Publications by authors named "Ozanna Burnicka-Turek"

11 Publications

  • Page 1 of 1

Transcriptional Patterning of the Ventricular Cardiac Conduction System.

Circ Res 2020 Jul 15;127(3):e94-e106. Epub 2020 Apr 15.

From the Department of Pediatrics (O.B.-T., J.D.S., K.I., R.D.N., D.E.A., X.H.Y., I.P.M.), University of Chicago, Chicago, IL.

Rationale: The heartbeat is organized by the cardiac conduction system (CCS), a specialized network of cardiomyocytes. Patterning of the CCS into atrial node versus ventricular conduction system (VCS) components with distinct physiology is essential for the normal heartbeat. Distinct node versus VCS physiology has been recognized for more than a century, but the molecular basis of this regional patterning is not well understood.

Objective: To study the genetic and genomic mechanisms underlying node versus VCS distinction and investigate rhythm consequences of failed VCS patterning.

Methods And Results: Using mouse genetics, we found that the balance between T-box transcriptional activator, , and T-box transcriptional repressor, , determined the molecular and functional output of VCS myocytes. Adult VCS-specific removal of or overexpression of re-patterned the fast VCS into slow, nodal-like cells based on molecular and functional criteria. In these cases, gene expression profiling showed diminished expression of genes required for VCS-specific fast conduction but maintenance of expression of genes required for nodal slow conduction physiology. Action potentials of -deficient VCS myocytes adopted nodal-specific characteristics, including increased action potential duration and cellular automaticity. Removal of in vivo precipitated inappropriate depolarizations in the atrioventricular (His)-bundle associated with lethal ventricular arrhythmias. TBX5 bound and directly activated -regulatory elements at fast conduction channel genes required for fast physiological characteristics of the VCS action potential, defining the identity of the adult VCS.

Conclusions: The CCS is patterned entirely as a slow, nodal ground state, with a T-box dependent, physiologically dominant, fast conduction network driven specifically in the VCS. Disruption of the fast VCS gene regulatory network allowed nodal physiology to emerge, providing a plausible molecular mechanism for some lethal ventricular arrhythmias.
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http://dx.doi.org/10.1161/CIRCRESAHA.118.314460DOI Listing
July 2020

Transcription-factor-dependent enhancer transcription defines a gene regulatory network for cardiac rhythm.

Elife 2017 12 27;6. Epub 2017 Dec 27.

Department of Pediatrics, The University of Chicago, Chicago, United States.

The noncoding genome is pervasively transcribed. Noncoding RNAs (ncRNAs) generated from enhancers have been proposed as a general facet of enhancer function and some have been shown to be required for enhancer activity. Here we examine the transcription-factor-(TF)-dependence of ncRNA expression to define enhancers and enhancer-associated ncRNAs that are involved in a TF-dependent regulatory network. TBX5, a cardiac TF, regulates a network of cardiac channel genes to maintain cardiac rhythm. We deep sequenced wildtype and -mutant mouse atria, identifying ~2600 novel -dependent ncRNAs. Tbx5-dependent ncRNAs were enriched for tissue-specific marks of active enhancers genome-wide. Tbx5-dependent ncRNAs emanated from regions that are enriched for TBX5-binding and that demonstrated Tbx5-dependent enhancer activity. -dependent ncRNA transcription provided a quantitative metric of -dependent enhancer activity, correlating with target gene expression. We identified , a novel -dependent long noncoding RNA (lncRNA) required for the expression of the calcium-handling gene . We illustrate that TF-dependent enhancer transcription can illuminate components of TF-dependent gene regulatory networks.
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http://dx.doi.org/10.7554/eLife.31683DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5745077PMC
December 2017

Cilia gene mutations cause atrioventricular septal defects by multiple mechanisms.

Hum Mol Genet 2016 07 23;25(14):3011-3028. Epub 2016 Jun 23.

