Sox9 switch links regeneration to fibrosis at the single-cell level in mammalian kidneys [RNA-Seq 2]
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ABSTRACT: The steps governing healing with or without fibrosis within the same microenvironment are unclear. After acute kidney injury (AKI), the injured proximal tubular epithelial cells activate Sox9 for self-restoration. Using head-to-head comparison of injury- induced Sox9-lineages via spatiotemporal mapping, single-cell sequencing, and single-nuclei chromatin accessibility profiling, we identified a dynamic SOX9 switch. Lineages that regenerated epithelia silenced SOX9 and healed without fibrosis (SOX9on-off). In contrast, lineages that maintained Sox9 activity in attempt to regenerate, demarcated by SOX9-induced Cadherin 6 (SOX9on-on CDH6pos ) cell state, generated single-cell Wnt activity to provoke a fibroproliferative response in adjacent fibroblasts, driving AKI to chronic kidney disease. Transplanted human kidneys displayed similar SOX9/CDH6/WNT2B responses post-injury. Thus, we uncovered a mechanism linking fibrosis to sustained efforts to regenerate the injured tissue.
Project description:The steps governing healing with or without fibrosis within the same microenvironment are unclear. After acute kidney injury (AKI), the injured proximal tubular epithelial cells activate Sox9 for self-restoration. Using head-to-head comparison of injury- induced Sox9-lineages via spatiotemporal mapping, single-cell sequencing, and single-nuclei chromatin accessibility profiling, we identified a dynamic SOX9 switch. Lineages that regenerated epithelia silenced SOX9 and healed without fibrosis (SOX9on-off). In contrast, lineages that maintained Sox9 activity in attempt to regenerate, demarcated by SOX9-induced Cadherin 6 (SOX9on-on CDH6pos ) cell state, generated single-cell Wnt activity to provoke a fibroproliferative response in adjacent fibroblasts, driving AKI to chronic kidney disease. Transplanted human kidneys displayed similar SOX9/CDH6/WNT2B responses post-injury. Thus, we uncovered a mechanism linking fibrosis to sustained efforts to regenerate the injured tissue.
Project description:The steps governing healing with or without fibrosis within the same microenvironment are unclear. After acute kidney injury (AKI), the injured proximal tubular epithelial cells activate Sox9 for self-restoration. Using head-to-head comparison of injury- induced Sox9-lineages via spatiotemporal mapping, single-cell sequencing, and single-nuclei chromatin accessibility profiling, we identified a dynamic SOX9 switch. Lineages that regenerated epithelia silenced SOX9 and healed without fibrosis (SOX9on-off). In contrast, lineages that maintained Sox9 activity in attempt to regenerate, demarcated by SOX9-induced Cadherin 6 (SOX9on-on CDH6pos ) cell state, generated single-cell Wnt activity to provoke a fibroproliferative response in adjacent fibroblasts, driving AKI to chronic kidney disease. Transplanted human kidneys displayed similar SOX9/CDH6/WNT2B responses post-injury. Thus, we uncovered a mechanism linking fibrosis to sustained efforts to regenerate the injured tissue.
Project description:The steps governing healing with or without fibrosis within the same microenvironment are unclear. After acute kidney injury (AKI), the injured proximal tubular epithelial cells activate Sox9 for self-restoration. Using head-to-head comparison of injury- induced Sox9-lineages via spatiotemporal mapping, single-cell sequencing, and single-nuclei chromatin accessibility profiling, we identified a dynamic SOX9 switch. Lineages that regenerated epithelia silenced SOX9 and healed without fibrosis (SOX9on-off). In contrast, lineages that maintained Sox9 activity in attempt to regenerate, demarcated by SOX9-induced Cadherin 6 (SOX9on-on CDH6pos ) cell state, generated single-cell Wnt activity to provoke a fibroproliferative response in adjacent fibroblasts, driving AKI to chronic kidney disease. Transplanted human kidneys displayed similar SOX9/CDH6/WNT2B responses post-injury. Thus, we uncovered a mechanism linking fibrosis to sustained efforts to regenerate the injured tissue.
