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Deletion of the epidermal growth factor receptor in renal proximal tubule epithelial cells delays recovery from acute kidney injury.

Chen J, Chen JK, Harris RC - Kidney Int. (2012)

Bottom Line: To determine the role of epidermal growth factor receptor (EGFR) activation in renal functional and structural recovery from acute kidney injury (AKI), we generated mice with a specific EGFR deletion in the renal proximal tubule (EGFR(ptKO)).Additionally, renal cell proliferation was delayed due to decreased ERK and Akt signaling.Thus, our studies provide both genetic and pharmacologic evidence that proximal tubule EGFR activation plays an important role in the recovery phase after acute kidney injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. ray.harris@vanderbilt.edu

ABSTRACT
To determine the role of epidermal growth factor receptor (EGFR) activation in renal functional and structural recovery from acute kidney injury (AKI), we generated mice with a specific EGFR deletion in the renal proximal tubule (EGFR(ptKO)). Ischemia-reperfusion injury markedly activated EGFR in control littermate mice; however, this was inhibited in either the knockout or wild-type mice given erlotinib, a specific EGFR tyrosine kinase inhibitor. Blood urea nitrogen and serum creatinine increased to a comparable level in EGFR(ptKO) and control mice 24 h after reperfusion, but the subsequent rate of renal function recovery was markedly slowed in the knockout mice. Twenty-four hours after reperfusion, both the knockout and the inhibitor-treated mice had a similar degree of histologic renal injury as control mice, but at day 6 there was minimal evidence of injury in the control mice while both EGFR(ptKO) and erlotinib-treated mice still had persistent proximal tubule dilation, epithelial simplification, and cast formation. Additionally, renal cell proliferation was delayed due to decreased ERK and Akt signaling. Thus, our studies provide both genetic and pharmacologic evidence that proximal tubule EGFR activation plays an important role in the recovery phase after acute kidney injury.

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Renal proximal tubular epithelial cell epidermal growth factor receptor (EGFR) deletion attenuated increases in phospho-EGFR expression and activation of pEGFR-ERK, pEGFR-Akt pathways in response to ischemia–reperfusion (I–R) injury. EGFRptKO mice were subjected to sham or bilateral renal I–R injury. Renal cortex tissue lysates pooled from five mice were analyzed by Phospho-RTK Array 48 h after surgery (a and b). EGFRptKO or EGFRf/f mouse renal cortex tissue lysates were prepared at different time points and subjected to immunoprecipitation (IP; c) or immunoblotting (IB; c and d) analysis with the indicated antibodies. MSPR, macrophage-stimulating protein receptor; pPDGF-Rα, phosphorylation of platelet-derived growth factor receptor alpha.
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fig5: Renal proximal tubular epithelial cell epidermal growth factor receptor (EGFR) deletion attenuated increases in phospho-EGFR expression and activation of pEGFR-ERK, pEGFR-Akt pathways in response to ischemia–reperfusion (I–R) injury. EGFRptKO mice were subjected to sham or bilateral renal I–R injury. Renal cortex tissue lysates pooled from five mice were analyzed by Phospho-RTK Array 48 h after surgery (a and b). EGFRptKO or EGFRf/f mouse renal cortex tissue lysates were prepared at different time points and subjected to immunoprecipitation (IP; c) or immunoblotting (IB; c and d) analysis with the indicated antibodies. MSPR, macrophage-stimulating protein receptor; pPDGF-Rα, phosphorylation of platelet-derived growth factor receptor alpha.

Mentions: To determine the specific role of renal proximal tubule epithelial cell EGFR in kidney tubular epithelia cell regeneration after I–R injury, we developed a renal proximal tubule–specific EGFRptKO mouse by crossing EGFRf/f mice with the Cre recombinase driven by the γ-GT promoter mice (EGFRptKO).23 Phospho-RTK array analysis showed that the deletion of EGFR in proximal tubule cells markedly decreased EGFR phosphorylation without affecting increases in ErbB2 phosphorylation in response to I–R injury, as shown in Figure 5a and b. Immunoblotting confirmed a marked decrease in phospho-EGFR expression following I–R injury in the EGFRptKO mice. Similarly, in the EGFRptKO mice, activation of 44/p42 ERK and Akt were markedly inhibited compared with wild-type mice, Figure 5c and d. We found similar renal function impairment in EGFRptKO and their littermate control mice 24 h after I–R injury. Blood urea nitrogen levels were 104±24 vs. 101±22 mg/dl and serum creatinine levels were 0.698±0.027 vs. 0.695±0.040 mg/dl (n=5–6). However, 6 days after reperfusion, both blood urea nitrogen and serum creatinine levels remained elevated in EGFRptKO mice compared with their littermate control mice (blood urea nitrogen, 57±11 vs. 22±1.5 mg/dl, P<0.0001; serum creatinine, 0.432±0.060 vs. 0.198±0.023 mg/dl, P<0.001, n=5–6; Figure 6a and b). Histology indicated comparable injury at 24 h; however, there was minimal residual injury in littermate controls, whereas EGFRptKO mice had persistent proximal tubule dilation and epithelial simplification and cast formation at day 6, as shown in Figure 6c and d.


