Failure to ubiquitinate c-Met leads to hyperactivation of mTOR signaling in a mouse model of autosomal dominant polycystic kidney disease
Shan Qin, … , Jing Zhou, Jordan A. Kreidberg
Shan Qin, … , Jing Zhou, Jordan A. Kreidberg
Published September 13, 2010
Citation Information: J Clin Invest. 2010;120(10):3617-3628. https://doi.org/10.1172/JCI41531.
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Failure to ubiquitinate c-Met leads to hyperactivation of mTOR signaling in a mouse model of autosomal dominant polycystic kidney disease

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disorder that is caused by mutations at two loci, polycystin 1 (PKD1) and polycystin 2 (PKD2). It is characterized by the formation of multiple cysts in the kidneys that can lead to chronic renal failure. Previous studies have suggested a role for hyperactivation of mammalian target of rapamycin (mTOR) in cystogenesis, but the etiology of mTOR hyperactivation has not been fully elucidated. In this report we have shown that mTOR is hyperactivated in Pkd1-null mouse cells due to failure of the HGF receptor c-Met to be properly ubiquitinated and subsequently degraded after stimulation by HGF. In Pkd1-null cells, Casitas B-lineage lymphoma (c-Cbl), an E3-ubiquitin ligase for c-Met, was sequestered in the Golgi apparatus with α3β1 integrin, resulting in the inability to ubiquitinate c-Met. Treatment of mouse Pkd1-null cystic kidneys in organ culture with a c-Met pharmacological inhibitor resulted in inhibition of mTOR activity and blocked cystogenesis in this mouse model of ADPKD. We therefore suggest that blockade of c-Met is a potential novel therapeutic approach to the treatment of ADPKD.

Authors

Shan Qin, Mary Taglienti, Surya M. Nauli, Leah Contrino, Ayumi Takakura, Jing Zhou, Jordan A. Kreidberg

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Figure 4

α3 integrin and GM130 localization in Pkd1+/+ and Pkd1–/– cells.

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α3 integrin and GM130 localization in Pkd1+/+ and Pkd1–/– cells. (A ...
(A and B) Colocalization of c-Cbl and α3β1 integrin. Both c-Cbl and α3β integrin are present in at cell-cell junctions in Pkd1+/+ cells. In Pkd1–/– cells (A) or Pkd1-knockdown cells (KD4) (B), c-Cbl is concentrated in the perinuclear area, and α3β1 integrin both is present at cell-cell junctions and colocalizes with c-Cbl in a perinuclear pattern. (C) c-Cbl and (D) α3β1 integrin colocalize (yellow staining) with GM130, a Golgi marker, in Pkd1–/– but not Pkd1+/+ cells. (E) In Itga3–/–Pkd1-knockdown (KD8) cells, c-Cbl is localized at the plasma membrane, as demonstrated by overlapping staining with ZO-1. (F) c-Cbl does not colocalize with GM130 in KD8 cells. Scale bars: 20 μm. (G) Discontinuous sucrose gradient enrichment of the Golgi apparatus from Pkd1+/+ and Pkd1–/– cells. Both α3β1 integrin and c-Cbl are present in the Golgi-enriched fraction from Pkd1–/– cells, but neither was detected in the Golgi-enriched fraction from Pkd1+/+ cells. The Western blot of GM130 in the lower panel validates the Golgi enrichment.