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Rosenberg EM, Jian X, Soubias O, Yoon HY, Yadav MP, Hammoudeh S, Pallikkuth S, Akpan I, Chen PW, Maity TK, Jenkins LM, Yohe ME, Byrd RA, Randazzo PA. The small molecule inhibitor NAV-2729 has a complex target profile including multiple ADP-ribosylation factor regulatory proteins. J Biol Chem 2023; 299:102992. [PMID: 36758799 PMCID: PMC10023970 DOI: 10.1016/j.jbc.2023.102992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/18/2023] [Accepted: 01/20/2023] [Indexed: 02/11/2023] Open
Abstract
The ADP-ribosylation factor (Arf) GTPases and their regulatory proteins are implicated in cancer progression. NAV-2729 was previously identified as a specific inhibitor of Arf6 that reduced progression of uveal melanoma in an orthotopic xenograft. Here, our goal was to assess the inhibitory effects of NAV-2729 on the proliferation of additional cell types. We found NAV-2729 inhibited proliferation of multiple cell lines, but Arf6 expression did not correlate with NAV-2729 sensitivity, and knockdown of Arf6 affected neither cell viability nor sensitivity to NAV-2729. Furthermore, binding to native Arf6 was not detected; however, we determined that NAV-2729 inhibited both Arf exchange factors and Arf GTPase-activating proteins. ASAP1, a GTPase-activating protein linked to cancer progression, was further investigated. We demonstrated that NAV-2729 bound to the PH domain of ASAP1 and changed ASAP1 cellular distribution. However, ASAP1 knockdown did not fully recapitulate the cytoskeletal effects of NAV-2729 nor affect cell proliferation. Finally, our screens identified 48 other possible targets of NAV-2729. These results illustrate the complexities of defining targets of small molecules and identify NAV-2729 as a model PH domain-binding inhibitor.
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Affiliation(s)
- Eric M Rosenberg
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Xiaoying Jian
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Olivier Soubias
- Center for Structural Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Hye-Young Yoon
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Mukesh P Yadav
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Sarah Hammoudeh
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Sandeep Pallikkuth
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, Massachusetts, USA
| | - Tapan K Maity
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Lisa M Jenkins
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | - Marielle E Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA; Laboratory of Cell and Developmental Signaling, Center for Cancer Research, Frederick, Maryland, USA
| | - R Andrew Byrd
- Center for Structural Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA.
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Yoon HY, Maron BY, Girald-Berlingeri S, Gasilina A, Gollin JC, Jian X, Akpan I, Yohe ME, Randazzo PA, Chen PW. ERK phosphorylation is dependent on cell adhesion in a subset of pediatric sarcoma cell lines. Biochim Biophys Acta Mol Cell Res 2022; 1869:119264. [PMID: 35381293 DOI: 10.1016/j.bbamcr.2022.119264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 03/15/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
Osteosarcoma (OS) and Pax-Foxo1 fusion negative rhabdomyosarcoma (FN-RMS) are pediatric sarcomas with poor prognoses in patients with advanced disease. In both malignancies, an actin binding protein has been linked to poor prognosis. Integrin adhesion complexes (IACs) are closely coupled to actin networks and IAC-mediated signaling has been implicated in the progression of carcinomas. However, the relationship of IACs and actin cytoskeleton remodeling with cell signaling is understudied in pediatric sarcomas. Here, we tested the hypothesis that IAC dynamics affect ERK activation in OS and FN-RMS cell lines. Adhesion dependence of ERK activation differed among the OS and FN-RMS cells examined. In the OS cell lines, adhesion did not have a consistent effect on phospho-ERK (pERK). ERK phosphorylation in response to fetal calf serum or 1 ng/ml EGF was nearly as efficient in OS cell lines and one FN-RMS cell line in suspension as cells adherent to poly-l-lysine (PL) or fibronectin (FN). By contrast, adhesion to plastic, PL or FN increased ERK phosphorylation and was greater than additive with a 15 min exposure to 1 ng/ml EGF in three FN-RMS cell lines. Increases in pERK were partly dependent on FAK and PAK1/2 but independent of IAC maturation. As far as we are aware, this examination of adhesion-dependent signaling is the first in pediatric sarcomas and has led to the discovery of differences from the prevailing paradigms and differences in the degree of coupling between components in the signaling pathways among the cell lines.
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Affiliation(s)
- Hye-Young Yoon
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America
| | - Ben Y Maron
- Department of Biology, Williams College, Williamstown, MA, United States of America
| | - Sofia Girald-Berlingeri
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America
| | - Anjelika Gasilina
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America
| | - Josephine C Gollin
- Department of Biology, Williams College, Williamstown, MA, United States of America
| | - Xiaoying Jian
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America
| | - Marielle E Yohe
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - Paul A Randazzo
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States of America.
