Six1 and Six2 of the sine oculis homeobox subfamily are not functionally interchangeable in mouse nephron formation
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ABSTRACT:
PROVIDER: PRJNA781611 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR16975729.fastq.gz | Fastqsanger.gz | |||
| SRR16975730.fastq.gz | Fastqsanger.gz | |||
| SRR16975731.fastq.gz | Fastqsanger.gz |
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Project description:The vertebrate Six1 and Six2 arose by gene duplication from the Drosophila so (sine oculis) and have since diverged in their developmental expression patterns. Both genes are expressed in nephron progenitors of human fetal kidneys, and mutations in SIX1 or SIX2 cause branchio-oto-renal or renal hypodysplasia respectively. Since ~80% of SIX1 target sites are shared by SIX2, it is speculated that SIX1 and SIX2 may be functionally interchangeable by targeting common downstream genes. In contrast, in mouse kidneys, the expression of Six1 and Six2 only transiently overlaps in the metanephric mesenchyme before the onset of ureteric branching, and only Six2 expression is maintained in the nephron progenitors throughout development. This non-overlapping expression between Six1 and Six2 in mouse nephron progenitors promoted us to examine if Six1 can replace Six2. Surprisingly, forced expression of Six1 failed to rescue Six2-deficient kidney hypoplasia. We found that Six1 mediated Eya1 nuclear translocation and inhibited premature epithelialization of the progenitors but failed to rescue the proliferation defects and cell death caused by Six2-knockout. Genome-wide binding analyses showed that Six1 only bound to a small subset of Six2 target sites, but many Six2-bound loci that are crucial to the renewal and differentiation of nephron progenitors lacked Six1 occupancy. Thus, these data indicate that Six1 cannot substitute Six2 to drive nephrogenesis in mouse kidneys, demonstrating that these two transcription factors have not maintained equivalent biochemical properties since their divergence early in vertebrate evolution.
2022-01-27 | GSE189131 | GEO
Project description:The vertebrate Six1 and Six2 arose by gene duplication from the Drosophila sine oculis and have since diverged in their developmental expression patterns. Both genes are expressed in nephron progenitors of human fetal kidneys, and mutations in SIX1 or SIX2 cause branchio-oto-renal syndrome or renal hypodysplasia respectively. Since ∼80% of SIX1 target sites are shared by SIX2, it is speculated that SIX1 and SIX2 may be functionally interchangeable by targeting common downstream genes. In contrast, in mouse kidneys, Six1 expression in the metanephric mesenchyme lineage overlaps with Six2 only transiently, while Six2 expression is maintained in the nephron progenitors throughout development. This non-overlapping expression between Six1 and Six2 in mouse nephron progenitors promoted us to examine if Six1 can replace Six2. Surprisingly, forced expression of Six1 failed to rescue Six2-deficient kidney phenotype. We found that Six1 mediated Eya1 nuclear translocation and inhibited premature epithelialization of the progenitors but failed to rescue the proliferation defects and cell death caused by Six2-knockout. Genome-wide binding analyses showed that Six1 selectively occupied a small subset of Six2 target sites, but many Six2-bound loci crucial to the renewal and differentiation of nephron progenitors lacked Six1 occupancy. Altogether, these data indicate that Six1 cannot substitute Six2 to drive nephrogenesis in mouse kidneys, thus demonstrating that the difference in physiological roles of Six1 and Six2 in kidney development stems from both transcriptional regulations of the genes and divergent biochemical properties of the proteins.
| S-EPMC8844495 | biostudies-literature
Project description:Nephron endowment is determined by the self-renewal and induction of a nephron progenitor pool established at the onset of kidney development. In the mouse, the related transcriptional regulators Six1 and Six2 play non-overlapping roles in nephron progenitors. Transient Six1 activity prefigures, and is essential for, active nephrogenesis. In contrast, Six2 maintains later progenitor self-renewal from the onset of nephrogenesis. We compared Six2’s regulatory actions in mouse and human nephron progenitors by chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq). Surprisingly, SIX1 was identified as a SIX2 target unique to the human nephron progenitors. Further, RNA-seq and immunostaining revealed overlapping SIX1 and SIX2 progenitor activity in the 16 week human fetal kidney. Human SIX1 ChIP-seq revealed a similar set of targets to SIX2, and predicted both factors bind DNA through an identical recognition site. In contrast to the mouse where Six2 binds its own enhancers but doesn’t interact with DNA around Six1, both human SIX1 and SIX2 bind homologous SIX2 enhancers and putative enhancers positioned around SIX1. Transgenic analysis of a putative human SIX1 enhancer in the mouse revealed a transient, mouse-like, pre-nephrogenic, Six1 regulatory pattern. Together, these data demonstrate a divergence in SIX-factor regulation between mouse and human nephron progenitors. In the human, an auto/cross-regulatory loop drives continued SIX1 and SIX2 expression during active nephrogenesis. In contrast, the mouse establishes only an auto-regulatory Six2 loop. It is tempting to speculate that differential SIX-factor regulation may contribute to species differences in the duration of progenitor programs and nephron output.