Departments of Pediatrics, Pathology, and Human Genetics, The University of Chicago, Chicago, IL 60637, USA,

Atrioventricular septal defects (AVSDs) are a common severe form of congenital heart disease (CHD). In this study we identified deleterious non-synonymous mutations in two cilia genes, Dnah11 and Mks1, in independent N-ethyl-N-nitrosourea-induced mouse mutant lines with heritable recessive AVSDs by whole-exome sequencing. Cilia are required for left/right body axis determination and second heart field (SHF) Hedgehog (Hh) signaling, and we find that cilia mutations affect these requirements differentially. Dnah11 did not disrupt SHF Hh signaling and caused AVSDs only concurrently with heterotaxy, a left/right axis abnormality. In contrast, Mks1 disrupted SHF Hh signaling and caused AVSDs without heterotaxy. We performed unbiased whole-genome SHF transcriptional profiling and found that cilia motility genes were not expressed in the SHF whereas cilia structural and signaling genes were highly expressed. SHF cilia gene expression predicted the phenotypic concordance between AVSDs and heterotaxy in mice and humans with cilia gene mutations. A two-step model of cilia action accurately predicted the AVSD/heterotaxyu phenotypic expression pattern caused by cilia gene mutations. We speculate that cilia gene mutations contribute to both syndromic and non-syndromic AVSDs in humans and provide a model that predicts the phenotypic consequences of specific cilia gene mutations.
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http://dx.doi.org/10.1093/hmg/ddw155DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5181596PMC
July 2016

Foxf genes integrate tbx5 and hedgehog pathways in the second heart field for cardiac septation.

PLoS Genet 2014 Oct 30;10(10):e1004604. Epub 2014 Oct 30.

Departments of Pediatrics, Pathology, and Human Genetics, The University of Chicago, Chicago, Illinois, United States of America.

The Second Heart Field (SHF) has been implicated in several forms of congenital heart disease (CHD), including atrioventricular septal defects (AVSDs). Identifying the SHF gene regulatory networks required for atrioventricular septation is therefore an essential goal for understanding the molecular basis of AVSDs. We defined a SHF Hedgehog-dependent gene regulatory network using whole genome transcriptional profiling and GLI-chromatin interaction studies. The Forkhead box transcription factors Foxf1a and Foxf2 were identified as SHF Hedgehog targets. Compound haploinsufficiency for Foxf1a and Foxf2 caused atrioventricular septal defects, demonstrating the biological relevance of this regulatory network. We identified a Foxf1a cis-regulatory element that bound the Hedgehog transcriptional regulators GLI1 and GLI3 and the T-box transcription factor TBX5 in vivo. GLI1 and TBX5 synergistically activated transcription from this cis-regulatory element in vitro. This enhancer drove reproducible expression in vivo in the posterior SHF, the only region where Gli1 and Tbx5 expression overlaps. Our findings implicate Foxf genes in atrioventricular septation, describe the molecular underpinnings of the genetic interaction between Hedgehog signaling and Tbx5, and establish a molecular model for the selection of the SHF gene regulatory network for cardiac septation.
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http://dx.doi.org/10.1371/journal.pgen.1004604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4214600PMC
October 2014

A common genetic variant within SCN10A modulates cardiac SCN5A expression.

J Clin Invest 2014 Apr 18;124(4):1844-52. Epub 2014 Mar 18.

Variants in SCN10A, which encodes a voltage-gated sodium channel, are associated with alterations of cardiac conduction parameters and the cardiac rhythm disorder Brugada syndrome; however, it is unclear how SCN10A variants promote dysfunctional cardiac conduction. Here we showed by high-resolution 4C-seq analysis of the Scn10a-Scn5a locus in murine heart tissue that a cardiac enhancer located in Scn10a, encompassing SCN10A functional variant rs6801957, interacts with the promoter of Scn5a, a sodium channel-encoding gene that is critical for cardiac conduction. We observed that SCN5A transcript levels were several orders of magnitude higher than SCN10A transcript levels in both adult human and mouse heart tissue. Analysis of BAC transgenic mouse strains harboring an engineered deletion of the enhancer within Scn10a revealed that the enhancer was essential for Scn5a expression in cardiac tissue. Furthermore, the common SCN10A variant rs6801957 modulated Scn5a expression in the heart. In humans, the SCN10A variant rs6801957, which correlated with slowed conduction, was associated with reduced SCN5A expression. These observations establish a genomic mechanism for how a common genetic variation at SCN10A influences cardiac physiology and predisposes to arrhythmia.
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http://dx.doi.org/10.1172/JCI73140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3973109PMC
April 2014

Tbx5-hedgehog molecular networks are essential in the second heart field for atrial septation.