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, MA, United States of America
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Dimitriou ID, Lee K, Akpan I, Lind EF, Barr VA, Ohashi PS, Samelson LE, Rottapel R. Timed Regulation of 3BP2 Induction Is Critical for Sustaining CD8 + T Cell Expansion and Differentiation. Cell Rep 2019; 24:1123-1135. [PMID: 30067970 PMCID: PMC6701191 DOI: 10.1016/j.celrep.2018.06.075] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/17/2018] [Accepted: 06/18/2018] [Indexed: 12/28/2022] Open
Abstract
Successful anti-viral response requires the sustained activation and expansion of CD8+ T cells for periods that far exceed the time limit of physical T cell interaction with antigen-presenting cells (APCs). The expanding CD8+ T cell pool generates the effector and memory cell populations that provide viral clearance and long-term immunity, respectively. Here, we demonstrate that 3BP2 is recruited in cytoplasmic microclusters and nucleates a signaling complex that facilitates MHC:peptide-independent activation of signaling pathways downstream of the TCR. We show that induction of the adaptor molecule 3BP2 is a sensor of TCR signal strength and is critical for sustaining CD8+ T cell proliferation and regulating effector and memory differentiation. Dimitriou et al. show that the adaptor protein 3BP2 lowers the threshold of T cell activation and that the induction of the 3BP2 signaling module at later time points may serve to recapitulate and prolong the biochemical signals emanating from the TCR required for sustained MHC:peptide-independent T cell proliferation.
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Affiliation(s)
- Ioannis D Dimitriou
- Princess Margaret Cancer Center, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada
| | - Korris Lee
- Princess Margaret Cancer Center, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research (CCR), National Cancer Institute (NCI), NIH, Bethesda, MD 20892, USA
| | - Evan F Lind
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Valarie A Barr
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research (CCR), National Cancer Institute (NCI), NIH, Bethesda, MD 20892, USA
| | - Pamela S Ohashi
- Campbell Family Institute for Breast Cancer Research, Princess Margaret Cancer Centre, Toronto, ON M5G 2C1, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5S 1L7, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1L7, Canada
| | - Lawrence E Samelson
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research (CCR), National Cancer Institute (NCI), NIH, Bethesda, MD 20892, USA
| | - Robert Rottapel
- Princess Margaret Cancer Center, Toronto Medical Discovery Tower, Toronto, ON M5G 1L7, Canada; Department of Medical Biophysics, University of Toronto, Toronto, ON M5S 1L7, Canada; Department of Immunology, University of Toronto, Toronto, ON M5S 1L7, Canada; Department of Medicine, University of Toronto, Toronto, ON M5S 1L7, Canada.
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Guittard G, Dios-Esponera A, Palmer DC, Akpan I, Barr VA, Manna A, Restifo NP, Samelson LE. The Cish SH2 domain is essential for PLC-γ1 regulation in TCR stimulated CD8 + T cells. Sci Rep 2018; 8:5336. [PMID: 29593227 PMCID: PMC5871872 DOI: 10.1038/s41598-018-23549-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/06/2018] [Indexed: 12/22/2022] Open
Abstract
Cish, participates within a multi-molecular E3 ubiquitin ligase complex, which ubiquitinates target proteins. It has an inhibitory effect on T cell activation mediated by PLC-γ1 regulation, and it functions as a potent checkpoint in CD8+ T cell tumor immunotherapy. To study the structural and functional relationships between Cish and PLC-γ1 during CD8+ T cell activation, we tested mutants of the Cish-SH2 (R107K) and D/BC (L222Q, C226Q) domains. We confirmed that Cish-SH2-specific binding was essential for PLC-γ1 ubiquitination and degradation. This domain was essential for the Cish-mediated inhibition of Ca2+ release upon TCR stimulation. No effect on inhibition of cytokine release was observed with SH2 or D/BC mutants, although the absence of Cish led to an increased release of IFN-γ and TNF-α. Using imaging we showed that Cish was expressed mostly in the cytoplasm and we did not see any Cish clustering at the plasma membrane upon stimulation. We conclude that the Cish-SH2 domain is essential for PLC-γ1 regulation in TCR-stimulated CD8+ T cells.
