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David Cortez - One of the best experts on this subject based on the ideXlab platform.
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functions of SMARCAL1 zranb3 and hltf in maintaining genome stability
Critical Reviews in Biochemistry and Molecular Biology, 2017Co-Authors: Lisa A. Poole, David CortezAbstract:A large number of SNF2 family, DNA and ATP-dependent motor proteins are needed during transcription, DNA replication, and DNA repair to manipulate protein–DNA interactions and change DNA structure....
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Functions of SMARCAL1, ZRANB3, and HLTF in maintaining genome stability.
Critical reviews in biochemistry and molecular biology, 2017Co-Authors: Lisa A. Poole, David CortezAbstract:A large number of SNF2 family, DNA and ATP-dependent motor proteins are needed during transcription, DNA replication, and DNA repair to manipulate protein-DNA interactions and change DNA structure. SMARCAL1, ZRANB3, and HLTF are three related members of this family with specialized functions that maintain genome stability during DNA replication. These proteins are recruited to replication forks through protein-protein interactions and bind DNA using both their motor and substrate recognition domains (SRDs). The SRD provides specificity to DNA structures like forks and junctions and confers DNA remodeling activity to the motor domains. Remodeling reactions include fork reversal and branch migration to promote fork stabilization, template switching, and repair. Regulation ensures these powerful activities remain controlled and restricted to damaged replication forks. Inherited mutations in SMARCAL1 cause a severe developmental disorder and mutations in ZRANB3 and HLTF are linked to cancer illustrating the importance of these enzymes in ensuring complete and accurate DNA replication. In this review, we examine how these proteins function, concentrating on their common and unique attributes and regulatory mechanisms.
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SMARCAL1 and telomeres: Replicating the troublesome ends.
Nucleus (Austin Tex.), 2016Co-Authors: Lisa A. Poole, David CortezAbstract:ABSTRACTDNA replication is constantly challenged by both endogenous and exogenous sources of replication stress. SMARCAL1, an SNF2 family DNA translocase, functions in the DNA damage response to address these obstacles and promote the completion of replication. Most studies examining the function of SMARCAL1 and related enzymes have relied on the addition of exogenous genotoxic agents, but SMARCAL1 is needed even in the absence of these drugs to maintain genome stability during DNA replication. We recently determined that SMARCAL1 functions to limit DNA damage during replication of difficult-to-replicate telomere sequences. SMARCAL1-deficient cells display several markers of telomere instability including extrachromosomal telomere circles and co-localization with DNA damage markers. Furthermore, cells lacking the highly related proteins ZRANB3 and HLTF do not exhibit similar problems suggesting a unique function for SMARCAL1. These studies identified the first source of endogenous replication stress that ...
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identification of a substrate recognition domain in the replication stress response protein zinc finger ran binding domain containing protein 3 zranb3
Journal of Biological Chemistry, 2016Co-Authors: Akosua Badunkansah, Brandt F. Eichman, Aaron C. Mason, David CortezAbstract:DNA damage and other forms of replication stress can cause replication forks to stall. Replication stress response proteins stabilize and resolve stalled forks by mechanisms that include fork remodeling to facilitate repair or bypass of damaged templates. Several enzymes including SMARCAL1, HLTF, and ZRANB3 catalyze these reactions. SMARCAL1 and HLTF utilize structurally distinct accessory domains attached to an ATPase motor domain to facilitate DNA binding and catalysis of fork remodeling reactions. Here we describe a substrate recognition domain within ZRANB3 that is needed for it to recognize forked DNA structures, hydrolyze ATP, catalyze fork remodeling, and act as a structure-specific endonuclease. Thus, substrate recognition domains are a common feature of fork remodeling, SNF2-family, DNA-dependent ATPases, and our study provides further mechanistic understanding of how these enzymes maintain genome integrity during DNA replication.