Dev Cell 2012 Aug;23(2):280-91

Department of Pediatrics, The University of Chicago, Chicago, IL 60637, USA.

The developmental mechanisms underlying human congenital heart disease (CHD) are poorly understood. Atrial septal defects (ASDs) can result from haploinsufficiency of cardiogenic transcription factors including TBX5. We demonstrated that Tbx5 is required in the second heart field (SHF) for atrial septation in mice. Conditional Tbx5 haploinsufficiency in the SHF but not the myocardium or endocardium caused ASDs. Tbx5 SHF knockout embryos lacked atrial septum progenitors. We found that Tbx5 mutant SHF progenitors demonstrated cell-cycle progression defects and that Tbx5 regulated cell-cycle progression genes including Cdk6. Activated hedgehog (Hh) signaling rescued ASDs in Tbx5 mutant embryos, placing Tbx5 upstream or parallel to Hh in cardiac progenitors. Tbx5 regulated SHF Gas1 and Osr1 expression, supporting both pathways. These results describe a SHF Tbx5-Hh network required for atrial septation. A paradigm defining molecular requirements in SHF cardiac progenitors for cardiac septum morphogenesis has implications for the ontogeny of CHD.
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http://dx.doi.org/10.1016/j.devcel.2012.06.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3912192PMC
August 2012

INSL5-deficient mice display an alteration in glucose homeostasis and an impaired fertility.

Endocrinology 2012 Oct 20;153(10):4655-65. Epub 2012 Jul 20.

Institute of Human Genetics, Heinrich-Düker-Weg 12, D-37073 Göttingen, Germany.

Insulin-like factor 5 (INSL5), a member of the insulin superfamily, is expressed in the colorectum and hypothalamus. To facilitate studies into the role of INSL5, we generated Insl5(-/-) mice by gene targeting. Insl5(-/-) mice were born in the expected Mendelian ratio, reached normal body weight, but displayed impaired male and female fertility that are due to marked reduction in sperm motility and irregular length of the estrous cycle. Furthermore, Insl5(-/-) mice showed impairment in glucose homeostasis with characteristic elevation of serum glucose levels at an advanced age. Glucose and insulin tolerance tests revealed that the increased blood glucose in Insl5(-/-) mice was due to glucose intolerance resulting from reduced insulin secretion. Morphometric and immunohistological analyses revealed that the Insl5(-/-) mice had markedly reduced average islets area and β-cell numbers. Furthermore, immunohistochemistry showed the expression of INSL5 in enteroendocrine cells in the colorectal epithelium and the presence of its putative receptor relaxin family peptide receptor 4 in pancreatic islet cells. These results suggest the potential role of INSL5 signaling in the regulation of insulin secretion and β-cell homeostasis.
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http://dx.doi.org/10.1210/en.2012-1161DOI Listing
October 2012

Spermatogonial stem cells, infertility and testicular cancer.

J Cell Mol Med 2011 Mar;15(3):468-83

Mouse Cancer Genetics Program, National Institutes of Health, National Cancer Institute at Frederick, Frederick, MD 21702, USA.

