scholarly journals Prostaglandins temporally regulate cytoplasmic actin bundle formation during Drosophila oogenesis

2014 ◽  
Vol 25 (3) ◽  
pp. 397-411 ◽  
Author(s):  
Andrew J. Spracklen ◽  
Daniel J. Kelpsch ◽  
Xiang Chen ◽  
Cassandra N. Spracklen ◽  
Tina L. Tootle
Keyword(s):  
Elongation Factor ◽  
Low Frequency ◽  
Actin Dynamics ◽  
Nurse Cells ◽  
Wild Type ◽  
Actin Remodeling ◽  
Drosophila Oogenesis ◽  
Cytoplasmic Actin ◽  
Temporal Restriction ◽  
Filament Bundle

Prostaglandins (PGs)—lipid signals produced downstream of cyclooxygenase (COX) enzymes—regulate actin dynamics in cell culture and platelets, but their roles during development are largely unknown. Here we define a new role for Pxt, the Drosophila COX-like enzyme, in regulating the actin cytoskeleton—temporal restriction of actin remodeling during oogenesis. PGs are required for actin filament bundle formation during stage 10B (S10B). In addition, loss of Pxt results in extensive early actin remodeling, including actin filaments and aggregates, within the posterior nurse cells of S9 follicles; wild-type follicles exhibit similar structures at a low frequency. Hu li tai shao (Hts-RC) and Villin (Quail), an actin bundler, localize to all early actin structures, whereas Enabled (Ena), an actin elongation factor, preferentially localizes to those in pxt mutants. Reduced Ena levels strongly suppress early actin remodeling in pxt mutants. Furthermore, loss of Pxt results in reduced Ena localization to the sites of bundle formation during S10B. Together these data lead to a model in which PGs temporally regulate actin remodeling during Drosophila oogenesis by controlling Ena localization/activity, such that in S9, PG signaling inhibits, whereas at S10B, it promotes Ena-dependent actin remodeling.

scholarly journals RUNX1 and REXO2 are associated with the heterogeneity and prognosis of IDH wild type lower grade glioma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haiwei Wang ◽  
Xinrui Wang ◽  
Liangpu Xu ◽  
Ji Zhang ◽  
Hua Cao
Keyword(s):  
Transcription Factor ◽  
Low Frequency ◽  
Tumor Grade ◽  
The Cancer Genome Atlas ◽  
Lower Grade ◽  
Wild Type ◽  
Lower Grade Glioma ◽  
Cancer Genome Atlas ◽  
Worse Prognosis ◽  
Genome Atlas

AbstractBased on isocitrate dehydrogenase (IDH) alterations, lower grade glioma (LGG) is divided into IDH mutant and wild type subgroups. However, the further classification of IDH wild type LGG was unclear. Here, IDH wild type LGG patients in The Cancer Genome Atlas and Chinese Glioma Genome Atlas were divided into two sub-clusters using non-negative matrix factorization. IDH wild type LGG patients in sub-cluster2 had prolonged overall survival and low frequency of CDKN2A alterations and low immune infiltrations. Differentially expressed genes in sub-cluster1 were positively correlated with RUNX1 transcription factor. Moreover, IDH wild type LGG patients with higher stromal score or immune score were positively correlated with RUNX1 transcription factor. RUNX1 and its target gene REXO2 were up-regulated in sub-cluster1 and associated with the worse prognosis of IDH wild type LGG. RUNX1 and REXO2 were associated with the higher immune infiltrations. Furthermore, RUNX1 and REXO2 were correlated with the worse prognosis of LGG or glioma. IDH wild type LGG in sub-cluster2 was hyper-methylated. REXO2 hyper-methylation was associated with the favorable prognosis of LGG or glioma. At last, we showed that, age, tumor grade and REXO2 expression were independent prognostic factors in IDH wild type LGG.

scholarly journals Microtubule–microtubule sliding by kinesin-1 is essential for normal cytoplasmic streaming in Drosophila oocytes

2016 ◽  
Vol 113 (34) ◽  
pp. E4995-E5004 ◽  
Author(s):  
Wen Lu ◽  
Michael Winding ◽  
Margot Lakonishok ◽  
Jill Wildonger ◽  
Vladimir I. Gelfand
Keyword(s):  
Cytoplasmic Streaming ◽  
Cell Types ◽  
Nurse Cells ◽  
Wild Type ◽  
Actin Cortex ◽  
Microtubule Motor ◽  
Multiple Cell ◽  
Cytoplasmic Microtubules ◽  
Two Populations

