Volume 53, Issue 6, Pages 1608-1615 (June 1998) Protein overload stimulates RANTES production by proximal tubular cells depending on NF-kB activation  Carla Zoja, Roberta Donadelli, Stella Colleoni, Marina Figliuzzi, Samantha Bonazzola, Marina Morigi, Giuseppe Remuzzi  Kidney International  Volume 53, Issue 6, Pages 1608-1615 (June 1998) DOI: 10.1046/j.1523-1755.1998.00905.x Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 1 Effect of increasing concentrations of bovine serum albumin (BSA) on RANTES production by proximal tubular cells. Confluent cells were incubated with control medium or with BSA-containing medium (1, 10, 30 mg/ml) for 24 (A) and 48 (B) hours. Results are expressed as mean ±SE. °P < 0.05 versus control; °°P < 0.01 versus control and BSA 1 mg/ml;*P < 0.05 versus BSA 10 mg/ml. Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 2 Effect of proximal tubular cell loading with IgG on RANTES production. Confluent cells were incubated with control medium or medium containing BSA (10 mg/ml) or IgG (10 mg/ml) for 48 hours. Results are expressed as mean ±SE.*P < 0.01 versus control. Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 3 Electron micrograph of LLC-PK1 cells grown in a bicameral system for four days after reaching confluence. Cells show clear polarization with an apical domain bearing microvilli and a basolateral domain showing well-defined tight junctions (original magnification ×3,000). Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 4 Polarized production of RANTES by proximal tubular cells after apical exposure to BSA for 48 hours. Cells were grown on a Transwell chamber for four days after reaching confluence. Then medium was removed and control medium or BSA-containing medium (10 mg/ml) was added to the upper chamber, while medium alone was added to the lower chamber. Results are expressed as mean ±SE. °P < 0.05, °°P < 0.01 versus corresponding apical compartments; *P < 0.01 versus control basolateral compartment. Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 5 Electrophoretic mobility shift assay (EMSA) for NF-kB activity in nuclear extracts from LLC-PK1 cells exposed for 30 minutes to medium alone (control), BSA (10, 30 mg/ml), BSA plus PDTC (25μM, added 1 hour before the addition of BSA), or TNF-α (100 U/ml) as positive control. Complexes I, II, III denote the inducible kB specific DNA-protein complexes. The results shown are representative of three independent experiments. Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions

Figure 6 Subunit composition of NF-kB activated by proximal tubular cell exposure to an high concentration of BSA. Antibody-EMSAs were performed with nuclear extracts of LLC-PK1 cells treated with BSA (30 mg/ml) for 30 minutes. Nuclear extracts were incubated with antibodies against p50 (α p50), p65 (α p65), and cRel (α cRel) subunits to verify the identity of the BSA-activated NF-kB. Antibody supershifts produced by binding of the antibody to the Rel protein-DNA complex are indicated. To demonstrate the specificity of binding of the NF-kB oligonucleotide, 1000-fold molar excess unlabeled NF-kB (cold) was used to compete with the labeled NF-kB probe for binding to BSA-induced nuclear proteins. The results shown are representative of three independent experiments employing different nuclear extracts. Kidney International 1998 53, 1608-1615DOI: (10.1046/j.1523-1755.1998.00905.x) Copyright © 1998 International Society of Nephrology Terms and Conditions