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1.
Aging Cell ; 23(6): e14155, 2024 06.
Artigo em Inglês | MEDLINE | ID: mdl-38529808

RESUMO

Parkinson's disease (PD) is characterised by progressive loss of dopaminergic (DA) neurons from the substantia nigra (SN) and α-synuclein (αSyn) accumulation. Age is the biggest risk factor for PD and may create a vulnerable pre-parkinsonian state, but the drivers of this association are unclear. It is known that ageing increases αSyn expression in DA neurons and that this may alter molecular processes that are central to maintaining nigrostriatal integrity. To model this, adult female Sprague-Dawley rats received a unilateral intranigral injection of adeno-associated viral (AAV) vector carrying wild-type human αSyn (AAV-αSyn) or control vector (AAV-Null). AAV-αSyn induced no detrimental effects on motor behaviour, but there was expression of human wild-type αSyn throughout the midbrain and ipsilateral striatum at 20 weeks post-surgery. Microarray analysis revealed that the gene most-upregulated in the ipsilateral SN of the AAV-αSyn group was the SKI Family Transcriptional Corepressor 1 (SKOR1). Bioenergetic state analysis of mitochondrial function found that SKOR1 overexpression reduced the maximum rate of cellular respiration in SH-SY5Y cells. Furthermore, experiments in SH-SY5Y cells revealed that SKOR1 overexpression impaired neurite growth to the same extent as αSyn, and inhibited BMP-SMAD-dependent transcription, a pathway that promotes DA neuronal survival and growth. Given the normal influence of ageing on DA neuron loss in human SN, the extent of αSyn-induced SKOR1 expression may influence whether an individual undergoes normal nigrostriatal ageing or reaches a threshold for prodromal PD. This provides new insight into mechanisms through which ageing-related increases in αSyn may influence molecular mechanisms important for the maintenance of neuronal integrity.


Assuntos
Envelhecimento , Ratos Sprague-Dawley , Substância Negra , alfa-Sinucleína , Animais , Feminino , Humanos , Ratos , Envelhecimento/metabolismo , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Corpo Estriado/metabolismo , Corpo Estriado/patologia , Modelos Animais de Doenças , Neurônios Dopaminérgicos/metabolismo , Doença de Parkinson/metabolismo , Doença de Parkinson/genética , Doença de Parkinson/patologia , Substância Negra/metabolismo , Substância Negra/patologia , Regulação para Cima
2.
J Chem Neuroanat ; 131: 102288, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37178741

RESUMO

Adenosine 5'-triphosphate (ATP) is the principal source of cellular energy, which is essential for neuronal health and maintenance. Parkinson's disease (PD) and other neurodegenerative disorders are characterised by impairments in mitochondrial function and reductions in cellular ATP levels. Thus there is a need to better understand the biology of intracellular regulators of ATP production, in order to inform the development of new neuroprotective therapies for diseases such as PD. One such regulator is Zinc finger HIT-domain containing protein 1 (ZNHIT1). ZNHIT1 is an evolutionarily-conserved component of a chromatin-remodelling complex, which has been recently shown to increase cellular ATP production in SH-SY5Y cells and to protect against impairments in mitochondrial function caused by alpha-synuclein, a protein which is integral to PD pathophysiology. This effect of ZNHIT1 on cellular ATP production is thought to be due to increased expression of genes associated with mitochondrial function, but it is also possible that ZNHIT1 regulates mitochondrial function by binding to mitochondrial proteins. To examine this question, we performed a combined proteomics and bioinformatics analysis to identify ZNHIT1-interacting proteins in SH-SY5Y cells. We report that ZNHIT1-interacting proteins are significantly enriched in multiple functional categories, including mitochondrial transport, ATP synthesis and ATP-dependent activity. Furthermore we also report that the correlation between ZNHIT1 and dopaminergic markers is reduced in the PD brain. These data suggest that the reported beneficial effects of ZNHIT1 on ATP production may be mediated, at least in part, by its direct interaction with mitochondrial proteins and suggest that potential alterations in ZNHIT1 in PD may contribute to the known impairments in ATP generation in midbrain dopaminergic neurons in PD.


