Deep mutational scanning quantifies DNA binding and predicts clinical outcomes of PAX6 variants
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ABSTRACT:
PROVIDER: PRJNA1066311 | ENA |
REPOSITORIES: ENA
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Project description:Nonsense and missense mutations in the transcription factor PAX6 cause a wide range of eye development defects, including aniridia, microphthalmia and coloboma. To understand how changes of PAX6:DNA binding cause these phenotypes, we combined saturation mutagenesis of the paired domain of PAX6 with a yeast one-hybrid (Y1H) assay in which expression of a PAX6-GAL4 fusion gene drives antibiotic resistance. We quantified binding of more than 2,700 single amino-acid variants to two DNA sequence elements. Mutations in DNA-facing residues of the N-terminal subdomain and linker region were most detrimental, as were mutations to prolines and to negatively charged residues. Many variants caused sequence-specific molecular gain-of-function effects, including variants in position Ile71 that increased binding to the LE9 enhancer but decreased binding to a SELEX-derived binding site. In the absence of antibiotic selection, variants that retained DNA binding slowed yeast growth, likely because such variants perturbed the yeast transcriptome. Benchmarking against known patient variants and applying ACMG/AMP guidelines to variant classification, we obtained supporting to moderate evidence to suggest that 1,306 variants are likely benign, and 977, likely pathogenic. Our analysis shows that most pathogenic mutations in the paired domain of PAX6 can be explained simply by the effects of these mutations on PAX6:DNA association, and establishes Y1H as a generalisable assay for the interpretation of variant effects in transcription factors.
2024-03-21 | GSE253580 | GEO
Project description:Mutations in the transcription factor PAX6 cause eye development defects, including aniridia, microphthalmia and coloboma. To understand the molecular mechanisms, we combined saturation mutagenesis of the paired domain of PAX6 with a yeast one-hybrid (Y1H) assay in which expression of a PAX6-GAL4 fusion gene drives antibiotic resistance. We quantified binding of more than 2,700 single amino-acid variants to two DNA sequence elements. Mutations in DNA-facing residues of the N-terminal subdomain and linker region were most detrimental, as were mutations to prolines and to negatively charged residues. Some variants, including Ile71Tyr, increased binding to one of the DNA elements. In the absence of antibiotic selection, variants that retained DNA binding slowed yeast growth, likely because such variants perturbed the yeast transcriptome. Benchmarking against known patient variants, we obtained supporting-to-moderate evidence that 977 variants are likely pathogenic and 1,306 are likely benign. Our analysis shows that most pathogenic mutations in PAX6 can be explained by effects on PAX6:DNA association, and establishes Y1H as a generalisable assay for the interpretation of variant effects in transcription factors.
| S-SCDT-10_1038-S44320-024-00043-8 | biostudies-other
Project description:Nonsense and missense mutations in the transcription factor PAX6 cause a wide range of eye development defects, including aniridia, microphthalmia and coloboma. To understand how changes of PAX6:DNA binding cause these phenotypes, we combined saturation mutagenesis of the paired domain of PAX6 with a yeast one-hybrid (Y1H) assay in which expression of a PAX6-GAL4 fusion gene drives antibiotic resistance. We quantified binding of more than 2700 single amino-acid variants to two DNA sequence elements. Mutations in DNA-facing residues of the N-terminal subdomain and linker region were most detrimental, as were mutations to prolines and to negatively charged residues. Many variants caused sequence-specific molecular gain-of-function effects, including variants in position 71 that increased binding to the LE9 enhancer but decreased binding to a SELEX-derived binding site. In the absence of antibiotic selection, variants that retained DNA binding slowed yeast growth, likely because such variants perturbed the yeast transcriptome. Benchmarking against known patient variants and applying ACMG/AMP guidelines to variant classification, we obtained supporting-to-moderate evidence that 977 variants are likely pathogenic and 1306 are likely benign. Our analysis shows that most pathogenic mutations in the paired domain of PAX6 can be explained simply by the effects of these mutations on PAX6:DNA association, and establishes Y1H as a generalisable assay for the interpretation of variant effects in transcription factors.
| S-EPMC11219921 | biostudies-literature
Project description:Despite the importance of Aβ aggregation in Alzheimer’s disease etiology, our understanding of the sequence determinants of aggregation is sparse and largely derived from in vitro studies. For example, in vitro proline and alanine scanning mutagenesis of Aβ40 proposed core regions important for aggregation. However, we lack even this limited mutagenesis data for the more disease-relevant Aβ42. Thus, to better understand the molecular determinants of Aβ42 aggregation in a cell-based system, we combined a yeast DHFR aggregation assay with deep mutational scanning. We measured the effect of 791 of the 798 possible single amino acid substitutions on the aggregation propensity of Aβ42. We found that ~75% of substitutions, largely to hydrophobic residues, maintained or increased aggregation. We identified 11 positions at which substitutions, particularly to hydrophilic and charged amino acids, disrupted Aβ aggregation. These critical positions were similar but not identical to critical positions identified in previous Aβ mutagenesis studies. Finally, we analyzed our large-scale mutagenesis data in the context of different Aβ aggregate structural models, finding that the mutagenesis data agreed best with models derived from fibrils seeded using brain-derived Aβ aggregates.
