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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

A Persistence Detector For Metabolic Network Rewiring In An Animal, Jote T. Bulcha, Gabrielle E. Giese, Zulfikar Ali, Yong-Uk Lee, Melissa D. Walker, Amy D. Holdorf, L. Safak Yilmaz, Robert C. Brewster, Albertha J. M. Walhout Jan 2019

A Persistence Detector For Metabolic Network Rewiring In An Animal, Jote T. Bulcha, Gabrielle E. Giese, Zulfikar Ali, Yong-Uk Lee, Melissa D. Walker, Amy D. Holdorf, L. Safak Yilmaz, Robert C. Brewster, Albertha J. M. Walhout

Open Access Articles

Biological systems must possess mechanisms that prevent inappropriate responses to spurious environmental inputs. Caenorhabditis elegans has two breakdown pathways for the short-chain fatty acid propionate: a canonical, vitamin B12-dependent pathway and a propionate shunt that is used when vitamin B12 levels are low. The shunt pathway is kept off when there is sufficient flux through the canonical pathway, likely to avoid generating shunt-specific toxic intermediates. Here, we discovered a transcriptional regulatory circuit that activates shunt gene expression upon propionate buildup. Nuclear hormone receptor 10 (NHR-10) and NHR-68 function together as a "persistence detector" in a type 1, coherent feed-forward loop ...


Neurexin Directs Partner-Specific Synaptic Connectivity In C. Elegans, Alison Philbrook, Shankar Ramachandran, Christopher M. Lambert, Devyn Oliver, Jeremy Florman, Mark J. Alkema, Michele Lemons, Michael M. Francis Jul 2018

Neurexin Directs Partner-Specific Synaptic Connectivity In C. Elegans, Alison Philbrook, Shankar Ramachandran, Christopher M. Lambert, Devyn Oliver, Jeremy Florman, Mark J. Alkema, Michele Lemons, Michael M. Francis

Open Access Articles

In neural circuits, individual neurons often make projections onto multiple postsynaptic partners. Here, we investigate molecular mechanisms by which these divergent connections are generated, using dyadic synapses in C. elegans as a model. We report that C. elegans nrx-1/neurexin directs divergent connectivity through differential actions at synapses with partnering neurons and muscles. We show that cholinergic outputs onto neurons are, unexpectedly, located at previously undefined spine-like protrusions from GABAergic dendrites. Both these spine-like features and cholinergic receptor clustering are strikingly disrupted in the absence of nrx-1. Excitatory transmission onto GABAergic neurons, but not neuromuscular transmission, is also disrupted. Our ...


Uncovering Transcriptional Activators And Targets Of Hsf-1 In Caenorhabditis Elegans, Jessica Brunquell Apr 2017

Uncovering Transcriptional Activators And Targets Of Hsf-1 In Caenorhabditis Elegans, Jessica Brunquell

Graduate Theses and Dissertations

In order to survive, cells must be able to cope with a variety of environmental stressors. The heat shock response (HSR) is a pro-survival mechanism employed by cells in response to protein denaturing stress, such as heat. Since its discovery in 1960, the heat shock response has been found to be regulated by the transcription factor heat shock factor 1 (HSF1). During periods of increased stress, HSF1 undergoes a multi-step process of activation that involves homotrimerization, DNA-binding, and post-translational regulatory modifications, all of which ultimately function to control the transcription of chaperone genes. These chaperone genes encode molecular chaperone proteins ...


Efn-4 Functions In Lad-2-Mediated Axon Guidance In Caenorhabditis Elegans, Alicia A. Schwieterman, Cory J. Donelson, Jonathan L. Mcmurry, Martin L. Hudson Mar 2017

Efn-4 Functions In Lad-2-Mediated Axon Guidance In Caenorhabditis Elegans, Alicia A. Schwieterman, Cory J. Donelson, Jonathan L. Mcmurry, Martin L. Hudson

Jonathan McMurry

During development of the nervous system, growing axons rely on guidance molecules to direct axon pathfinding. A well-characterized family of guidance molecules are the membrane-associated ephrins, which together with their cognate Eph receptors, direct axon navigation in a contact-mediated fashion. InC. elegans, the ephrin-Eph signaling system is conserved and is best characterized for their roles in neuroblast migration during early embryogenesis. This study demonstrates a role for theC. elegansephrin EFN-4 in axon guidance. We provide both genetic and biochemical evidence that is consistent with theC. elegansdivergent L1 cell adhesion molecule LAD-2 acting as a non-canonical ephrin receptor to EFN-4 to ...