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SMARCAL1 maintains telomere integrity during DNA replication
Proceedings of the National Academy of Sciences of the United States of America, 2015Co-Authors: Lisa A. Poole, Courtney A Lovejoy, Gloria G Glick, Runxiang Zhao, Christine M. Eischen, David CortezAbstract:The SMARCAL1 (SWI/SNF related, matrix-associated, actin-dependent, regulator of chromatin, subfamily A-like 1) DNA translocase is one of several related enzymes, including ZRANB3 (zinc finger, RAN-binding domain containing 3) and HLTF (helicase-like transcription factor), that are recruited to stalled replication forks to promote repair and restart replication. These enzymes can perform similar biochemical reactions such as fork reversal; however, genetic studies indicate they must have unique cellular activities. Here, we present data showing that SMARCAL1 has an important function at telomeres, which present an endogenous source of replication stress. SMARCAL1-deficient cells accumulate telomere-associated DNA damage and have greatly elevated levels of extrachromosomal telomere DNA (C-circles). Although these telomere phenotypes are often found in tumor cells using the alternative lengthening of telomeres (ALT) pathway for telomere elongation, SMARCAL1 deficiency does not yield other ALT phenotypes such as elevated telomere recombination. The activity of SMARCAL1 at telomeres can be separated from its genome-maintenance activity in bulk chromosomal replication because it does not require interaction with replication protein A. Finally, this telomere-maintenance function is not shared by ZRANB3 or HLTF. Our results provide the first identification, to our knowledge, of an endogenous source of replication stress that requires SMARCAL1 for resolution and define differences between members of this class of replication fork-repair enzymes.
Cornelius F. Boerkoel - One of the best experts on this subject based on the ideXlab platform.
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Chromatin changes in SMARCAL1 deficiency: A hypothesis for the gene expression alterations of Schimke immuno-osseous dysplasia.
Nucleus (Austin Tex.), 2016Co-Authors: Marie Morimoto, Kunho Choi, Cornelius F. Boerkoel, Kyoung Sang ChoAbstract:Mutations in SMARCAL1, which encodes a DNA annealing helicase with roles in DNA replication fork restart, DNA repair, and gene expression modulation, cause Schimke immuno-osseous dysplasia (SIOD), an autosomal recessive disease characterized by skeletal dysplasia, renal disease, T-cell immunodeficiency, and arteriosclerosis. The clinical features of SIOD arise from pathological changes in gene expression; however, the underlying mechanism for these gene expression alterations remains unclear. We hypothesized that changes of the epigenome alter gene expression in SIOD. To test this, we performed a genetic screen for interaction between Marcal1, the Drosophila melanogaster ortholog of SMARCAL1, and the genes of the trithorax group (trxG) and Polycomb group (PcG), which encode epigenetic regulators. SMARCAL1 and Marcal1 genetically interacted with trxG and PcG members. A homozygous null mutation of Marcal1 suppressed the wing-to-haltere transformation, ectopic Ultrabithorax (Ubx) expression, and ectopic Ubx minigene expression caused by PcG deficiency. The suppression of ectopic Ubx expression correlated with reduced chromatin accessibility of the Ubx promoter. To our knowledge, this is the first in vivo evidence for deficiency of a SMARCAL1 ortholog altering the chromatin structure of a gene.
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Insights into the renal pathogenesis in Schimke immuno-osseous dysplasia: A renal histological characterization and expression analysis.
The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 2014Co-Authors: Sanjay Sarin, Cornelius F. Boerkoel, Alireza Baradaran-heravi, Ashkan Javidan, Felix J. Boivin, Iakovina Alexopoulou, Dusan Lukic, Bruno Svajger, Stephanie Chu, Norman D. RosenblumAbstract:Schimke immuno-osseous dysplasia (SIOD) is a pleiotropic disorder caused by mutations in the SWI/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like-1 (SMARCAL1) gene, with multiple clinical features, notably end-stage renal disease. Here we characterize the renal pathology in SIOD patients. Our analysis of SIOD patient renal biopsies demonstrates the tip and collapsing variants of focal segmental glomerulosclerosis (FSGS). Additionally, electron microscopy revealed numerous glomerular abnormalities most notably in the podocyte and Bowman's capsule. To better understand the role of SMARCAL1 in the pathogenesis of FSGS, we defined SMARCAL1 expression in the developing and mature kidney. In the developing fetal kidney, SMARCAL1 is expressed in the ureteric epithelium, stroma, metanephric mesenchyme, and in all stages of the developing nephron, including the maturing glomerulus. In postnatal kidneys, SMARCAL1 expression is localized to epithelial tubules of the nephron, collecting ducts, and glomerulus (podocytes and endothelial cells). Interestingly, not all cells within the same lineage expressed SMARCAL1. In renal biopsies from SIOD patients, TUNEL analysis detected marked increases in DNA fragmentation. Our results highlight the cells that may contribute to the renal pathogenesis in SIOD. Further, we suggest that disruptions in genomic integrity during fetal kidney development contribute to the pathogenesis of FSGS in SIOD patients.
