Molecular physiology and epigenetics of NF-kB/BMP interactions in the post-ischemic kidney
Final Report Abstract
Acute kidney injury (AKI) precipitates the development of chronic kidney disease (CKD). Chronic progression of kidney injury results in tubulo-interstitial fibrosis. Nuclear factor κB (NF-κB) is a key regulator of innate and adaptive immunity and had previously been implicated in the pathogenesis of AKI. However, the cell type–specific functions of NF-κB in the kidney were unknown. In this project, we first analyzed the role of tubular epithelial-specific NF-κB signaling in a mouse model of ischemia-reperfusion injury (IRI)–induced AKI. NF-κB reporter activity and nuclear localization of phosphorylated NF-κB subunit p65 analyses in mice revealed that IRI induced widespread NF-κB activation in renal tubular epithelia and in interstitial cells that peaked 2–3 days after injury. To genetically antagonize tubular epithelial NF-κB activity, we generated mice expressing the human NF-κB super-repressor IκBa-DN in renal proximal, distal, and collecting duct epithelial cells. Compared with control mice, these mice exhibited improved renal function, reduced tubular apoptosis, and attenuated neutrophil and macrophage infiltration after IRI-induced AKI. Furthermore, tubular NF-κB–dependent gene expression profiles revealed temporally distinct functional gene clusters for apoptosis, chemotaxis, and morphogenesis. Primary proximal tubular cells isolated from IκBa-DN-expressing mice and exposed to hypoxia-mimetic agent cobalt chloride exhibited less apoptosis and expressed lower levels of chemokines than cells from control mice did. Our results indicated that postischemic NF-κB activation in renal tubular epithelia aggravates tubular injury and exacerbates a maladaptive inflammatory response. We also provided evidence that tubular NF-κB signaling up-regulated pro-inflammatory mediators and blocked the constitutive canonical bone morphogenetic protein (BMP) signal in renal tubules. Bone morphogenetic protein (BMP) signaling had previously been shown to modulate the development of renal fibrosis in animal models of kidney injury, but the downstream mediators were incompletely understood. We therefore analyzed in detail the targets of canonical BMP in AKI and during progression of AKI-to-CKD. In wild-type mice, canonical BMP signaling mediated by SMAD1/5/8 transcription factors was constitutively active in healthy renal tubules, transiently down-regulated after ischemia reperfusion injury (IRI), and reactivated during successful tubular regeneration. We then induced IRI in mice with a tubular-specific BMP receptor 1A (BMPR1A) deletion. These mice failed to reactivate SMAD1/5/8 signaling in the postischemic phase and developed renal fibrosis after injury. Using unbiased genomic analyses, we identified three genes encoding inhibitor of DNA-binding (ID) proteins (Id1, Id2, and Id4) as key targets of BMPR1A-SMAD1/5/8 signaling. BMPR1A-deficient mice failed to re-induce these targets following IRI. Instead, BMPR1A-deficiency resulted in activation of pro-fibrotic signaling proteins that are normally repressed by ID proteins, namely, p38 mitogen-activated protein kinase and cell cycle inhibitor p27. These data indicated that the postischemic activation of canonical BMP signaling acts endogenously to repress pro-fibrotic signaling in tubular cells and may help to prevent the progression of acute kidney injury to chronic kidney disease. Overall, this project elucidated the detailed molecular roles and interactions of NF-κB and BMP signaling in postischemic renal tubules, their relevant downstream targets and how these pathways regulate AKI severity, progression of renal fibrosis, and the development of CKD. Our findings provide important insights into the molecular pathogenesis of acute and chronic kidney diseases and identify novel pharmacological targets for the treatment of AKI.