A Gene-Centered C. Elegans Protein-Dna Interaction Network Provides A Framework For Functional Predictions, Juan Fuxman Bass, Carles Pons, Lucie Kozlowski, John S. Reece-Hoyes, Shaleen Shrestha, Amy D. Holdorf, Akihiro Mori, Chad L. Myers, Albertha J. M. Walhout Oct 2016

A Gene-Centered C. Elegans Protein-Dna Interaction Network Provides A Framework For Functional Predictions, Juan Fuxman Bass, Carles Pons, Lucie Kozlowski, John S. Reece-Hoyes, Shaleen Shrestha, Amy D. Holdorf, Akihiro Mori, Chad L. Myers, Albertha J. M. Walhout

Open Access Articles

Transcription factors (TFs) play a central role in controlling spatiotemporal gene expression and the response to environmental cues. A comprehensive understanding of gene regulation requires integrating physical protein-DNA interactions (PDIs) with TF regulatory activity, expression patterns, and phenotypic data. Although great progress has been made in mapping PDIs using chromatin immunoprecipitation, these studies have only characterized ~10% of TFs in any metazoan species. The nematode C. elegans has been widely used to study gene regulation due to its compact genome with short regulatory sequences. Here, we delineated the largest gene-centered metazoan PDI network to date by examining interactions between 90 ...


Efn-4 Functions In Lad-2-Mediated Axon Guidance In Caenorhabditis Elegans, Alicia A. Schwieterman, Cory J. Donelson, Jonathan L. Mcmurry, Martin L. Hudson Feb 2016

Efn-4 Functions In Lad-2-Mediated Axon Guidance In Caenorhabditis Elegans, Alicia A. Schwieterman, Cory J. Donelson, Jonathan L. Mcmurry, Martin L. Hudson

Faculty Publications

During development of the nervous system, growing axons rely on guidance molecules to direct axon pathfinding. A well-characterized family of guidance molecules are the membrane-associated ephrins, which together with their cognate Eph receptors, direct axon navigation in a contact-mediated fashion. InC. elegans, the ephrin-Eph signaling system is conserved and is best characterized for their roles in neuroblast migration during early embryogenesis. This study demonstrates a role for theC. elegansephrin EFN-4 in axon guidance. We provide both genetic and biochemical evidence that is consistent with theC. elegansdivergent L1 cell adhesion molecule LAD-2 acting as a non-canonical ephrin receptor to EFN-4 to ...


Reactive Oxygen Species-Mediated Neurodegeneration Is Independent Of The Ryanodine Receptor In Caenorhabditis Elegans, Lyndsay E.A. Young, Daniel C. Williams Oct 2015

Reactive Oxygen Species-Mediated Neurodegeneration Is Independent Of The Ryanodine Receptor In Caenorhabditis Elegans, Lyndsay E.A. Young, Daniel C. Williams

Journal of the South Carolina Academy of Science

Despite the significant impacts on human health caused by neurodegeneration, our understanding of the degeneration process is incomplete. The nematode Caenorhabditis elegans is emerging as a genetic model organism well suited for identification of conserved cellular mechanisms and molecular pathways of neurodegeneration. Studies in the worm have identified factors that contribute to neurodegeneration, including excitotoxicity and stress due to reactive oxygen species (ROS). Disruption of the gene unc-68, which encodes the ryanodine receptor, abolishes excitotoxic cell death, indicating a role for calcium (Ca2+) signaling in neurodegeneration. We tested the requirement for unc-68 in ROS-mediated neurodegeneration using the genetically encoded ...


Mapping And Analysis Of Caenorhabditis Elegans Transcription Factor Sequence Specificities, Kamesh Narasimhan, Samuel A. Lambert, Ally Yang, Jeremy Riddell, Sanie Mnaimneh, Hong Zheng, Mihai Albu, Hamed S. Najafabadi, John S. Reece-Hoyes, Juan Fuxman Bass, Albertha J. M. Walhout, Matthew T. Weirauch, Timothy R. Hughes Apr 2015

Mapping And Analysis Of Caenorhabditis Elegans Transcription Factor Sequence Specificities, Kamesh Narasimhan, Samuel A. Lambert, Ally Yang, Jeremy Riddell, Sanie Mnaimneh, Hong Zheng, Mihai Albu, Hamed S. Najafabadi, John S. Reece-Hoyes, Juan Fuxman Bass, Albertha J. M. Walhout, Matthew T. Weirauch, Timothy R. Hughes

Program in Systems Biology Publications and Presentations

Caenorhabditis elegans is a powerful model for studying gene regulation, as it has a compact genome and a wealth of genomic tools. However, identification of regulatory elements has been limited, as DNA-binding motifs are known for only 71 of the estimated 763 sequence-specific transcription factors (TFs). To address this problem, we performed protein binding microarray experiments on representatives of canonical TF families in C. elegans, obtaining motifs for 129 TFs. Additionally, we predict motifs for many TFs that have DNA-binding domains similar to those already characterized, increasing coverage of binding specificities to 292 C. elegans TFs (~40%). These data highlight ...


