Cubilin-, Megalin- and Dab2-dependent transcription revealed by CRISPR/Cas9 knockout in kidney proximal tubule cells
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ABSTRACT:
ORGANISM(S): Didelphis virginiana
PROVIDER: GSE176090 | GEO | 2021/12/29
REPOSITORIES: GEO
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Project description:Autoimmune diseases that affect the kidney proximal tubule (PT) cause proteinuria and are implicated in the pathogenesis of kidney failure. Previous evidence demonstrated that circulating anti-brush border antibodies (ABBA) target megalin (LRP2) but whether other components of the PT drive autoimmunity was unknown. Here we investigate a patient with LRP2-negative ABBA disease, and applied immunoprecipitation, mass spectrometry, and confocal imaging to identify cubilin as a novel antigen associated with the autoimmune disorder.
2023-04-06 | PXD030159 | Pride
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: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:Cubilin-, Megalin- and Dab2-dependent transcription revealed by CRISPR/Cas9 knockout in kidney proximal tubule cells
| PRJNA734899 | ENA
Project description:This study reports the cellular self-organization of primary human renal proximal tubule epithelial cells (RPTECs) around a minimal Matrigel scaffold to produce basal-in and apical-out proximal tubule organoids (tubuloids). These tubuloids are produced and maintained in hanging drop cultures for 90+ days, the longest such culture of any kind reported to date. The tubuloids upregulate maturity markers, such as aquaporin-1 (AQP1) and megalin (LRP2), and exhibit less mesenchymal and proliferation markers, such as vimentin and Ki67, compared to 2D cultures. They also experience changes over time as revealed by a comparison of gene expression patterns of cells in 2D culture and in day 31 and day 67 tubuloids. Gene expression analysis and immunohistochemistry reveal an increase in the expression of megalin, an endocytic receptor that can directly bind and uptake protein or potentially assist protein uptake. The tubuloids, including day 90 tubuloids, uptake fluorescent albumin and reveal punctate fluorescent patterns, suggesting functional endocytic uptake through these receptors. Furthermore, the tubuloids release kidney injury molecule-1 (KIM-1), a common biomarker for kidney injury, when exposed to albumin in both dose- and time-dependent manners. While this study focuses on potential applications for modeling proteinuric kidney disease, the tubuloids may have broad utility for studies where apical proximal tubule cell access is required.
2022-10-07 | GSE198857 | GEO
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
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 Experiment Overall Design: 6 samples RFC KO mouse embryos, E9.5, folic acid treated: 3 Control, Wildtype, normal; 3 Affected, Nullizygous, CR/chorioallantoic defect; as paired-littermates with one normal and one affected embryo per set from each of three separate litters for RNA extraction and hybridization on Affymetrix microarrays.
2008-04-05 | E-GEOD-10659 | biostudies-arrayexpress
Project description:Chronic kidney disease (CKD) affects more than 20 million Americans and approximately 10% of the population worldwide, and thus represents a major public health concern. Genome-wide association studies (GWAS) of kidney functional decline have identified genes associated with CKD, but the precise roles and mechanisms by which they influence kidney function remained largely unexplored. Here, we examine the role of one GWAS identified gene by creating mice deficient for Galnt11, which encodes a member of the enzyme family that initiates protein Oglycosylation, an essential post-translational modification known to influence protein function and stability. We find that Galnt11-deficient mice display low molecular weight proteinuria and have specific defects in proximal tubule-mediated resorption of vitamin D binding protein, a1-microglobulin and retinol binding protein. Moreover, we identify the endocytic receptor megalin (LRP2) as a direct target of Galnt11 in vivo. Megalin in Galnt11-deficient mice displays reduced ligand binding and undergoes age-related loss within the kidney. Differential mass spectrometry revealed specific sites of Galnt11-mediated glycosylation within mouse kidney megalin/LRP2 that are known to be involved in ligand binding, suggesting that Oglycosylation directly influences the ability to bind ligands. In support of this, recombinant megalin containing these sites displayed reduced albumin binding in cells deficient for Galnt11. Our results provide insight into the association between GALNT11 and CKD, and identify a role for Galnt11 in proper kidney function.
2019-11-04 | PXD015429 | Pride
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. 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