2016-01-31 | GSE73865 | GEO
Project description:SIX2 is expressed by the self-renewing nephron progenitors in the human fetal kidney. We have also discovered that SIX1 is expressed in nephron progenitor population of the human fetal kidney, which is in contrast to the mouse. We performed ChIP-seq of SIX1 and SIX2 in order to identify the target genes of each factor and compare the role that each factor plays in transcriptional regulation of the nephron progenitors. We additionally performed ChIP-seq for p300 and H3K27ac in order to identify active loci and complement the transcription factor data.
2016-05-23 | GSE75948 | GEO
Project description:Nephron endowment is determined by the self-renewal and induction of a nephron progenitor pool established at the onset of kidney development. In the mouse, the related transcriptional regulators Six1 and Six2 play non-overlapping roles in nephron progenitors. Transient Six1 activity prefigures, and is essential for, active nephrogenesis. In contrast, Six2 maintains later progenitor self-renewal from the onset of nephrogenesis. We compared Six2’s regulatory actions in mouse and human nephron progenitors by chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq). Surprisingly, SIX1 was identified as a SIX2 target unique to the human nephron progenitors. Further, RNA-seq and immunostaining revealed overlapping SIX1 and SIX2 progenitor activity in the 16 week human fetal kidney. Human SIX1 ChIP-seq revealed a similar set of targets to SIX2, and predicted both factors bind DNA through an identical recognition site. In contrast to the mouse where Six2 binds its own enhancers but doesn’t interact with DNA around Six1, both human SIX1 and SIX2 bind homologous SIX2 enhancers and putative enhancers positioned around SIX1. Transgenic analysis of a putative human SIX1 enhancer in the mouse revealed a transient, mouse-like, pre-nephrogenic, Six1 regulatory pattern. Together, these data demonstrate a divergence in SIX-factor regulation between mouse and human nephron progenitors. In the human, an auto/cross-regulatory loop drives continued SIX1 and SIX2 expression during active nephrogenesis. In contrast, the mouse establishes only an auto-regulatory Six2 loop. It is tempting to speculate that differential SIX-factor regulation may contribute to species differences in the duration of progenitor programs and nephron output.
2016-01-31 | GSE73866 | GEO
Project description:Nephron progenitors in the embryonic kidney propagate while generating differentiated nephrons. However, the progenitors in mice terminally differentiate shortly after birth. We defined culture conditions to selectively propagated nephron progenitors in vitro in an undifferentiated state. To understand how expression profiles of Six2+ cells changed during culture in vitro compared with in vivo, we performed microarray analysis of Six2+ cells at E11.5 (starting material) and P0 (experiencing 8 days in vivo), and cultured Six2+ cells at E11.5 for 8 days or 19 days. Microarray analysis were performed with isolated Six2-positive nephron progenitors from transgenic mice embryo at E11.5 or P0, and cultured E11.5 Six2+ cells for 8 or 19 days in conditioned media. P0 non-progenitors represent Six2-GFP-negative cells at P0.
2016-04-14 | E-GEOD-79024 | biostudies-arrayexpress
Project description:Self-renewing undifferentiated nephron progenitors express Six2, a transcription factor that is required for their maintenance as undifferentiated progenitors. Differentiation of nephron progenitors is triggered by Wnt/b-catenin signaling. In order to understand how Six2 and Wnt signaling counteract each other, we performed ChIP-seq of Six2 and b-catenin in mesenchymal nephron progenitor cells. Nephron progenitors were FACS-isolated from BAC transgenic Six2GFPcre-positive embryonic kidneys at E16.5. For Six2 ChIP, freshly FACS isolated Six2+ cells were used. For b-catenin ChIP, FACS isolated Six2+ cells were aggregated by centrifugation at 850g for 5min and incubated in 10%FBS/DMEM containing 4uM BIO for 24hrs.
