A Switch in Iron Transport Mechanisms Defines Novel Forms of Congenital Chronic Kidney Disease [P15 FeD]
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE100252 | GEO | 2025/09/08
REPOSITORIES: GEO
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Project description:Periconceptual maternal iron deficiency (FeD) is a worldwide problem resulting in prematurity and low birth weights. Yet, it is not known whether FeD affects all developing tissues, or rather targets specific lineages. To address these questions, we investigated the targeting of the kidney by FeD. We found that FeD reduced both serum transferrin-iron and non-transferrin-bound-iron (NTBI), and these deficiencies targeted the renal proximal nephron rather than renal collecting ducts or stroma. In contrast, proximal tubular deletions of TfR1 (TfD) caused only modest defects in kidney development implying compensation by NTBI in the embryo. Yet, after the first two postnatal weeks, proximal TfD resulted in striking segmentally specific hypoplasia, as well as well as pervasive cystic transformation with Bardet-Biedel or Nephronothesis protein deficiencies. Treatment with NTBI as well as systemic activators of HIF which induce iron trafficking bypassed TfD and rescued the cystic disease and suppressed kidney damage. In sum, iron depletion resulted in new forms of chronic kidney disease. Its phenotype resulted from the alternative use of two different forms of iron, NTBI and Tf-iron at different stages and in different cells of the developing kidney.
2025-09-08 | GSE100253 | GEO
Project description:Periconceptual maternal iron deficiency (FeD) is a worldwide problem resulting in prematurity and low birth weights. Yet, it is not known whether FeD affects all developing tissues, or rather targets specific lineages. To address these questions, we investigated the targeting of the kidney by FeD. We found that FeD reduced both serum transferrin-iron and non-transferrin-bound-iron (NTBI), and these deficiencies targeted the renal proximal nephron rather than renal collecting ducts or stroma. In contrast, proximal tubular deletions of TfR1 (TfD) caused only modest defects in kidney development implying compensation by NTBI in the embryo. Yet, after the first two postnatal weeks, proximal TfD resulted in striking segmentally specific hypoplasia, as well as well as pervasive cystic transformation with Bardet-Biedel or Nephronothesis protein deficiencies. Treatment with NTBI as well as systemic activators of HIF which induce iron trafficking bypassed TfD and rescued the cystic disease and suppressed kidney damage. In sum, iron depletion resulted in new forms of chronic kidney disease. Its phenotype resulted from the alternative use of two different forms of iron, NTBI and Tf-iron at different stages and in different cells of the developing kidney.
2025-09-08 | GSE100251 | GEO
Project description:In plasma, iron is normally bound to transferrin, but in conditions of iron overload when the iron-binding capacity of transferrin is exceeded, non-transferrin-bound iron (NTBI) appears in plasma. NTBI is taken up by hepatocytes and other parenchymal cells via NTBI transporters and can cause cellular damage by promoting the generation of reactive oxygen species. However, how NTBI affects endothelial cells, the most proximal cell type exposed to circulating NTBI, has not been explored. We modeled in vitro the effects of systemic iron overload on endothelial cells by treating primary human umbilical vein endothelial cells (HUVECs) with NTBI (ferric ammonium citrate, FAC). Using an unbiased approach, we showed by RNA-Seq that iron loading alters lipid homeostasis in HUVECs by inducing SREBP2-mediated cholesterol biosynthesis. We also determined that FAC increased the susceptibility of HUVECs to apoptosis induced by TNFα. Moreover, we showed that cholesterol biosynthesis contributes to iron-potentiated apoptosis. Treating HUVECs with a cholesterol chelator hydroxypropyl-β-cyclodextrin demonstrated that depletion of cholesterol was sufficient to rescue HUVECs from TNFa-induced apoptosis, even in the presence of FAC. Finally, we showed that FAC or cholesterol treatment modulated the TNFα pathway by inducing novel proteolytic processing of TNFR1 to a short isoform that localizes to lipid rafts. Our study raises the possibility that iron-mediated toxicity in human iron overload disorders is at least in part dependent on alterations in cholesterol metabolism in endothelial cells, increasing their susceptibility to apoptosis.