2019-10-21 | GSE139122 | GEO
Project description:Deep mutational scanning is a powerful method for exploring the mutational fitness landscape of proteins. Its adaptation to anti-CRISPR proteins, which are natural CRISPR-Cas inhibitors and key players in the co-evolution of microbes and phages, facilitates their characterization and optimization. Here, we developed a robust anti-CRISPR deep mutational scanning pipeline in Escherichia coli that combines synthetic gene circuits based on CRISPR interference with flow cytometry coupled sequencing and mathematical modeling. Using this pipeline, we characterized comprehensive single point mutation libraries for AcrIIA4 and AcrIIA5, two potent inhibitors of CRISPR-Cas9. The resulting mutational fitness landscapes revealed considerable mutational tolerance for both Acrs, suggesting an intrinsic redundancy with respect to Cas9 inhibitory features, and – for AcrIIA5 – indicated mutations that boost Cas9 inhibition. Subsequent in vitro characterization suggested that the observed differences in inhibitory potency between mutant inhibitors were mostly due to changes in binding affinity rather than protein expression levels. Finally, to demonstrate that our pipeline can inform Acrs-based genome editing applications, we employed a selected subset of mutant inhibitors to increase CRISPR-Cas9 target specificity by modulating Cas9 activity. Taken together, our work establishes deep mutational scanning as a powerful method for anti-CRISPR protein characterization and optimization.
2024-03-01 | GSE254101 | GEO
Project description:Pax6 is a transcription factor with key functional roles in embryonic development. In order to identify downstream effectors of Pax6 in the developing cerebral cortex we performed microarray analysis. We compared gene expression profiles of cortical tissues isolated from wild type and Pax6-/- mouse embryos. In order to identify Pax6 downstream targets we carried out microarray analysis of Pax6-/- mutant mice. Pax6 is highly expressed in the mouse cerebral cortex at embryonic day E14.5, therefore we selected this tissue in order to compare gene expression profiles between wild type and Pax6-/- homozygous cortici. RNA samples were isolated from three mutant and three wild type embryos.
2011-10-31 | E-GEOD-32271 | biostudies-arrayexpress
Project description:Pax6 is a highly conserved transcription factor among vertebrates and is important in various aspects of the central nervous system (CNS) development. However, the gene regulatory circuitry of Pax6 underlying these functions remains elusive. We find that, following expression in neural progenitor cells, Pax6 targets many promoters embedded in an active chromatin environment. Intriguingly, many of these sites are also bound by another progenitor factor, Sox2, which cooperates with Pax6 in gene regulation. A combinatorial analysis of Pax6 binding dataset with transcriptome changes in Pax6-deficient neural progenitors reveals a dual role for Pax6, in which it activates the neuronal (ectodermal) genes while concurrently represses the mesodermal and endodermal genes thereby ensuring the unidirectionality of lineage commitment towards glutamatergic neuronal differentiation. Furthermore, Pax6 is critical for inducing activity of transcription factors that elicit neurogenesis and repress others that promote non-neuronal lineages. In addition to many established downstream effectors, Pax6 directly binds and activates a number of genes that are specifically expressed in neural progenitors but have not been previously implicated in neurogenesis. The in utero knockdown of one such gene, Ift74, during brain development impairs polarity and migration of new-born neurons. These findings demonstrate new aspects of the gene regulatory circuitry of Pax6, revealing how it functions to control neuronal development at multiple levels to ensure unidirectionality and proper execution of the neurogenic program.
2016-05-02 | GSE75255 | GEO
Project description:Novel target genes for the two transcription factor isoforms Pax6 and Pax6(5a) were identified by generating mouse embryonic fibroblast cell lines stably expressing either Pax6 or Pax6(5a), and comparing their gene expression pattern with the original mouse embryonic fibroblast cell line. Flp-In-3T3 cell lines were generated according to the manufacturers instruction (Invitrogen), using the mouse Pax6 and Pax6(5a) cDNA as insert. Correct inserts were verified by PCR, sequencing and Westernblot.
2012-03-22 | E-GEOD-31402 | biostudies-arrayexpress
Project description:Pax6 is a transcription factor with key functional roles in embryonic development. In order to identify downstream effectors of Pax6 in the developing cerebral cortex we performed microarray analysis. We compared gene expression profiles of cortical tissues isolated from wild type and Pax6-/- mouse embryos.
2011-10-31 | GSE32271 | GEO
Project description:Novel target genes for the two transcription factor isoforms Pax6 and Pax6(5a) were identified by generating mouse embryonic fibroblast cell lines stably expressing either Pax6 or Pax6(5a), and comparing their gene expression pattern with the original mouse embryonic fibroblast cell line.
2012-03-22 | GSE31402 | GEO