Assuntos
Neuroblastoma , Doença de Parkinson , Fosfoproteínas , Humanos , Trifosfato de Adenosina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Neuroblastoma/metabolismo , Doença de Parkinson/metabolismo , Proteômica , Fosfoproteínas/metabolismo
3.
Clin Gastroenterol Hepatol ; 21(7): 1802-1809.e6, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-36967102

RESUMO

BACKGROUND & AIMS: Early detection of pancreatic cancer (PaC) can drastically improve survival rates. Approximately 25% of subjects with PaC have type 2 diabetes diagnosed within 3 years prior to the PaC diagnosis, suggesting that subjects with type 2 diabetes are at high risk of occult PaC. We have developed an early-detection PaC test, based on changes in 5-hydroxymethylcytosine (5hmC) signals in cell-free DNA from plasma. METHODS: Blood was collected from 132 subjects with PaC and 528 noncancer subjects to generate epigenomic and genomic feature sets yielding a predictive PaC signal algorithm. The algorithm was validated in a blinded cohort composed of 102 subjects with PaC, 2048 noncancer subjects, and 1524 subjects with non-PaCs. RESULTS: 5hmC differential profiling and additional genomic features enabled the development of a machine learning algorithm capable of distinguishing subjects with PaC from noncancer subjects with high specificity and sensitivity. The algorithm was validated with a sensitivity for early-stage (stage I/II) PaC of 68.3% (95% confidence interval [CI], 51.9%-81.9%) and an overall specificity of 96.9% (95% CI, 96.1%-97.7%). CONCLUSIONS: The PaC detection test showed robust early-stage detection of PaC signal in the studied cohorts with varying type 2 diabetes status. This assay merits further clinical validation for the early detection of PaC in high-risk individuals.


Assuntos
Ácidos Nucleicos Livres , Diabetes Mellitus Tipo 2 , Neoplasias Pancreáticas , Humanos , Diabetes Mellitus Tipo 2/diagnóstico , Epigenômica , Detecção Precoce de Câncer , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/genética
4.
Cancer Res ; 82(21): 3888-3902, 2022 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-36251389

RESUMO

Analysis of DNA methylation is a valuable tool to understand disease progression and is increasingly being used to create diagnostic and prognostic clinical biomarkers. While conversion of cytosine to 5-methylcytosine (5mC) commonly results in transcriptional repression, further conversion to 5-hydroxymethylcytosine (5hmC) is associated with transcriptional activation. Here we perform the first study integrating whole-genome 5hmC with DNA, 5mC, and transcriptome sequencing in clinical samples of benign, localized, and advanced prostate cancer. 5hmC is shown to mark activation of cancer drivers and downstream targets. Furthermore, 5hmC sequencing revealed profoundly altered cell states throughout the disease course, characterized by increased proliferation, oncogenic signaling, dedifferentiation, and lineage plasticity to neuroendocrine and gastrointestinal lineages. Finally, 5hmC sequencing of cell-free DNA from patients with metastatic disease proved useful as a prognostic biomarker able to identify an aggressive subtype of prostate cancer using the genes TOP2A and EZH2, previously only detectable by transcriptomic analysis of solid tumor biopsies. Overall, these findings reveal that 5hmC marks epigenomic activation in prostate cancer and identify hallmarks of prostate cancer progression with potential as biomarkers of aggressive disease. SIGNIFICANCE: In prostate cancer, 5-hydroxymethylcytosine delineates oncogene activation and stage-specific cell states and can be analyzed in liquid biopsies to detect cancer phenotypes. See related article by Wu and Attard, p. 3880.


Assuntos
5-Metilcitosina , Neoplasias da Próstata , Masculino , Humanos , Próstata , Biópsia
5.
Blood Cancer Discov ; 3(4): 346-367, 2022 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-35532363

RESUMO

The conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) is a key step in DNA demethylation that is mediated by ten-eleven translocation (TET) enzymes, which require ascorbate/vitamin C. Here, we report the 5hmC landscape of normal hematopoiesis and identify cell type-specific 5hmC profiles associated with active transcription and chromatin accessibility of key hematopoietic regulators. We utilized CRISPR/Cas9 to model TET2 loss-of-function mutations in primary human hematopoietic stem and progenitor cells (HSPC). Disrupted cells exhibited increased colonies in serial replating, defective erythroid/megakaryocytic differentiation, and in vivo competitive advantage and myeloid skewing coupled with reduction of 5hmC at erythroid-associated gene loci. Azacitidine and ascorbate restored 5hmC abundance and slowed or reverted the expansion of TET2-mutant clones in vivo. These results demonstrate the key role of 5hmC in normal hematopoiesis and TET2-mutant phenotypes and raise the possibility of utilizing these agents to further our understanding of preleukemia and clonal hematopoiesis. SIGNIFICANCE: We show that 5-hydroxymethylation profiles are cell type-specific and associated with transcriptional abundance and chromatin accessibility across human hematopoiesis. TET2 loss caused aberrant growth and differentiation phenotypes and disrupted 5hmC and transcriptional landscapes. Treatment of TET2 KO HSPCs with ascorbate or azacitidine reverted 5hmC profiles and restored aberrant phenotypes. This article is highlighted in the In This Issue feature, p. 265.


