Project description:DNA replication stress is a threat to genome integrity. The large SNF2-family of ATPases participates in preventing and mitigating DNA replication stress by employing their ATP-driven motor to remodel DNA or DNA-bound proteins. To understand the contribution of these ATPases in genome maintenance, we undertook CRISPR-based synthetic lethality screens with three SNF2-type ATPases: SMARCAL1, ZRANB3 and HLTF. Here we show that SMARCAL1 displays a profound synthetic lethal interaction with FANCM, another ATP-dependent translocase involved in DNA replication and genome stability. Their combined loss causes severe genome instability that we link to chromosome breakage at loci enriched in simple repeats, which are known to challenge replication fork progression. Our findings illuminate a critical genetic buffering mechanism that provides an essential function for maintaining genome integrity.
Project description:DNA replication stress is a threat to genome integrity. The large SNF2-family of ATPases participates in preventing and mitigating DNA replication stress by employing their ATP-driven motor to remodel DNA or DNA-bound proteins. To understand the contribution of these ATPases in genome maintenance, we undertook CRISPR-based synthetic lethality screens with three SNF2-type ATPases: SMARCAL1, ZRANB3 and HLTF. Here we show that SMARCAL1 displays a profound synthetic lethal interaction with FANCM, another ATP-dependent translocase involved in DNA replication and genome stability. Their combined loss causes severe genome instability that we link to chromosome breakage at loci enriched in simple repeats, which are known to challenge replication fork progression. Our findings illuminate a critical genetic buffering mechanism that provides an essential function for maintaining genome integrity.
Project description:DNA replication stress is a threat to genome integrity. The large SNF2-family of ATPases participates in preventing and mitigating DNA replication stress by employing their ATP-driven motor to remodel DNA or DNA-bound proteins. To understand the contribution of these ATPases in genome maintenance, we undertook CRISPR-based synthetic lethality screens with three SNF2-type ATPases: SMARCAL1, ZRANB3 and HLTF. Here we show that SMARCAL1 displays a profound synthetic lethal interaction with FANCM, another ATP-dependent translocase involved in DNA replication and genome stability. Their combined loss causes severe genome instability that we link to chromosome breakage at loci enriched in simple repeats, which are known to challenge replication fork progression. Our findings illuminate a critical genetic buffering mechanism that provides an essential function for maintaining genome integrity.
Project description:This SuperSeries is composed of the following subset Series: GSE35551: Penetrance of biallelic SMARCAL1 mutations is associated with environmental and genetic disturbances of gene expression (1) GSE35552: Penetrance of biallelic SMARCAL1 mutations is associated with environmental and genetic disturbances of gene expression (2) GSE35553: Penetrance of biallelic SMARCAL1 mutations is associated with environmental and genetic disturbances of gene expression (3) Refer to individual Series
Project description:SMARCAL1 is a chromatin regulator. Biallelic mutations of SMARCAL1 cause Schimke Immunoosseous Dysplasia (SIOD), a disease with severe growth defects and premature death. Atherosclerosis and hyperlipidemia are common phenotypes among SIOD patients. However, little is known about their genesis and development. Here we show that SMARCAL1 is vital in regulating cellular lipid metabolism. Using a proteomic approach, we found that SmarcAL1 interacts with angiopoietin-like 3 (Angptl3), a key lipoprotein regulator. SmarcAL1 deficiency in cell models resulted in substantial accumulation of triglycerides (TGs) and fatty acids (FAs). SmarcAL1 KO in mice drastically increased plasma TG level. The nuclear SmarcAL1 translocates into cytoplasm, surprisingly, enriched at peroxisomes, where it interacts with Angptl3. This shuttling provides a regulatory control over cellular lipid metabolism via SmarcAL1-regulated gene expression, in response to cell growth states. Inactivation of SmarcAL1 gene reduced the expression of the genes responsible for FA metabolism, suggesting that SmarcAL1 plays a key role in regulating lipid metabolism. Indeed, the Angptl3-mediated TG partition is largely dependent on SmarcAL1 activity. This activity was further supported by two opposite SMARCAL1 single-tissue expression profiles linked to two quantitative trait loci that are differentially associated with body mass index. Thus, SMARCAL1 is crucial for cellular lipid metabolism, and ANGPTL3-regulated SMARCAL1 activities enable cells to response to cell growth states for TG storage or expenditure.
Project description:Biallelic mutations of the DNA annealing helicase SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1) cause Schimke immuno-osseous dysplasia (SIOD, MIM 242900), an incompletely penetrant autosomal recessive disorder. Using human, Drosophila, and mouse models, we show that the proteins encoded by SMARCAL1 orthologues localize to transcriptionally active chromatin and modulate gene expression. We also show that similar to SIOD patients, deficiency of the SMARCAL1 orthologues alone is insufficient to cause disease in fruit flies and mice although such deficiency causes modest diffuse alterations in gene expression. Rather, disease manifests when SMARCAL1 deficiency interacts with genetic and environmental factors that further alter gene expression. We conclude that the SMARCAL1 annealing helicase buffers fluctuations in gene expression and that alterations in gene expression contribute to the penetrance of SIOD. For analysis of gene expression in primary cultured human dermal fibroblasts, 5.0 μg of total RNA from three biologically independent replicates was extracted from two SIOD (SD8 and SD60) and a control skin fibroblast cell lines, labeled and hybridized to Affymetrix Human Genome U133 Plus 2.0 Arrays.
Project description:Biallelic mutations of the DNA annealing helicase SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1) cause Schimke immuno-osseous dysplasia (SIOD, MIM 242900), an incompletely penetrant autosomal recessive disorder. Using human, Drosophila, and mouse models, we show that the proteins encoded by SMARCAL1 orthologues localize to transcriptionally active chromatin and modulate gene expression. We also show that similar to SIOD patients, deficiency of the SMARCAL1 orthologues alone is insufficient to cause disease in fruit flies and mice although such deficiency causes modest diffuse alterations in gene expression. Rather, disease manifests when SMARCAL1 deficiency interacts with genetic and environmental factors that further alter gene expression. We conclude that the SMARCAL1 annealing helicase buffers fluctuations in gene expression and that alterations in gene expression contribute to the penetrance of SIOD. The RNA sequencing libraries were constructed from the liver RNA of 3-4-month Smarcal1del/del and wt female mice (n=3/group) at 20M-BM-0C and after 1 hour at 39.5M-BM-0C. These libraries were sequenced using the whole transcriptome shotgun sequencing procedure.
Project description:Biallelic mutations of the DNA annealing helicase SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1) cause Schimke immuno-osseous dysplasia (SIOD, MIM 242900), an incompletely penetrant autosomal recessive disorder. Using human, Drosophila, and mouse models, we show that the proteins encoded by SMARCAL1 orthologues localize to transcriptionally active chromatin and modulate gene expression. We also show that similar to SIOD patients, deficiency of the SMARCAL1 orthologues alone is insufficient to cause disease in fruit flies and mice although such deficiency causes modest diffuse alterations in gene expression. Rather, disease manifests when SMARCAL1 deficiency interacts with genetic and environmental factors that further alter gene expression. We conclude that the SMARCAL1 annealing helicase buffers fluctuations in gene expression and that alterations in gene expression contribute to the penetrance of SIOD. For analysis of gene expression in flies, 5.0 ?g of total RNA from three biologically independent replicates was extracted from 1) yw, 2) Marcal1del/del, 3) RpII2154/FM7, and 4) RpII2154/FM7;Marcal1del/del ovaries at 20°C and from yw and Marcal1del/del at 25°C, labeled and hybridized to Affymetrix Drosophila Genome 2.0 arrays.