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  1. Article ; Online: EGFR signal transduction is downregulated in C. elegans vulval precursor cells during dauer diapause.

    O'Keeffe, Catherine / Greenwald, Iva

    Development (Cambridge, England)

    2022  Volume 149, Issue 21

    Abstract: Caenorhabditis elegans larvae display developmental plasticity in response to environmental conditions: in adverse conditions, second-stage larvae enter a reversible, long-lived dauer stage instead of proceeding to reproductive adulthood. Dauer entry ... ...

    Abstract Caenorhabditis elegans larvae display developmental plasticity in response to environmental conditions: in adverse conditions, second-stage larvae enter a reversible, long-lived dauer stage instead of proceeding to reproductive adulthood. Dauer entry interrupts vulval induction and is associated with a reprogramming-like event that preserves the multipotency of vulval precursor cells (VPCs), allowing vulval development to reinitiate if conditions improve. Vulval induction requires the LIN-3/EGF-like signal from the gonad, which activates EGFR-Ras-ERK signal transduction in the nearest VPC, P6.p. Here, using a biosensor and live imaging we show that EGFR-Ras-ERK activity is downregulated in P6.p in dauers. We investigated this process using gene mutations or transgenes to manipulate different steps of the pathway, and by analyzing LET-23/EGFR subcellular localization during dauer life history. We found that the response to EGF is attenuated at or upstream of Ras activation, and discuss potential membrane-associated mechanisms that could achieve this. We also describe other findings pertaining to the maintenance of VPC competence and quiescence in dauer larvae. Our analysis indicates that VPCs have L2-like and unique dauer stage features rather than features of L3 VPCs in continuous development.
    MeSH term(s) Animals ; Female ; Caenorhabditis elegans/metabolism ; Caenorhabditis elegans Proteins/metabolism ; Epidermal Growth Factor/genetics ; Epidermal Growth Factor/metabolism ; Vulva ; Signal Transduction/genetics ; Diapause ; ErbB Receptors/genetics ; ErbB Receptors/metabolism
    Chemical Substances Caenorhabditis elegans Proteins ; Epidermal Growth Factor (62229-50-9) ; ErbB Receptors (EC 2.7.10.1)
    Language English
    Publishing date 2022-10-31
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 90607-4
    ISSN 1477-9129 ; 0950-1991
    ISSN (online) 1477-9129
    ISSN 0950-1991
    DOI 10.1242/dev.201094
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Genetic analysis of DAF-18/PTEN missense mutants for the ability to maintain quiescence of the somatic gonad and germ line in Caenorhabditis elegans dauer larvae.

    Wittes, Julia / Greenwald, Iva

    G3 (Bethesda, Md.)

    2022  Volume 12, Issue 6

    Abstract: The mammalian tumor suppressor PTEN has well-established lipid phosphatase and protein phosphatase activities. DAF-18, the Caenorhabditis elegans ortholog of PTEN, has a high degree of conservation in the catalytic domain, and human PTEN complements a ... ...

    Abstract The mammalian tumor suppressor PTEN has well-established lipid phosphatase and protein phosphatase activities. DAF-18, the Caenorhabditis elegans ortholog of PTEN, has a high degree of conservation in the catalytic domain, and human PTEN complements a null allele of daf-18, suggesting conserved protein function. Insights gleaned from studies of mammalian PTEN have been applied to studies of DAF-18 in C. elegans, including predicted enzymatic properties of mutants. Here, we characterize DAF-18 missense mutants previously treated as selectively disrupting either protein or lipid phosphatase activity in genetic assays to connect distinct phenotypes to specific enzymatic activities of DAF-18/PTEN. We analyze the ability of these mutants to maintain quiescence of the somatic gonad and germ line in dauer larvae, a state of diapause during which development is suspended. We show that transgenes expressing either the putative lipid phosphatase-deficient or putative protein phosphatase-deficient form fail to complement a daf-18 null allele, and that the corresponding homozygous endogenous missense mutant alleles fail to maintain developmental quiescence. We also show that the endogenous daf-18 missense alleles fail to complement each other, suggesting that one or both of the missense forms are not activity-selective. Furthermore, homozygous daf-18 missense mutants have a more severe phenotype than a daf-18 null mutant, suggesting the presence of functionally compromised mutant DAF-18 is more deleterious than the absence of DAF-18. We discuss how these genetic properties complicate the interpretation of genetic assays to associate specific enzymatic activities with specific phenotypes.
    MeSH term(s) Animals ; Caenorhabditis elegans/metabolism ; Caenorhabditis elegans Proteins/genetics ; Caenorhabditis elegans Proteins/metabolism ; Germ Cells/metabolism ; Gonads/metabolism ; Larva ; Lipids ; Mammals ; Mutation
    Chemical Substances Caenorhabditis elegans Proteins ; DAF-18 protein, C elegans ; Lipids
    Language English
    Publishing date 2022-04-21
    Publishing country England
    Document type Journal Article
    ZDB-ID 2629978-1
    ISSN 2160-1836 ; 2160-1836
    ISSN (online) 2160-1836
    ISSN 2160-1836
    DOI 10.1093/g3journal/jkac093
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  3. Article ; Online: Floxed exon (Flexon): A flexibly positioned stop cassette for recombinase-mediated conditional gene expression.