Assuntos
Dioxigenases , Síndromes Mielodisplásicas , Pré-Leucemia , Azacitidina/farmacologia , Cromatina/genética , Proteínas de Ligação a DNA/genética , Dioxigenases/genética , Hematopoese/genética , Humanos , Proteínas Proto-Oncogênicas/genética
6.
Mol Cancer Ther ; 20(11): 2274-2279, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34465593

RESUMO

When tissue biopsy is not medically prudent or tissue is insufficient for molecular testing, alternative methods are needed. Because cell-free DNA (cfDNA) has been shown to provide a representative surrogate for tumor tissue, we sought to evaluate its utility in this clinical scenario. cfDNA was isolated from the plasma of patients and assayed with low-coverage (∼0.3×), genome-wide sequencing. Copy-number alterations (CNA) were identified and characterized using analytic methods originally developed for noninvasive prenatal testing (NIPT) and quantified using the genomic instability number (GIN), a metric that reflects the quantity and magnitude of CNAs across the genome. The technical variability of the GIN was first evaluated in an independent cohort comprising genome-wide sequencing results from 27,754 women who consented to have their samples used for research and whose NIPT results yielded no detected CNAs to establish a detection threshold. Subsequently, cfDNA sequencing data from 96 patients with known cancers but for whom a tissue biopsy could not be obtained are presented. An elevated GIN was detected in 35% of patients and detection rates varied by tumor origin. Collectively, CNAs covered 96.6% of all autosomes. Survival was significantly reduced in patients with an elevated GIN relative to those without. Overall, these data provide a proof of concept for the use of low-coverage, genome-wide sequencing of cfDNA from patients with cancer to obtain relevant molecular information in instances where tissue is difficult to access. These data may ultimately serve as an informative complement to other molecular tests.


Assuntos
Biomarcadores Tumorais/genética , Ácidos Nucleicos Livres/genética , Variações do Número de Cópias de DNA/genética , Neoplasias/genética , Sequenciamento Completo do Genoma/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medicina de Precisão , Adulto Jovem
7.
Methods Mol Biol ; 2353: 307-332, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34292556

RESUMO

Lipoic acid is an essential sulfur-containing cofactor used by several multienzyme complexes involved in energy metabolism and the breakdown of certain amino acids. It is composed of n-octanoic acid with sulfur atoms appended at C6 and C8. Lipoic acid is biosynthesized de novo in its cofactor form, in which it is covalently bound in an amide linkage to a target lysyl residue on a lipoyl carrier protein (LCP). The n-octanoyl moiety of the cofactor is derived from type 2 fatty acid biosynthesis and is transferred to an LCP to afford an octanoyllysyl amino acid. Next, lipoyl synthase (LipA in bacteria) catalyzes the attachment of the two sulfur atoms to afford the intact cofactor. LipA is a radical S-adenosylmethionine (SAM) enzyme that contains two [4Fe-4S] clusters. One [4Fe-4S] cluster is used to facilitate a reductive cleavage of SAM to render the highly oxidizing 5'-deoxyadenosyl 5'-radical needed to abstract C6 and C8 hydrogen atoms to allow for sulfur attachment. By contrast, the second cluster is the sulfur source, necessitating its destruction during turnover. In Escherichia coli, this auxiliary cluster can be restored after each turnover by NfuA or IscU, which are two iron-sulfur cluster carrier proteins that are implicated in iron-sulfur cluster biogenesis. In this chapter, we describe methods for purifying and characterizing LipA and NfuA from Mycobacterium tuberculosis, a human pathogen for which endogenously synthesized lipoic acid is essential. These studies provide the foundation for assessing lipoic acid biosynthesis as a potential target for the design of novel antituberculosis agents.


Assuntos
Mycobacterium tuberculosis , Proteínas de Transporte , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli , Humanos , Ferro/metabolismo , Proteínas Ferro-Enxofre , Metabolismo dos Lipídeos , Lipídeos , Mycobacterium tuberculosis/metabolismo , S-Adenosilmetionina , Enxofre/metabolismo , Ácido Tióctico
8.
Nat Commun ; 11(1): 5270, 2020 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-33077732

