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1.
Mol Cell ; 71(4): 554-566.e7, 2018 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-30078722

RESUMO

Chromosomal rearrangements resulting in the fusion of TMPRSS2, an androgen-regulated gene, and the ETS family transcription factor ERG occur in over half of prostate cancers. However, the mechanism by which ERG promotes oncogenic gene expression and proliferation remains incompletely understood. Here, we identify a binding interaction between ERG and the mammalian SWI/SNF (BAF) ATP-dependent chromatin remodeling complex, which is conserved among other oncogenic ETS factors, including ETV1, ETV4, and ETV5. We find that ERG drives genome-wide retargeting of BAF complexes in a manner dependent on binding of ERG to the ETS DNA motif. Moreover, ERG requires intact BAF complexes for chromatin occupancy and BAF complex ATPase activity for target gene regulation. In a prostate organoid model, BAF complexes are required for ERG-mediated basal-to-luminal transition, a hallmark of ERG activity in prostate cancer. These observations suggest a fundamental interdependence between ETS transcription factors and BAF chromatin remodeling complexes in cancer.


Assuntos
Carcinogênese/genética , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Proteínas Nucleares/genética , Proteínas de Fusão Oncogênica/genética , Neoplasias da Próstata/genética , Serina Endopeptidases/genética , Proteínas E1A de Adenovirus/genética , Proteínas E1A de Adenovirus/metabolismo , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Proliferação de Células , Cromatina/química , Cromatina/metabolismo , Montagem e Desmontagem da Cromatina , DNA/genética , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Células HEK293 , Humanos , Masculino , Camundongos Transgênicos , Proteínas Nucleares/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Organoides/metabolismo , Organoides/patologia , Próstata/metabolismo , Próstata/patologia , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Ligação Proteica , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-ets , Serina Endopeptidases/metabolismo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Regulador Transcricional ERG/genética , Regulador Transcricional ERG/metabolismo
2.
PLoS Genet ; 16(12): e1008857, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33370780

RESUMO

Studies of the severely pancytopenic scat mouse model first demonstrated the crucial role of RASA3, a dual RAS and RAP GTPase activating protein (GAP), in hematopoiesis. RASA3 is required for survival in utero; germline deletion is lethal at E12.5-13.5 due to severe hemorrhage. Here, conditional deletion in hematopoietic stem and progenitor cells (HSPCs) using Vav-iCre recapitulates the null phenotype demonstrating that RASA3 is required at the stem and progenitor level to maintain blood vessel development and integrity and effective blood production. In adults, bone marrow blood cell production and spleen stress erythropoiesis are suppressed significantly upon induction of RASA3 deficiency, leading to pancytopenia and death within two weeks. Notably, RASA3 missense mutations in two mouse models, scat (G125V) and hlb381 (H794L), show dramatically different hematopoietic consequences specific to both genetic background and molecular variant. The mutation effect is mediated at least in part by differential effects on RAS and RAP activation. In addition, we show that the role of RASA3 is conserved during human terminal erythropoiesis, highlighting a potential function for the RASA3-RAS axis in disordered erythropoiesis in humans. Finally, global transcriptomic studies in scat suggest potential targets to ameliorate disease progression.


Assuntos
Proteínas Ativadoras de GTPase/genética , Patrimônio Genético , Hematopoese , Mutação , Pancitopenia/genética , Animais , Células Cultivadas , Feminino , Proteínas Ativadoras de GTPase/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C
3.
Vet Surg ; 2023 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-37574868