Mirnas Collaborate With A Conserved Rna Binding Protein To Ensure Development And Stress Response In C. Elegans, Rebecca A. Zabinsky Jan 2015

Mirnas Collaborate With A Conserved Rna Binding Protein To Ensure Development And Stress Response In C. Elegans, Rebecca A. Zabinsky

Molecular, Cellular, and Developmental Biology Graduate Theses & Dissertations

miRNAs play critical roles in development and other cellular processes in C. elegans even though most individual miRNAs are not essential for development or viability (Miska et al., 2007). Extensive studies in the field have suggested that most miRNA functions are executed through complex miRNA-target interaction networks. Furthermore, such networks may also function semi-redundantly with other regulatory systems to shape gene expression dynamics for proper physiological functions. Hypothesizing that miRNAs function in stress conditions, I collaborated with a postdoctoral fellow to investigate the role of a specific miRNA miR-71 in starvation induced L1 diapause. Hypothesizing that miRNAs collaborate with other ...


The Effects Of Supplemented Metabolites On Lifespan And Stress Response Pathways In Caenorhabditis Elegans, Clare B. Edwards Jan 2015

The Effects Of Supplemented Metabolites On Lifespan And Stress Response Pathways In Caenorhabditis Elegans, Clare B. Edwards

Graduate Theses and Dissertations

Understanding how metabolites contribute to anaplerosis, antioxidant effects, and hormetic pathways during aging is fundamental to creating supplements and dietary habits that may decrease age-associated disease and decline, thus improving the quality of life in old age. In order to uncover metabolic pathways that delay aging, the effects of large sets of metabolites associated with mitochondrial function on lifespan were investigated.

Malate, the tricarboxylic acid (TCA) cycle metabolite, increased lifespan and thermotolerance in C. elegans. Addition of fumarate and succinate also extended lifespan and all three metabolites activated nuclear translocation of the cytoprotective DAF-16/FOXO transcription factor and protected from ...


Investigation Of Fshr-L Protein Function In Regulating Synaptic Transmission At The Neuromuscular Junction In C. Elegans, Julie Christine Kolnik May 2014

Investigation Of Fshr-L Protein Function In Regulating Synaptic Transmission At The Neuromuscular Junction In C. Elegans, Julie Christine Kolnik

Undergraduate Honors Thesis Collection

euronal communication (synaptic transmission) is critical for nervous system function. This communication occurs at specialized junctions called synapses where chemical neurotransmitters signal from presynaptic to postsynaptic cells. Additional signaling via neuropeptide activated G protein-coupled receptors (GPCRs) fine-tunes synaptic communication. GPCRs are a large family of transmembrane receptor proteins that bind extracellular neurotransmitters and neuropeptides to activate intracellular signaling pathways. My project investigated the function of FSHR-l, a GPCR and potential neuropeptide receptor, in regulating synaptic transmission at the neuromuscular junction (NMJ) in Caenorhabditis elegans roundworms, which share conservation of nervous system structure and function with humans. Worms lacking the fshr-I ...


Transcriptional Regulation Of Caenorhabditis Elegans Foxo/Daf-16 Modulates Lifespan, Ankita Bansal, Eun-Soo Kwon, Darryl Conte Jr., Haibo Liu, Michael J. Gilchrist, Lesley T. Macneil, Heidi A. Tissenbaum Apr 2014

Transcriptional Regulation Of Caenorhabditis Elegans Foxo/Daf-16 Modulates Lifespan, Ankita Bansal, Eun-Soo Kwon, Darryl Conte Jr., Haibo Liu, Michael J. Gilchrist, Lesley T. Macneil, Heidi A. Tissenbaum

Program in Gene Function and Expression Publications and Presentations

BACKGROUND: Insulin/IGF-1 signaling plays a central role in longevity across phylogeny. In C. elegans, the forkhead box O (FOXO) transcription factor, DAF-16, is the primary target of insulin/IGF-1 signaling, and multiple isoforms of DAF-16 (a, b, and d/f) modulate lifespan, metabolism, dauer formation, and stress resistance. Thus far, across phylogeny modulation of mammalian FOXOs and DAF-16 have focused on post-translational regulation with little focus on transcriptional regulation. In C. elegans, we have previously shown that DAF-16d/f cooperates with DAF-16a to promote longevity. In this study, we generated transgenic strains expressing near-endogenous levels of either daf-16a or ...


