scholarly journals Extracellular Localisation of the C-Terminus of DDX4 Confirmed by Immunocytochemistry and Fluorescence-Activated Cell Sorting

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 578 ◽  
Author(s):  
Yvonne L. Clarkson ◽  
Emma Weatherall ◽  
Martin Waterfall ◽  
Marie McLaughlin ◽  
Haojiang Lu ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Sorting ◽  
Ovarian Tissue ◽  
Fluorescence Activated Cell Sorting ◽  
Rt Pcr ◽  
Rna Helicases ◽  
Dead Box ◽  
C Terminus ◽  
Expression Construct ◽  
C And N

Putative oogonial stem cells (OSCs) have been isolated by fluorescence-activated cell sorting (FACS) from adult human ovarian tissue using an antibody against DEAD-box helicase 4 (DDX4). DDX4 has been reported to be germ cell specific within the gonads and localised intracellularly. White et al. (2012) hypothesised that the C-terminus of DDX4 is localised on the surface of putative OSCs but is internalised during the process of oogenesis. This hypothesis is controversial since it is assumed that RNA helicases function intracellularly with no extracellular expression. To determine whether the C-terminus of DDX4 could be expressed on the cell surface, we generated a novel expression construct to express full-length DDX4 as a DsRed2 fusion protein with unique C- and N-terminal epitope tags. DDX4 and the C-terminal myc tag were detected at the cell surface by immunocytochemistry and FACS of non-permeabilised human embryonic kidney HEK 293T cells transfected with the DDX4 construct. DDX4 mRNA expression was detected in the DDX4-positive sorted cells by RT-PCR. This study clearly demonstrates that the C-terminus of DDX4 can be expressed on the cell surface despite its lack of a conventional membrane-targeting or secretory sequence. These results validate the use of antibody-based FACS to isolate DDX4-positive putative OSCs.

Purification of functional lactotrophs and somatotrophs from female rats using fluorescence-activated cell sorting

1990 ◽  
Vol 126 (2) ◽  
pp. 269-274 ◽  
Author(s):  
D. Wynick ◽  
R. Critchley ◽  
M. S. Venetikou ◽  
J. M. Burrin ◽  
S. R. Bloom
Keyword(s):  
Cell Surface ◽  
Cell Sorting ◽  
Anterior Pituitary ◽  
Cell Types ◽  
Female Rats ◽  
Normal Female ◽  
Pituitary Cells ◽  
Female Rat ◽  
Fluorescence Activated Cell Sorting ◽  
Surface Labelling

ABSTRACT As the secretory granules of anterior pituitary cells fuse with the cell surface, there would appear to be sufficient hormone present on the cell surface to be labelled by polyclonal hormone antibodies and thus analysed by flow cytometry. We have therefore applied fluorescence-activated cell sorting to these labelled pituitary cells. Percentage purity and depletion of other cell types was assessed by immunocytochemistry and the reverse haemolytic plaque assay (RHPA). Results demonstrate that fluorescence-activated cell sorting allows almost complete purification of functional lactotrophs and somatotrophs to 96·7 ±1·7 (s.e.m.)% and 98±1·0% respectively by immunocytochemistry, and to 95·8 ±1·1% and 97±0·8% respectively by RHPA. Depletion of other anterior pituitary cell types to less than 2% was demonstrated by both immunocytochemistry and RHPA. Fluorescence-activated cell sorting to this degree of purity was routinely possible with cell yields of 91 ±3·4%. To obtain such purity/depletion, it was necessary to use specific antisera of high titre, at concentrations which ensured maximal cell-surface labelling associated with maximal stimulation of hormonal secretion by the appropriate hypothalamic stimulatory factor. Separating cells on the basis of the intensity of prolactin cell-surface labelling demonstrated a low level of binding of the prolactin antibody to gonadotrophs (but not of sufficient fluorescence intensity to be sorted into the prolactin enriched population), raising the possibility of prolactin receptors on gonadotrophs. We were unable to demonstrate the presence of mammosomatotrophs in the normal female rat, since purified lactotrophs did not contain or secrete GH nor did purified somatotrophs contain or secrete prolactin. Journal of Endocrinology (1990) 126, 269–274

scholarly journals Variant cell lines selected for alterations in the function of the hyaluronan receptor CD44 show differences in glycosylation.

