| 1. |
- Tomic, Tajana Tesan, et al.
(författare)
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MYO5B mutations in pheochromocytoma/paraganglioma promote cancer progression
- 2020
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Ingår i: PLOS Genetics. - : Public Library of Science. - 1553-7390 .- 1553-7404. ; 16:6
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Tidskriftsartikel (refereegranskat)abstract
- Identification of additional cancer-associated genes and secondary mutations driving the metastatic progression in pheochromocytoma and paraganglioma (PPGL) is important for subtyping, and may provide optimization of therapeutic regimens. We recently reported novel recurrent nonsynonymous mutations in the MYO5B gene in metastatic PPGL. Here, we explored the functional impact of these MYO5B mutations, and analyzed MYO5B expression in primary PPGL tumor cases in relation to mutation status. Immunohistochemistry and mRNA expression analysis in 30 PPGL tumors revealed an increased MYO5B expression in metastatic compared to non-metastatic cases. In addition, subcellular localization of MYO5B protein was altered from cytoplasmic to membranous in some metastatic tumors, and the strongest and most abnormal expression pattern was observed in a paraganglioma harboring a somatic MYO5B:p.G1611S mutation. In addition to five previously discovered MYO5B mutations, the present study of 30 PPGL (8 previous and 22 new samples) also revealed two, and hence recurrent, mutations in the gene paralog MYO5A. The three MYO5B missense mutations with the highest prediction scores (p.L587P, p.G1611S and p.R1641C) were selected and functionally validated using site directed mutagenesis and stable transfection into human neuroblastoma cells (SK-N-AS) and embryonic kidney cells (HEK293). In vitro analysis showed a significant increased proliferation rate in all three MYO5B mutated clones. The two somatically derived mutations, p.L587P and p.G1611S, were also found to increase the migration rate. Expression analysis of MYO5B mutants compared to wild type clones, demonstrated a significant enrichment of genes involved in migration, proliferation, cell adhesion, glucose metabolism, and cellular homeostasis. Our study validates the functional role of novel MYO5B mutations in proliferation and migration, and suggest the MYO5-pathway to be involved in the malignant progression in some PPGL tumors. © 2020 Tomic et al.
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| 2. |
- Basu, Swaraj, et al.
(författare)
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Accurate mapping of mitochondrial DNA deletions and duplications using deep sequencing
- 2020
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:12
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Tidskriftsartikel (refereegranskat)abstract
- Deletions and duplications in mitochondrial DNA (mtDNA) cause mitochondrial disease and accumulate in conditions such as cancer and age-related disorders, but validated high-throughput methodology that can readily detect and discriminate between these two types of events is lacking. Here we establish a computational method, MitoSAlt, for accurate identification, quantification and visualization of mtDNA deletions and duplications from genomic sequencing data. Our method was tested on simulated sequencing reads and human patient samples with single deletions and duplications to verify its accuracy. Application to mouse models of mtDNA maintenance disease demonstrated the ability to detect deletions and duplications even at low levels of heteroplasmy. Author summary Deletions in the mitochondrial genome cause a wide variety of rare disorders, but are also linked to more common conditions such as neurodegeneration, diabetes type 2, and the normal ageing process. There is also a growing awareness that mtDNA duplications, which are also relevant for human disease, may be more common than previously thought. Despite their clinical importance, our current knowledge about the abundance, characteristics and diversity of mtDNA deletions and duplications is fragmented, and based to large extent on a limited view provided by traditional low-throughput analyses. Here, we describe a bioinformatics method, MitoSAlt, that can accurately map and classify mtDNA deletions and duplications using high-throughput sequencing. Application of this methodology to mouse models of mitochondrial deficiencies revealed a large number of duplications, suggesting that these may previously have been underestimated.
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| 3. |
- Busayavalasa, Kiran, et al.
(författare)
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Leveraging a gain-of-function allele of Caenorhabditis elegans paqr-1 to elucidate membrane homeostasis by PAQR proteins
- 2020
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Ingår i: Plos Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:8
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Tidskriftsartikel (refereegranskat)abstract
- TheC.elegansproteins PAQR-2 (a homolog of the human seven-transmembrane domain AdipoR1 and AdipoR2 proteins) and IGLR-2 (a homolog of the mammalian LRIG proteins characterized by a single transmembrane domain and the presence of immunoglobulin domains and leucine-rich repeats in their extracellular portion) form a complex that protects against plasma membrane rigidification by promoting the expression of fatty acid desaturases and the incorporation of polyunsaturated fatty acids into phospholipids, hence increasing membrane fluidity. In the present study, we leveraged a novel gain-of-function allele of PAQR-1, a PAQR-2 paralog, to carry out structure-function studies. We found that the transmembrane domains of PAQR-2 are responsible for its functional requirement for IGLR-2, that PAQR-1 does not require IGLR-2 but acts via the same pathway as PAQR-2, and that the divergent N-terminal cytoplasmic domains of the PAQR-1 and PAQR-2 proteins serve a regulatory function and may regulate access to the catalytic site of these proteins. We also show that overexpression of human AdipoR1 or AdipoR2 alone is sufficient to confer increased palmitic acid resistance in HEK293 cells, and thus act in a manner analogous to the PAQR-1 gain-of-function allele. Author summary Cells are enclosed within membranes primarily composed of fat. When membranes contain much saturated fats, they tend to become more rigid, as with butter. Conversely, when membranes are rich in unsaturated fats, they become more fluid, as with vegetable oils. Our goal is to better understand how cells monitor and adjust the composition and properties of their membranes. We focus on a small group of proteins found in all animals, and called AdipoR1 and AdipoR2 in humans, and PAQR-1 and PAQR-2 in the wormCaenorhabditis elegans. We now found a version of PAQR-1 that is more "active", and promotes increased levels of unsaturated fats in membranes. By swapping different parts of the PAQR-1 protein with those of PAQR-2, we were able to determine which protein parts played which roles. We found that it is the transmembrane domains of PAQR-2 that dictate its requirements for another protein called IGLR-2 and that the intracellular domains of PAQR-1 and PAQR-2 play a regulatory role. These studies help understand how AdipoR1 and AdipoR2 regulate membrane composition in human cells, which is a vital function for us to thrive on diets that vary greatly in the types of fats that they contain.