Publications
- The Ngal reporter mouse detects the response of the kidney to injury in real time. Nature Medicine 17: 216-222, 2011
Paragas N, Qiu A, Zhang Q, Samstein B, Deng SX, Schmidt-Ott KM, Viltard M, Yu W, Forster CS, Gong G, Liu Y, Kulkarni R, Mori K, Kalandadze A, Ratner AJ, Devarajan P, Landry DW, D'Agati V, Lin CS, Barasch J
(See online at https://doi.org/10.1038/nm.2290) - α-Intercalated cells defend the urinary system from bacterial infection. Journal of Clinical Investigation 124: 2963-2976, 2014
Paragas N, Kulkarni R, Werth M, Schmidt-Ott KM, Forster C, Deng R, Zhang Q, Singer E, Klose AD, Shen TH, Francis KP, Ray S, Vijayakumar S, Seward S, Bovino ME, Xu K, Takabe Y, Amaral FE, Mohan S, Wax R, Corbin K, Sanna-Cherchi S, Mori K, Johnson L, Nickolas T, D'Agati V, Lin CS, Qiu A, Al-Awqati Q, Ratner AJ, Barasch J:
(See online at https://doi.org/10.1172/JCI71630) - Redox Regulation of Cell Contacts by Tricellulin and Occludin: Redox-Sensitive Cysteine Sites in Tricellulin Regulate Both Tri- and Bicellular Junctions in Tissue Barriers as Shown in Hypoxia and Ischemia. Antioxid Redox Signal 23:1035-1049, 2015
Cording J, Günther R, Vigolo E, Tscheik C, Winkler L, Schlattner I, Lorenz D, Haseloff RF, Schmidt- Ott KM, Wolburg H, Blasig IE
(See online at https://doi.org/10.1089/ars.2014.6162) - Role of Cystathionine Gamma-Lyase in Immediate Renal Impairment and Inflammatory Response in Acute Ischemic Kidney Injury. Sci Rep 6: 27517, 2016
Markó L, Szijártó IA, Filipovic MR, Kaßmann M, Balogh A, Park JK, Przybyl L, N'diaye G, Krämer S, Anders J, Ishii I, Müller DN, Gollasch M
(See online at https://doi.org/10.1038/srep27517) - Tubular Epithelial NF-κB Activity Regulates Ischemic AKI. Journal of the American Society of Nephrology 27: 2658-2669, 2016
Marko L, Vigolo E, Hinze C, Park JK, Roel G, Balogh A, Choi M, Wuebken A, Cording J, Blasig IE, Luft FC, Scheidereit C, Schmidt-Ott KM, Schmidt-Ullrich R, Muller DN
(See online at https://doi.org/10.1681/ASN.2015070748) - Unique transcriptional programs identify subtypes of AKI. Journal of the American Society of Nephrology 28: 1729-1740, 2017
Xu K, Rosenstiel P, Paragas N, Hinze C, Gao X, Huai Shen T, Werth M, Forster C, Deng R, Bruck E, Boles RW, Tornato A, Gopal T, Jones M, Konig J, Stauber J, D'Agati V, Erdjument-Bromage H, Saggi S, Wagener G, Schmidt-Ott KM, Tatonetti N, Tempst P, Oliver JA, Guarnieri P, Barasch J
(See online at https://doi.org/10.1681/ASN.2016090974) - SGK1 induces vascular smooth muscle cell calcification through NF-κB signaling. J Clin Invest 128(7): 3024-3040, 2018
Voelkl J, Luong TT, Tuffaha R, Musculus K, Auer T, Lian X, Daniel C, Zickler D, Boehme B, Sacherer M, Metzler B, Kuhl D, Gollasch M, Amann K, Müller DN, Pieske B, Lang F, Alesutan I
(See online at https://doi.org/10.1172/JCI96477) - Transient receptor potential vanilloid 4 channel deficiency aggravates tubular damage after acute renal ischaemia reperfusion. Scientific Reports 8: 4878, 2018
Mannaa M, Markó L, Balogh A, Vigolo E, N'diaye G, Kaßmann M, Michalick L, Weichelt U, Schmidt-Ott KM, Liedtke WB, Huang Y, Müller DN, Kuebler WM, Gollasch M
(See online at https://doi.org/10.1038/s41598-018-23165-0) - Canonical BMP signaling in tubular cells mediates recovery after acute kidney injury. Kidney International 95: 108-122, 2019
Vigolo E, Marko L, Hinze C, Müller DN, Schmidt-Ullrich R, Schmidt-Ott KM
(See online at https://doi.org/10.1016/j.kint.2018.08.028)