Deletion of the epidermal growth factor receptor in renal proximal tubule epithelial cells delays recovery from acute kidney injury.

Chen J, Chen JK, Harris RC - Kidney Int. (2012)

Renal proximal tubular epithelial cell epidermal growth factor receptor (EGFR) deletion attenuated increases in phospho-EGFR expression and activation of pEGFR-ERK, pEGFR-Akt pathways in response to ischemia–reperfusion (I–R) injury. EGFRptKO mice were subjected to sham or bilateral renal I–R injury. Renal cortex tissue lysates pooled from five mice were analyzed by Phospho-RTK Array 48 h after surgery (a and b). EGFRptKO or EGFRf/f mouse renal cortex tissue lysates were prepared at different time points and subjected to immunoprecipitation (IP; c) or immunoblotting (IB; c and d) analysis with the indicated antibodies. MSPR, macrophage-stimulating protein receptor; pPDGF-Rα, phosphorylation of platelet-derived growth factor receptor alpha.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376190&req=5

fig5: Renal proximal tubular epithelial cell epidermal growth factor receptor (EGFR) deletion attenuated increases in phospho-EGFR expression and activation of pEGFR-ERK, pEGFR-Akt pathways in response to ischemia–reperfusion (I–R) injury. EGFRptKO mice were subjected to sham or bilateral renal I–R injury. Renal cortex tissue lysates pooled from five mice were analyzed by Phospho-RTK Array 48 h after surgery (a and b). EGFRptKO or EGFRf/f mouse renal cortex tissue lysates were prepared at different time points and subjected to immunoprecipitation (IP; c) or immunoblotting (IB; c and d) analysis with the indicated antibodies. MSPR, macrophage-stimulating protein receptor; pPDGF-Rα, phosphorylation of platelet-derived growth factor receptor alpha.
Mentions: To determine the specific role of renal proximal tubule epithelial cell EGFR in kidney tubular epithelia cell regeneration after I–R injury, we developed a renal proximal tubule–specific EGFRptKO mouse by crossing EGFRf/f mice with the Cre recombinase driven by the γ-GT promoter mice (EGFRptKO).23 Phospho-RTK array analysis showed that the deletion of EGFR in proximal tubule cells markedly decreased EGFR phosphorylation without affecting increases in ErbB2 phosphorylation in response to I–R injury, as shown in Figure 5a and b. Immunoblotting confirmed a marked decrease in phospho-EGFR expression following I–R injury in the EGFRptKO mice. Similarly, in the EGFRptKO mice, activation of 44/p42 ERK and Akt were markedly inhibited compared with wild-type mice, Figure 5c and d. We found similar renal function impairment in EGFRptKO and their littermate control mice 24 h after I–R injury. Blood urea nitrogen levels were 104±24 vs. 101±22 mg/dl and serum creatinine levels were 0.698±0.027 vs. 0.695±0.040 mg/dl (n=5–6). However, 6 days after reperfusion, both blood urea nitrogen and serum creatinine levels remained elevated in EGFRptKO mice compared with their littermate control mice (blood urea nitrogen, 57±11 vs. 22±1.5 mg/dl, P<0.0001; serum creatinine, 0.432±0.060 vs. 0.198±0.023 mg/dl, P<0.001, n=5–6; Figure 6a and b). Histology indicated comparable injury at 24 h; however, there was minimal residual injury in littermate controls, whereas EGFRptKO mice had persistent proximal tubule dilation and epithelial simplification and cast formation at day 6, as shown in Figure 6c and d.

Bottom Line: To determine the role of epidermal growth factor receptor (EGFR) activation in renal functional and structural recovery from acute kidney injury (AKI), we generated mice with a specific EGFR deletion in the renal proximal tubule (EGFR(ptKO)).Additionally, renal cell proliferation was delayed due to decreased ERK and Akt signaling.Thus, our studies provide both genetic and pharmacologic evidence that proximal tubule EGFR activation plays an important role in the recovery phase after acute kidney injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA. ray.harris@vanderbilt.edu

ABSTRACT
To determine the role of epidermal growth factor receptor (EGFR) activation in renal functional and structural recovery from acute kidney injury (AKI), we generated mice with a specific EGFR deletion in the renal proximal tubule (EGFR(ptKO)). Ischemia-reperfusion injury markedly activated EGFR in control littermate mice; however, this was inhibited in either the knockout or wild-type mice given erlotinib, a specific EGFR tyrosine kinase inhibitor. Blood urea nitrogen and serum creatinine increased to a comparable level in EGFR(ptKO) and control mice 24 h after reperfusion, but the subsequent rate of renal function recovery was markedly slowed in the knockout mice. Twenty-four hours after reperfusion, both the knockout and the inhibitor-treated mice had a similar degree of histologic renal injury as control mice, but at day 6 there was minimal evidence of injury in the control mice while both EGFR(ptKO) and erlotinib-treated mice still had persistent proximal tubule dilation, epithelial simplification, and cast formation. Additionally, renal cell proliferation was delayed due to decreased ERK and Akt signaling. Thus, our studies provide both genetic and pharmacologic evidence that proximal tubule EGFR activation plays an important role in the recovery phase after acute kidney injury.

Show MeSH
Related in: MedlinePlus