Medicine and Health Sciences Commons^™

Factors Associated With Blood Mercury Concentrations And Their Interactions With Three Glutathione S-Transferase Genes (Gstt1, Gstm1, And Gstp1): An Exposure Assessment Study Of Typically Developing Jamaican Children, Sheikh Farzana Zaman, Maureen Samms-Vaughan, Sepideh Saroukhani, Jan Bressler, Manouchehr Hessabi, Megan L Grove, Sydonnie Shakespeare Pellington, Katherine A Loveland, Mohammad H Rahbar

Journal Articles

BACKGROUND: Jamaican soil is abundant in heavy metals including mercury (Hg). Due to availability and ease of access, fish is a traditional dietary component in Jamaica and a significant source of Hg exposure. Mercury is a xenobiotic and known neuro-toxicant that affects children's neurodevelopment. Human glutathione S-transferase (GST) genes, including GSTT1, GSTM1, and GSTP1, affect Hg conjugation and elimination mechanisms.

METHODS: In this exposure assessment study we used data from 375 typically developing (TD) 2-8-year-old Jamaican children to explore the association between environmental Hg exposure, GST genes, and their interaction effects on blood Hg concentrations (BHgCs). We used multivariable general …

Factors Associated With Blood Mercury Concentrations And Their Interactions With Three Glutathione S-Transferase Genes (Gstt1, Gstm1, And Gstp1): An Exposure Assessment Study Of Typically Developing Jamaican Children, Sheikh Farzana Zaman, Maureen Samms-Vaughan, Sepideh Saroukhani, Jan Bressler, Manouchehr Hessabi, Megan L Grove, Sydonnie Shakespeare Pellington, Katherine A Loveland, Mohammad H Rahbar

Journal Articles

BACKGROUND: Jamaican soil is abundant in heavy metals including mercury (Hg). Due to availability and ease of access, fish is a traditional dietary component in Jamaica and a significant source of Hg exposure. Mercury is a xenobiotic and known neuro-toxicant that affects children's neurodevelopment. Human glutathione S-transferase (GST) genes, including GSTT1, GSTM1, and GSTP1, affect Hg conjugation and elimination mechanisms.

METHODS: In this exposure assessment study we used data from 375 typically developing (TD) 2-8-year-old Jamaican children to explore the association between environmental Hg exposure, GST genes, and their interaction effects on blood Hg concentrations (BHgCs). We used multivariable general …

Factors Associated With Blood Mercury Concentrations And Their Interactions With Three Glutathione S-Transferase Genes (Gstt1, Gstm1, And Gstp1): An Exposure Assessment Study Of Typically Developing Jamaican Children, Sheikh Farzana Zaman, Maureen Samms-Vaughan, Sepideh Saroukhani, Jan Bressler, Manouchehr Hessabi, Megan L Grove, Sydonnie Shakespeare Pellington, Katherine A Loveland, Mohammad H Rahbar

Journal Articles

BACKGROUND: Jamaican soil is abundant in heavy metals including mercury (Hg). Due to availability and ease of access, fish is a traditional dietary component in Jamaica and a significant source of Hg exposure. Mercury is a xenobiotic and known neuro-toxicant that affects children's neurodevelopment. Human glutathione S-transferase (GST) genes, including GSTT1, GSTM1, and GSTP1, affect Hg conjugation and elimination mechanisms.

METHODS: In this exposure assessment study we used data from 375 typically developing (TD) 2-8-year-old Jamaican children to explore the association between environmental Hg exposure, GST genes, and their interaction effects on blood Hg concentrations (BHgCs). We used multivariable general …

Multi-Tissue Epigenetic Analysis Identifies Distinct Associations Underlying Insulin Resistance And Alzheimer's Disease At Cpt1a Locus, Chloé Sarnowski, Tianxiao Huan, Yiyi Ma, Roby Joehanes, Alexa Beiser, Charles S Decarli, Nancy L Heard-Costa, Daniel Levy, Honghuang Lin, Ching-Ti Liu, Chunyu Liu, James B Meigs, Claudia L Satizabal, Jose C Florez, Marie-France Hivert, Josée Dupuis, Philip L De Jager, David A Bennett, Sudha Seshadri, Alanna C Morrison

Journal Articles

BACKGROUND: Insulin resistance (IR) is a major risk factor for Alzheimer's disease (AD) dementia. The mechanisms by which IR predisposes to AD are not well-understood. Epigenetic studies may help identify molecular signatures of IR associated with AD, thus improving our understanding of the biological and regulatory mechanisms linking IR and AD.