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Bone marrow transplantation in Schimke immuno‐osseous dysplasia
American Journal of Medical Genetics Part A, 2013Co-Authors: Alireza Baradaran-heravi, Yumi Asakura, Jonas Lange, Pierre Cochat, Laura Massella, Cornelius F. BoerkoelAbstract:Schimke immuno-osseous dysplasia (SIOD, OMIM 242900) is a rare autosomal recessive multisystem childhood disorder characterized by short stature, renal failure, T-cell immunodeficiency, and hypersensitivity to genotoxic agents. SIOD is associated with biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA stress response enzyme with annealing helicase activity. Two features of SIOD causing much morbidity and mortality are bone marrow failure and T-cell deficiency with the consequent opportunistic infections. To address the safety and efficacy of bone marrow transplantation (BMT) in SIOD, we reviewed the outcomes of the only five SIOD patients known to us in whom bone marrow or hematopoietic stem cell transplantation has been attempted. We find that only one patient survived the transplantation procedure and that the existing indicators of a good prognosis for bone marrow transplantation were not predictive in this small cohort. Given these observations, we also discuss some considerations for the poor outcomes.
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Lack of IL-7 Receptor Alpha Chain (CD127) Expression In T Cells Is a Hallmark of T-Cell Immunodeficiency In Schimke Immuno-Osseous Dysplasia (SIOD)
Blood, 2010Co-Authors: Mrinmoy Sanyal, Cornelius F. Boerkoel, Arend Bökenkamp, Alireza Baradaran-heravi, Benjamin Dekel, Kira Y. Dionis, David B. LewisAbstract:Abstract 2767 Schimke immuno-osseous dysplasia (SIOD) is an autosomal recessive, incompletely penetrant, childhood disorder associated with biallelic loss-of-function mutations of SMARCAL1 (swi/snf-related matrix-associated actin-dependent regulator of chromatin, subfamily-a-like-1) gene. The SMARCAL1 gene encodes for the DNA annealing helicase although it is unknown why this impairment results in skeletal dysplasia, renal dysfunction, and T-cell lymphopenia. The representation of T-cell subsets in SIOD patients is further characterized by a high proportion of memory (CD45RA−CD45RO+) T cells, however, the etiology of T-cell immunodeficiency has not been elucidated. Here, we demonstrate that T cells in individuals affected by SIOD express markedly reduced surface levels of IL-7 receptor alpha chain (CD127) as compared to their unaffected sibling or normal individuals. In contrast, the alpha-chain component of the IL-2 receptor (CD25) was expressed normally. This reduction in IL-7 receptor alpha chain was observed in all T-cell subsets including naive T cells. This suggests that the origin of the IL-7 receptor alpha chain deficiency is likely intrathymic, rather than occurring after emigration to the periphery. In addition, T cells from SIOD patients were less responsive to stimulation with IL-7, indicating a loss of functional receptor. From these observations, we propose the lack of functional IL-7 receptor expression in T cells, and possibly their earlier progenitors, may have restricted T-cell development in SIOD patients. The mechanism for reduced IL-7 receptor expression is currently under investigation. Disclosures: No relevant conflicts of interest to declare.