The spermatogonial stem cells (SSCs) are responsible for the transmission of genetic information from an individual to the next generation. SSCs play critical roles in understanding the basic reproductive biology of gametes and treatments of human infertility. SSCs not only maintain normal spermatogenesis, but also sustain fertility by critically balancing both SSC self-renewal and differentiation. This self-renewal and differentiation in turn is tightly regulated by a combination of intrinsic gene expression within the SSC as well as the extrinsic gene signals from the niche. Increased SSCs self-renewal at the expense of differentiation result in germ cell tumours, on the other hand, higher differentiation at the expense of self-renewal can result in male sterility. Testicular germ cell cancers are the most frequent cancers among young men in industrialized countries. However, understanding the pathogenesis of testis cancer has been difficult because it is formed during foetal development. Recent studies suggest that SSCs can be reprogrammed to become embryonic stem (ES)-like cells to acquire pluripotency. In the present review, we summarize the recent developments in SSCs biology and role of SSC in testicular cancer. We believe that studying the biology of SSCs will not only provide better understanding of stem cell regulation in the testis, but eventually will also be a novel target for male infertility and testicular cancers.
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http://dx.doi.org/10.1111/j.1582-4934.2010.01242.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3064728PMC
March 2011

Pelota interacts with HAX1, EIF3G and SRPX and the resulting protein complexes are associated with the actin cytoskeleton.

BMC Cell Biol 2010 Apr 20;11:28. Epub 2010 Apr 20.

Institute of Human Genetics, Georg-August-University, Göttingen, Germany.

Background: Pelota (PELO) is an evolutionary conserved protein, which has been reported to be involved in the regulation of cell proliferation and stem cell self-renewal. Recent studies revealed the essential role of PELO in the No-Go mRNA decay, by which mRNA with translational stall are endonucleotically cleaved and degraded. Further, PELO-deficient mice die early during gastrulation due to defects in cell proliferation and/or differentiation.

Results: We show here that PELO is associated with actin microfilaments of mammalian cells. Overexpression of human PELO in Hep2G cells had prominent effect on cell growth, cytoskeleton organization and cell spreading. To find proteins interacting with PELO, full-length human PELO cDNA was used as a bait in a yeast two-hybrid screening assay. Partial sequences of HAX1, EIF3G and SRPX protein were identified as PELO-interacting partners from the screening. The interactions between PELO and HAX1, EIF3G and SRPX were confirmed in vitro by GST pull-down assays and in vivo by co-immunoprecipitation. Furthermore, the PELO interaction domain was mapped to residues 268-385 containing the c-terminal and acidic tail domain. By bimolecular fluorescence complementation assay (BiFC), we found that protein complexes resulting from the interactions between PELO and either HAX1, EIF3G or SRPX were mainly localized to cytoskeletal filaments.

Conclusion: We could show that PELO is subcellularly localized at the actin cytoskeleton, interacts with HAX1, EIF3G and SRPX proteins and that this interaction occurs at the cytoskeleton. Binding of PELO to cytoskeleton-associated proteins may facilitate PELO to detect and degrade aberrant mRNAs, at which the ribosome is stalled during translation.
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http://dx.doi.org/10.1186/1471-2121-11-28DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2867792PMC
April 2010

Inactivation of insulin-like factor 6 disrupts the progression of spermatogenesis at late meiotic prophase.

Endocrinology 2009 Sep 11;150(9):4348-57. Epub 2009 Jun 11.

Institute of Human Genetics, University of Göttingen, D-37073 Göttingen, Germany.

Insulin-like factor 6 (INSL6), a member of the insulin-like superfamily, is predominantly expressed in male germ cells. Expression of the Insl6 is first detected in mouse testis at postnatal d 15 when the first wave of spermatogenesis progresses to pachytene spermatocytes. To elucidate the role of INSL6 in germ cell development, we generated Insl6-deficient mice. The majority of the Insl6-deficient males on a hybrid genetic background exhibited impaired fertility, whereas females were fertile. The number of mature sperm and sperm motility were drastically reduced in the epididymis. The reduced sperm count could be due to apoptotic death of a significant number of developing germ cells. Analysis of germ cell development during the juvenile life showed an arrest of the first wave of spermatogenesis in late meiotic prophase. RNA analysis revealed a significant decrease in expression of late meiotic- and postmeiotic-specific marker genes, whereas expression of early meiotic-specific genes remains unaffected in the Insl6(-/-) testes. These results demonstrate that INSL6 is required for the progression of spermatogenesis.
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http://dx.doi.org/10.1210/en.2009-0201DOI Listing
September 2009