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Mutational analysis of Rap1 reveals specific vulnerability for long telomeres fusions

ABSTRACT: The conserved Rap1 protein is part of the shelterin complex that plays critical roles in chromosome end protection and telomere length homeostasis. Previous studies addressed how fission yeast Rap1 contributes to telomere length maintenance, but the mechanism by which the protein inhibits end fusions has remained elusive. Here, we use a genetic screen in combination with high throughput sequencing to identify several amino acid positions in Rap1 that have a key role in end protection. Interestingly, mutations at these sites render cells susceptible to genome instability in a conditional manner with longer telomeres being prone to undergoing end fusions, while short telomeres are sufficiently protected. The protection of long telomeres requires their nuclear envelope attachment mediated by the Rap1-Bqt4 interaction. Our data demonstrates that longer telomeres pose an additional challenge for the maintenance of genome integrity and provides an explanation for a species-specific upper limit in telomere length.

ORGANISM(S): Escherichia coli Schizosaccharomyces pombe

PROVIDER: GSE190759 | GEO | 2022/08/10

REPOSITORIES: GEO

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ZNF524 directly binds telomeres and supports their integrity via TRF2/RAP1

Project description:Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex consists of six proteins (TRF1, TRF2, RAP1, POT1, TPP1 and TIN2) and blocks unwanted DNA damage repair at telomeres, e.g. by suppressing non-homologous end joining (NHEJ) through its subunit TRF2. While shelterin does not work autonomously, additional direct telomere binding proteins have been described to function in a supplementary role. We here describe ZNF524, a zinc finger protein that directly binds to telomeric repeats with nanomolar affinity and reveal the base-specific sequence recognition by co-crystallization with telomeric DNA. ZNF524 localizes to telomeres and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting the other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, we identified ZNF524 as a direct telomere binding protein and propose that ZNF524 is involved in the maintenance of telomere integrity by promoting TRF2/RAP1 subcomplex binding.

2023-10-22 | PXD031416 | Pride

ZNF524 directly binds telomeres and supports their integrity via TRF2/RAP1

2023-10-21 | PXD024630 | Pride

A genetic interaction between RAP1 and telomerase reveals an unanticipated role for RAP1 in telomere protection

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2023-10-21 | PXD043084 | Pride

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Project description:Telomeres are nucleoprotein structures at the ends of linear chromosomes. In humans, they consist of TTAGGG repeats, which are bound by dedicated proteins such as the shelterin complex. This complex blocks unwanted DNA damage repair at telomeres, e.g. by suppressing non-homologous end joining (NHEJ) through its subunit TRF2. We here describe ZNF524, a zinc finger protein that directly binds telomeric repeats with nanomolar affinity and reveal the base-specific sequence recognition by co-crystallization with telomeric DNA. ZNF524 localizes to telomeres in vivo, as shown among other approaches by ChIP-seq analysis, and specifically maintains the presence of the TRF2/RAP1 subcomplex at telomeres without affecting the other shelterin members. Loss of ZNF524 concomitantly results in an increase in DNA damage signaling and recombination events. Overall, ZNF524 is a direct telomere-binding protein involved in the maintenance of telomere integrity.

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2019-11-25 | PXD014843 | Pride

RAP1 protects from obesity, diabetes and metabolic syndrome through its extra telomeric role regulating gene expression (old mouse liver)

Project description:RAP1 is one of the components of shelterin, the capping complex at chromosome ends or telomeres. Unlike other shelterins, however, RAP1 is not essential for preventing telomere fusions. RAP1 also binds along chromosome arms, where it is proposed to regulate gene expression. To investigate the non-telomeric roles of RAP1 in vivo, we generated a RAP1 whole-body knock-out mouse model. Unexpectedly, these mice presented an early onset of obesity, which was particularly severe in females and was aggravated under a high-fat diet. Rap1-deficient mice showed abnormal accumulation of fat in abdominal depots and developed signs of type II diabetes and metabolic syndrome, including hepatic steatosis and high fasting plasma levels of insulin, glucose, cholesterol, and alanine transaminase. Gene expression analyses of the liver and visceral white fat from Rap1-deficient mice before the onset of obesity indicated deregulation of key metabolic transcriptional programs including fatty acid metabolism, PPARa signalling and glucose metabolism. Transcriptome and Western blotting analyses in liver further identified Ppara and Pgc1a and their target genes as the key metabolic pathways affected by Rap1 deletion. Finally, we show here that RAP1 binds to Ppara and Pgc1a loci and modulates their transcription. These findings underscore an unprecedented role for a telomere-binding protein in the regulation of metabolism. 2 condition experiment: WT versus Rap1 knockout. Tissue: liver. 3 biological replicates per genotype. Mice were 30 weeks old.

