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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 DOI: 10.1681/asn.0000000000000324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [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 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] [What about the content of this article? (0)] [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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Perl AJ, Schuh MP, Kopan R. Regulation of nephron progenitor cell lifespan and nephron endowment. Nat Rev Nephrol 2022; 18:683-695. [PMID: 36104510 DOI: 10.1038/s41581-022-00620-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/27/2022] [Indexed: 11/08/2022]
Abstract
Low nephron number - resulting, for example, from prematurity or developmental anomalies - is a risk factor for the development of hypertension, chronic kidney disease and kidney failure. Considerable interest therefore exists in the mechanisms that regulate nephron endowment and contribute to the premature cessation of nephrogenesis following preterm birth. The cessation of nephrogenesis in utero or shortly after birth is synchronized across multiple niches in all mammals, and is coupled with the exhaustion of nephron progenitor cells. Consequently, no nephrons are formed after the cessation of developmental nephrogenesis, and lifelong renal function therefore depends on the complement of nephrons generated during gestation. In humans, a tenfold variation in nephron endowment between individuals contributes to differences in susceptibility to kidney disease; however, the mechanisms underlying this variation are not yet clear. Salient advances in our understanding of environmental inputs, and of intrinsic molecular mechanisms that contribute to the regulation of cessation timing or nephron progenitor cell exhaustion, have the potential to inform interventions to enhance nephron endowment and improve lifelong kidney health for susceptible individuals.
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Affiliation(s)
- Alison J Perl
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Meredith P Schuh
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Raphael Kopan
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
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Duvall K, Crist L, Perl AJ, Pode Shakked N, Chaturvedi P, Kopan R. Revisiting the role of Notch in nephron segmentation confirms a role for proximal fate selection during mouse and human nephrogenesis. Development 2022; 149:275412. [PMID: 35451473 PMCID: PMC9188758 DOI: 10.1242/dev.200446] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/14/2022] [Indexed: 12/16/2022]
Abstract
Notch signaling promotes maturation of nephron epithelia, but its proposed contribution to nephron segmentation into proximal and distal domains has been called into doubt. We leveraged single cell and bulk RNA-seq, quantitative immunofluorescent lineage/fate tracing, and genetically modified human induced pluripotent stem cells (iPSCs) to revisit this question in developing mouse kidneys and human kidney organoids. We confirmed that Notch signaling is needed for maturation of all nephron lineages, and thus mature lineage markers fail to detect a fate bias. By contrast, early markers identified a distal fate bias in cells lacking Notch2, and a concomitant increase in early proximal and podocyte fates in cells expressing hyperactive Notch1 was observed. Orthogonal support for a conserved role for Notch signaling in the distal/proximal axis segmentation is provided by the demonstration that nicastrin (NCSTN)-deficient human iPSC-derived organoids differentiate into TFA2B+ distal tubule and CDH1+ connecting segment progenitors, but not into HNF4A+ or LTL+ proximal progenitors.
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Affiliation(s)
- Kathryn Duvall
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Lauren Crist
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Alison J Perl
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Naomi Pode Shakked
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Praneet Chaturvedi
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Raphael Kopan
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.,Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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