Spns1 controls megalin dependent endocytosis via iron misregulation
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PROVIDER: PRJNA1118826 | ENA |
REPOSITORIES: ENA
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Project description:Proximal tubule endocytosis is essential for protecting the kidney from potentially damaging proteinuria and for mediating metabolic pathways, such as the activation of Vitamin D. We have identified the lysosomal membrane protein, Spns1, as a novel iron conductance that is indispensable for the normal endocytic function of the proximal tubule. Conditional knockout of Spns1 with a Cre-lox system in megalin-expressing cells in mice leads to arrest of both pinocytosis and receptor-mediated endocytosis in the proximal tubule. This endocytic defect is associated with iron overload in proximal tubules as measured by immunofluorescence of ferritin abundance and by a reduction in nascent TfRc mRNA transcripts. We have recapitulated previous findings in drosophila and zebrafish that Spns1 knockout causes endolysosomal dysfunction including abnormally enlarged lysosomes. The endocytic defect resulting from conditional Spns1 knockout can be rescued nutritionally with an iron deficient diet or genetically through double knockout of both Spns1 and the Fe2+ transporter, DMT1. Surprisingly, the endocytic defect in mice with Spns1 conditional knockout occurs despite normal megalin expression at the proximal tubule apical membrane. This data raises the possibilty that post-translational regulation of megalin activation may be nutrient-responsive.
2024-09-06 | GSE268837 | GEO
Project description:Proximal tubule endocytosis is essential because it both protects the kidney from potentially damaging proteinuria and mediates metabolic pathways, such as the activation of Vitamin D. We have determined that the proximal tubule expresses an endolysosomal membrane protein, protein spinster homolog 1 (Spns1), as a novel iron conductance that is indispensable during embryonic development
2024-06-04 | MSV000094931 | MassIVE
Project description:Presently, genes regulated by steroid hormones during induced regression of the CSL (cranial suspensory ligament) are unknown. To identify such genes and to evaluate their expression levels in megalin-deficient mice, we performed global gene expression profiling on gonads from E14.5 megalin+/+ and megalin-/- embryos.
2005-06-30 | E-MEXP-352 | biostudies-arrayexpress
Project description:The endocytic receptor megalin constitutes the main pathway for clearance of plasma proteins from the glomerular filtrate in the proximal tubules. However, little is know about the mechanisms that control receptor activity. A widely discussed hypothesis states that the intracellular domain (ICD) of megalin, released upon ligand binding, acts as a transcription regulator to suppress receptor expression - a mechanism proposed to safeguard the proximal tubules from protein overload. Here, we have put this hypothesis to the test by generating a mouse model co-expressing the soluble ICD and the full-length receptor. Despite pronounced expression in the proximal tubules, the ICD failed to exert any effects on renal proximal tubular function such as megalin expression, protein retrieval, or renal gene transcription. Thus, our data argue that the ICD does not play a role in regulation of megalin activity in vivo in the proximal tubules. We used microarrays to compare gene expression profile in adult kidney from a new mouse model expressing the intracellular domain of megalin with wildtype. 10 week old mice were collected for RNA extraction and hybridization on Affymetrix microarrays. Three individuals for each genotype were analyzed comparing heterozygous animals for the intracellular domain of megalin with littermates controls.
2011-01-01 | E-GEOD-19778 | biostudies-arrayexpress
Project description:Pharmacological inhibition of megalin (also known as low-density lipoprotein receptor-related protein 2: LRP2) attenuates atherosclerosis in hypercholesterolemic mice. Since megalin is abundant in renal proximal tubule cells (PTCs), PTC-LRP2 +/+ and -/- littermates in an LDL receptor -/- background were generated and fed a Western diet to determine effects of PTC-derived megalin on atherosclerosis. PTC-specific megalin deletion did not attenuate atherosclerosis in LDL receptor -/- mice in either sex. Serendipitously, we discovered that PTC-specific megalin deletion led to interstitial infiltration of CD68+ cells and tubular atrophy. The pathology was only evident in male PTC-LRP2 -/- mice fed the Western diet, but not in mice fed a normal laboratory diet. Renal pathologies were also observed in male PTC-LRP2 -/- mice in an LDL receptor +/+ background fed the same Western diet, demonstrating that the renal pathologies were dependent on diet and not hypercholesterolemia. By contrast, female PTC-LRP2 -/- mice had no apparent renal pathologies. In vivo multiphoton microscopy demonstrated that PTC-specific megalin deletion dramatically diminished albumin accumulation in PTCs within 10 days of Western diet feeding. RNA sequencing analyses demonstrated the upregulation of inflammation-related pathways in kidney. Overall, PTC-specific megalin deletion leads to tubulointerstitial nephritis in mice fed Western diet, with severe pathologies in male mice.