    Shaffer, Justin M / Greenwald, Iva

    Proceedings of the National Academy of Sciences of the United States of America

    2022  Volume 119, Issue 3

    Abstract: Conditional gene expression is a powerful tool for genetic analysis of biological phenomena. In the widely used "lox-stop-lox" approach, insertion of a stop cassette consisting of a series of stop codons and polyadenylation signals flanked ... ...

    Abstract Conditional gene expression is a powerful tool for genetic analysis of biological phenomena. In the widely used "lox-stop-lox" approach, insertion of a stop cassette consisting of a series of stop codons and polyadenylation signals flanked by
    MeSH term(s) Animals ; Caenorhabditis elegans/metabolism ; DNA Nucleotidyltransferases ; Exons ; Gene Expression ; Green Fluorescent Proteins/metabolism ; Integrases ; Promoter Regions, Genetic ; RNA Interference ; Recombinases/metabolism ; Recombination, Genetic ; Transgenes
    Chemical Substances Recombinases ; Green Fluorescent Proteins (147336-22-9) ; Cre recombinase (EC 2.7.7.-) ; DNA Nucleotidyltransferases (EC 2.7.7.-) ; Integrases (EC 2.7.7.-) ; Site-specific recombinase (EC 2.7.7.-)
    Language English
    Publishing date 2022-01-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2117451119
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  4. Article ; Online: SALSA, a genetically encoded biosensor for spatiotemporal quantification of Notch signal transduction in vivo.

    Shaffer, Justin M / Greenwald, Iva

    Developmental cell

    2022  Volume 57, Issue 7, Page(s) 930–944.e6

    Abstract: Notch-mediated lateral specification is a fundamental mechanism to resolve stochastic cell fate choices by amplifying initial differences between equivalent cells. To study how stochastic events impact Notch activity, we developed a biosensor, SALSA ( ... ...

    Abstract Notch-mediated lateral specification is a fundamental mechanism to resolve stochastic cell fate choices by amplifying initial differences between equivalent cells. To study how stochastic events impact Notch activity, we developed a biosensor, SALSA (sensor able to detect lateral signaling activity), consisting of an amplifying "switch"-Notch tagged with TEV protease-and a "reporter"-GFP fused to a nuclearly localized red fluorescent protein, separated by a TEVp cut site. When ligand activates Notch, TEVp enters the nucleus and releases GFP from its nuclear tether, allowing Notch activation to be quantified based on the changes in GFP subcellular localization. We show that SALSA accurately reports Notch activity in different signaling paradigms in Caenorhabditis elegans and use time-lapse imaging to test hypotheses about how stochastic elements ensure a reproducible and robust outcome in a canonical lin-12/Notch-mediated lateral signaling paradigm. SALSA should be generalizable to other experimental systems and be adaptable to increase options for bespoke "SynNotch" applications.
    MeSH term(s) Animals ; Biosensing Techniques ; Caenorhabditis elegans/genetics ; Caenorhabditis elegans/metabolism ; Caenorhabditis elegans Proteins/genetics ; Caenorhabditis elegans Proteins/metabolism ; Female ; Receptors, Notch/genetics ; Receptors, Notch/metabolism ; Signal Transduction/physiology ; Vulva
    Chemical Substances Caenorhabditis elegans Proteins ; Receptors, Notch
    Language English
    Publishing date 2022-04-22
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2054967-2
    ISSN 1878-1551 ; 1534-5807
    ISSN (online) 1878-1551
    ISSN 1534-5807
    DOI 10.1016/j.devcel.2022.03.008
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  5. Article ; Online: WormBook: WormBiology for the 21st Century.