Project description:Mammalian kidney has very limited ability to repair or regenerate after acute kidney injury (AKI). The maladaptive repair of AKI promotes the progression to chronic kidney disease (CKD). Therefore, it is extremely urgent to explore new strategies to promote the repair/regeneration of injured renal tubules after AKI. It has been shown that hypoxia induces heart regeneration in adult mice. However, it is unknown whether hypoxia can induce kidney regeneration after AKI. In this study, we used a prolyl hydroxylase domain inhibitor (PHDI), MK-8617, to mimic hypoxia condition and found that MK-8617 significantly ameliorates ischemia reperfusion injury (IRI) induced acute kidney injury. We then showed that MK-8617 dramatically facilitates renal regeneration via promoting the proliferation of injured renal proximal tubular cells (RPTCs) after IRI-induced AKI. We then performed bulk mRNA sequencing and discovered that multiple nephrogenesis- related genes were significantly upregulated with MK-8617 pretreatment. Furthermore, we showed that MK-8617 may alleviate proximal tubule injury via stabilizing HIF-1α protein specifically in renal proximal tubular cells. We also demonstrated that MK-8617 promotes the reprogramming of renal proximal tubular cells to Sox9+ renal progenitor cells, and the regeneration of renal proximal tubules. In summary, we discovered that inhibition of prolyl hydroxylase improves renal proximal tubule regeneration after IRI-induced AKI via promoting the reprogramming of renal proximal tubular cells to Sox9+ renal progenitor cells.
Project description:Altered cellular metabolism in kidney proximal tubule (PT) cells plays a critical role in the development and progression of acute kidney injury (AKI). The transcription factor Krüppel-like factor 6 (KLF6) is rapidly and robustly induced in the PT after AKI, suggesting an early-inducible injury response gene. PT-specific Klf6 knockdown (Klf6PTKO) are protected from AKI and resulting fibrosis in mice. Combined RNA-sequencing and ChIP-sequencing demonstrated preserved expression of genes encoding branched chain amino acid (BCAA) catabolic enzymes in Klf6PTKO mice, with several of the genes also having KLF6 binding sites close to their transcription start sites. Conversely, inducible KLF6 overexpression suppressed expression of BCAA genes and exacerbated kidney injury and fibrosis in mice. Injured kidney cells could not respond to the BCAA catabolic activator BT2, and injured cells overexpressing KLF6 were less able to utilize BCAA. Thus, targeting KLF6-mediated suppression of BCAA catabolism may serve as key therapeutic target in AKI and kidney fibrosis.
Project description:Acute kidney injury (AKI) have been thought to be reversible condition, however, emerging evidence demonstrated association between AKI and subsequent development of irreversible fibrosis and chronic kidney disease. In the present study, since recovery of AKI depends on renal tubular regeneration, factors expressing in renal tubules in adaptive or maladaptive repair process were investigated to predict reversibility of kidney injury. In the kidney of female F344 rats subjected to ischemia/reperfusion (I/R), regenerative tubules and dilated tubules were observed at 3 and 7 days after I/R. In fibrotic areas of the kidney of male SD rats subjected to I/R, renal tubules were dilated or atrophied. From microarray data of regenerative tubules, survivin, sex-determining region Y (SRY)-box 9 (SOX9), and CD44 were extracted as factors possibly relating to tubular regeneration or fibrosis. Immunohistochmical analysis demonstrated that survivin and SOX9 expressed in regenerative tubules, while SOX9 also expressed in renal tubules in fibrotic area, indicating that survivin and SOX9 contribute renal tubular regeneration, but sustained SOX9 expression may lead fibrosis. CD44 expressed in dilated tubules at day 3 and 7, and tubules in fibrotic area, suggesting that CD44 expressed in maladaptive tubules. These information will be helpful to consider reversibility of kidney injury.