RESUMO

OBJECTIVE: To compare antimicrobial activity as demonstrated by the zone of inhibition (ZOI) produced by antibiotic-impregnated calcium sulfate (CaSO4 ) beads after storage for 0, 3, 6, 9, and 12 months. STUDY DESIGN: Controlled laboratory study. SAMPLE POPULATION: Three-millimeter diameter CaSO4 beads impregnated with vancomycin (125 mg/mL), or amikacin (250 mg/mL), or without antibiotic (control). METHODS: Calcium sulfate beads were created at the onset of the study. Individual beads were separated in sterile containers and stored in a closed cabinet at room temperature and humidity for 0, 3, 6, 9, or 12 months until testing. The ZOI against methicillin-resistant Staphylococcus pseudintermedius, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa was recorded with serial replating on a fresh lawn of bacteria every 24 h until beads failed to produce a ZOI. The ZOIs and their changes were compared with mixed-effects linear models. Eluted concentrations of vancomycin measured with high-performance liquid chromatography were reported. RESULTS: At 24 h, ZOIs were comparable regardless of time since formulation, except vancomycin against P. aeruginosa, which failed to generate a ZOI. The daily changes of ZOI and duration of activity of antibiotics did not vary between storage length (p > .05). There was no consistent change in eluted drug concentration between storage length of beads. CONCLUSION: Light protected storage at room temperature for up to 12 months did not impair the in vitro activity of antibiotic-impregnated CaSO4 beads, as demonstrated through ZOIs. CLINICAL SIGNIFICANCE: When stored correctly, antibiotic-impregnated CaSO4 beads can be used at least up to 12 months after formulation.

4.
J Perianesth Nurs ; 38(4): 543-552, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-36599790

RESUMO

PURPOSE: The purpose of this project was to improve the consistency of verbal and written discharge instructions for women of childbearing age (13-55 years) taking hormonal contraceptives who receive aprepitant perioperatively, to address the need to use a secondary form of birth control for 28 days, as well as to increase the knowledge and confidence of Registered Nurses when providing discharge instructions. DESIGN: This quality improvement project used a pre-/postdesign to evaluate two separate groups of patients and registered nurses. METHODS: The patient sample consisted of 30 total women of childbearing age who received aprepitant during the perioperative period (15 pre and 15 post). The PACU nurse sample included 15 ambulatory surgery center nurses and 58 main hospital nurses for a combined sample of 73 PACU nurses. The PACU nurses were provided with educational in-service regarding information about aprepitant and its drug interactions. PACU nurses were additionally instructed to provide patient discharge instructions using both a written and verbal format. Patients were called postoperatively before and after both the written after visit summary (AVS) changes and the PACU nurse in-services, PACU nurses were evaluated on their knowledge, confidence, and frequency of discharge teaching before and after their educational in-service. The PACU nurses were surveyed 90 days after the intervention to assess their long-term knowledge retention. FINDINGS: There was a significant increase in nurse knowledge about aprepitant from preimplementation to postimplementation (61.39% vs 81.95%, P < .001). Nursing knowledge showed a nonsignificant decline at 90-days postimplementation (81.95% vs 73.68%, P = .096) although remained significantly higher than preimplementation scores (73.68% vs 61.39%, P = .003). There was an overall 33.3% increase in the percentage of patients who were able to recall receiving aprepitant and the need to use a secondary form of birth control when comparing the preintervention group to the postintervention group (26.7% vs 60%, P = .123). CONCLUSIONS: The findings suggest that providing a standardized presentation about aprepitant may improve the PACU nurses' ability to verbalize key information about aprepitant, including the need for patients to use a secondary form of birth control. This increase in nursing knowledge and confidence, along with improved written discharge instructions, may have led to improved patient comprehension of aprepitant discharge education. Additionally, there was an increase in the percentage of patients who were able to recall the need to use a secondary form birth control for 28 days, to reduce the likelihood of an unintentional pregnancy.


Assuntos
Contracepção Hormonal , Enfermeiras e Enfermeiros , Humanos , Feminino , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Aprepitanto , Competência Clínica , Educação de Pacientes como Assunto
5.
J Perianesth Nurs ; 36(4): 351-358, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33745828