    Greenwald, Iva

    Genetics

    2016  Volume 202, Issue 3, Page(s) 883–884

    MeSH term(s) Animals ; Caenorhabditis elegans/genetics ; Databases, Factual ; Internet ; Periodicals as Topic ; Reference Books ; Review Literature as Topic
    Language English
    Publishing date 2016-03
    Publishing country United States
    Document type Editorial
    ZDB-ID 2167-2
    ISSN 1943-2631 ; 0016-6731
    ISSN (online) 1943-2631
    ISSN 0016-6731
    DOI 10.1534/genetics.116.187575
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  6. Article ; Online: Influences of HLH-2 stability on anchor cell fate specification during Caenorhabditis elegans gonadogenesis.

    Benavidez, Justin M / Kim, Jee Hun / Greenwald, Iva

    G3 (Bethesda, Md.)

    2022  Volume 12, Issue 4

    Abstract: The Caenorhabditis elegans E protein ortholog HLH-2 is required for the specification and function of the anchor cell, a unique, terminally differentiated somatic gonad cell that organizes uterine and vulval development. Initially, 4 cells-2 α cells and ... ...

    Abstract The Caenorhabditis elegans E protein ortholog HLH-2 is required for the specification and function of the anchor cell, a unique, terminally differentiated somatic gonad cell that organizes uterine and vulval development. Initially, 4 cells-2 α cells and their sisters, the β cells-have the potential to be the sole anchor cell. The β cells rapidly lose anchor cell potential and invariably become ventral uterine precursor cells, while the 2 α cells interact via LIN-12/Notch to resolve which will be the anchor cell and which will become another ventral uterine precursor cell. HLH-2 protein stability is dynamically regulated in cells with anchor cell potential; initially present in all 4 cells, HLH-2 is degraded in presumptive ventral uterine precursor cells while remaining stable in the anchor cell. Here, we demonstrate that stability of HLH-2 protein is regulated by the activity of lin-12/Notch in both α and β cells. Our analysis provides evidence that activation of LIN-12 promotes degradation of HLH-2 as part of a negative feedback loop during the anchor cell/ventral uterine precursor cell decision by the α cells, and that absence of lin-12 activity in β cells increases HLH-2 stability and may account for their propensity to adopt the anchor cell fate in a lin-12 null background. We also performed an RNA interference screen of 232 ubiquitin-related genes and identified 7 genes that contribute to HLH-2 degradation in ventral uterine precursor cells; however, stabilizing HLH-2 by depleting ubiquitin ligases in a lin-12(+) background does not result in supernumerary anchor cells, suggesting that LIN-12 activation does not oppose hlh-2 activity solely by causing HLH-2 protein degradation. Finally, we provide evidence for lin-12-independent transcriptional regulation of hlh-2 in β cells that correlates with known differences in POP-1/TCF levels and anchor cell potential between α and β cells. Together, our results indicate that hlh-2 activity is regulated at multiple levels to restrict the anchor cell fate to a single cell.
    MeSH term(s) Animals ; Basic Helix-Loop-Helix Transcription Factors/metabolism ; Caenorhabditis elegans/metabolism ; Caenorhabditis elegans Proteins/metabolism ; Female ; Receptors, Notch/genetics ; Receptors, Notch/metabolism ; Sex Differentiation ; Vulva/metabolism
    Chemical Substances Basic Helix-Loop-Helix Transcription Factors ; Caenorhabditis elegans Proteins ; HLH-2 protein, C elegans ; Receptors, Notch
    Language English
    Publishing date 2022-02-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 2629978-1
    ISSN 2160-1836 ; 2160-1836
    ISSN (online) 2160-1836
    ISSN 2160-1836
    DOI 10.1093/g3journal/jkac028
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  7. Article: Music, Math, and Working Memory: Magnetoencephalography Mapping of Brain Activation in Musicians.