Project description:Induction of SRY box transcription factor 9 (SOX9) has been shown to occur in response to kidney injury in rodents, where SOX9-positive cells proliferate and regenerate the proximal tubules of injured kidneys. Additionally, SOX9-positive cells demonstrate a capacity to differentiate toward other nephron segments. Here, we characterized the role of SOX9 in normal and injured human kidneys. SOX9 expression was found to colocalize with a proportion of so-called scattered tubular cells in the uninjured kidney, a cell population previously shown to be involved in kidney injury and regeneration. Following injury and in areas adjacent to inflammatory cell infiltrates, SOX9-positive cells were increased in number. With the use of primary tubular epithelial cells (PTECs) obtained from human kidney tissue, SOX9 expression was spontaneously induced in culture and further increased by TGF-β1, whereas it was suppressed by IFN-γ. siRNA-mediated knockdown of SOX9 in PTECs followed by analysis of differential gene expression, immunohistochemical expression, and luciferase promoter assays suggested lamin B receptor (LBR), high mobility group AT-hook 2 (HMGA2), and homeodomain interacting protein kinase 3 (HIPK3) as possible target genes of SOX9. Moreover, a kidney explant model was used to demonstrate that only SOX9-positive cells survive the massive injury associated with kidney ischemia and that the surviving SOX9-positive cells spread and repopulate the tubules. Using a wound healing assay, we also showed that SOX9 positively regulated the migratory capacity of PTECs. These findings shed light on the functional and regulatory aspects of SOX9 activation in the human kidney during injury and regeneration.
Project description:Altered expression and activation of the Epidermal Growth Factor Receptor (EGFR) is implicated in acute and chronic kidney injury. In addition to expression in intrinsic kidney cells, EGFR is expressed in myeloid cells, which play important roles to promote both acute kidney injury and subsequent fibrosis. In murine ischemic acute kidney injury (AKI), myeloid deletion of EGFR promoted a proresolving, anti-inflammatory phenotype and increased efferocytotic capacity in macrophages, accelerated recovery in response to AKI and inhibited subsequent development of tubulointerstitial fibrosis. We found that selective EGFR expression and activation in neutrophils also accelerated recovery from ischemic kidney injury and reduced subsequent fibrosis. EGFR activation played an essential role in increasing the life span of neutrophils in the injured kidney, and deletion of EGFR expression either in all murine myeloid cells or selectively in neutrophils decreased kidney neutrophil Mcl-1 expression and promoted neutrophil apoptosis, which was accompanied by accelerated recovery from organ injury and reduced subsequent fibrosis. These studies identify previously undescribed coordinated and complementary roles for EGFR activation in neutrophils and macrophages to exacerbate kidney injury.
Project description:After acute kidney injury (AKI), patients either recover or alternatively develop fibrosis and chronic kidney disease. Interactions between injured epithelia, stroma and inflammatory cells determine whether kidneys repair or undergo fibrosis, but the molecular events that drive these processes are poorly understood. Here, we use single nucleus RNA sequencing of a mouse model of AKI to characterize cell states during repair from acute injury. We identify a distinct proinflammatory and profibrotic proximal tubule cell state that fails to repair. Deconvolution of bulk RNA-seq datasets indicates that this “failed-repair proximal tubule cell” or FR-PTC, state can be detected in other models of kidney injury, increasing in the aging rat kidney and over time in human kidney allografts. We also describe dynamic intercellular communication networks and discern transcriptional pathways driving successful vs. failed repair. Our study provides a detailed description of cellular responses after injury and suggests that the FR-PTC state may represent a therapeutic target to improve repair.
Project description:The kidney has large regenerative capacity that is impeded when injured renal tubular epithelial cells (TECs) undergo SNAI1-driven partial epithelial mesenchymal transition (pEMT). Here we investigate the role of IL11 in TEC pEMT and kidney repair. Wild-type mice with acute kidney injury (AKI) upregulate IL11 in TECs triggering an ERK/P90RSK/GSK3β axis of SNAI1 expression leading to impaired renal function, which is abrogated in Il11 null mice. In mouse models of AKI, a neutralizing IL11 antibody promotes kidney regeneration, while attenuating pEMT, fibrosis and kidney dysfunction. In TECs, TGFβ1 induces autocrine IL11/ERK-dependent pEMT leading to paracrine, IL11-mediated fibroblast activation. Mice with TEC-specific deletion of Il11ra1 are protected from pEMT, inflammation, fibrosis and renal failure. In a mouse model of chronic kidney disease, administration of anti-IL11 reverses fibrosis, regenerates kidney parenchyma and restores renal function. Therapeutic inhibition of IL11 signaling appears permissive for promoting kidney regeneration and improving kidney function.