2021-09-01 | GSE168534 | GEO
Project description:Homeostatic adaptation to systemic iron overload involves transcriptional induction of bone morphogenetic protein 6 (BMP6) in liver sinusoidal endothelial cells (LSECs). BMP6 is then secreted to activate signaling to the iron hormone hepcidin (Hamp) in neighboring hepatocytes. To explore the mechanism for iron sensing by LSECs, we generated TfrcTek-Cre mice with endothelial cell-specific ablation of transferrin receptor 1 (Tfr1). We also used wild type mice to characterize LSEC-specific molecular responses to iron by single cell transcriptomics. TfrcTek-Cre animals tend to have increased liver iron content compared to Tfrcfl/fl controls but do not exhibit blunted Bmp6 or Hamp mRNA expression. They respond to dietary iron challenges with Bmp6 and Hamp induction, yet sometimes to levels slightly lower relative to liver iron load. We noted that liver Bmp6 and Hamp mRNA levels significantly correlated with serum non-transferrin bound iron (NTBI) that emerged following dietary iron loading in both TfrcTek-Cre and Tfrcfl/fl mice. High dietary iron triggered more profound alterations in the LSEC transcriptome of Tfrcfl/fl mice compared to holo-transferrin injection. These culminated in robust induction of Bmp6 and other nuclear factor erythroid 2-related factor 2 (Nrf2) target genes, as well as Myc target genes involved in ribosomal biogenesis and protein synthesis. Taken together, our data suggest that during systemic iron overload, LSECs internalize NTBI, which promotes oxidative stress and thereby transcriptionally induces Bmp6 via Nrf2. The contribution of Tfr1 and transferrin-bound iron to Bmp6 induction is minimal.
2022-12-21 | GSE215324 | GEO
Project description:Systemic iron metabolism is disrupted in chronic kidney disease (CKD). However, little is known about local kidney iron homeostasis and its role in kidney fibrosis. Kidney-specific effects of iron therapy in CKD also remain elusive. Here, we elucidate the role of macrophage iron status in kidney fibrosis and demonstrate that it is a potential therapeutic target. In CKD, kidney macrophages exhibited depletion of labile iron pool (LIP) and induction of transferrin receptor 1, indicating intracellular iron deficiency. Low LIP in kidney macrophages was associated with their defective antioxidant response and proinflammatory polarization. Repletion of LIP in kidney macrophages through knockout of ferritin heavy chain (Fth1) reduced oxidative stress and mitigated fibrosis. Similar to Fth1 knockout, iron dextran therapy, through replenishing macrophage LIP, reduced oxidative stress, decreased the production of proinflammatory cytokines, and alleviated kidney fibrosis. Interestingly, iron markedly decreased TGF-β expression and suppressed TGF-β–driven fibrotic response of macrophages. Iron dextran therapy and FtH suppression had an additive protective effect against fibrosis. Adoptive transfer of iron-loaded macrophages alleviated kidney fibrosis, validating the protective effect of iron-replete macrophages in CKD. Thus, targeting intracellular iron deficiency of kidney macrophages in CKD can serve as a therapeutic opportunity to mitigate disease progression.
2023-02-01 | GSE221598 | GEO
Project description:Chronic kidney disease is the main cause of mortality in patients with tuberous sclerosis complex disease (TSC). The mechanisms underlying TSC cystic kidney disease remain unclear with no available interventions to prevent cyst formation. Using targeted deletion of TSC1 in nephron progenitor cells, we showed that cysts in TSC1 null embryonic kidneys originate from injured proximal tubular cells with high mTOR complex 1 activity. Injection of rapamycin to pregnant mice inhibited the mTOR pathway and tubular cell proliferation in kidneys of TSC1 null offspring. Rapamycin also prevented renal cystogenesis and prolonged the life span of TSC newborns. Gene expression analysis of proximal tubule cells, identified sets of genes and pathways that were modified secondary to TSC1 deletion and rescued by rapamycin administration during nephrogenesis. Inflammation with mononuclear infiltration was observed in the cystic areas of TSC1 null kidneys. Dexamethasone administration during pregnancy decreased cyst formation not only by inhibiting the inflammatory response but also by interfering with the mTORC1 pathway. These results reveal novel mechanisms of cystogenesis in TSC disease and suggest new interventions prior to birth to ameliorate cystic disease in offspring.