    Lu, Ching-I / Greenwald, Margaret / Lin, Yung-Yang / Bowyer, Susan M

    Frontiers in human neuroscience

    2022  Volume 16, Page(s) 866256

    Abstract: Musical transposing is highly demanding of working memory, as it involves mentally converting notes from one musical key (i.e., pitch scale) to another key for singing or instrumental performance. Because musical transposing involves mental adjustment of ...

    Abstract Musical transposing is highly demanding of working memory, as it involves mentally converting notes from one musical key (i.e., pitch scale) to another key for singing or instrumental performance. Because musical transposing involves mental adjustment of notes up or down by a specific amount, it may share cognitive elements with arithmetical operations of addition and subtraction. We compared brain activity during high and low working memory load conditions of musical transposing versus math calculations in classically trained musicians. Magnetoencephalography (MEG) was sensitive to differences of task and working memory load. Frontal-occipital connections were highly active during transposing, but not during math calculations. Right motor and premotor regions were highly active in the more difficult condition of the transposing task. Multiple frontal lobe regions were highly active across tasks, including the left medial frontal area during both transposing and calculation tasks but the right medial frontal area only during calculations. In the more difficult calculation condition, right temporal regions were highly active. In coherence analyses and neural synchrony analyses, several similarities were seen across calculation tasks; however, latency analyses were sensitive to differences in task complexity across the calculation tasks due to the high temporal resolution of MEG. MEG can be used to examine musical cognition and the neural consequences of music training. Further systematic study of brain activity during high versus low memory load conditions of music and other cognitive tasks is needed to illuminate the neural bases of enhanced working memory ability in musicians as compared to non-musicians.
    Language English
    Publishing date 2022-05-16
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2425477-0
    ISSN 1662-5161
    ISSN 1662-5161
    DOI 10.3389/fnhum.2022.866256
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  8. Article ; Online: Cell Non-autonomous Function of daf-18/PTEN in the Somatic Gonad Coordinates Somatic Gonad and Germline Development in C. elegans Dauer Larvae.

    Tenen, Claudia C / Greenwald, Iva

    Current biology : CB

    2019  Volume 29, Issue 6, Page(s) 1064–1072.e8

    Abstract: C. elegans larvae integrate environmental information and developmental decisions [1-3]. In favorable conditions, worms develop rapidly and continuously through four larval stages into reproductive adulthood. However, if conditions are unfavorable ... ...

    Abstract C. elegans larvae integrate environmental information and developmental decisions [1-3]. In favorable conditions, worms develop rapidly and continuously through four larval stages into reproductive adulthood. However, if conditions are unfavorable through the second larval stage, worms enter dauer diapause, a state of global and reversible developmental arrest in which precursor cells remain quiescent and preserve developmental potential, anticipating developmental progression if conditions improve. Signaling from neurons, hypodermis, and intestine regulate the appearance and behavior of dauer larvae and many aspects of developmental arrest of the non-gonadal soma [1, 4, 5]. Here, we show that the decision of somatic gonad blast cells (SGBs) and germline stem cells (GSCs) to be quiescent or progress developmentally is regulated differently from the non-gonadal soma: daf-18/PTEN acts non-autonomously within the somatic gonad to maintain developmental quiescence of both SGBs and GSCs. Our analysis suggests that daf-18 acts in somatic gonad cells to produce a "pro-quiescence" signal (or signals) that acts inter se and between the somatic gonad and the germline. The inferred signal does not require DAF-2/insulin receptor or maintain quiescence of the nearby sex myoblasts, and developmental progression in daf-18(0) does not require dafachronic acids. Abrogating quiescence in dauer results in post-dauer sterility. Our results implicate the somatic gonad as an endocrine organ to synchronize somatic gonad and germline development during dauer diapause and recovery, and our finding that PTEN acts non-autonomously to control blast cell quiescence may be relevant to its function as a tumor suppressor in mammals and to combating parasitic nematodes.
    MeSH term(s) Animals ; Caenorhabditis elegans/genetics ; Caenorhabditis elegans/growth & development ; Caenorhabditis elegans Proteins/genetics ; Caenorhabditis elegans Proteins/metabolism ; Germ Cells/growth & development ; Gonads/growth & development ; Larva/genetics ; Larva/growth & development
    Chemical Substances Caenorhabditis elegans Proteins ; DAF-18 protein, C elegans
    Language English
    Publishing date 2019-02-28
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2019.01.076
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  9. Article ; Online: Molecular basis of Gabija anti-phage supramolecular assemblies.