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SMARCAL1 and replication stress an explanation for siod
Nucleus, 2010Co-Authors: Carol E Bansbach, Cornelius F. Boerkoel, David CortezAbstract:The SNF2 family of ATPases acts in the context of chromatin to regulate transcription, replication, repair and recombination. Defects in SNF2 genes cause many human diseases. For example, mutations in SMARCAL1 (also named HARP) cause Schimke immuno-osseous dysplasia (SIOD); a multi-system disorder characterized by growth defects, immune deficiencies, renal failure and other complex phenotypes. Several groups including ours recently identified SMARCAL1 as a replication stress response protein. Importantly, SMARCAL1 localizes to stalled replication forks and this localization of SMARCAL1 activity prevents DNA damage accumulation during DNA replication. We determined that SIOD-related SMARCAL1 mutants could not prevent replication-associated DNA damage in cells in which endogenous SMARCAL1 was silenced, establishing the first link between SIOD and a defect in a specific biological activity. Here, we also report that cells from patients with SIOD exhibit elevated levels of DNA damage that can be rescued by re-introduction of wild-type SMARCAL1. Our data suggest that loss of SMARCAL1 function in patients may cause DNA replication-associated genome instability that contributes to the pleiotropic phenotypes of SIOD.
Michael Grimm - One of the best experts on this subject based on the ideXlab platform.
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donor serum SMARCAL1 concentrations predict primary graft dysfunction in cardiac transplantation
Circulation, 2009Co-Authors: Seyedhossein Aharinejad, Olena Andrukhova, Matthias Gmeiner, Anita Thomas, A Z Aliabadi, A Zuckermann, Katharina Krenn, Michael GrimmAbstract:Background— Primary graft dysfunction (PGD) is a life-threatening complication in cardiac transplantation. A sensitive, specific, and easily measurable predictor in donors could facilitate PGD prevention. Methods and Results— SMARCAL1 is a matrix-associated regulator of chromatin with helicase and ATPase activities, and its serum concentrations were significantly increased in a targeted protein array in donors whose grafts developed PGD. Therefore, this study analyzed SMARCAL1 serum concentrations by ELISA in 336 heart donors before and after aortic cross-clamping (ACC) and in recipients at 10, 30, and 60 minutes reperfusion. Demographic and hemodynamic parameters of donors and recipients as well as transplant procedure characteristics were documented. PGD (n=68) was defined as ventricular dilation and hypocontractility associated with systolic blood pressure 20 mm Hg, and decreased mixed venous oxygen saturation necessitating mechanical circulatory support. SMARCAL1 serum protein concentration was significantly increased only before and after ACC in donors ( P <0.0001) whose grafts developed PGD compared to those who did not. In receiver operating characteristic curve analysis, SMARCAL1 serum concentration at a cut-off level of ≥1.25 ng/mL before ACC in donors predicted PGD ( P <0.0001, AUC=0.988, OR=17.050, 95% CI=5.200 to 55.901) with 96% sensitivity and 88% specificity. SMARCAL1 serum concentrations <1.25 ng/mL in donors before ACC resulted in 97% PGD-free outcome and SMARCAL1 concentrations ≥1.25 resulted in 83% PGD occurrence. Conclusions— Donor serum SMARCAL1 may serve as a specific, sensitive, and noninvasive predictive marker in the assessment of cardiac graft quality.
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Donor serum SMARCAL1 concentrations predict primary graft dysfunction in cardiac transplantation.
Circulation, 2009Co-Authors: Seyedhossein Aharinejad, Olena Andrukhova, Matthias Gmeiner, Anita Thomas, A Zuckermann, Katharina Krenn, Arezu Aliabadi, Michael GrimmAbstract:Primary graft dysfunction (PGD) is a life-threatening complication in cardiac transplantation. A sensitive, specific, and easily measurable predictor in donors could facilitate PGD prevention. SMARCAL1 is a matrix-associated regulator of chromatin with helicase and ATPase activities, and its serum concentrations were significantly increased in a targeted protein array in donors whose grafts developed PGD. Therefore, this study analyzed SMARCAL1 serum concentrations by ELISA in 336 heart donors before and after aortic cross-clamping (ACC) and in recipients at 10, 30, and 60 minutes reperfusion. Demographic and hemodynamic parameters of donors and recipients as well as transplant procedure characteristics were documented. PGD (n=68) was defined as ventricular dilation and hypocontractility associated with systolic blood pressure <90 mm Hg, pulmonary capillary wedge pressure >20 mm Hg, and decreased mixed venous oxygen saturation necessitating mechanical circulatory support. SMARCAL1 serum protein concentration was significantly increased only before and after ACC in donors (P<0.0001) whose grafts developed PGD compared to those who did not. In receiver operating characteristic curve analysis, SMARCAL1 serum concentration at a cut-off level of > or =1.25 ng/mL before ACC in donors predicted PGD (P<0.0001, AUC=0.988, OR=17.050, 95% CI=5.200 to 55.901) with 96% sensitivity and 88% specificity. SMARCAL1 serum concentrations <1.25 ng/mL in donors before ACC resulted in 97% PGD-free outcome and SMARCAL1 concentrations > or =1.25 resulted in 83% PGD occurrence. Donor serum SMARCAL1 may serve as a specific, sensitive, and noninvasive predictive marker in the assessment of cardiac graft quality.