2024-07-04 | GSE268879 | GEO
Project description:Trimethylamine-N-oxide (TMAO) is a uremic toxin, which has been associated with chronic kidney disease (CKD). Renal tubular epithelial cells play a central role in the pathophysiology of CKD. Megalin is an albumin-binding surface receptor on tubular epithelial cells, which is indispensable for urine protein reabsorption. To date, no studies have investigated the effect of TMAO on megalin expression and the functional properties of human tubular epithelial cells. The aim of this study was first to identify the functional effect of TMAO on human renal proximal tubular cells and second, to unravel the effects of TMAO on megalin-cubilin receptor expression. We found through global gene expression analysis that TMAO was associated with kidney disease. The microarray analysis also showed that megalin expression was suppressed by TMAO, which was also validated at the gene and protein level. High glucose and TMAO was shown to downregulate megalin expression and albumin uptake similarly. We also found that TMAO suppressed megalin expression via PI3K and ERK signaling. Furthermore, we showed that candesartan, dapagliflozin and enalaprilat counter-acted the suppressive effect of TMAO on megalin expression. Our results may further help us un-ravel the role of TMAO in CKD development and to identify new therapeutic targets to counteract TMAOs effects.
2022-08-10 | GSE210692 | GEO
Project description:The endocytic receptor megalin constitutes the main pathway for clearance of plasma proteins from the glomerular filtrate in the proximal tubules. However, little is know about the mechanisms that control receptor activity. A widely discussed hypothesis states that the intracellular domain (ICD) of megalin, released upon ligand binding, acts as a transcription regulator to suppress receptor expression - a mechanism proposed to safeguard the proximal tubules from protein overload. Here, we have put this hypothesis to the test by generating a mouse model co-expressing the soluble ICD and the full-length receptor. Despite pronounced expression in the proximal tubules, the ICD failed to exert any effects on renal proximal tubular function such as megalin expression, protein retrieval, or renal gene transcription. Thus, our data argue that the ICD does not play a role in regulation of megalin activity in vivo in the proximal tubules. We used microarrays to compare gene expression profile in adult kidney from a new mouse model expressing the intracellular domain of megalin with wildtype.
2011-01-01 | GSE19778 | GEO
Project description:The multiligand receptor megalin and its endocytic adaptor protein Dab2 play essential roles in maintaining the integrity of the apical endocytic pathway of proximal tubule cells, and have complex and poorly understood roles in the development of chronic kidney disease. Here we used RNASeq in CRISPR/Cas9 knockout technology in a well-differentiated cell culture model to identify PT-specific transcriptional changes that are directly consequent to the loss of megalin (Lrp2), cubilin (Cubn), or Dab2 (Dab2) expression.
2021-12-29 | GSE176090 | GEO
Project description:Zc3h10 controls mitochondrial function coupling iron and cardiolipin homeostasis.
| PRJNA387412 | ENA
Project description:The reduced folate carrier (RFC1) is an integral membrane protein and facilitative anion exchanger that mediates delivery of 5-methyltetrahydrofolate into mammalian cells. Adequate maternal-fetal transport of folate is necessary for normal embryogenesis. Targeted inactivation of the murine RFC1 gene results in post-implantation embryo lethality, but daily folic acid supplementation of pregnant dams prolongs survival of homozygous embryos until mid-gestation. At E10.5 RFC1-/- embryos are developmentally delayed relative to wildtype littermates, have multiple malformations, including neural tube defects, and die due to failure of chorioallantoic fusion. The mesoderm is sparse and disorganized, and there is a marked absence of erythrocytes in yolk sac blood islands. Affymetrix microarray analysis and quantitative RT-PCR validation of the relative gene expression profiles in E9.5 RFC1-/- vs. RFC1+/+ embryos indicates a dramatic downregulation of multiple genes involved in erythropoiesis, and upregulation of several genes that form the cubilin-megalin multiligand endocytic receptor complex. Megalin protein expression disappears from the visceral yolk sac of RFC1-/- embryos, and cubilin protein is widely misexpressed. Inactivation of RFC1 impacts the expression of several ligands and interacting proteins in the cubilin-amnionless-megalin complex that are involved in the maternal-fetal transport of folate, vitamin B12, and other nutrients, lipids and morphogens required for normal embryogenesis. Comparison of RFC KO, wildtype normal embryos vs. RFC KO, nullizygous affected embryos Keywords: reduced folate carrier knockout, folate receptor, cubilin, megalin, embryos, gene expression, neural tube defect, chorioallantoic fusion
2008-03-17 | GSE10659 | GEO