RESUMO

PURPOSE: The purpose of this quality improvement project was to improve consistency of discharge teaching in women who used progesterone-containing hormonal contraceptive medications and received sugammadex during general anesthesia, as there is a risk of unintended pregnancy for 1 week after administration of sugammadex. DESIGN: This project used a predesign and postdesign using two separate sample groups of patients and postanesthesia care unit (PACU) nurses. METHODS: The sample consisted of 31 total women of childbearing age and 59 PACU nurses. Simplification of sugammadex discharge instructions was achieved by incorporating evidence-based recommendations for electronic discharge instructions and nursing education. PACU nurses were educated and surveyed before and after regarding frequency of discharge teaching, clarity, and comprehension of the after-visit summary and knowledge of sugammadex. Patients were called via telephone postoperatively to assess recall of sugammadex discharge teaching. FINDINGS: Postoperative patient phone calls identified a small increase in patient recall of discharge instructions from 5 of 14 patients (35.7%) before implementation to 7 of 17 after implementation (41.2%). PACU nurse surveys indicated an increase in self-reported frequency of sugammadex discharge teaching (34.8% vs 64.2%, P = .024) and that new discharge instructions contained more clear, comprehensive information as compared with previous instructions (29.4% vs 75.5%, P = .001). CONCLUSIONS: This quality improvement project successfully implemented more consistent and comprehensive discharge instructions for women who receive sugammadex intraoperatively. Limitations of the project included a small sample size and short implementation intervals. As a result of switching to uniform discharge instructions, more patients received important discharge teaching from PACU nurses, and the percentage of patients who recalled this information increased.


Assuntos
Contracepção Hormonal , Melhoria de Qualidade , Anestesia Geral , Feminino , Humanos , Pessoa de Meia-Idade , Gravidez , Sugammadex , Inquéritos e Questionários
6.
Biomacromolecules ; 21(10): 4194-4204, 2020 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-32880435

RESUMO

Peptide insertions in the primary sequence of proteins expand functionality by introducing new binding sequences, chemical handles, or membrane disrupting motifs. With these properties, proteins can be engineered as scaffolds for vaccines or targeted drug delivery vehicles. Virus-like particles (VLPs) are promising platforms for these applications since they are genetically simple, mimic viral structure for cell uptake, and can deliver multiple copies of a therapeutic agent to a given cell. Peptide insertions in the coat protein of VLPs can increase VLP uptake in cells by increasing cell binding, but it is difficult to predict how an insertion affects monomer folding and higher order assembly. To this end, we have engineered the MS2 VLP using a high-throughput technique, called Systematic Mutagenesis and Assembled Particle Selection (SyMAPS). In this work, we applied SyMAPS to investigate a highly mutable loop in the MS2 coat protein to display 9,261 non-native tripeptide insertions. This library generates a discrete map of three amino acid insertions permitted at this location, validates the FG loop as a valuable position for peptide insertion, and illuminates how properties such as charge, flexibility, and hydrogen bonding can interact to preserve or disrupt capsid assembly. Taken together, the results highlight the potential to engineer VLPs in a systematic manner, paving the way to exploring the applications of peptide insertions in biomedically relevant settings.


Assuntos
Peptídeos , Vacinas de Partículas Semelhantes a Vírus , Sequência de Aminoácidos , Capsídeo , Proteínas do Capsídeo/genética , Peptídeos/genética
7.
Biochemistry ; 58(11): 1527-1538, 2019 03 19.
Artigo em Inglês | MEDLINE | ID: mdl-30418759

RESUMO

Protein evolution occurs via restricted evolutionary paths that are influenced by both previous and subsequent mutations. This effect, termed epistasis, is critical in population genetics, drug resistance, and immune escape; however, the effect of epistasis on the level of protein fitness is less well characterized. We generated and characterized a 6615-member library of all two-amino acid combinations in a highly mutable loop of a virus-like particle. This particle is a model of protein self-assembly and a promising vehicle for drug delivery and imaging. In addition to characterizing the effect of all double mutants on assembly, thermostability, and acid stability, we observed many instances of epistasis, in which combinations of mutations are either more deleterious or more beneficial than expected. These results were used to generate rules governing the effects of multiple mutations on the self-assembly of the virus-like particle.