Cytoplasmic streaming in Drosophila oocytes is a microtubule-based bulk cytoplasmic movement. Streaming efficiently circulates and localizes mRNAs and proteins deposited by the nurse cells across the oocyte. This movement is driven by kinesin-1, a major microtubule motor. Recently, we have shown that kinesin-1 heavy chain (KHC) can transport one microtubule on another microtubule, thus driving microtubule–microtubule sliding in multiple cell types. To study the role of microtubule sliding in oocyte cytoplasmic streaming, we used a Khc mutant that is deficient in microtubule sliding but able to transport a majority of cargoes. We demonstrated that streaming is reduced by genomic replacement of wild-type Khc with this sliding-deficient mutant. Streaming can be fully rescued by wild-type KHC and partially rescued by a chimeric motor that cannot move organelles but is active in microtubule sliding. Consistent with these data, we identified two populations of microtubules in fast-streaming oocytes: a network of stable microtubules anchored to the actin cortex and free cytoplasmic microtubules that moved in the ooplasm. We further demonstrated that the reduced streaming in sliding-deficient oocytes resulted in posterior determination defects. Together, we propose that kinesin-1 slides free cytoplasmic microtubules against cortically immobilized microtubules, generating forces that contribute to cytoplasmic streaming and are essential for the refinement of posterior determinants.

Apoptosis in late stage Drosophila nurse cells does not require genes within the H99 deficiency

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1075-1082 ◽  
Author(s):  
K. Foley ◽  
L. Cooley
Keyword(s):  
Dna Fragmentation ◽  
Late Stage ◽  
Expression Patterns ◽  
Nuclear Material ◽  
Nurse Cells ◽  
Wild Type ◽  
Negative Regulators ◽  
Egg Chambers ◽  
Positive Regulators ◽  
Egg Chamber

We have determined that nurse cells are cleared from the Drosophila egg chamber by apoptosis. DNA fragmentation begins in nurse cells at stage 12, following the completion of cytoplasm transfer from the nurse cells to the oocyte. During stage 13, nurse cells increasingly contain highly fragmented DNA and disappear from the egg chamber concomitantly with the formation of apoptotic vesicles containing highly fragmented nuclear material. In dumpless mutant egg chambers that fail to complete cytoplasm transport from the nurse cells, DNA fragmentation is markedly delayed and begins during stage 13, when the majority of cytoplasm is lost from the nurse cells. These data suggest the presence of cytoplasmic factors in nurse cells that inhibit the initiation of DNA fragmentation. In addition, we have examined the ovarian expression patterns of regulatory genes implicated in Drosophila apoptosis. The positive regulators, reaper (rpr), head involution defective (hid) and grim, as well as the negative regulators, DIAP1 and DIAP2, are transcribed during oogenesis. However, germline clones homozygous for the deficiency Df(3)H99, which deletes rpr, hid and grim, undergo oogenesis in a manner morphologically indistinguishable from wild type, indicating that genes within this region are not necessary for apoptosis in nurse cells.

PATH-40. SPORADIC NF2 WILD-TYPE MULTIPLE MENINGIOMAS HARBOR DISTINCT DRIVER MUTATIONS

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi124-vi124
Author(s):  
Insa Prilop ◽  
Thomas Pinzer ◽  
Daniel Cahill ◽  
Priscilla Brastianos ◽  
Gabriele Schackert ◽  
...  
Keyword(s):  
Hot Spot ◽  
Low Frequency ◽  
Neurofibromatosis Type ◽  
Driver Mutations ◽  
Wild Type ◽  
Driver Genes ◽  
Who Grade ◽  
Genetic Changes ◽  
Histologic Subtype ◽  
Multiple Meningiomas