METHODS: We conducted an epigenome-wide association study of IR, quantified using the homeostatic model assessment of IR (HOMA-IR) and adjusted for body mass index, in 3,167 participants from the Framingham Heart Study (FHS) without type 2 diabetes at the time of blood draw used for methylation measurement. We identified …

Structural Basis Of A Transcription Pre-Initiation Complex On A Divergent Promoter, Jose J Gorbea Colón, Leon Palao, Shin-Fu Chen, Hee Jong Kim, Laura Snyder, Yi-Wei Chang, Kuang-Lei Tsai, Kenji Murakami

Journal Articles

Most eukaryotic promoter regions are divergently transcribed. As the RNA polymerase II pre-initiation complex (PIC) is intrinsically asymmetric and responsible for transcription in a single direction, it is unknown how divergent transcription arises. Here, the Saccharomyces cerevisiae Mediator complexed with a PIC (Med-PIC) was assembled on a divergent promoter and analyzed by cryoelectron microscopy. The structure reveals two distinct Med-PICs forming a dimer through the Mediator tail module, induced by a homodimeric activator protein localized near the dimerization interface. The tail dimer is associated with ∼80-bp upstream DNA, such that two flanking core promoter regions are positioned and oriented in …

Systemic Interindividual Epigenetic Variation In Humans Is Associated With Transposable Elements And Under Strong Genetic Control, Chathura J Gunasekara, Harry Mackay, C Anthony Scott, Shaobo Li, Eleonora Laritsky, Maria S Baker, Sandra L Grimm, Goo Jun, Yumei Li, Rui Chen, Joseph L Wiemels, Cristian Coarfa, Robert A Waterland

Journal Articles

BACKGROUND: Genetic variants can modulate phenotypic outcomes via epigenetic intermediates, for example at methylation quantitative trait loci (mQTL). We present the first large-scale assessment of mQTL at human genomic regions selected for interindividual variation in CpG methylation, which we call correlated regions of systemic interindividual variation (CoRSIVs). These can be assayed in blood DNA and do not reflect interindividual variation in cellular composition.

RESULTS: We use target-capture bisulfite sequencing to assess DNA methylation at 4086 CoRSIVs in multiple tissues from each of 188 donors in the NIH Gene-Tissue Expression (GTEx) program. At CoRSIVs, DNA methylation in peripheral blood correlates with …

Integrative Analysis Of Clinical And Epigenetic Biomarkers Of Mortality, Tianxiao Huan, Steve Nguyen, Elena Colicino, Carolina Ochoa-Rosales, W David Hill, Jennifer A Brody, Mette Soerensen, Yan Zhang, Antoine Baldassari, Mohamed Ahmed Elhadad, Tanaka Toshiko, Yinan Zheng, Arce Domingo-Relloso, Dong Heon Lee, Jiantao Ma, Chen Yao, Chunyu Liu, Shih-Jen Hwang, Roby Joehanes, Myriam Fornage, Jan Bressler, Joyce B J Van Meurs, Birgit Debrabant, Jonas Mengel-From, Jacob Hjelmborg, Kaare Christensen, Pantel Vokonas, Joel Schwartz, Sina A Gahrib, Nona Sotoodehnia, Colleen M Sitlani, Sonja Kunze, Christian Gieger, Annette Peters, Melanie Waldenberger, Ian J Deary, Luigi Ferrucci, Yishu Qu, Philip Greenland, Donald M Lloyd-Jones, Lifang Hou, Stefania Bandinelli, Trudy Voortman, Brenner Hermann, Andrea Baccarelli, Eric Whitsel, James S Pankow, Daniel Levy

Journal Articles

DNA methylation (DNAm) has been reported to be associated with many diseases and with mortality. We hypothesized that the integration of DNAm with clinical risk factors would improve mortality prediction. We performed an epigenome-wide association study of whole blood DNAm in relation to mortality in 15 cohorts (n = 15,013). During a mean follow-up of 10 years, there were 4314 deaths from all causes including 1235 cardiovascular disease (CVD) deaths and 868 cancer deaths. Ancestry-stratified meta-analysis of all-cause mortality identified 163 CpGs in European ancestry (EA) and 17 in African ancestry (AA) participants at p < 1 × 10