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Donor serum SMARCAL1 concentrations predict primary graft dysfunction in cardiac transplantation.
Circulation, 2009Co-Authors: Seyedhossein Aharinejad, Olena Andrukhova, Matthias Gmeiner, Anita Thomas, A Zuckermann, Katharina Krenn, Arezu Aliabadi, Michael GrimmAbstract:Background— Primary graft dysfunction (PGD) is a life-threatening complication in cardiac transplantation. A sensitive, specific, and easily measurable predictor in donors could facilitate PGD prevention. Methods and Results— SMARCAL1 is a matrix-associated regulator of chromatin with helicase and ATPase activities, and its serum concentrations were significantly increased in a targeted protein array in donors whose grafts developed PGD. Therefore, this study analyzed SMARCAL1 serum concentrations by ELISA in 336 heart donors before and after aortic cross-clamping (ACC) and in recipients at 10, 30, and 60 minutes reperfusion. Demographic and hemodynamic parameters of donors and recipients as well as transplant procedure characteristics were documented. PGD (n=68) was defined as ventricular dilation and hypocontractility associated with systolic blood pressure 20 mm Hg, and decreased mixed venous oxygen saturation necessitating mechanical circulatory support. SMARCAL1 serum protein concentration was significantly increased only before and after ACC in donors ( P
Clinton Carroll - One of the best experts on this subject based on the ideXlab platform.
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A novel splice site mutation in SMARCAL1 results in aberrant exon definition in a child with Schimke immunoosseous dysplasia.
American journal of medical genetics. Part A, 2015Co-Authors: Clinton Carroll, Tracy E Hunley, Yan Guo, David CortezAbstract:Schimke Immunoosseous Dysplasia (SIOD) is a rare, autosomal recessive disorder of childhood characterized by spondyloepiphyseal dysplasia, focal segmental glomerulosclerosis and renal failure, T-cell immunodeficiency, and cancer in certain instances. Approximately half of patients with SIOD are reported to have biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA translocase that localizes to sites of DNA replication and repairs damaged replication forks. We present a novel mutation (NM_014140.3:c.2070+2insT) that results in defective SMARCAL1 mRNA splicing in a child with SIOD. This mutation, within the donor site of intron 12, results in the skipping of exon 12, which encodes part of a critical hinge region connecting the two lobes of the ATPase domain. This mutation was not recognized as deleterious by diagnostic SMARCAL1 sequencing, but discovered through next generation sequencing and found to result in absent SMARCAL1 expression in patient-derived lymphoblasts. The splicing defect caused by this mutation supports the concept of exon definition. Furthermore, it illustrates the need to broaden the search for SMARCAL1 mutations in patients with SIOD lacking coding sequence variants.
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A novel splice site mutation in SMARCAL1 results in aberrant exon definition in a child with Schimke immunoosseous dysplasia.
American Journal of Medical Genetics Part A, 2015Co-Authors: Clinton Carroll, Tracy E Hunley, Yan Guo, David CortezAbstract:Schimke Immunoosseous Dysplasia (SIOD) is a rare, autosomal recessive disorder of childhood characterized by spondyloepiphyseal dysplasia, focal segmental glomerulosclerosis and renal failure, T-cell immunodeficiency, and cancer in certain instances. Approximately half of patients with SIOD are reported to have biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA translocase that localizes to sites of DNA replication and repairs damaged replication forks. We present a novel mutation ({"type":"entrez-nucleotide","attrs":{"text":"NM_014140.3","term_id":"187761312","term_text":"NM_014140.3"}}NM_014140.3:c.2070+2insT) that results in defective SMARCAL1 mRNA splicing in a child with SIOD. This mutation, within the donor site of intron 12 results in the skipping of exon 12, which encodes part of a critical hinge region connecting the two lobes of the ATPase domain. This mutation was not identified as deleterious by diagnostic SMARCAL1 sequencing, but discovered through next generation sequencing, confirmed by Sanger sequencing, and found to result in absent SMARCAL1 expression in patient-derived lymphoblasts. The splicing defect caused by this mutation supports the concept of exon definition. Furthermore, it illustrates the need to broaden the search for SMARCAL1 defects in patients with SIOD lacking coding sequence mutations.