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Affiliation(s)
- Geoffrey Guittard
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA. .,INSERM, U1068, CNRS UMR7258, Aix-Marseille Université UM105, Institut Paoli-Calmettes, Centre de Recherche en Cancérologie de Marseille, 13009, Marseille, France.
| | - Ana Dios-Esponera
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Douglas C Palmer
- Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 10/CRC, Room 3W-3840, Bethesda, MD, 20892, USA
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Valarie A Barr
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Asit Manna
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA
| | - Nicholas P Restifo
- Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Building 10/CRC, Room 3W-3840, Bethesda, MD, 20892, USA
| | - Lawrence E Samelson
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, 20892-4256, USA.
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Dutta D, Barr VA, Akpan I, Mittelstadt PR, Singha LI, Samelson LE, Ashwell JD. Recruitment of calcineurin to the T cell receptor positively regulates T cell activation. The Journal of Immunology 2017. [DOI: 10.4049/jimmunol.198.supp.52.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Calcineurin is a phosphatase whose primary targets in T cells are NFAT transcription factors, and its inhibition with cyclosporin A (CsA) or FK506 is a cornerstone of immunosuppressive therapies. Here we show that calcineurin is recruited to the T cell receptor signaling complex where it reverses the inhibitory phosphorylation of Lck on Ser-59 (LckS59). Loss of calcineurin activity impaired phosphorylation of ZAP-70Y493 and some downstream pathways in a manner consistent with signaling in cells expressing LckS59A (non-phosphorylatable) or LckS59E (phosphomimetic). Importantly, CsA inhibited activation-induced LFA-1-dependent and NFAT-independent adhesion of T cells to ICAM-1, with little effect on cells expressing mutant Lck. These results provide a new understanding of how widely-used immunosuppressive drugs interfere with essential processes in the immune response.
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Barr VA, Sherman E, Yi J, Akpan I, Rouquette-Jazdanian AK, Samelson LE. Development of nanoscale structure in LAT-based signaling complexes. J Cell Sci 2016; 129:4548-4562. [PMID: 27875277 PMCID: PMC5201021 DOI: 10.1242/jcs.194886] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/04/2016] [Indexed: 12/30/2022] Open
Abstract
The adapter molecule linker for activation of T cells (LAT) plays a crucial role in forming signaling complexes induced by stimulation of the T cell receptor (TCR). These multi-molecular complexes are dynamic structures that activate highly regulated signaling pathways. Previously, we have demonstrated nanoscale structure in LAT-based complexes where the adapter SLP-76 (also known as LCP2) localizes to the periphery of LAT clusters. In this study, we show that initially LAT and SLP-76 are randomly dispersed throughout the clusters that form upon TCR engagement. The segregation of LAT and SLP-76 develops near the end of the spreading process. The local concentration of LAT also increases at the same time. Both changes require TCR activation and an intact actin cytoskeleton. These results demonstrate that the nanoscale organization of LAT-based signaling complexes is dynamic and indicates that different kinds of LAT-based complexes appear at different times during T cell activation.
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Affiliation(s)
- Valarie A Barr
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
| | - Eilon Sherman
- Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel
| | - Jason Yi
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
| | - Itoro Akpan
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
| | | | - Lawrence E Samelson
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
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Abstract
Palm kernel is a cheap natural resource which is abundantly available in the tropics, parts of Asia and South and Central America. A culture medium was developed by incorporating fresh palm kernel extract for the detection of aflatoxigenic fungi. Aflatoxin positive isolates of Aspergilliexhibited a characteristic blue or blue green fluorescence of agar under long wave UV light against a pink background which was confirmed by thin layer chromatography. As compared to conventional desiccated coconut agar, the fluorescent nature of the medium, the intensity and diffusion of the hot water soluble fluorescent compounds of the fungus was unique on this medium. The optimal pH and temperature conditions of aflatoxin production were 7 and 30 ºC respectively. Additives (synthetic and natural) either had no effect or adversely affected the fluorescence of the medium. Aflatoxin detection was possible within 36h in palm kernel broth compared to 40 h in coconut broth. The optimal time of production of fluorescence was 44 h on palm kernel agar compared to 48 h on the conventional medium. Further tests with isolates from different sources showed that yellow pigmentation, fluorescence and aflatoxins were complementary thus obviating the need for UV light. It is thus possible to presumptively identify aflatoxin positive isolates.