Elucidating Mechanisms Of Genetic Cross-Disease Associations At The Procr Vascular Disease Locus, David Stacey, Lingyan Chen, Paulina J Stanczyk, Joanna M M Howson, Amy M Mason, Stephen Burgess, Stephen Macdonald, Jonathan Langdown, Harriett Mckinney, Kate Downes, Neda Farahi, James E Peters, Saonli Basu, James S Pankow, Weihong Tang, Nathan Pankratz, Maria Sabater-Lleal, Paul S De Vries, Nicholas L Smith, Amy D Gelinas, Daniel J Schneider, Nebojsa Janjic, Nilesh J Samani, Shu Ye, Charlotte Summers, Edwin R Chilvers, John Danesh, Dirk S Paul

Journal Articles

Many individual genetic risk loci have been associated with multiple common human diseases. However, the molecular basis of this pleiotropy often remains unclear. We present an integrative approach to reveal the molecular mechanism underlying the PROCR locus, associated with lower coronary artery disease (CAD) risk but higher venous thromboembolism (VTE) risk. We identify PROCR-p.Ser219Gly as the likely causal variant at the locus and protein C as a causal factor. Using genetic analyses, human recall-by-genotype and in vitro experimentation, we demonstrate that PROCR-219Gly increases plasma levels of (activated) protein C through endothelial protein C receptor (EPCR) ectodomain shedding in endothelial cells, …

Additive And Interactive Associations Of Environmental And Sociodemographic Factors With The Genotypes Of Three Glutathione S-Transferase Genes In Relation To The Blood Arsenic Concentrations Of Children In Jamaica, Mohammad H Rahbar, Maureen Samms-Vaughan, Yuansong Zhao, Sepideh Saroukhani, Sheikh F Zaman, Jan Bressler, Manouchehr Hessabi, Megan L Grove, Sydonnie Shakspeare-Pellington, Katherine A Loveland

Journal Articles

Arsenic (As) is a metalloid that has been classified as a xenobiotic with toxic effects on human beings, especially on children. Since the soil in Jamaica contains As, dietary intake is considered the main source of As exposure in Jamaicans. In addition, glutathione S-transferase (GST) genes, including

Integrated Single-Cell Atlas Of Endothelial Cells Of The Human Lung, Jonas C Schupp, Taylor S Adams, Carlos Cosme, Micha Sam Brickman Raredon, Yifan Yuan, Norihito Omote, Sergio Poli, Maurizio Chioccioli, Kadi-Ann Rose, Edward P Manning, Maor Sauler, Giuseppe Deiuliis, Farida Ahangari, Nir Neumark, Arun C Habermann, Austin J Gutierrez, Linh T Bui, Robert Lafyatis, Richard W Pierce, Kerstin B Meyer, Martijn C Nawijn, Sarah A Teichmann, Nicholas E Banovich, Jonathan A Kropski, Laura E Niklason, Dana Pe'er, Xiting Yan, Robert J Homer, Ivan O Rosas, Naftali Kaminski

Journal Articles

BACKGROUND: Cellular diversity of the lung endothelium has not been systematically characterized in humans. We provide a reference atlas of human lung endothelial cells (ECs) to facilitate a better understanding of the phenotypic diversity and composition of cells comprising the lung endothelium.

METHODS: We reprocessed human control single-cell RNA sequencing (scRNAseq) data from 6 datasets. EC populations were characterized through iterative clustering with subsequent differential expression analysis. Marker genes were validated by fluorescent microscopy and in situ hybridization. scRNAseq of primary lung ECs cultured in vitro was performed. The signaling network between different lung cell types was studied. For cross-species …

The Impact Of The Th17:Treg Axis On The Iga-Biome Across The Glycemic Spectrum, Heather T Essigmann, Kristi L Hoffman, Joseph F Petrosino, Goo Jun, David Aguilar, Craig L Hanis, Herbert L Dupont, Eric L Brown

Journal Articles

Secretory IgA (SIgA) is released into mucosal surfaces where its function extends beyond that of host defense to include the shaping of resident microbial communities by mediating exclusion/inclusion of respective microbes and regulating bacterial gene expression. In this capacity, SIgA acts as the fulcrum on which host immunity and the health of the microbiota are balanced. We recently completed an analysis of the gut and salivary IgA-Biomes (16S rDNA sequencing of SIgA-coated/uncoated bacteria) in Mexican-American adults that identified IgA-Biome differences across the glycemic spectrum. As Th17:Treg ratio imbalances are associated with gut microbiome dysbiosis and chronic inflammatory conditions such as …