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Phosphorylation of a C-terminal auto-inhibitory domain increases SMARCAL1 activity
Nucleic acids research, 2013Co-Authors: Clinton Carroll, Carol E Bansbach, Runxiang Zhao, Sung Yun Jung, Jun Qin, David CortezAbstract:SMARCAL1 promotes the repair and restart of damaged replication forks. Either overexpression or silencing SMARCAL1 causes the accumulation of replication-associated DNA damage. SMARCAL1 is heavily phosphorylated. Here we identify multiple phosphorylation sites, including S889, which is phosphorylated even in undamaged cells. S889 is highly conserved through evolution and it regulates SMARCAL1 activity. Specifically, S889 phosphorylation increases the DNA-stimulated ATPase activity of SMARCAL1 and increases its ability to catalyze replication fork regression. A phosphomimetic S889 mutant is also hyperactive when expressed in cells, while a non-phosphorylatable mutant is less active. S889 lies within a C-terminal region of the SMARCAL1 protein. Deletion of the C-terminal region also creates a hyperactive SMARCAL1 protein suggesting that S889 phosphorylation relieves an auto-inhibitory function of this SMARCAL1 domain. Thus, S889 phosphorylation is one mechanism by which SMARCAL1 activity is regulated to ensure the proper level of fork remodeling needed to maintain genome integrity during DNA synthesis.
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ATR phosphorylates SMARCAL1 to prevent replication fork collapse
Genes & development, 2013Co-Authors: Frank B. Couch, Carol E Bansbach, Remy Betous, Gloria G Glick, Clinton Carroll, Sung Yun Jung, Jun Qin, Robert Driscoll, Jessica W. Luzwick, Karlene A. CimprichAbstract:The DNA damage response kinase ataxia telangiectasia and Rad3-related (ATR) coordinates much of the cellular response to replication stress. The exact mechanisms by which ATR regulates DNA synthesis in conditions of replication stress are largely unknown, but this activity is critical for the viability and proliferation of cancer cells, making ATR a potential therapeutic target. Here we use selective ATR inhibitors to demonstrate that acute inhibition of ATR kinase activity yields rapid cell lethality, disrupts the timing of replication initiation, slows replication elongation, and induces fork collapse. We define the mechanism of this fork collapse, which includes SLX4-dependent cleavage yielding double-strand breaks and CtIP-dependent resection generating excess single-stranded template and nascent DNA strands. Our data suggest that the DNA substrates of these nucleases are generated at least in part by the SMARCAL1 DNA translocase. Properly regulated SMARCAL1 promotes stalled fork repair and restart; however, unregulated SMARCAL1 contributes to fork collapse when ATR is inactivated in both mammalian and Xenopus systems. ATR phosphorylates SMARCAL1 on S652, thereby limiting its fork regression activities and preventing aberrant fork processing. Thus, phosphorylation of SMARCAL1 is one mechanism by which ATR prevents fork collapse, promotes the completion of DNA replication, and maintains genome integrity.
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Schimke Immunoosseous Dysplasia associated with undifferentiated carcinoma and a novel SMARCAL1 mutation in a child.
Pediatric blood & cancer, 2013Co-Authors: Clinton Carroll, David Cortez, Alireza Baradaran-heravi, Tracy E Hunley, Akosua Badu-nkansah, Haydar FrangoulAbstract:Schimke Immunoosseous Dysplasia (SIOD) is a rare, autosomal recessive disorder of childhood with classical features of spondyloepiphyseal dysplasia, renal failure, and T cell immunodeficiency. SIOD has been associated with several malignancies, including non-Hodgkin lymphoma and osteosarcoma. About half of SIOD patients have biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1). This gene encodes an annealing helicase and replication stress response protein that localizes to damage-stalled DNA replication forks. We report a child with SIOD and a novel S859P missense mutation in SMARCAL1 who developed undifferentiated carcinoma of the sinus.