2020-06-10 | GSE152165 | GEO
Project description:Background: Disease severity of autosomal dominant polycystic kidney disease (ADPKD) is influenced by diet. Dietary protein, a recognized cyst-accelerating factor, is catabolized into amino acids (AA) and delivered to the kidney leading to renal hypertrophy. Injury-induced hypertrophic signaling in ADPKD results in increased macrophage (MФ) activation and inflammation followed by cyst growth. We hypothesize that the cystogenesis-prompting effects of HP diet are caused by increased delivery of specific AA to the kidney, ultimately stimulating MФs to promote cyst progression. Methods: Pkd1 flox/flox mice with and without Cre (CAGG-ER) were given tamoxifen to induce global gene deletion (Pkd1KO). Pkd1KO mice were fed either a low (LP; 6%), normal (NP; 18%), or high (HP; 60%) diet for 1 week (early) or 6 weeks (chronic). Mice were then euthanized and tissues were used for histology, immunofluorescence and various biochemical assays. One week fed kidney tissue was cell sorted to isolate tubular epithelial cells for RNA sequencing. Results: Chronic dietary protein load in Pkd1KO mice increased kidney weight, number of kidney infiltrating and resident MФs, chemokines, cytokines and cystic index compared to LP diet fed mice. Accelerated cyst growth induced by chronic HP were attenuated by liposomal clodronate-mediated MФ depletion. Early HP diet fed Pkd1KO mice had larger cystic kidneys compared to NP or LP fed counterparts, but without increases in the number of kidney MФs, cytokines, or markers of tubular injury. RNA sequencing of tubular epithelial cells in HP compared to NP or LP diet group revealed increased expression of sodium-glutamine transporter Snat3, chloride channel Clcnka, and gluconeogenesis marker Pepck1, accompanied by increased excretion of urinary ammonia, a byproduct of glutamine. Conclusion: Chronic dietary protein load-induced renal hypertrophy and accelerated cyst growth in Pkd1KO mice is dependent on both infiltrating and resident MФ recruitment and subsequent inflammatory response. Early cyst expansion by HP diet, however, is relient on increased delivery of glutamine to kidney epithelial cells, driving downstream metabolic changes prior to inflammatory provocation.
2024-02-16 | GSE225495 | GEO
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.
2024-10-10 | GSE247560 | GEO
Project description:End stage renal disease (ESRD) is associated with hyperplastic-cystic remodelling of the kidneys (ARCD) and increased rate of kidney tumours. Using the Affymetrix oligoarray, we have established the gene expression signature of ESRD/ARCD kidneys and compared to those of normal kidneys and of distinct types of renal tumours. Experiment Overall Design: We analysed several array per specific type of renal tumor and normal kidney tissue
2009-08-07 | E-GEOD-6280 | biostudies-arrayexpress
Project description:Obesity is a major risk factor for end-stage kidney disease. We previously found that lysosomal dysfunction and impaired autophagic flux contribute to lipotoxicity in experimental and human obesity-related kidney disease. However, the transcriptional regulators involved in renal lipotoxicity is largely unknown. Here we found palmitic acid (PA) strongly promoted dephosphorylation and nuclear translocation of transcription factor EB (TFEB), which was mediated by inhibition of MTORC1 (mechanistic target of rapamycin kinase complex 1) via Rag GTPase inactivation. PA-induced TFEB nuclear translocation was, however, gradually decreased over a longer treatment. We then investigated the role of TFEB in the pathogenesis of obesity-related kidney disease. High-fat diet (HFD)-fed proximal tubular epithelial cell (PTEC)-specific Tfeb-deficient mice exhibited greater phospholipid accumulation in enlarged lysosomes, which manifested as multilamellar bodies (MLBs). Activated TFEB mediated lysosomal exocytosis of phospholipids, to help PTECs to reduce MLBs/vacuole accumulation. Furthermore, HFD-fed PTEC-specific Tfeb-deficient mice showed autophagic stagnation and exacerbated injury upon renal ischemia-reperfusion. Finally, higher BMI was associated with increased vacuolation and decreased nuclear TFEB in the proximal tubule of CKD patients and we herein proposed a new disease concept “obesity-related tubulopathy (ORT)”. In conclusion, these results indicate a critical role of TFEB-mediated lysosomal exocytosis in counteracting renal lipotoxicity.
2023-01-17 | GSE191216 | GEO