Role Of Micro-Rna For Pain After Surgery: Narrative Review Of Animal And Human Studies, Juan P Cata, Aysegul Gorur, Xiaoyi Yuan, Nathaniel K Berg, Anil K Sood, Holger K Eltzschig

Journal Articles

One of the most prevalent symptoms after major surgery is pain. When postoperative pain treatment is unsatisfactory, it can lead to poor surgical recovery, decreased quality of life, and increased health care costs. Current analgesics, single or in combination, have limited efficacy due to low potency, limited duration of action, toxicities, and risk of addiction. The lack of nonaddictive strong analgesics along with the over prescription of opioids has led to an opioid epidemic in the United States. Therefore, there is an urgent need for the development of newer analgesics. Microribonucleic acids (miRNAs) are small noncoding RNA molecules that modulate …

A Primer On A Comprehensive Genetic Approach To Vascular Anomalies, A. J. Borst, T. A. Nakano, F. Blei, D. M. Adams, J. Duis

Journal Articles

No abstract provided.

Transcriptional Insights Into Pathogenesis Of Cutaneous Systemic Sclerosis Using Pathway Driven Meta-Analysis Assisted By Machine Learning Methods, Xiao Xu, Meera Ramanujam, Sudha Visvanathan, Shervin Assassi, Zheng Liu, Li Li

Journal Articles

Pathophysiology of systemic sclerosis (SSc, Scleroderma), an autoimmune rheumatic disease, comprises of mechanisms that drive vasculopathy, inflammation and fibrosis. Understanding of the disease and associated clinical heterogeneity has advanced considerably in the past decade, highlighting the necessity of more specific targeted therapy. While many of the recent trials in SSc failed to meet the primary end points that predominantly relied on changes in modified Rodnan skin scores (MRSS), sub-group analysis, especially those focused on the basal skin transcriptomic data have provided insights into patient subsets that respond to therapies. These findings suggest that deeper understanding of the molecular changes in …

The Non-Coding Rnome After Splenectomy, Mihnea P Dragomir, Stefan Tudor, Keishi Okubo, Masayoshi Shimizu, Meng Chen, Dana Elena Giza, William Ruixian He, Cristina Ivan, George A Calin, Catalin Vasilescu

Journal Articles

Splenectomy is a common surgical procedure performed in millions of people worldwide. Epidemiologic data show that splenectomy is followed by infectious (sepsis) and non-infectious complications, with unknown mechanisms. In order to explore the role of the non-coding transcripts involved in these complications, we analysed a panel of circulating microRNAs (miRNAs), which were previously reported to be deregulated in sepsis, in the plasma of splenectomized patients. MiR-223 was overexpressed immediately and late after splenectomy, while miR-146a was overexpressed immediately after splenectomy, returning latter to basal levels; and miR-16, miR-93, miR-26a and miR-26b were overexpressed only late after splenectomy, suggesting similarities with …

De Novo Mutations In Congenital Heart Disease With Neurodevelopmental And Other Congenital Anomalies, J. Homsy, S. Zaidi, Y. Shen, J. S. Ware, K. E. Samocha, K. J. Karczewski, S. R. Depalma, D. Mckean, A. Romano-Adesman, W. K. Chung, +31 Additional Authors

Journal Articles

Congenital heart disease (CHD) patients have an increased prevalence of extracardiac congenital anomalies (CAs) and risk of neurodevelopmental disabilities (NDDs). Exome sequencing of 1213 CHD parent-offspring trios identified an excess of protein-damaging de novo mutations, especially in genes highly expressed in the developing heart and brain. These mutations accounted for 20% of patients with CHD, NDD, and CA but only 2% of patients with isolated CHD. Mutations altered genes involved in morphogenesis, chromatin modification, and transcriptional regulation, including multiple mutations in RBFOX2, a regulator of mRNA splicing. Genes mutated in other cohorts examined for NDD were enriched in CHD cases, …

Highly Variable Recessive Lthal Or Nearly Lethal Mutation Rates During Germ-Line Development Of Male Drosophila Melanogaster, Jian-Jun Gao, Xue-Rong Pan, Jing Hu, Li Ma, Jian-Min Wu, Ye-Lin Shao, Sara A Barton, Ronny C Woodruff, Ya-Ping Zhang, Yun-Xin Fu