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| 4. |
- Fujiwara, Yasuhiro, et al.
(författare)
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Meiotic cohesins mediate initial loading of HORMAD1 to the chromosomes and coordinate SC formation during meiotic prophase.
- 2020
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:9
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Tidskriftsartikel (refereegranskat)abstract
- During meiotic prophase, sister chromatids are organized into axial element (AE), which underlies the structural framework for the meiotic events such as meiotic recombination and homolog synapsis. HORMA domain-containing proteins (HORMADs) localize along AE and play critical roles in the regulation of those meiotic events. Organization of AE is attributed to two groups of proteins: meiotic cohesins REC8 and RAD21L; and AE components SYCP2 and SYCP3. It has been elusive how these chromosome structural proteins contribute to the chromatin loading of HORMADs prior to AE formation. Here we newly generated Sycp2 null mice and showed that initial chromatin loading of HORMAD1 was mediated by meiotic cohesins prior to AE formation. HORMAD1 interacted not only with the AE components SYCP2 and SYCP3 but also with meiotic cohesins. Notably, HORMAD1 interacted with meiotic cohesins even in Sycp2-KO, and localized along cohesin axial cores independently of the AE components SYCP2 and SYCP3. Hormad1/Rad21L-double knockout (dKO) showed more severe defects in the formation of synaptonemal complex (SC) compared to Hormad1-KO or Rad21L-KO. Intriguingly, Hormad1/Rec8-dKO but not Hormad1/Rad21L-dKO showed precocious separation of sister chromatid axis. These findings suggest that meiotic cohesins REC8 and RAD21L mediate chromatin loading and the mode of action of HORMAD1 for synapsis during early meiotic prophase.
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| 5. |
- Liu, Qian, et al.
(författare)
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Yeast mismatch repair components are required for stable inheritance of gene silencing
- 2020
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Ingår i: Plos Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:5
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Tidskriftsartikel (refereegranskat)abstract
- Alterations in epigenetic silencing have been associated with ageing and tumour formation. Although substantial efforts have been made towards understanding the mechanisms of gene silencing, novel regulators in this process remain to be identified. To systematically search for components governing epigenetic silencing, we developed a genome-wide silencing screen for yeast (Saccharomyces cerevisiae) silent mating type locus HMR. Unexpectedly, the screen identified the mismatch repair (MMR) components Pms1, Mlh1, and Msh2 as being required for silencing at this locus. We further found that the identified genes were also required for proper silencing in telomeres. More intriguingly, the MMR mutants caused a redistribution of Sir2 deacetylase, from silent mating type loci and telomeres to rDNA regions. As a consequence, acetylation levels at histone positions H3K14, H3K56, and H4K16 were increased at silent mating type loci and telomeres but were decreased in rDNA regions. Moreover, knockdown of MMR components in human HEK293T cells increased subtelomeric DUX4 gene expression. Our work reveals that MMR components are required for stable inheritance of gene silencing patterns and establishes a link between the MMR machinery and the control of epigenetic silencing. Author summary During aging, gene silencing also decreases and it has been hypothesized that the collapse of epigenetic control networks may in part explain age-related diseases. For example, changes in epigenetic silencing are linked with different stages of tumor formation and progression. Great efforts have been made on investigating the mechanisms of establishment and maintenance silencing at silent mating cassettes in yeast. In this work, by applying a genome-wide silencing screening approach, we identified the conserved subunits of the mismatch repair (MMR) machinery (Pms1, Mlh1 and Msh2) as new components of the epigenetic silencing regulation machinery in yeast. We also found that depletion of mismatch repair subunits (Mlh1 and Msh2) led to impaired telomere-length related expression in mammalian cells. This indicates that these components probably have an evolutionarily conserved role on influencing gene silencing from yeast to humans. Further studies the functional roles of these MMR components on epigenetic silencing in mammalian model systems or relevant cancer patient samples will increase our understanding of MMR-related oncogenesis.
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| 6. |
- Vogelezang, Suzanne, et al.
(författare)
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Novel loci for childhood body mass index and shared heritability with adult cardiometabolic traits.
- 2020
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:10
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Tidskriftsartikel (refereegranskat)abstract
- The genetic background of childhood body mass index (BMI), and the extent to which the well-known associations of childhood BMI with adult diseases are explained by shared genetic factors, are largely unknown. We performed a genome-wide association study meta-analysis of BMI in 61,111 children aged between 2 and 10 years. Twenty-five independent loci reached genome-wide significance in the combined discovery and replication analyses. Two of these, located near NEDD4L and SLC45A3, have not previously been reported in relation to either childhood or adult BMI. Positive genetic correlations of childhood BMI with birth weight and adult BMI, waist-to-hip ratio, diastolic blood pressure and type 2 diabetes were detected (Rg ranging from 0.11 to 0.76, P-values <0.002). A negative genetic correlation of childhood BMI with age at menarche was observed. Our results suggest that the biological processes underlying childhood BMI largely, but not completely, overlap with those underlying adult BMI. The well-known observational associations of BMI in childhood with cardio-metabolic diseases in adulthood may reflect partial genetic overlap, but in light of previous evidence, it is also likely that they are explained through phenotypic continuity of BMI from childhood into adulthood.
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