Using Rnai In C. Elegans To Demonstrate Gene Knockdown Phenotypes In The Undergraduate Biology Lab Setting, Nicole Roy May 2013

Using Rnai In C. Elegans To Demonstrate Gene Knockdown Phenotypes In The Undergraduate Biology Lab Setting, Nicole Roy

Biology Faculty Publications

RNA interference (RNAi) is a powerful technology used to knock down genes in basic research and medicine. In 2006 RNAi technology using Caenorhabditis elegans (C. elegans) was awarded the Nobel Prize in medicine and thus students graduating in the biological sciences should have experience with this technology. However, students struggle conceptually with the molecular biology behind the RNAi technology and find the technology difficult to grasp. To this end, we have provided a simple, streamlined and inexpensive RNAi procedure using C. elegans that can be adopted in upper level biology classes. By using an unknown RNAi-producing bacteria, students perform novel ...


Regulation Of C. Elegans Developmental Timing By The Gata Transcription Factor Elt-1, Max Louis Cohen Jan 2013

Regulation Of C. Elegans Developmental Timing By The Gata Transcription Factor Elt-1, Max Louis Cohen

Molecular, Cellular, and Developmental Biology Graduate Theses & Dissertations

The heterochronic gene network controls developmental timing in the nematode roundworm Caenorhabditis elegans. Bi-stable switch-like changes in gene expression occur during its development as stage-specific microRNAs are expressed and subsequently down-regulate other stage-specific factors, allowing for developmental progression. Key genes in this regulatory network are phylogenetically conserved and include the post-transcriptional microRNA repressor lin-28; the nuclear hormone receptor daf-12; and the microRNAs lin-4, mir-48, mir-84, mir-241, and let-7. daf-12 is the only factor currently known to regulate transcription of the Let-7 microRNA family, but its contribution is insufficient to account for all of the transcriptional regulation observed. In this work ...


Sirt1 Regulation Of The Heat Shock Response In An Hsf1-Dependent Manner And The Impact Of Caloric Restriction, Rachel Rene Raynes Jan 2013

Sirt1 Regulation Of The Heat Shock Response In An Hsf1-Dependent Manner And The Impact Of Caloric Restriction, Rachel Rene Raynes

Graduate Theses and Dissertations

The heat shock response (HSR) is the cell's molecular reaction to protein damaging stress and is critical in the management of denatured proteins. Activation of HSF1, the master transcriptional regulator of the HSR, results in the induction of molecular chaperones called heat shock proteins (HSPs). Transcription of hsp genes is promoted by the hyperphosphorylation of HSF1, while the attenuation of the HSR is regulated by a dual mechanism involving negative feedback inhibition from HSPs and acetylation at a critical lysine residue within the DNA binding domain of HSF1, which results in a loss of affinity for DNA. SIRT1 is ...


Regulation And Dynamic Behavior Of The Heat Shock Transcription Factor Hsf-1 In C. Elegans, Elizabeth A. Morton Jan 2013

Regulation And Dynamic Behavior Of The Heat Shock Transcription Factor Hsf-1 In C. Elegans, Elizabeth A. Morton

Publicly Accessible Penn Dissertations

Eukaryotic cells respond to heat stress by activating the transcription factor HSF1. In addition to its role in stress response, HSF1 also functions in protein homeostasis, aging, innate immunity, and cancer. Despite prominent HSF1 involvement in processes pertinent to human health and disease, there are still gaps in our understanding of HSF1. For example, controversy exists regarding the localization of HSF1, the identity of HSF1 regulators, and the function and conservation of heat-induced HSF1 stress granules. Many of the physiological roles for HSF1 have been defined using the model organism Caenorhabditis elegans, yet little is known about how the molecular ...


Apoptosis In Neurodegeneration: Programmed Cell Death And Its Role In Alzheimer’S And Huntington’S Diseases, Elizabeth Dean Mar 2008

Apoptosis In Neurodegeneration: Programmed Cell Death And Its Role In Alzheimer’S And Huntington’S Diseases, Elizabeth Dean

Eukaryon

Chronic neurodegenerative diseases are characterized by progressive, irreversible neuronal cell loss. Since neurons have minimal regenerative potential, preventing their degeneration is vital to preventing disease progression; however, few effective therapies currently exist. Research in the last two decades has focused on uncovering neuronal cell loss mechanisms in hopes of devising new treatment strategies. These studies have evaluated the potential role of apoptosis within neurodegenerative diseases. Investigations of programmed cell death and its role in neurodegenerative disease has shed light on the possible apoptotic mechanisms employed by these disorders. This article will review general mechanisms of apoptosis and their implications within ...