Thomas Lücke - One of the best experts on this subject based on the ideXlab platform.
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Schimke immunoosseous dysplasia: defining skeletal features
European Journal of Pediatrics, 2010Co-Authors: Kshamta B. Hunter, Yumi Asakura, Dominique Bonneau, Thomas Lücke, Jürgen Spranger, Sarah F. Smithson, Harika Alpay, Jean-luc André, Radovan Bogdanovic, Robyn CairnsAbstract:Schimke immunoosseous dysplasia (SIOD) is an autosomal recessive multisystem disorder characterized by prominent spondyloepiphyseal dysplasia, T cell deficiency, and focal segmental glomerulosclerosis. Biallelic mutations in swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 ( SMARCAL1 ) are the only identified cause of SIOD, but approximately half of patients referred for molecular studies do not have detectable mutations in SMARCAL1 . We hypothesized that skeletal features distinguish between those with or without SMARCAL1 mutations. Therefore, we analyzed the skeletal radiographs of 22 patients with and 11 without detectable SMARCAL1 mutations. We found that patients with SMARCAL1 mutations have a spondyloepiphyseal dysplasia (SED) essentially limited to the spine, pelvis, capital femoral epiphyses, and possibly the sella turcica, whereas the hands and other long bones are basically normal. Additionally, we found that several of the adolescent and young adult patients developed osteoporosis and coxarthrosis. Of the 11 patients without detectable SMARCAL1 mutations, seven had a SED indistinguishable from patients with SMARCAL1 mutations. We conclude therefore that SED is a feature of patients with SMARCAL1 mutations and that skeletal features do not distinguish who of those with SED have SMARCAL1 mutations.
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SMARCAL1 Mutations: A Cause of Prepubertal Idiopathic Steroid-resistant Nephrotic Syndrome
Pediatric Research, 2009Co-Authors: Miroslav Živičnjak, Thomas Lücke, Doris Franke, Martin Zenker, Juliane Hoyer, Lars Pape, Jochen H H EhrichAbstract:Schimke immuno-osseous dysplasia (SIOD) is a rare autosomal-recessive multisystem disorder with disproportionate growth failure, impaired T cell function, and steroid-resistant nephrotic syndrome. Recently, we presented the typical anthropometric features of SIOD. We now present data on two siblings who were initially classified as suffering from familial steroid-resistant nephrotic syndrome of unknown genetic origin. Apart from growth failure, no syndrome-specific symptoms were found until the age of 10 y. However, serial anthropometric examinations showed the development of a SIOD-like pattern with a decreased ratio of trunk to leg length in early adolescence. The growth pattern was significantly different from that seen in children with chronic renal failure of other origins. In prepuberty the siblings had proportionate short stature but developed disproportion only during adolescence. Molecular genetic analysis revealed compound heterozygosity for a known and a new mutation in the SMARCAL1 gene. Conclusion: the disease spectrum associated with SMARCAL1 mutations includes previously undescribed milder phenotypes that may be clinically overlooked, particularly before puberty. Serial anthropometric assessment can eventually identify patients with a growth pattern similar to that of SIOD. These patients should be tested for SMARCAL1 mutations to avoid overtreatment with immunosuppressive agents.