1995 ◽  
Vol 182 (2) ◽  
pp. 431-437 ◽  
Author(s):  
J Lesley ◽  
N English ◽  
A Perschl ◽  
J Gregoroff ◽  
R Hyman
Keyword(s):  
Cell Surface ◽  
Cell Lines ◽  
Cell Sorting ◽  
Sodium Dodecyl ◽  
Parental Cell ◽  
Cell Surface Receptor ◽  
Fluorescence Activated Cell Sorting ◽  
Inactive State ◽  
Variant Cell ◽  
Constitutively Active

CD44 is a major cell surface receptor for the extracellular matrix glycosaminoglycan hyaluronan (HA). However, the ability of CD44 to bind ligand is strictly regulated. Three activation states of CD44 have been demonstrated: (a) inactive; (b) inducible (by certain CD44-specific mAb); and (c) constitutively active. Starting with two parental cell lines expressing CD44 in the inactive state, a pre-B cell (RAW 253) and a fibroblast (L cells), we used fluorescence-activated cell sorting with fluorescein-conjugated hyaluronan in the presence of inducing mAb to derive variant cell lines with CD44 in the inducible state. Constitutively active derivatives were isolated from the inducible variants by a further round of fluorescence-activated cell sorting in the absence of inducing antibody. However, constitutively active variants could not be isolated directly from parental cells expressing CD44 in the inactive state. These results suggest that two genetic events must occur to obtain an active CD44-HA receptor from an inactive receptor. Variant and parental cell-derived CD44 molecules exhibited differences in migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis that were partly attributable to differences in N-linked glycosylation. Furthermore, culture in tunicamycin for 2-3 d converted parental and inducible cell lines into cells showing constitutive CD44-mediated HA binding. Also, removal of cell surface glycosaminoglycan chains by culture of cells in p-nitrophenyl beta-D-xylopyranoside or treatment with chondroitinase ABC resulted in conversion of cells with an inactive CD44 receptor to an inducible state. These results indicate that carbohydrate side chains of CD44 and/or other molecules on the cell surface that interact with CD44 are potentially involved in regulating the HA-binding function of CD44 on the cell surface.

scholarly journals EVALUATION OF APOPTOGENIC EFFECTS OF AVERRHOA BILIMBI EXTRACT ON EHRLICH ASCITES CARCINOMA BEARING MICE

2016 ◽  
Vol 9 (9) ◽  
pp. 348
Author(s):  
Jyoti Bala Chauhan ◽  
K S Balaji ◽  
S Jayarama ◽  
Wethroe Kapfo
Keyword(s):  
Cell Sorting ◽  
Protocatechuic Acid ◽  
Ehrlich Ascites Carcinoma ◽  
Giemsa Staining ◽  
Phytochemical Analysis ◽  
Fluorescence Activated Cell Sorting ◽  
Rt Pcr ◽  
Facs Analysis ◽  
Ehrlich Ascites ◽  
Eac Cells

