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Hewang Li, Ines Armando, Peiying Yu, Crisanto Escano, Susette C. Mueller, Laureano Asico, Annabelle Pascua, Quansheng Lu, Xiaoyan Wang, Van Anthony M. Villar, John E. Jones, Zheng Wang, Ammasi Periasamy, Yuen-Sum Lau, Patricio Soares-da-Silva, Karen Creswell, Gaétan Guillemette, David R. Sibley, Gilbert Eisner, Robin A. Felder, Pedro A. Jose
Published in Volume 118, Issue 6
J Clin Invest. 2008; 118(6):2180–2189 doi:10.1172/JCI33637
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Figure 5
Fen-stimulated AT1R degradation occurs in proteasomes but not lysosomes.

(A) AT1R/D5R HEK293 cells treated with Fen (1 μM for 2 h) and either Chlor (100 μM for 3 h) or CLBL (4 μM for 3 h) were pulsed with [35S] Met/Cys and chased with cold amino acids for the indicated times. Shown is 1 autoradiograph of each treatment. Data (mean ± SEM) followed a first-order exponential curve for both treatments. The AT1R protein half-life was 43.8 min for Fen plus Chlor and 149.5 min for Fen plus CLBL. n = 3. (B) Sub­cellular distribution of AT1R in AT1R/D5R HEK293 cells treated as in A. Green, AT1R-EGFP; red, lysosomes or proteasomes (detected by Alexa Fluor 633–conjugated anti–LAMP 1 or anti-p44S10); yellow, colocalization. Scale bars: 10 μm; 2.5 μm (insets). (C) AT1R/D5R HEK293 cells were treated with vehicle, Fen (1 μM for 6 h), Chlor (100 μM for 10 h), CLBL (4 μM for 10 h), Chlor plus Fen, or CLBL plus Fen. Nontransfected D5R HEK293 cells are shown as a control. Right: MFI of AT1R-EGFP. n = 3. *P < 0.05, **P < 0.001 versus vehicle, ANOVA, Student-Newman-Keuls test. Data are mean ± SEM. (D) Human RPT cells were treated with vehicle, Ang II, or Fen; cell lysates were incubated with control or proteasome-affinity beads for 4 hours at 4°C. After washing, the matrix was suspended in SDS sample buffer, separated by SDS-PAGE, and transferred onto nitrocellulose. Membranes were immunoblotted for either AT1R or p44S10. Experiments were repeated twice with similar results.