Journal Articles

Each cell of higher organism adults is derived from a fertilized egg through a series of divisions, during which mutations can occur. Both the rate and timing of mutations can have profound impacts on both the individual and the population, because mutations that occur at early cell divisions will affect more tissues and are more likely to be transferred to the next generation. Using large-scale multigeneration screening experiments for recessive lethal or nearly lethal mutations of Drosophila melanogaster and recently developed statistical analysis, we show for male D. melanogaster that (i) mutation rates (for recessive lethal or nearly lethal) are …

Foxm1b Transcriptionally Regulates Vascular Endothelial Growth Factor Expression And Promotes The Angiogenesis And Growth Of Glioma Cells., Yujian Zhang, Nu Zhang, Bingbing Dai, Mingguang Liu, Raymond Sawaya, Keping Xie, Suyun Huang

Journal Articles

We previously found that FoxM1B is overexpressed in human glioblastomas and that forced FoxM1B expression in anaplastic astrocytoma cells leads to the formation of highly angiogenic glioblastoma in nude mice. However, the molecular mechanisms by which FoxM1B enhances glioma angiogenesis are currently unknown. In this study, we found that vascular endothelial growth factor (VEGF) is a direct transcriptional target of FoxM1B. FoxM1B overexpression increased VEGF expression, whereas blockade of FoxM1 expression suppressed VEGF expression in glioma cells. Transfection of FoxM1 into glioma cells directly activated the VEGF promoter, and inhibition of FoxM1 expression by FoxM1 siRNA suppressed VEGF promoter activation. …

The Ubiquitin-Proteasome System Is Necessary For Long-Term Synaptic Depression In Aplysia, Diasinou Fioravante, Rong-Yu Liu, John H. Byrne

Journal Articles

The neuropeptide Phe-Met-Arg-Phe-NH(2) (FMRFa) can induce transcription-dependent long-term synaptic depression (LTD) in Aplysia sensorimotor synapses. We investigated the role of the ubiquitin-proteasome system and the regulation of one of its components, ubiquitin C-terminal hydrolase (ap-uch), in LTD. LTD was sensitive to presynaptic inhibition of the proteasome and was associated with upregulation of ap-uch mRNA and protein. This upregulation appeared to be mediated by CREB2, which is generally regarded as a transcription repressor. Binding of CREB2 to the promoter region of ap-uch was accompanied by histone hyperacetylation, suggesting that CREB2 cannot only inhibit but also promote gene expression. CREB2 was phosphorylated …

Genetic Variation In Genes For The Xenobiotic-Metabolizing Enzymes Cyp1a1, Ephx1, Gstm1, Gstt1, And Gstp1 And Susceptibility To Colorectal Cancer In Lynch Syndrome., Mala Pande, Christopher I Amos, Daniel R Osterwisch, Jinyun Chen, Patrick M Lynch, Russell Broaddus, Marsha L Frazier

Journal Articles

Individuals with Lynch syndrome are predisposed to cancer due to an inherited DNA mismatch repair gene mutation. However, there is significant variability observed in disease expression likely due to the influence of other environmental, lifestyle, or genetic factors. Polymorphisms in genes encoding xenobiotic-metabolizing enzymes may modify cancer risk by influencing the metabolism and clearance of potential carcinogens from the body. In this retrospective analysis, we examined key candidate gene polymorphisms in CYP1A1, EPHX1, GSTT1, GSTM1, and GSTP1 as modifiers of age at onset of colorectal cancer among 257 individuals with Lynch syndrome. We found that subjects heterozygous for CYP1A1 I462V …

An Sp1/Sp3 Binding Polymorphism Confers Methylation Protection., Yanis A. Boumber, Yutaka Kondo, Xuqi Chen, Lanlan Shen, Yi Guo, Carmen Tellez, Marcos R H Estécio, Saira Ahmed, Jean-Pierre J. Issa