ABSTRACTObjective: The proapoptotic potential of aqueous methanol extract of Averrhoa bilimbi fruit (AMBE) in vivo against Ehrlich ascites carcinoma (EAC)bearing Swiss albino mice was studied.Methods: Cytotoxicity of the extract on the EAC cells was monitored by tumor growth response, trypan blue exclusion assay, Giemsa staining, DNAfragmentation, fluorescence-activated cell sorting (FACS) analysis, and reverse transcription-polymerase chain reaction (RT-PCR). The phytochemicalscreening using LC-MS and Fourier transform infrared (FT-IR) was conducted.Results: The extract at 100 mg/kg body weight was significantly cytotoxic toward the cells with approximately 73% growth inhibition on day 12. Itmarkedly decreased the tumor volume by 65% and viable tumor cell by 72%. Giemsa staining of AMBE treated cells displayed apoptotic morphologiessuch as membrane blebbing, cytoplasmic condensation, and apoptotic bodies. Cytotoxicity of the extract to the carcinoma cells through apoptosis wasfurther highlighted by DNA fragmentation in treated cells, while FACS analysis showed that growth arrest took place at G0/G1 phase. RT-PCR analysisdisplayed reduced level of Bcl-2/Bax ratio in test cells as compared to control cells. Phytochemical analysis of the extract using LC-MS and FT-IRstudies showed that protocatechuic acid was the predominant component present in the extract.Conclusion: Our studies indicated that Averrhoa bilimbi extract expressed significant apoptogenic potential against EAC cells in vivo.Keywords: Ehrlich ascites carcinoma, Apoptosis, Fluorescence-activated cell sorting, Bax/Bcl-2, Protocatechuic acid.

scholarly journals The E1∧E4 Protein of Human Papillomavirus Type 16 Associates with a Putative RNA Helicase through Sequences in Its C Terminus

2000 ◽  
Vol 74 (21) ◽  
pp. 10081-10095 ◽  
Author(s):  
John Doorbar ◽  
Robert C. Elston ◽  
Sawsan Napthine ◽  
Kenneth Raj ◽  
Elizabeth Medcalf ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Cell Lines ◽  
Mrna Stability ◽  
Ribosome Biogenesis ◽  
Coat Proteins ◽  
Rna Helicases ◽  
Human Papillomavirus Type 16 ◽  
Dead Box ◽  
C Terminus

ABSTRACT Human papillomavirus type 16 (HPV16) infects cervical epithelium and is associated with the majority of cervical cancers. The E1∧E4 protein of HPV16 but not those of HPV1 or HPV6 was found to associate with a novel member of the DEAD box protein family of RNA helicases through sequences in its C terminus. This protein, termed E4-DBP (E4-DEAD box protein), has a molecular weight of 66,000 (66K) and can shuttle between the nucleus and the cytoplasm. It binds to RNA in vitro, including the major HPV16 late transcript (E1∧E4.L1), and has an RNA-independent ATPase activity which can be partially inhibited by E1∧E4. E4-DBP was detectable in the cytoplasm of cells expressing HPV16 E1∧E4 (in vivo and in vitro) and could be immunoprecipitated as an E1∧E4 complex from cervical epithelial cell lines. In cell lines lacking cytoplasmic intermediate filaments, loss of the leucine cluster-cytoplasmic anchor region of HPV16 E1∧E4 resulted in both proteins colocalizing exclusively to the nucleoli. Two additional HPV16 E1∧E4-binding proteins, of 80K and 50K, were identified in pull-down experiments but were not recognized by antibodies to E4-DBP or the conserved DEAD box motif. Sequence analysis of E4-DBP revealed homology in its E4-binding region with threeEscherichia coli DEAD box proteins involved in the regulation of mRNA stability and degradation (RhlB, SrmB, and DeaD) and with the Rrp3 protein of Saccharomyces cerevisiae, which is involved in ribosome biogenesis. The synthesis of HPV16 coat proteins occurs after E1∧E4 expression and genome amplification and is regulated at the level of mRNA stability and translation. Identification of E4-DBP as an HPV16 E1∧E4-associated protein indicates a possible role for E1∧E4 in virus synthesis.

scholarly journals Distinct Ring1b complexes defined by DEAD-box helicases and EMT transcription factors synergistically enhance E-cadherin silencing in breast cancer