    Yang, Xiao-Yuan / Shen, Zhangfei / Xie, Jiale / Greenwald, Jacelyn / Marathe, Ila / Lin, Qingpeng / Xie, Wen Jun / Wysocki, Vicki H / Fu, Tian-Min

    Nature structural & molecular biology

    2024  

    Abstract: As one of the most prevalent anti-phage defense systems in prokaryotes, Gabija consists of a Gabija protein A (GajA) and a Gabija protein B (GajB). The assembly and function of the Gabija system remain unclear. Here we present cryo-EM structures of ... ...

    Abstract As one of the most prevalent anti-phage defense systems in prokaryotes, Gabija consists of a Gabija protein A (GajA) and a Gabija protein B (GajB). The assembly and function of the Gabija system remain unclear. Here we present cryo-EM structures of Bacillus cereus GajA and GajAB complex, revealing tetrameric and octameric assemblies, respectively. In the center of the complex, GajA assembles into a tetramer, which recruits two sets of GajB dimer at opposite sides of the complex, resulting in a 4:4 GajAB supramolecular complex for anti-phage defense. Further biochemical analysis showed that GajA alone is sufficient to cut double-stranded DNA and plasmid DNA, which can be inhibited by ATP. Unexpectedly, the GajAB displays enhanced activity for plasmid DNA, suggesting a role of substrate selection by GajB. Together, our study defines a framework for understanding anti-phage immune defense by the GajAB complex.
    Language English
    Publishing date 2024-04-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2126708-X
    ISSN 1545-9985 ; 1545-9993
    ISSN (online) 1545-9985
    ISSN 1545-9993
    DOI 10.1038/s41594-024-01283-w
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  10. Article ; Online: HIV chronicity as a predictor of hippocampal memory deficits in daily cannabis users living with HIV.

    Woodcock, Eric A / Greenwald, Mark K / Chen, Irene / Feng, Danni / Cohn, Jonathan A / Lundahl, Leslie H

    Drug and alcohol dependence reports

    2023  Volume 9, Page(s) 100189

    Abstract: Background: Antiretroviral medications have increased the lifespan of persons living with HIV (PLWH) thereby unmasking memory decline that may be attributed to chronological age, HIV symptomatology, HIV disease chronicity, and/or substance use ( ... ...

    Abstract Background: Antiretroviral medications have increased the lifespan of persons living with HIV (PLWH) thereby unmasking memory decline that may be attributed to chronological age, HIV symptomatology, HIV disease chronicity, and/or substance use (especially cannabis use which is common among PLWH). To date, few studies have attempted to disentangle these effects. In a sample of daily cannabis-using PLWH, we investigated whether hippocampal memory function, assessed via an object-location associative learning task, was associated with age, HIV chronicity and symptom severity, or substance use.
    Methods: 48 PLWH (12.9 ± 9.6 years since HIV diagnosis), who were 44 years old on average (range: 24-64 years; 58 % male) and reported daily cannabis use (recent use confirmed by urinalysis) completed the study. We assessed each participant's demographics, substance use, medical history, current HIV symptoms, and hippocampal memory function via a well-validated object-location associative learning task.
    Results: Multiple regression analyses found that living more years since HIV+ diagnosis predicted significantly worse associative learning total score (
    Conclusions: In daily cannabis-using PLWH, HIV chronicity was related to worse hippocampal memory function independent from cannabis use, age, and HIV symptomatology. Object-location associative learning performance could serve as an 'early-warning' metric of cognitive decline among PLWH. Future research should examine longitudinal changes in associative learning proficiency and evaluate interventions to prevent hippocampal memory decline among PLWH. ClinicalTrials.gov: NCT01536899.
    Language English
    Publishing date 2023-09-13
    Publishing country Netherlands
    Document type Journal Article
    ISSN 2772-7246
    ISSN (online) 2772-7246
    DOI 10.1016/j.dadr.2023.100189
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