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Affiliation(s)
- O. O. Atanda
- Departmentof Food Science and Technology, University of Agriculture. P.M.B 2240, Abeokuta, Nigeria
| | - I. Akpan
- Departmentof Microbiology, University of Agriculture, Abeokuta, Nigeria
| | - E. R. Rati
- Departmentof Food Microbiology, Central Food Technological Research Institute, Mysore 570 013, India
| | - M. Ozoje
- Departmentof Animal Breeding and Genetics, University of Agriculture, Abeokuta, Nigeria
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Elechi I, Ifabiyi O, Ugbene K, Akpan I, Uzim J, Aisiri A, Adeusi O, Aiyenigba B. Assessment of uptake of intermittent preventive therapy for malaria in pregnancy following a health facility based training approach in Akwa Ibom state, Nigeria. Int J Infect Dis 2016. [DOI: 10.1016/j.ijid.2016.02.503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
CONTEXT The persistent increase in the number of antibiotic-resistant strains of microorganisms has led to the development of more potent but also more expensive antibiotics. In most developing countries of the world these antibiotics are not readily affordable, thus making compliance difficult. This calls for research into alternative sources of antimicrobials. Dialium guineense is a shrub of the family Leguminosae. Its stem bark is used for the treatment of cough, toothache, and bronchitis. AIMS Despite the acclaimed efficacy of D guineense, there is no scientific evidence in its support. This work was carried out to assess the antimicrobial activity of D guineense in vitro against some clinical isolates. MATERIALS AND METHODS D guineense stem bark was collected and 50 gm of air-dried and powdered stem bark of the plant was soaked for 72 hours in 1 l of each of the six solvents used in this study. Each mixture was refluxed, agitated at 200 rpm for 1 hour, filtered using Whatman No. 1 filter paper and, finally, freeze dried. The extracts were then tested for antimicrobial activity using the agar diffusion method. RESULTS The highest percentage yield of 23.2% was obtained with ethanol. Phytochemical screening showed that D guineense contains anthraquinone, alkaloids, flavonoids, tannins, and saponins. The antimicrobial activity of the extracts revealed a broad spectrum of activity, with Salmonella typhi and Staphylococcus aureusa showing the greatest zones of inhibition (18.0 mm). Only Candida albicans among the fungi tested was inhibited by the extract. The greatest zone of inhibition among the fractions was 16.0 mm. D guineense exhibited bactericidal activity at the 7th and 9th hours against Streptococcus pneumoniae and S. aureus 25923 while the 10th hour against S. typhi and C. albicans. The greatest activity was noted against S pneumoniae, where there was reduced viable cell count after 6 hours of exposure. CONCLUSION Stem bark extract of D guineense (Wild.) has the potential to be developed into an antimicrobial agent.
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Affiliation(s)
- Fa Olajubu
- Department of Medical Microbiology and Parasitology, Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria
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Kareem SO, Akpan I, Popoola TOS, Sanni LO. Activated charcoal-a potential material in glucoamylase recovery. Enzyme Res 2012; 2011:483943. [PMID: 22235364 PMCID: PMC3251798 DOI: 10.4061/2011/483943] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 09/20/2011] [Accepted: 09/21/2011] [Indexed: 11/20/2022] Open
Abstract
The potential of activated charcoal in the purification of fungal glucoamylase was investigated. Various concentrations of activated charcoal (1–4% w/v) were used to concentrate crude glucoamylase from Rhizopus oligosporus at different temperature values (30–50°C). Effects of pH (3.0–6.0) and contact time (0–60 min) on enzyme purification were also monitored. Activated charcoal (3% w/v) gave a 16-fold purification in a single-step purification at 50°C for 20 min and pH 5.5. The result of SDS-PAGE analysis of purified glucoamylase showed two major protein bands with corresponding molecular weight of 36 kDa and 50 kDa. The method is inexpensive, rapid, and simple which could facilitate downstream processing of industrial enzyme.
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Affiliation(s)
- S O Kareem
- Department of Microbiology, University of Agriculture, PMB 2240, Abeokuta, Nigeria
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Abstract
A preliminary investigation was conducted to screen for astrovirus in Lagos. Two hundred and fifteen (215) faecal samples collected from children under 5 years old with diarrhoea (161) and without diarrhoea (54) admitted at paediatric clinics in Lagos State were studied. The stool specimens were examined for the presence of human astrovirus antigen using a monoclonal antibody-based ELISA (Astrovirus RIDASCREEN(®) r-Biopharm, Germany) technique. Astrovirus was detected in 40.4 percent (65/161) of the diarrhoeal stools compared to 11.1 percent (6/54) of the control specimens. Astrovirus was found to infect younger children and about three quarter of the children infected was under 12 months of age. The prevalence of infection decreases with age group and was statistically significant (P = 0.0470). Although, prevalence of infection is more in males than females but this is not significant. This study shows that astrovirus is an important agent of acute gastroenteritis among children in Lagos state.
