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Perl AJ, Liu H, Hass M, Adhikari N, Chaturvedi P, Hu YC, Jiang R, Liu Y, Kopan R. Reduced Nephron Endowment in Six2-TGCtg Mice Is Due to Six3 Misexpression by Aberrant Enhancer-Promoter Interactions in the Transgene. J Am Soc Nephrol 2024; 35:566-577. [PMID: 38447671 PMCID: PMC11149036 DOI: 10.1681/asn.0000000000000324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 02/27/2024] [Indexed: 03/08/2024] Open
Abstract
Key Points Aberrant enhancer–promoter interactions detected by Hi-C drive ectopic expression of Six3 in the Six2TGCtg line. Disruption of Six3 in the Six2TGCtg line restores nephron number, implicating SIX3 interference with SIX2 function in nephron progenitor cell renewal. Background Lifelong kidney function relies on the complement of nephrons generated during mammalian development from a mesenchymal nephron progenitor cell population. Low nephron endowment confers increased susceptibility to CKD. Reduced nephron numbers in the popular Six2TGC transgenic mouse line may be due to disruption of a regulatory gene at the integration site and/or ectopic expression of a gene(s) contained within the transgene. Methods Targeted locus amplification was performed to identify the integration site of the Six2TGC transgene. Genome-wide chromatin conformation capture (Hi-C) datasets were generated from nephron progenitor cells isolated from the Six2TGC +/tg mice, the Cited1 CreERT2/+ control mice, and the Six2TGC +/tg ; Tsc1 +/Flox mice that exhibited restored nephron number compared with Six2TGC +/tg mice. Modified transgenic mice lacking the C-terminal domain of Six3 were used to evaluate the mechanism of nephron number reduction in the Six2TGC +/tg mouse line. Results Targeted locus amplification revealed integration of the Six2TGC transgene within an intron of Cntnap5a on chr1, and Hi-C analysis mapped the precise integration of Six2TGC and Cited1 CreERT2 transgenes to chr1 and chr14, respectively. No changes in topology, accessibility, or expression were observed within the 50-megabase region centered on Cntnap5a in Six2TGC +/tg mice compared with control mice. By contrast, we identified an aberrant regulatory interaction between a Six2 distal enhancer and the Six3 promoter contained within the transgene. Increasing the Six2TGC tg to Six2 locus ratio or removing one Six2 allele in Six2TGC +/tg mice caused severe renal hypoplasia. Furthermore, clustered regularly interspaced short palindromic repeats disruption of Six3 within the transgene (Six2TGC ∆Six3CT ) restored nephron endowment to wild-type levels and abolished the stoichiometric effect. Conclusions These findings broadly demonstrate the utility of Hi-C data in mapping transgene integration sites and architecture. Data from genetic and biochemical studies together suggest that in Six2TGC kidneys, SIX3 interferes with SIX2 function in nephron progenitor cell renewal through its C-terminal domain.
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Affiliation(s)
- Alison J. Perl
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Han Liu
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Matthew Hass
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Nirpesh Adhikari
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Praneet Chaturvedi
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Yueh-Chiang Hu
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Rulang Jiang
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Yaping Liu
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Raphael Kopan
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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Perl AJ, Liu H, Hass M, Adhikari N, Chaturvedi P, Hu YC, Jiang R, Liu Y, Kopan R. Reduced nephron endowment in the common Six2-TGC tg mouse line is due to Six3 misexpression by aberrant enhancer-promoter interactions in the transgene. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561202. [PMID: 37873415 PMCID: PMC10592608 DOI: 10.1101/2023.10.06.561202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Lifelong kidney function relies on the complement of nephrons generated during mammalian development from a mesenchymal nephron progenitor cell (NPC) population. Low nephron endowment confers increased susceptibility to chronic kidney disease. We asked whether reduced nephron numbers in the popular Six2TGC transgenic mouse line 1 was due to disruption of a regulatory gene at the integration site or to ectopic expression of a gene(s) contained within the transgene. Targeted locus amplification identified integration of the Six2TGC transgene within an intron of Cntnap5a on chr1. We generated Hi-C datasets from NPCs isolated from the Six2TGC tg/+ mice, the Cited1 CreERT2/+ control mice, and the Six2TGC tg/+ ; Tsc1 +/Flox,2 mice that exhibited restored nephron number compared with Six2TGC tg/+ mice, and mapped the precise integration of Six2TGC and Cited1 CreERT2 transgenes to chr1 and chr14, respectively. No changes in topology, accessibility, or expression were observed within the 50-megabase region centered on Cntnap5a in Six2TGC tg/+ mice compared with control mice. By contrast, we identified an aberrant regulatory interaction between a Six2 distal enhancer and the Six3 promoter contained within the transgene. Increasing the Six2TGC tg to Six2 locus ratio or removing one Six2 allele in Six2TGC tg/+ mice, caused severe renal hypoplasia. Furthermore, CRISPR disruption of Six3 within the transgene ( Six2TGC Δ Six3CT ) restored nephron endowment to wildtype levels and abolished the stoichiometric effect. Data from genetic and biochemical studies together suggest that in Six2TGC, SIX3 interferes with SIX2 function in NPC renewal through its C-terminal domain. Significance Using high-resolution chromatin conformation and accessibility datasets we mapped the integration site of two popular transgenes used in studies of nephron progenitor cells and kidney development. Aberrant enhancer-promoter interactions drive ectopic expression of Six3 in the Six2TGC tg line which was correlated with disruption of nephrogenesis. Disruption of Six3 within the transgene restored nephron numbers to control levels; further genetic and biochemical studies suggest that Six3 interferes with Six2 -mediated regulation of NPC renewal.
