression of mesenchymal markers in KCP transgenic kidneys after UUO. (A) The interstitial area is measured by morphometry of αSMA positive surface area (left) or collagen IV positive surface area (right) in WT and KCP transgenic kidney sections. At each time point, 15 random sections are scanned and the positive surface area is calculated. All data are the mean percent area, with error bars being 1 SD (*P<0.01). (B) Quantitative RT-PCR for mRNAs corresponding to the genes as indicated. Note decreased expression in KCP transgenic kidneys for the mesenchymal genes Zeb1 and Snail1 at 7 days and 14 days after UUO and for Wnt11 and Pai1 at 14 days after UUO. Data are mean of three samples; error bars are 1 SD from the mean (*P<0.01; **P<0.05).
Figure 6.
Figure 6.
Enhanced survival and altered signaling in KCP transgenic mice after AKI. (A) Survival curves of WT and KCP transgenic mice after administration of a high dose of folic acid (275 mg/dl). (B) Morphometric analysis of collagen IV area in micrographs of WT and KCP transgenic kidneys at the indicated times after folic acid injection. (C) Morphometric analysis of αSMA area in micrographs of WT and KCP transgenic kidneys at the indicated times after folic acid injection. Significant differences (P<0.05) are seen between WT and KCP kidneys for collagen IV at 2 days and αSMA at 14 days. (D) Western blots of protein lysates isolated from WT and KCP transgenic kidneys before (0) or at 2, 14, and 28 days after folic acid injection. The blots are probed with antibodies to the indicated proteins and three independent samples are used for each time point. (E) Quantitation of P-Smad1 and P-Smad3 from D are shown in relative units after normalizing for total protein levels using tubulin. The mean values from three samples are shown, with error bars being 1 SD (*P<0.05).
Figure 7.
Figure 7.
Reduced fibrosis after AKI in KCP transgenic kidneys. Representative sections are shown from WT and KCP transgenic kidneys before and after folic acid injection and stained with the indicated antibodies. (A) Collagen IV is red and Kim1 is green. (B) αSMA is red and Kim1 is green. The times after folic acid injection are indicated below.
See this image and copyright information in PMC

Comment in

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Harris RC, Neilson EG: Toward a unified theory of renal progression. Annu Rev Med 57: 365–380, 2006 - PubMed
    1. Gewin L, Zent R: How does TGF-β mediate tubulointerstitial fibrosis? Semin Nephrol 32: 228–235, 2012 - PMC - PubMed
    1. Böttinger EP, Bitzer M: TGF-beta signaling in renal disease. J Am Soc Nephrol 13: 2600–2610, 2002 - PubMed
    1. Kopp JB, Factor VM, Mozes M, Nagy P, Sanderson N, Böttinger EP, Klotman PE, Thorgeirsson SS: Transgenic mice with increased plasma levels of TGF-beta 1 develop progressive renal disease. Lab Invest 74: 991–1003, 1996 - PubMed
    1. Ledbetter S, Kurtzberg L, Doyle S, Pratt BM: Renal fibrosis in mice treated with human recombinant transforming growth factor-beta2. Kidney Int 58: 2367–2376, 2000 - PubMed

Publication types

MeSH terms

Substances

  NODES
admin 1
Note 4
twitter 2