Assuntos
Epistasia Genética/genética , Proteínas/metabolismo , Proteínas/fisiologia , Aminoácidos/metabolismo , Evolução Biológica , Epistasia Genética/fisiologia , Evolução Molecular , Aptidão Genética/genética , Genótipo , Modelos Genéticos , Mutação , Biblioteca de Peptídeos , Conformação Proteica , Proteínas/genética
8.
J Am Chem Soc ; 141(9): 3875-3884, 2019 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-30730722

RESUMO

Site-specific protein modification is a widely used strategy to attach drugs, imaging agents, or other useful small molecules to protein carriers. N-terminal modification is particularly useful as a high-yielding, site-selective modification strategy that can be compatible with a wide array of proteins. However, this modification strategy is incompatible with proteins with buried or sterically hindered N termini, such as virus-like particles (VLPs) composed of the well-studied MS2 bacteriophage coat protein. To assess VLPs with improved compatibility with these techniques, we generated a targeted library based on the MS2-derived protein cage with N-terminal proline residues followed by three variable positions. We subjected the library to assembly, heat, and chemical selections, and we identified variants that were modified in high yield with no reduction in thermostability. Positive charge adjacent to the native N terminus is surprisingly beneficial for successful extension, and over 50% of the highest performing variants contained positive charge at this position. Taken together, these studies described nonintuitive design rules governing N-terminal extensions and identified successful extensions with high modification potential.


Assuntos
Bacteriófagos/metabolismo , Proteínas do Capsídeo/biossíntese , Nanopartículas/metabolismo , Engenharia de Proteínas , Bacteriófagos/química , Proteínas do Capsídeo/química , Estrutura Molecular , Nanopartículas/química
9.
J Chem Educ ; 96(10): 2149-2157, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-35370303

RESUMO

Women and some racial and ethnic groups remain underrepresented in chemistry departments across the United States, and generally, efforts to improve representation have resulted in minimal or no improvements in the last 10 years. Here, we present the outcomes of a graduate-student-led initiative that sought to assess the issues affecting inclusivity, diversity, and wellness within the Department of Chemistry at the University of California, Berkeley. We report how the results of a department-tailored academic climate survey were used to develop a method to foster open, productive discussion among graduate students, postdoctoral researchers, and faculty. This event format led to an improved understanding of the challenges facing our community members, as well as the identification of strategies that can be used to make the Department of Chemistry more welcoming for all members. We report the success of this student-led effort to highlight the value of assessing diversity and inclusion at the department-level, as well as the benefits of using community data to stimulate productive, evidence-based discussions. Furthermore, we envision that these methods can be implemented within any research-focused academic community to promote positive cultural change.

10.
Nano Lett ; 16(9): 5944-50, 2016 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-27549001

RESUMO

Virus-like particles are used to encapsulate drugs, imaging agents, enzymes, and other biologically active molecules in order to enhance their function. However, the size of most virus-like particles is inflexible, precluding the design of appropriately sized containers for different applications. Here, we describe a chromatographic selection for virus-like particle assembly. Using this selection, we identified a single amino acid substitution to the coat protein of bacteriophage MS2 that mediates a uniform switch in particle geometry from T = 3 to T = 1 icosahedral symmetry. The resulting smaller particle retains the ability to be disassembled and reassembled in vitro and to be chemically modified to load cargo into its interior cavity. The pair of 27 and 17 nm MS2 particles will allow direct examination of the effect of size on function in established applications of virus-like particles, including drug delivery and imaging.


Assuntos
Aminoácidos/genética , Proteínas do Capsídeo/genética , Levivirus/genética , Montagem de Vírus
11.
Breast Cancer Res Treat ; 160(2): 347-360, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27683280