Abstract OBJECTIVE Multiple meningiomas (MM) are rare and present a unique management challenge. While the mutational landscape of single meningiomas has been extensively studied, understanding the molecular pathogenesis of sporadic MM remains incomplete. The objective of this study is to elucidate the genetic features of sporadic MM. METHODS We identified nine patients with MM (n=19) defined as ≥2 spatially separated synchronous or metachronous meningiomas. We profiled genetic changes in these tumors using next-generation sequencing (NGS) assay that covers a large number of targetable and frequently mutated genes in meningiomas including AKT1, KLF4, NF2, PIK3CA/PIK3R1, POLR2A, SMARCB1, SMO, SUFU, TRAF7, and the TERT promoter. RESULTS Most of MM were WHO grade 1 (n= 16, 84.2%). Within individual patients, no driver mutation was shared between separate tumors. All but two cases harbored different hot spot mutations in known meningioma-driver genes like TRAF7 (n= 5), PIK3CA (n= 4), AKT1 (n= 3), POLR2A (n=1) and SMO (n= 1). Moreover, individual tumors differed in histologic subtype in 8/9 patients. The low frequency of NF2 mutations in our series stands in contrast to previous studies that included hereditary cases arising in the setting of neurofibromatosis type 2 (NF2). CONCLUSIONS Our findings provide evidence for genomic inter-tumor heterogeneity and an independent molecular origin of sporadic NF2 wild-type MM. Furthermore, these findings suggest that genetic characterization of each lesion is warranted in sporadic MM.

Mutation at autosomal loci of Chinese hamster ovary cells: involvement of a high-frequency event silencing two linked alleles

1983 ◽  
Vol 3 (7) ◽  
pp. 1172-1181
Author(s):  
W E Bradley
Keyword(s):  
Cell Lines ◽  
Chinese Hamster Ovary ◽  
High Frequency ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Low Frequency ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Ovary Cells

Two classes of cell lines heterozygous at the galactokinase (glk) locus have been isolated from Chinese hamster ovary cells. Class I, selected by plating nonmutagenized wild-type cells at low density in medium containing 2-deoxygalactose at a partially selective concentration, underwent subsequent mutation to the glk-/- genotype at a low frequency (approximately 10(-6) per cell), which was increased by mutagenesis. Class II heterozygotes, isolated by sib selection from mutagenized wild-type cells, had a higher spontaneous frequency of mutation to the homozygous state (approximately 10(-4) per cell), which was not affected by mutagenesis. About half of the glk-/- mutants derived from a class II heterozygote, but not the heterozygote itself, were functionally hemizygous at the syntenic thymidine kinase (tk) locus. Similarly, a tk+/- heterozygote with characteristics analogous to the class II glk+/- cell lines underwent high-frequency mutation to tk-/-, and most of these mutants, but not the tk+/- heterozygote, were functionally hemizygous at the glk locus. A model is proposed, similar to that for the mutational events at the adenine phosphoribosyl transferase locus (W. E. C. Bradley and D. Letovanec, Somatic Cell Genet. 8:51-66, 1982), of two different events, high and low frequency, being responsible for mutation at either of the linked loci tk and glk. The low-frequency event may be a point mutation, but the high-frequency event, in many instances, involves coordinated inactivation of a portion of a chromosome carrying the two linked alleles. Class II heterozygotes would be generated as a result of a low-frequency event at one allele, and class I heterozygotes would be generated by a high-frequency event. Supporting this model was the demonstration that all class I glk+/- lines examined were functionally hemizygous at tk.

scholarly journals The Two ADF-H Domains of Twinfilin Play Functionally Distinct Roles in Interactions with Actin Monomers

2002 ◽  
Vol 13 (11) ◽  
pp. 3811-3821 ◽  
Author(s):  
Pauli J. Ojala ◽  
Ville O. Paavilainen ◽  
Maria K. Vartiainen ◽  
Roman Tuma ◽  
Alan G. Weeds ◽  
...  
Keyword(s):  
Binding Site ◽  
Binding Activity ◽  
Size Exclusion ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Actin Monomer ◽  
Wild Type ◽  
Native Page ◽  
Exclusion Chromatography