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Yawei Wang ◽  
Yingying Sun ◽  
Chao Shang ◽  
Lili Chen ◽  
Hongyu Chen ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Transcription Factors ◽  
Cancer Cells ◽  
Epithelial Mesenchymal Transition ◽  
Epigenetic Mechanism ◽  
Regulation Mechanism ◽  
Rna Helicases ◽  
Mesenchymal Transition ◽  
Dead Box ◽  
E Cadherin

AbstractRing1b is a core subunit of polycomb repressive complex 1 (PRC1) and is essential in several high-risk cancers. However, the epigenetic mechanism of Ring1b underlying breast cancer malignancy is poorly understood. In this study, we showed increased expression of Ring1b promoted metastasis by weakening cell–cell adhesions of breast cancer cells. We confirmed that Ring1b could downregulate E-cadherin and contributed to an epigenetic rewiring via PRC1-dependent function by forming distinct complexes with DEAD-box RNA helicases (DDXs) or epithelial-mesenchymal transition transcription factors (EMT TFs) on site-specific loci of E-cadherin promoter. DDXs-Ring1b complexes moderately inhibited E-cadherin, which resulted in an early hybrid EMT state of epithelial cells, and EMT TFs-Ring1b complexes cooperated with DDXs-Ring1b complexes to further repress E-cadherin in mesenchymal-like cancer cells. Clinically, high expression of Ring1b with DDXs or EMT TFs predicted low levels of E-cadherin, metastatic behavior, and poor prognosis. These findings provide an epigenetic regulation mechanism of Ring1b complexes in E-cadherin expression. Ring1b complexes may be potential therapeutic targets and biomarkers for diagnosis and prognosis in invasion breast cancer.

scholarly journals A High-Throughput Screening System Based on Fluorescence-Activated Cell Sorting for the Directed Evolution of Chitinase A

2021 ◽  
Vol 22 (6) ◽  
pp. 3041
Author(s):  
Gheorghita Menghiu ◽  
Vasile Ostafe ◽  
Radivoje Prodanović ◽  
Rainer Fischer ◽  
Raluca Ostafe
Keyword(s):  
High Throughput ◽  
Cell Sorting ◽  
High Throughput Screening ◽  
Screening Method ◽  
Enzymatic Reaction ◽  
Hydrolytic Enzymes ◽  
Screening System ◽  
Fluorescence Activated Cell Sorting ◽  
Fungal Cell ◽  
Chitinase A

Chitinases catalyze the degradation of chitin, a polymer of N-acetylglucosamine found in crustacean shells, insect cuticles, and fungal cell walls. There is great interest in the development of improved chitinases to address the environmental burden of chitin waste from the food processing industry as well as the potential medical, agricultural, and industrial uses of partially deacetylated chitin (chitosan) and its products (chito-oligosaccharides). The depolymerization of chitin can be achieved using chemical and physical treatments, but an enzymatic process would be more environmentally friendly and more sustainable. However, chitinases are slow-acting enzymes, limiting their biotechnological exploitation, although this can be overcome by molecular evolution approaches to enhance the features required for specific applications. The two main goals of this study were the development of a high-throughput screening system for chitinase activity (which could be extrapolated to other hydrolytic enzymes), and the deployment of this new method to select improved chitinase variants. We therefore cloned and expressed the Bacillus licheniformis DSM8785 chitinase A (chiA) gene in Escherichia coli BL21 (DE3) cells and generated a mutant library by error-prone PCR. We then developed a screening method based on fluorescence-activated cell sorting (FACS) using the model substrate 4-methylumbelliferyl β-d-N,N′,N″-triacetyl chitotrioside to identify improved enzymes. We prevented cross-talk between emulsion compartments caused by the hydrophobicity of 4-methylumbelliferone, the fluorescent product of the enzymatic reaction, by incorporating cyclodextrins into the aqueous phases. We also addressed the toxicity of long-term chiA expression in E. coli by limiting the reaction time. We identified 12 mutants containing 2–8 mutations per gene resulting in up to twofold higher activity than wild-type ChiA.

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