RESUMO

OBJECTIVE: Previous meta-analyses have examined the prognosis of women with pregnancy-associated breast cancer (PABC) as well as pregnancy that follows breast cancer diagnosis. Since then, many additional studies have been performed. We conducted an updated meta-analysis to examine the prognosis for women who become pregnant before, during and after a diagnosis of breast cancer. We also performed analyses on the various subgroups within PABC such as pregnancy and postpartum cases, as well as on time periods postpartum. METHODS: We identified studies that reported on overall (OS) and disease-free survival (DFS) in patients diagnosed with breast cancer during pregnancy or up to 5 years postpartum from four electronic databases. We also identified studies that reported on OS and DFS where pregnancy up to 5 years occurred after a breast cancer diagnosis. RESULTS: 41 studies met our inclusion criteria (cases = 4929; controls = 61,041) for pregnancy occurring during or before breast cancer diagnosis. There was an overall increased risk of death amongst patients compared to non-pregnant controls [HR 1.57; 95 % CI 1.35-1.82]. Subgroup analysis indicated poor survival outcomes for those diagnosed either during pregnancy or postpartum (PABC) [HR 1.46; 95 % CI 1.17-1.82] as well as those diagnosed during pregnancy alone [HR 1.47; 95 % CI 1.04-2.08]. Those diagnosed postpartum had the poorest overall survival [HR 1.79; 95 % CI 1.39-2.29]. Similarly, patients with PABC had decreased DFS compared to controls [HR 1.51; 95 % CI 1.22-1.88]. Those diagnosed postpartum were the most at risk of disease progression or relapse [HR 1.86; 95 % CI 1.17-2.93]. 19 studies met our inclusion criteria (cases = 1829; controls = 21,907) for pregnancy following breast cancer diagnosis. Such women had a significantly reduced risk of death compared to those who did not become pregnant [pHR 0.63; 95 % CI 0.51-0.79]. A subgroup analysis to account for the "healthy mother effect" generated similar results [pHR 0.65; 95 % CI 0.52-0.81]. CONCLUSION: Pregnancy that occurs before or concurrently with a diagnosis of breast cancer is more likely to result in death and decreased disease-free survival. On the other hand, pregnancy occurring after a breast cancer diagnosis reduces the risk of death.


Assuntos
Neoplasias da Mama/epidemiologia , Complicações Neoplásicas na Gravidez/epidemiologia , Neoplasias da Mama/mortalidade , Feminino , Humanos , Razão de Chances , Período Pós-Parto , Gravidez , Complicações Neoplásicas na Gravidez/mortalidade , Prognóstico
12.
Bioconjug Chem ; 27(10): 2480-2485, 2016 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-27712069

RESUMO

Current approaches to nanoscale therapeutic delivery rely on the attachment of a drug of interest to a nanomaterial scaffold that is capable of releasing the drug selectively in a tumor environment. One class of nanocarriers receiving significant attention is protein nanomaterials, which are biodegradable and homogeneous in morphology and can be equipped with multiple functional handles for drug attachment. Although most protein-based nanocarriers are spherical in morphology, recent research has revealed that nonspherical nanomaterials may have favorable tumor uptake in comparison to their spherical counterparts. It is therefore important to expand the number of nonspherical protein-based nanocarriers that are available. Herein, we report the development of a self-assembling nanoscale disk derived from a double arginine mutant of recombinantly expressed tobacco mosaic virus coat protein (RR-TMV). RR-TMV disks display highly stable double-disk assembly states. These RR-TMV disks were functionalized with the chemotherapy drug doxorubicin (DOX) and further modified with polyethylene glycol (PEG) for improved solubility. RR-TMVDOX-PEG displayed cytotoxic properties similar to those of DOX alone when incubated with U87MG glioblastoma cells, but unmodified RR-TMV did not cause any cytotoxicity. The RR-TMV disk assembly represents a promising protein-based nanomaterial for applications in drug delivery.

13.
Ecotoxicology ; 23(3): 396-403, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24522617

RESUMO

Agricultural fungicide application has increased tenfold since 2005 in the United States. Active ingredients and formulations of strobilurin fungicides at environmentally relevant concentrations cause mortality to larval and metamorph amphibians; however, little is known about chronic exposure effects in amphibians. We exposed larval amphibians (Bufo cognatus) throughout metamorphosis to the common fungicide formulations Headline(®), Stratego(®), Quilt(®), and a control to determine effects on development and growth. Formulations were tested at 1.7, 50, and 400 µg/L of the active strobilurin ingredient for Headline(®), Stratego(®), and Quilt(®), respectively. Fungicide exposure did not affect body mass or snout-vent length at metamorphosis. However, exposure to Headline(®) at 1.7 µg/L increased the development rate of tadpoles by approximately 5 days compared to the control, an effect not observed for Stratego(®) and Quilt(®). Stratego(®) also caused approximately 35 % cumulative mortality. Results from the experiment suggest that chronic effects of strobilurin fungicides on development, growth, and mortality to B. cognatus are apparent at environmentally relevant concentrations.