2013-06-21 | E-GEOD-43173 | biostudies-arrayexpress

RAP1 protects from obesity, diabetes and metabolic syndrome through its extra telomeric role regulating gene expression (young mouse liver)

Project description:RAP1 is one of the components of shelterin, the capping complex at chromosome ends or telomeres. Unlike other shelterins, however, RAP1 is not essential for preventing telomere fusions. RAP1 also binds along chromosome arms, where it is proposed to regulate gene expression. To investigate the non-telomeric roles of RAP1 in vivo, we generated a RAP1 whole-body knock-out mouse model. Unexpectedly, these mice presented an early onset of obesity, which was particularly severe in females and was aggravated under a high-fat diet. Rap1-deficient mice showed abnormal accumulation of fat in abdominal depots and developed signs of type II diabetes and metabolic syndrome, including hepatic steatosis and high fasting plasma levels of insulin, glucose, cholesterol, and alanine transaminase. Gene expression analyses of the liver and visceral white fat from Rap1-deficient mice before the onset of obesity indicated deregulation of key metabolic transcriptional programs including fatty acid metabolism, PPARa signalling and glucose metabolism. Transcriptome and Western blotting analyses in liver further identified Ppara and Pgc1a and their target genes as the key metabolic pathways affected by Rap1 deletion. Finally, we show here that RAP1 binds to Ppara and Pgc1a loci and modulates their transcription. These findings underscore an unprecedented role for a telomere-binding protein in the regulation of metabolism. 2 condition experiment: WT versus Rap1 knockout. Tissue: liver. 4 biological replicates per genotype. Mice were 10 weeks old.

2013-06-21 | E-GEOD-43171 | biostudies-arrayexpress

RAP1 protects from obesity, diabetes and metabolic syndrome through its extra telomeric role regulating gene expression (young mouse white fat)

Project description:RAP1 is one of the components of shelterin, the capping complex at chromosome ends or telomeres. Unlike other shelterins, however, RAP1 is not essential for preventing telomere fusions. RAP1 also binds along chromosome arms, where it is proposed to regulate gene expression. To investigate the non-telomeric roles of RAP1 in vivo, we generated a RAP1 whole-body knock-out mouse model. Unexpectedly, these mice presented an early onset of obesity, which was particularly severe in females and was aggravated under a high-fat diet. Rap1-deficient mice showed abnormal accumulation of fat in abdominal depots and developed signs of type II diabetes and metabolic syndrome, including hepatic steatosis and high fasting plasma levels of insulin, glucose, cholesterol, and alanine transaminase. Gene expression analyses of the liver and visceral white fat from Rap1-deficient mice before the onset of obesity indicated deregulation of key metabolic transcriptional programs including fatty acid metabolism, PPARa signalling and glucose metabolism. Transcriptome and Western blotting analyses in liver further identified Ppara and Pgc1a and their target genes as the key metabolic pathways affected by Rap1 deletion. Finally, we show here that RAP1 binds to Ppara and Pgc1a loci and modulates their transcription. These findings underscore an unprecedented role for a telomere-binding protein in the regulation of metabolism. 2 condition experiment: WT versus Rap1 knockout. Tissue: white gonadal fat. 4 biological replicates per genotype. Mice were 10 weeks old.

2013-06-21 | E-GEOD-43172 | biostudies-arrayexpress

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2017-05-11 | PXD006074 | Pride

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