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Martins WFS, Subramaniam K, Steen K, Mawejje H, Liloglou T, Donnelly MJ, Wilding CS. Detection and quantitation of copy number variation in the voltage-gated sodium channel gene of the mosquito Culex quinquefasciatus. Sci Rep 2017; 7:5821. [PMID: 28725028 PMCID: PMC5517494 DOI: 10.1038/s41598-017-06080-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 06/07/2017] [Indexed: 01/23/2023] Open
Abstract
Insecticide resistance is typically associated with alterations to the insecticidal target-site or with gene expression variation at loci involved in insecticide detoxification. In some species copy number variation (CNV) of target site loci (e.g. the Ace-1 target site of carbamate insecticides) or detoxification genes has been implicated in the resistance phenotype. We show that field-collected Ugandan Culex quinquefasciatus display CNV for the voltage-gated sodium channel gene (Vgsc), target-site of pyrethroid and organochlorine insecticides. In order to develop field-applicable diagnostics for Vgsc CN, and as a prelude to investigating the possible association of CN with insecticide resistance, three assays were compared for their accuracy in CN estimation in this species. The gold standard method is droplet digital PCR (ddPCR), however, the hardware is prohibitively expensive for widespread utility. Here, ddPCR was compared to quantitative PCR (qPCR) and pyrosequencing. Across all platforms, CNV was detected in ≈10% of mosquitoes, corresponding to three or four copies (per diploid genome). ddPCR and qPCR-Std-curve yielded similar predictions for Vgsc CN, indicating that the qPCR protocol developed here can be applied as a diagnostic assay, facilitating monitoring of Vgsc CN in wild populations and the elucidation of association between the Vgsc CN and insecticide resistance.
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Affiliation(s)
- Walter Fabricio Silva Martins
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Departamento de Biologia, Universidade Estadual da Paraíba, Campina Grande, Brazil
| | | | - Keith Steen
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Henry Mawejje
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Triantafillos Liloglou
- Department of Molecular and Clinical Cancer Medicine, Roy Castle Lung Cancer Research, Liverpool, UK
| | - Martin James Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge, UK
| | - Craig Stephen Wilding
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK.
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Kringen MK. Analysis of Copy Number Variation by Pyrosequencing® Using Paralogous Sequences. Methods Mol Biol 2016; 1315:115-21. [PMID: 26103895 DOI: 10.1007/978-1-4939-2715-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The determination of gene copy numbers of highly similar genes is difficult with conventional PCR-based methods. However, by amplification of similar genes in the same PCR reaction followed by Pyrosequencing(®), one may distinguish the genes based on a single-nucleotide difference. The ratio between the peak heights of gene-specific nucleotides obtained in the Pyrosequencing reaction may thereby be used to calculate the relative copy numbers of target genes. This method is easy and cost effective compared to other methods, and allows for the determination of copy numbers of genes that were previously difficult to achieve.
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Liu Z, Chen S, Boyle S, Zhu Y, Zhang A, Piwnica-Worms DR, Ilagan MXG, Kopan R. The extracellular domain of Notch2 increases its cell-surface abundance and ligand responsiveness during kidney development. Dev Cell 2013; 25:585-98. [PMID: 23806616 DOI: 10.1016/j.devcel.2013.05.022] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 04/24/2013] [Accepted: 05/23/2013] [Indexed: 12/11/2022]
Abstract
Notch2, but not Notch1, plays indispensable roles in kidney organogenesis, and Notch2 haploinsufficiency is associated with Alagille syndrome. We proposed that proximal nephron fates are regulated by a threshold that requires nearly all available free Notch intracellular domains (NICDs) but could not identify the mechanism that explains why Notch2 (N2) is more important than Notch1 (N1). By generating mice that swap their ICDs, we establish that the overall protein concentration, expression domain, or ICD amino acid composition does not account for the differential requirement of these receptors. Instead, we find that the N2 extracellular domain (NECD) increases Notch protein localization to the cell surface during kidney development and is cleaved more efficiently upon ligand binding. This context-specific asymmetry in NICD release efficiency is further enhanced by Fringe. Our results indicate that an elevated N1 surface level could compensate for the loss of N2 signal in specific cell contexts.
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Affiliation(s)
- Zhenyi Liu
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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