Assuntos
Acetatos/toxicidade , Bufonidae/crescimento & desenvolvimento , Carbamatos/toxicidade , Fungicidas Industriais/toxicidade , Larva/efeitos dos fármacos , Pirazóis/toxicidade , Triazóis/toxicidade , Animais , Peso Corporal/efeitos dos fármacos , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Feminino , Masculino , Metamorfose Biológica/efeitos dos fármacos , Metacrilatos/análise , Metacrilatos/toxicidade , Mortalidade , Pirimidinas/análise , Pirimidinas/toxicidade , Estrobilurinas , Testes de Toxicidade Crônica , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
14.
BMJ Case Rep ; 16(12)2023 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-38103900

RESUMO

Our patient is a female in her 70s who initially presented following an episode of bowel and bladder incontinence, as well as unresponsiveness. Her family denied any preceding illness or sick symptoms. During her workup, it was noted that she was wearing a medical bracelet, which listed prednisone as one of her daily medications, raising concern for an acute adrenal crisis (AC). Ultimately, our patient's condition improved with high-dose intravenous steroids before being tapered to her home regimen. Current literature highlights the pathophysiological complexity of an AC but fails to identify clear risk factors that trigger such events, especially in asymptomatic patients. Accordingly, our case highlights this gap, arguing the importance of appropriate patient education and timely intervention for such clinically ambiguous yet life-threatening presentations.


Assuntos
Insuficiência Adrenal , Hipopituitarismo , Humanos , Feminino , Prednisona/uso terapêutico , Insuficiência Adrenal/diagnóstico , Insuficiência Adrenal/tratamento farmacológico , Insuficiência Adrenal/etiologia , Hipopituitarismo/tratamento farmacológico
15.
Virology ; 579: 137-147, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36669330

RESUMO

Virus-like particles (VLPs) are promising scaffolds for biomaterials as well as diagnostic and therapeutic applications. However, there are some key challenges to be solved, such as the ability to engineer alternate sizes for varied use cases. To this end, we created a library of MS2 VLP variants at two key residues in the coat protein which have been implicated as important to controlling VLP size and geometry. By adapting a method for systematic mutagenesis coupled with size-based selections and high-throughput sequencing as a readout, we developed a quantitative assessment of two residues in MS2 coat protein that govern the size shift in MS2 VLPs. We then applied the strategy to the equivalent residues in Qß VLPs, an MS2 homolog, and demonstrate that the analogous pair of residues are also able to impact Qß VLP size and shape. These results underscore the power of fitness landscapes in identifying critical features for assembly.


Assuntos
Vacinas de Partículas Semelhantes a Vírus , Tamanho da Partícula , Biblioteca Gênica , Vacinas de Partículas Semelhantes a Vírus/genética
17.
18.
Front Physiol ; 9: 689, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29922180

RESUMO

RASA3 is a Ras GTPase activating protein that plays a critical role in blood formation. The autosomal recessive mouse model scat (severe combined anemia and thrombocytopenia) carries a missense mutation in Rasa3. Homozygotes present with a phenotype characteristic of bone marrow failure that is accompanied by alternating episodes of crisis and remission. The mechanism leading to impaired erythropoiesis and peripheral cell destruction as evidenced by membrane fragmentation in scat is unclear, although we previously reported that the mislocalization of RASA3 to the cytosol of reticulocytes and mature red cells plays a role in the disease. In this study, we further characterized the bone marrow failure in scat and found that RASA3 plays a central role in cell cycle progression and maintenance of reactive oxygen species (ROS) levels during terminal erythroid differentiation, without inducing apoptosis of the precursors. In scat mice undergoing crises, there is a consistent pattern of an increased proportion of cells in the G0/G1 phase at the basophilic and polychromatophilic stages of erythroid differentiation, suggesting that RASA3 is involved in the G1 checkpoint. However, this increase in G1 is transient, and either resolves or becomes indiscernible by the orthochromatic stage. In addition, while ROS levels are normal early in erythropoiesis, there is accumulation of superoxide levels at the reticulocyte stage (DHE increased 40% in scat; p = 0.02) even though mitochondria, a potential source for ROS, are eliminated normally. Surprisingly, apoptosis is significantly decreased in the scat bone marrow at the proerythroblastic (15.3%; p = 0.004), polychromatophilic (8.5%; p = 0.01), and orthochromatic (4.2%; p = 0.02) stages. Together, these data indicate that ROS accumulation at the reticulocyte stage, without apoptosis, contributes to the membrane fragmentation observed in scat. Finally, the cell cycle defect and increased levels of ROS suggest that scat is a model of bone marrow failure with characteristics of aplastic anemia.