Twinfilin is a ubiquitous and abundant actin monomer–binding protein that is composed of two ADF-H domains. To elucidate the role of twinfilin in actin dynamics, we examined the interactions of mouse twinfilin and its isolated ADF-H domains with G-actin. Wild-type twinfilin binds ADP-G-actin with higher affinity (K D = 0.05 μM) than ATP-G-actin (K D = 0.47 μM) under physiological ionic conditions and forms a relatively stable (k off = 1.8 s−1) complex with ADP-G-actin. Data from native PAGE and size exclusion chromatography coupled with light scattering suggest that twinfilin competes with ADF/cofilin for the high-affinity binding site on actin monomers, although at higher concentrations, twinfilin, cofilin, and actin may also form a ternary complex. By systematic deletion analysis, we show that the actin-binding activity is located entirely in the two ADF-H domains of twinfilin. Individually, these domains compete for the same binding site on actin, but the C-terminal ADF-H domain, which has >10-fold higher affinity for ADP-G-actin, is almost entirely responsible for the ability of twinfilin to increase the amount of monomeric actin in cosedimentation assays. Isolated ADF-H domains associate with ADP-G-actin with rapid second-order kinetics, whereas the association of wild-type twinfilin with G-actin exhibits kinetics consistent with a two-step binding process. These data suggest that the association with an actin monomer induces a first-order conformational change within the twinfilin molecule. On the basis of these results, we propose a kinetic model for the role of twinfilin in actin dynamics and its possible function in cells.

scholarly journals Effects of Diazepam on Low-Frequency and High-Frequency Electrocortical γ-Power Mediated by α1- and α2-GABAA Receptors

2019 ◽  
Vol 20 (14) ◽  
pp. 3486 ◽  
Author(s):  
Julian I. Hofmann ◽  
Cornelius Schwarz ◽  
Uwe Rudolph ◽  
Bernd Antkowiak
Keyword(s):  
Power Density ◽  
Gabaa Receptors ◽  
Barrel Cortex ◽  
Spectral Power ◽  
Low Frequency ◽  
Electric Activity ◽  
Spectral Power Density ◽  
Wild Type ◽  
Potential Activity ◽  
Α2 Receptors

Patterns of spontaneous electric activity in the cerebral cortex change upon administration of benzodiazepines. Here we are testing the hypothesis that the prototypical benzodiazepine, diazepam, affects spectral power density in the low (20–50 Hz) and high (50–90 Hz) γ-band by targeting GABAA receptors harboring α1- and α2-subunits. Local field potentials (LFPs) and action potentials were recorded in the barrel cortex of wild type mice and two mutant strains in which the drug exclusively acted via GABAA receptors containing either α1- (DZα1-mice) or α2-subunits (DZα2-mice). In wild type mice, diazepam enhanced low γ-power. This effect was also evident in DZα2-mice, while diazepam decreased low γ-power in DZα1-mice. Diazepam increased correlated local LFP-activity in wild type animals and DZα2- but not in DZα1-mice. In all genotypes, spectral power density in the high γ-range and multi-unit action potential activity declined upon diazepam administration. We conclude that diazepam modifies low γ-power in opposing ways via α1- and α2-GABAA receptors. The drug’s boosting effect involves α2-receptors and an increase in local intra-cortical synchrony. Furthermore, it is important to make a distinction between high- and low γ-power when evaluating the effects of drugs that target GABAA receptors.

scholarly journals Domain II plays a crucial role in the function of ribosome recycling factor

2006 ◽  
Vol 393 (3) ◽  
pp. 767-777 ◽  
Author(s):  
Peng Guo ◽  
Liqiang Zhang ◽  
Hongjie Zhang ◽  
Yanming Feng ◽  
Guozhong Jing
Keyword(s):  
Crucial Role ◽  
Specific Interaction ◽  
Elongation Factor ◽  
Wild Type ◽  
Ribosome Recycling Factor ◽  
E Coli ◽  
Thermoanaerobacter Tengcongensis ◽  
The Individual

RRF (ribosome recycling factor) consists of two domains, and in concert with EF-G (elongation factor-G), triggers dissociation of the post-termination ribosomal complex. However, the function of the individual domains of RRF remains unclear. To clarify this, two RRF chimaeras, EcoDI/TteDII and TteDI/EcoDII, were created by domain swaps between the proteins from Escherichia coli and Thermoanaerobacter tengcongensis. The ribosome recycling activity of the RRF chimaeras was compared with their wild-type RRFs by using in vivo and in vitro activity assays. Like wild-type TteRRF (T. tengcongensis RRF), the EcoDI/TteDII chimaera is non-functional in E. coli, but both wild-type TteRRF, and EcoDI/TteDII can be activated by coexpression of T. tengcongensis EF-G in E. coli. By contrast, like wild-type E. coli RRF (EcoRRF), TteDI/EcoDII is fully functional in E. coli. These findings suggest that domain II of RRF plays a crucial role in the concerted action of RRF and EF-G for the post-termination complex disassembly, and the specific interaction between RRF and EF-G on ribosomes mainly depends on the interaction between domain II of RRF and EF-G. This study provides direct genetic and biochemical evidence for the function of the individual domains of RRF.