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Affiliation(s)
- Ci Ayolabi
- Dept. of Microbiology, University of Lagos, Nigeria
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Sherman E, Barr V, Manley S, Patterson G, Balagopalan L, Akpan I, Regan CK, Merrill RK, Sommers CL, Lippincott-Schwartz J, Samelson LE. Functional nanoscale organization of signaling molecules downstream of the T cell antigen receptor. Immunity 2011; 35:705-20. [PMID: 22055681 DOI: 10.1016/j.immuni.2011.10.004] [Citation(s) in RCA: 228] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 08/03/2011] [Accepted: 10/05/2011] [Indexed: 01/16/2023]
Abstract
Receptor-regulated cellular signaling often is mediated by formation of transient, heterogeneous protein complexes of undefined structure. We used single and two-color photoactivated localization microscopy to study complexes downstream of the T cell antigen receptor (TCR) in single-molecule detail at the plasma membrane of intact T cells. The kinase ZAP-70 distributed completely with the TCRζ chain and both partially mixed with the adaptor LAT in activated cells, thus showing localized activation of LAT by TCR-coupled ZAP-70. In resting and activated cells, LAT primarily resided in nanoscale clusters as small as dimers whose formation depended on protein-protein and protein-lipid interactions. Surprisingly, the adaptor SLP-76 localized to the periphery of LAT clusters. This nanoscale structure depended on polymerized actin and its disruption affected TCR-dependent cell function. These results extend our understanding of the mechanism of T cell activation and the formation and organization of TCR-mediated signaling complexes, findings also relevant to other receptor systems.
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Affiliation(s)
- Eilon Sherman
- Laboratory of Cellular and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
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Akpan I, Goncalves MD, Dhir R, Yin X, Pistilli EE, Bogdanovich S, Khurana TS, Ucran J, Lachey J, Ahima RS. The effects of a soluble activin type IIB receptor on obesity and insulin sensitivity. Int J Obes (Lond) 2009; 33:1265-73. [PMID: 19668253 PMCID: PMC2783781 DOI: 10.1038/ijo.2009.162] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Myostatin, also known as Growth and Differentiation Factor 8, is a secreted protein that inhibits muscle growth. Disruption of myostatin signaling increases muscle mass and decreases glucose, but it is unclear whether these changes are related. We treated mice on chow and high-fat diets with a soluble activin receptor type IIB (ActRIIB.Fc) which is a putative endogenous signaling receptor for myostatin and other ligands of the TGF-β superfamily. After 4 weeks, RAP-031 increased lean and muscle mass, grip strength, and contractile force. RAP-031 enhanced the ability of insulin to suppress glucose production under clamp conditions in high-fat fed mice, but did not significantly change insulin-mediated glucose disposal. The hepatic insulin sensitizing effect of RAP-031 treatment was associated with increased adiponectin levels. RAP-031 treatment for 10 weeks further increased muscle mass and drastically reduced fat content in mice on either chow or high-fat diet. RAP-031 suppressed hepatic glucose production and increased peripheral glucose uptake in chow fed mice. In contrast, RAP-031 suppressed glucose production with no apparent change in glucose disposal in high-fat diet mice. Our findings demonstrate that disruption of ActRIIB signaling is a viable pharmacological approach for treating obesity and diabetes.
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Affiliation(s)
- I Akpan
- University of Pennsylvania School of Medicine, Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Philadelphia, PA 19104, USA
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Atanda O, Akpan I, Oluwafemi F. The potential of some spice essential oils in the control of A. parasiticus CFR 223 and aflatoxin production. Food Control 2007. [DOI: 10.1016/j.foodcont.2006.02.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Uwah A, Adedeji A, SalawuV O, Okunade A, Adebayo P, Akpan I. Assessment of knowledge, perceptions and acceptability of mandatory pre-medical tests for intending couples in churches in Abuja, Nigeria. Retrovirology 2006. [PMCID: PMC1716886 DOI: 10.1186/1742-4690-3-s1-p63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Abstract
A simple method based on precipitation with Calotropis procera latex was developed for the purification of crude enzyme from fermentation broth. C. procera latex (10(-2) dilution) clarified and concentrated the crude amylase of Aspergillus oryzae 4-fold with 97% recovery of the initial amylase activity in the filtrate in a single step operation. The latex was stable at pH < or = 4.5 and there was no significant difference (P < or = 0.05) in the purification potential of the latex at 4 and 28 degrees C. This method could prove useful to developing economies of the tropics where ambient temperature is around 28 degrees C.
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Affiliation(s)
- S O Kareem
- Department of Microbiology, University of Agriculture, P.M.B 2240, Abeokuta, Nigeria
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