19.
Sci Rep ; 8(1): 12793, 2018 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-30143664

RESUMO

Anemic Nan mice carry a mutation (E339D) in the second zinc finger of erythroid transcription factor KLF1. Nan-KLF1 fails to bind a subset of normal KLF1 targets and ectopically binds a large set of genes not normally engaged by KLF1, resulting in a corrupted fetal liver transcriptome. Here, we performed RNAseq using flow cytometric-sorted spleen erythroid precursors from adult Nan and WT littermates rendered anemic by phlebotomy to identify global transcriptome changes specific to the Nan Klf1 mutation as opposed to anemia generally. Mutant Nan-KLF1 leads to extensive and progressive transcriptome corruption in adult spleen erythroid precursors such that stress erythropoiesis is severely compromised. Terminal erythroid differentiation is defective in the bone marrow as well. Principle component analysis reveals two major patterns of differential gene expression predicting that defects in basic cellular processes including translation, cell cycle, and DNA repair could contribute to disordered erythropoiesis and anemia in Nan. Significant erythroid precursor stage specific changes were identified in some of these processes in Nan. Remarkably, however, despite expression changes in large numbers of associated genes, most basic cellular processes were intact in Nan indicating that developing red cells display significant physiological resiliency and establish new homeostatic set points in vivo.


Assuntos
Envelhecimento/patologia , Anemia/genética , Anemia/patologia , Diferenciação Celular/genética , Eritropoese/genética , Fatores de Transcrição Kruppel-Like/genética , Mutação/genética , Transcriptoma/genética , Animais , Sequência de Bases , Ciclo Celular/genética , Dano ao DNA , Células Eritroides/metabolismo , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Ontologia Genética , Fatores de Transcrição Kruppel-Like/metabolismo , Fígado/embriologia , Fígado/metabolismo , Camundongos , Camundongos Mutantes , Mitofagia/genética , Anotação de Sequência Molecular , Análise de Componente Principal , Espécies Reativas de Oxigênio/metabolismo , Baço/embriologia , Baço/metabolismo
20.
Nat Commun ; 9(1): 1385, 2018 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-29643335

RESUMO

Self-assembling proteins are critical to biological systems and industrial technologies, but predicting how mutations affect self-assembly remains a significant challenge. Here, we report a technique, termed SyMAPS (Systematic Mutation and Assembled Particle Selection), that can be used to characterize the assembly competency of all single amino acid variants of a self-assembling viral structural protein. SyMAPS studies on the MS2 bacteriophage coat protein revealed a high-resolution fitness landscape that challenges some conventional assumptions of protein engineering. An additional round of selection identified a previously unknown variant (CP[T71H]) that is stable at neutral pH but less tolerant to acidic conditions than the wild-type coat protein. The capsids formed by this variant could be more amenable to disassembly in late endosomes or early lysosomes-a feature that is advantageous for delivery applications. In addition to providing a mutability blueprint for virus-like particles, SyMAPS can be readily applied to other self-assembling proteins.


Assuntos
Aminoácidos/química , Proteínas do Capsídeo/química , Capsídeo/química , Levivirus/química , Mutação , Vírion/química , Aminoácidos/metabolismo , Capsídeo/metabolismo , Capsídeo/ultraestrutura , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Endossomos/metabolismo , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Levivirus/metabolismo , Levivirus/ultraestrutura , Modelos Moleculares , Mutagênese Sítio-Dirigida , Engenharia de Proteínas/métodos , Estabilidade Proteica , Estrutura Secundária de Proteína , Proteólise , Eletricidade Estática , Vírion/metabolismo , Vírion/ultraestrutura
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