scholarly journals The phosphorylation status of Ser-637 in dynamin-related protein 1 (Drp1) does not determine Drp1 recruitment to mitochondria

2019 ◽  
Vol 294 (46) ◽  
pp. 17262-17277 ◽  
Author(s):  
Rong Yu ◽  
Tong Liu ◽  
Chenfei Ning ◽  
Fei Tan ◽  
Shao-Bo Jin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Mitochondrial Fission ◽  
Elongation Factor ◽  
Subcellular Fractionation ◽  
Related Protein ◽  
Wild Type ◽  
Mitochondrial Elongation ◽  
Elongation Factor 1 ◽  
Kinase A

Recruitment of the GTPase dynamin-related protein 1 (Drp1) to mitochondria is a central step required for mitochondrial fission. Reversible Drp1 phosphorylation has been implicated in the regulation of this process, but whether Drp1 phosphorylation at Ser-637 determines its subcellular localization and fission activity remains to be fully elucidated. Here, using HEK 293T cells and immunofluorescence, immunoblotting, RNAi, subcellular fractionation, co-immunoprecipitation assays, and CRISPR/Cas9 genome editing, we show that Drp1 phosphorylated at Ser-637 (Drp1pS637) resides both in the cytosol and on mitochondria. We found that the receptors mitochondrial fission factor (Mff) and mitochondrial elongation factor 1/2 (MIEF1/2) interact with and recruit Drp1pS637 to mitochondria and that elevated Mff or MIEF levels promote Drp1pS637 accumulation on mitochondria. We also noted that protein kinase A (PKA), which mediates phosphorylation of Drp1 on Ser-637, is partially present on mitochondria and interacts with both MIEFs and Mff. PKA knockdown did not affect the Drp1-Mff interaction, but slightly enhanced the interaction between Drp1 and MIEFs. In Drp1-deficient HEK 293T cells, both phosphomimetic Drp1-S637D and phospho-deficient Drp1-S637A variants, like wild-type Drp1, located to the cytosol and to mitochondria and rescued a Drp1 deficiency-induced mitochondrial hyperfusion phenotype. However, Drp1-S637D was less efficient than Drp1-WT and Drp1-S637A in inducing mitochondrial fission. In conclusion, the Ser-637 phosphorylation status in Drp1 is not a determinant that controls Drp1 recruitment to mitochondria.

scholarly journals Coronin-1 Function Is Required for Phagosome Formation

2005 ◽  
Vol 16 (7) ◽  
pp. 3077-3087 ◽  
Author(s):  
Ming Yan ◽  
Richard F. Collins ◽  
Sergio Grinstein ◽  
William S. Trimble
Keyword(s):  
Actin Polymerization ◽  
Coiled Coil ◽  
Dominant Negative ◽  
Actin Dynamics ◽  
Raw 264.7 Cells ◽  
Live Cells ◽  
Raw 264.7 ◽  
Dimerization Domain ◽  
Actin Remodeling ◽  
Downstream Signaling

Coronin-1 is an actin-associated protein whose function in actin dynamics has remained obscure. All coronin proteins have a variable N-terminal domain, followed by WD repeats and a C-terminal coiled-coil dimerization domain. Transfection of coronin-1-GFP into RAW 264.7 cells revealed that coronin rapidly and transiently associates with the phagosome. To determine if coronin is involved in mammalian phagocytosis we used a dominant-negative approach by expressing only the central WD domains. However, this caused cell rounding and dissociation from the substratum, hampering analysis of their phenotype. We therefore developed TAT-fusion constructs of coronin-1 WD domains to acutely introduce the recombinant protein fragment into live cells. We show that although TAT-WD has no effect on binding of opsonized RBCs to RAW 264.7 cells, receptor clustering or several downstream signaling events, lamellipodial extensions, and actin accumulation at the base of the bound particle were diminished. Furthermore, Arp3 accumulation at the phagosome was impaired after TAT-WD treatment. Interestingly, whereas coronin-1 also accumulates at the sites of actin remodeling associated with Salmonella invasion, TAT-WD had no effect on this process. Together, our data demonstrates that coronin-1 is required for an early step in phagosome formation, consistent with a role in actin polymerization.

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