Journal Articles

Hundreds of genes show aberrant DNA hypermethylation in cancer, yet little is known about the causes of this hypermethylation. We identified RIL as a frequent methylation target in cancer. In search for factors that influence RIL hypermethylation, we found a 12-bp polymorphic sequence around its transcription start site that creates a long allele. Pyrosequencing of homozygous tumors revealed a 2.1-fold higher methylation for the short alleles (P<0.001). Bisulfite sequencing of cancers heterozygous for RIL showed that the short alleles are 3.1-fold more methylated than the long (P<0.001). The comparison of expression levels between unmethylated long and short EBV-transformed cell lines showed no difference in expression in vivo. Electrophorectic mobility shift assay showed that the inserted region of the long allele binds Sp1 and Sp3 transcription factors, a binding that is absent in the short allele. Transient transfection of RIL allele-specific transgenes showed no effects of the additional Sp1 site on transcription early on. However, stable transfection of methylation-seeded constructs showed gradually decreasing transcription levels from the short allele with eventual spreading of de novo methylation. In contrast, the long allele showed stable levels of expression over time as measured by luciferase and approximately 2-3-fold lower levels of methylation by bisulfite sequencing (P<0.001), suggesting that the polymorphic Sp1 site protects against time-dependent silencing. Our finding demonstrates that, in some genes, hypermethylation in cancer is dictated by protein-DNA interactions at the promoters and provides a novel mechanism by which genetic polymorphisms can influence an epigenetic state.

Rtr1 Is The Saccharomyces Cerevisiae Homolog Of A Novel Family Of Rna Polymerase Ii-Binding Proteins, Patrick A Gibney, Thomas Fries, Susanne M Bailer, Kevin A Morano

Journal Articles

Cells must rapidly sense and respond to a wide variety of potentially cytotoxic external stressors to survive in a constantly changing environment. In a search for novel genes required for stress tolerance in Saccharomyces cerevisiae, we identified the uncharacterized open reading frame YER139C as a gene required for growth at 37 degrees C in the presence of the heat shock mimetic formamide. YER139C encodes the closest yeast homolog of the human RPAP2 protein, recently identified as a novel RNA polymerase II (RNAPII)-associated factor. Multiple lines of evidence support a role for this gene family in transcription, prompting us to rename …

Activation Of Heat Shock And Antioxidant Responses By The Natural Product Celastrol: Transcriptional Signatures Of A Thiol-Targeted Molecule, Amy Trott, James D West, Lada Klaić, Sandy D Westerheide, Richard B Silverman, Richard I Morimoto, Kevin A Morano

Journal Articles

Stress response pathways allow cells to sense and respond to environmental changes and adverse pathophysiological states. Pharmacological modulation of cellular stress pathways has implications in the treatment of human diseases, including neurodegenerative disorders, cardiovascular disease, and cancer. The quinone methide triterpene celastrol, derived from a traditional Chinese medicinal herb, has numerous pharmacological properties, and it is a potent activator of the mammalian heat shock transcription factor HSF1. However, its mode of action and spectrum of cellular targets are poorly understood. We show here that celastrol activates Hsf1 in Saccharomyces cerevisiae at a similar effective concentration seen in mammalian cells. Transcriptional …

Sp1 Up-Regulates Camp-Response-Element-Binding Protein Expression During Retinoic Acid-Induced Mucous Differentiation Of Normal Human Bronchial Epithelial Cells., Jeong Soo Hong, Seung-Wook Kim, Ja Seok Koo

Journal Articles

CREB [CRE (cAMP-response element)-binding protein] is an important transcription factor that is differentially regulated in cells of various types. We recently reported that RA (retinoic acid) rapidly activates CREB without using RARs (RA receptors) or RXRs (retinoid X receptors) in NHTBE cells (normal human tracheobronchial epithelial cells). However, little is known about the role of RA in the physiological regulation of CREB expression in the early mucous differentiation of NHTBE cells. In the present study, we report that RA up-regulates CREB gene expression and that, using 5'-serial deletion promoter analysis and mutagenesis analyses, two Sp1 (specificity protein 1)-binding sites located …

Eomesodermin, A Target Gene Of Pou4f2, Is Required For Retinal Ganglion Cell And Optic Nerve Development In The Mouse., Chai-An Mao, Takae Kiyama, Ping Pan, Yasuhide Furuta, Anna-Katerina Hadjantonakis, William H Klein

Journal Articles

The mechanisms regulating retinal ganglion cell (RGC) development are crucial for retinogenesis and for the establishment of normal vision. However, these mechanisms are only vaguely understood. RGCs are the first neuronal lineage to segregate from pluripotent progenitors in the developing retina. As output neurons, RGCs display developmental features very distinct from those of the other retinal cell types. To better understand RGC development, we have previously constructed a gene regulatory network featuring a hierarchical cascade of transcription factors that ultimately controls the expression of downstream effector genes. This has revealed the existence of a Pou domain transcription factor, Pou4f2, that …