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Neurologic Phenotype of Schimke Immuno-Osseous Dysplasia and Neurodevelopmental Expression of SMARCAL1
Journal of neuropathology and experimental neurology, 2008Co-Authors: Kimiko Deguchi, Kunho Choi, Leah I. Elizondo, Cheng Huang, Emily A. Sloan, Thomas Lücke, Johanna Marietta Clewing, Ryuki Hirano, Katja M. Marwedel, Ralph D. PowellAbstract:Schimke immuno-osseous dysplasia (OMIM 242900) is an uncommon autosomal-recessive multisystem disease caused by mutations in SMARCAL1 (swi/snf-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1), a gene encoding a putative chromatin remodeling protein. Neurologic manifestations identified to date relate to enhanced atherosclerosis and cerebrovascular disease. Based on a clinical survey, we determined that half of Schimke immuno-osseous dysplasia patients have a small head circumference, and 15% have social, language, motor, or cognitive abnormalities. Postmortem examination of 2 Schimke immuno-osseous dysplasia patients showed low brain weights and subtle brain histologic abnormalities suggestive of perturbed neuron-glial migration such as heterotopia, irregular cortical thickness, incomplete gyral formation, and poor definition of cortical layers. We found that SMARCAL1 is highly expressed in the developing and adult mouse and human brain, including neural precursors and neuronal lineage cells. These observations suggest that SMARCAL1 deficiency may influence brain development and function in addition to its previously recognized effect on cerebral circulation.
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Schimke immunoosseous dysplasia: suggestions of genetic diversity.
Human mutation, 2007Co-Authors: J. Marietta Clewing, Kunho Choi, Yan Huang, Emily A. Sloan, Shu Lou, Thomas Lücke, Sarah F. Smithson, Helen Fryssira, David Goodman, Harika AlpayAbstract:Schimke immunoosseous dysplasia (SIOD), which is characterized by prominent spondyloepiphyseal dysplasia, T-cell deficiency, and focal segmental glomerulosclerosis, is a panethnic autosomal recessive multisystem disorder with variable expressivity. Biallelic mutations in switch/sucrose nonfermenting (swi/snf) related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1) are the only identified cause of SIOD. However, among 72 patients from different families, we identified only 38 patients with biallelic mutations in the coding exons and splice junctions of the SMARCAL1 gene. This observation, the variable expressivity, and poor genotype-phenotype correlation led us to test several hypotheses including modifying haplotypes, oligogenic inheritance, or locus heterogeneity in SIOD. Haplotypes associated with the two more common mutations, R820H and E848X, did not correlate with phenotype. Also, contrary to monoallelic SMARCAL1 coding mutations indicating oligogenic inheritance, we found that all these patients did not express RNA and/or protein from the other allele and thus have biallelic SMARCAL1 mutations. We hypothesize therefore that the variable expressivity among patients with biallelic SMARCAL1 mutations arises from environmental, genetic, or epigenetic modifiers. Among patients without detectable SMARCAL1 coding mutations, our analyses of cell lines from four of these patients showed that they expressed normal levels of SMARCAL1 mRNA and protein. This is the first evidence for nonallelic heterogeneity in SIOD. From analysis of the postmortem histopathology from two patients and the clinical data from most patients, we propose the existence of endophenotypes of SIOD.
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Schimke immuno-osseous dysplasia: a clinicopathological correlation
Journal of medical genetics, 2006Co-Authors: J. Marietta Clewing, Thomas Lücke, Katja M. Marwedel, Behzad Najafian, Barbara C. Antalfy, Akira Hori, Ralph M. Powel, A. F.safo, Lydia Najera, Karen SantacruzAbstract:Background: Schimke immuno-osseous dysplasia (SIOD) is a fatal autosomal recessive disorder caused by loss-of-function mutations in swi/snf-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1 (SMARCAL1). Methods: Analysis of detailed autopsies to correlate clinical and pathological findings in two men severely affected with SIOD. Results: As predicted by the clinical course, T cell deficiency in peripheral lymphoid organs, defective chondrogenesis, focal segmental glomerulosclerosis, cerebral ischaemic lesions and premature atherosclerosis were identified. Clinically unexpected findings included a paucity of B cells in the peripheral lymphoid organs, emperipolesis-like (penetration of one cell by another) abnormalities in the adenohypophysis, fatty infiltration of the cardiac right ventricular wall, pulmonary emphysema, testicular hypoplasia with atrophy and azospermia, and clustering of small cerebral vessels. Conclusions: A regulatory role for the SMARCAL1 protein in the proliferation of chondrocytes, lymphocytes and spermatozoa, as well as in the development or maintenance of cardiomyocytes and in vascular homoeostasis, is suggested. Additional clinical management guidelines are recommended as this study has shown that patients with SIOD may be at risk of pulmonary hypertension, combined immunodeficiency, subcortical ischaemic dementia and cardiac dysfunction.