2012-09-11 | E-GEOD-39837 | biostudies-arrayexpress
Project description:Eya1 interacts with Six1/2 to induce nephron fate and promote nephron progenitor self-renewal. Haploinsufficiency for these genes in humans causes kidney agenesis or hypoplasia. However, how the Eya1-centered network operates remains elusive. Here we identify Eya1's interacting factors via mass-spectrometry and show that Eya1 and Six2 interact with Brg1-based SWI/SNF chromatin-remodeling complex in the kidney. Depletion of Brg1 results in lack of metanephric mesenchyme and depletion of nephron progenitor cells, which is linked to loss of Eya1 expression. Transcriptional profiling reveals conspicuous downregulation of the proto-oncogene Pbx1 and the Dchs1/Fat4 signaling but premature upregulation of a large subset of genes for podocyte lineages and aberrant activation of oncogenic factors in Brg1-deficent cell. ChIP-seq identifies Brg1-occupancy to enhancers at Pbx1 to a distal enhancer of Eya1 that drives nephron progenitor-specific expression. We demonstrate Six2-dependent Brg1 enrichment to the proximal-promoter of Mycn and two distal enhancers of Pbx1, all of which govern nephron progenitor-specific expression in response to binding to Six2. Together, our results suggest a possible mechanism through which the functional specificity of Brg1-BAFs and Eya1-Six2 in cell cycle regulation and self-renewal of the nephron progenitors may be in part achieved.
2021-10-01 | GSE185050 | GEO
Project description:The regulation of final nephron number in the kidney is poorly understood. However, cessation of nephron formation occurs when the self-renewing nephron progenitor population commits to differentiation. Transcription factors within this progenitor population, such as SIX2, are assumed to control expression of genes promoting self-renewal such that homozygous Six2 deletion results in premature commitment and an early halt to kidney development. In contrast, Six2 heterozygotes were assumed to be unaffected. Using quantitative morphometry, we demonstrate here a paradoxical 18% increase in ureteric branching and final nephron number in Six2 heterozygotes, despite evidence for reduced levels of SIX2 protein and transcript. This is accompanied by a clear shift in nephron progenitor identity with a distinct subset of progenitor genes, including Cited1 and Meox1, downregulated, while others were unaffected. The net result was an increase in nephron progenitor proliferation, as assessed by elevated EDU labelling, an increase in MYC protein and transcriptional upregulation of MYC target genes. Reducing proliferation by introducing Six2 heterozygosity onto the Fgf20-/- background resulted in premature differentiation of the progenitor population. Overall, this data demonstrates a unique dose response of the nephron progenitors to the level of SIX2 protein in which the role of SIX2 in progenitor proliferation versus self-renewal is separable.
2017-12-31 | GSE103219 | GEO
Project description:Identification of the gene targets of the SIX transcription factors in myogenic stem cells and in whole back muscles during murine fetal development Pax7 expression marks stem cells in developing skeletal muscles and adult satellite cells during homeostasis and muscle regeneration. The genetic determinants that control the entrance into the myogenic program and the appearance of PAX7+ cells during embryogenesis are poorly understood. SIX homeoproteins are encoded by the Sine oculis homeobox related Six1-Six6 genes in vertebrates. Six1, Six2, Six4 and Six5 are expressed in the muscle lineage. Here we tested the hypothesis that Six1 and Six4 could participate in the genesis of myogenic stem cells. We show that fewer PAX7+ cells occupy a satellite cell position between the myofiber and its associated basal lamina in Six1 and Six4 (s1s4KO) at E18. However, PAX7+ cells are detected in remaining muscle masses present in the epaxial region of the double mutant embryos and are able to divide and contribute to muscle growth. To further characterize the properties of s1s4KO PAX7+ cells, we analyzed their transcriptome and tested their properties after transplantation in adult regenerating tibialis anterior (TA) muscle. Mutant stem cells form hypotrophic myofibers that are not innervated but retain the ability to self-renew.
2020-10-07 | GSE159079 | GEO