Messenger Rna Half-Life Measurements In Mammalian Cells, Chyi-Ying A Chen, Nader Ezzeddine, Ann-Bin Shyu

Journal Articles

The recognition of the importance of mRNA turnover in regulating eukaryotic gene expression has mandated the development of reliable, rigorous, and "user-friendly" methods to accurately measure changes in mRNA stability in mammalian cells. Frequently, mRNA stability is studied indirectly by analyzing the steady-state level of mRNA in the cytoplasm; in this case, changes in mRNA abundance are assumed to reflect only mRNA degradation, an assumption that is not always correct. Although direct measurements of mRNA decay rate can be performed with kinetic labeling techniques and transcriptional inhibitors, these techniques often introduce significant changes in cell physiology. Furthermore, many critical mechanistic …

Versatile Applications Of Transcriptional Pulsing To Study Mrna Turnover In Mammalian Cells, Chyi-Ying A Chen, Yukiko Yamashita, Tsung-Cheng Chang, Akio Yamashita, Wenmiao Zhu, Zhenping Zhong, Ann-Bin Shyu

Journal Articles

Development of transcriptional pulsing approaches using the c-fos and Tet-off promoter systems greatly facilitated studies of mRNA turnover in mammalian cells. However, optimal protocols for these approaches vary for different cell types and/or physiological conditions, limiting their widespread application. In this study, we have further optimized transcriptional pulsing systems for different cell lines and developed new protocols to facilitate investigation of various aspects of mRNA turnover. We apply the Tet-off transcriptional pulsing strategy to investigate ARE-mediated mRNA decay in human erythroleukemic K562 cells arrested at various phases of the cell cycle by pharmacological inhibitors. This application facilitates studies of the …

Computational Identification And Functional Validation Of Regulatory Motifs In Cartilage-Expressed Genes, Sherri R Davies, Li-Wei Chang, Debabrata Patra, Xiaoyun Xing, Karen Posey, Jacqueline Hecht, Gary D Stormo, Linda J Sandell

Journal Articles

Chondrocyte gene regulation is important for the generation and maintenance of cartilage tissues. Several regulatory factors have been identified that play a role in chondrogenesis, including the positive transacting factors of the SOX family such as SOX9, SOX5, and SOX6, as well as negative transacting factors such as C/EBP and delta EF1. However, a complete understanding of the intricate regulatory network that governs the tissue-specific expression of cartilage genes is not yet available. We have taken a computational approach to identify cis-regulatory, transcription factor (TF) binding motifs in a set of cartilage characteristic genes to better define the transcriptional regulatory …

Agrobacterium Para/Mind-Like Virc1 Spatially Coordinates Early Conjugative Dna Transfer Reactions, Krishnamohan Atmakuri, Eric Cascales, Oliver T Burton, Lois M Banta, Peter J Christie

Journal Articles

Agrobacterium tumefaciens translocates T-DNA through a polar VirB/D4 type IV secretion (T4S) system. VirC1, a factor required for efficient T-DNA transfer, bears a deviant Walker A and other sequence motifs characteristic of ParA and MinD ATPases. Here, we show that VirC1 promotes conjugative T-DNA transfer by stimulating generation of multiple copies per cell of the T-DNA substrate (T-complex) through pairwise interactions with the processing factors VirD2 relaxase, VirC2, and VirD1. VirC1 also associates with the polar membrane and recruits T-complexes to cell poles, the site of VirB/D4 T4S machine assembly. VirC1 Walker A mutations abrogate T-complex generation and polar recruitment, …

Dynamics Of A Minimal Model Of Interlocked Positive And Negative Feedback Loops Of Transcriptional Regulation By Camp-Response Element Binding Proteins, Hao Song, Paul Smolen, Evyatar Av-Ron, Douglas A Baxter, John H Byrne

Journal Articles

cAMP-response element binding (CREB) proteins are involved in transcriptional regulation in a number of cellular processes (e.g., neural plasticity and circadian rhythms). The CREB family contains activators and repressors that may interact through positive and negative feedback loops. These loops can be generated by auto- and cross-regulation of expression of CREB proteins, via CRE elements in or near their genes. Experiments suggest that such feedback loops may operate in several systems (e.g., Aplysia and rat). To understand the functional implications of such feedback loops, which are interlocked via cross-regulation of transcription, a minimal model with a positive and negative loop …