RESUMO

Pancreatic cancer is often detected late, when curative therapies are no longer possible. Here, we present non-invasive detection of pancreatic ductal adenocarcinoma (PDAC) by 5-hydroxymethylcytosine (5hmC) changes in circulating cell free DNA from a PDAC cohort (n = 64) in comparison with a non-cancer cohort (n = 243). Differential hydroxymethylation is found in thousands of genes, most significantly in genes related to pancreas development or function (GATA4, GATA6, PROX1, ONECUT1, MEIS2), and cancer pathogenesis (YAP1, TEAD1, PROX1, IGF1). cfDNA hydroxymethylome in PDAC cohort is differentially enriched for genes that are commonly de-regulated in PDAC tumors upon activation of KRAS and inactivation of TP53. Regularized regression models built using 5hmC densities in genes perform with AUC of 0.92 (discovery dataset, n = 79) and 0.92-0.94 (two independent test sets, n = 228). Furthermore, tissue-derived 5hmC features can be used to classify PDAC cfDNA (AUC = 0.88). These findings suggest that 5hmC changes enable classification of PDAC even during early stage disease.


Assuntos
5-Metilcitosina/análogos & derivados , Ácidos Nucleicos Livres/metabolismo , Neoplasias Pancreáticas/genética , 5-Metilcitosina/metabolismo , Adulto , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/metabolismo , Ácidos Nucleicos Livres/sangue , Ácidos Nucleicos Livres/genética , Estudos de Coortes , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Fator de Transcrição GATA4/genética , Fator de Transcrição GATA4/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Neoplasias Pancreáticas/sangue , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Fatores de Transcrição de Domínio TEA , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Neoplasias Pancreáticas
9.
Neuronal Signal ; 4(1): NS20200006, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32714600

RESUMO

Neuroblastoma (NB) is a paediatric cancer that arises in the sympathetic nervous system. Patients with stage 4 tumours have poor outcomes and 20% of high-risk cases have MYCN amplification. The bone morphogenetic proteins (BMPs) play roles in sympathetic neuritogenesis, by signalling through bone morphogenetic protein receptor (BMPR)2 and either BMPR1A or BMPR1B. Alterations in BMPR2 expression have been reported in NB; it is unknown if the expression of BMPR1A or BMPR1B is altered. We report lower BMPR2 and BMPR1B, and higher BMPR1A, expression in stage 4 and in MYCN-amplified NB. Kaplan-Meier plots showed that high BMPR2 or BMPR1B expression was linked to better survival, while high BMPR1A was linked to worse survival. Gene ontology enrichment and pathway analyses revealed that BMPR2 and BMPR1B co-expressed genes were enriched in those associated with NB differentiation. BMPR1A co-expressed genes were enriched in those associated with cell proliferation. Moreover, the correlation between BMPR2 and BMPR1A was strengthened, while the correlation between BMPR2 and BMPR1B was lost, in MYCN-amplified NB. This suggested that differentiation should decrease BMPR1A and increase BMPR1B expression. In agreement, nerve growth factor treatment of cultured sympathetic neurons decreased Bmpr1a expression and increased Bmpr1b expression. Overexpression of dominant negative BMPR1B, treatment with a BMPR1B inhibitor and treatment with GDF5, which signals via BMPR1B, showed that BMPR1B signalling is required for optimal neuritogenesis in NB cells, suggesting that loss of BMPR1B may alter neuritogenesis. The present study shows that expression of distinct BMPRs is associated with different survival outcomes in NB.

10.
Biochim Biophys Acta Gen Subj ; 1863(11): 129415, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31404619

RESUMO

BACKGROUND: AID/APOBEC3 (A3) enzymes instigate genomic mutations that are involved in immunity and cancer. Although they can deaminate any deoxycytidine (dC) to deoxyuridine (dU), each family member has a signature preference determined by nucleotides surrounding the target dC. This WRC (W = A/T, R = A/G) and YC (Y = T/C) hotspot preference is established for AID and A3A/A3B, respectively. Base alkylation and oxidation are two of the most common types of DNA damage induced environmentally or by chemotherapy. Here we examined the activity of AID, A3A and A3B on dCs neighboring such damaged bases. METHODS: Substrates were designed to contain target dCs either in normal WRC/YC hotspots, or in oxidized/alkylated DNA motifs. AID, A3A and A3B were purified and deamination kinetics of each were compared between substrates containing damaged vs. normal motifs. RESULTS: All three enzymes efficiently deaminated dC when common damaged bases were present in the -2 or -1 positions. Strikingly, some damaged motifs supported comparable or higher catalytic efficiencies by AID, A3A and A3B than the WRC/YC motifs which are their most favored normal sequences. Based on the resolved interactions of AID, A3A and A3B with DNA, we modeled interactions with alkylated or oxidized bases. Corroborating the enzyme assay data, the surface regions that recognize normal bases are predicted to also interact robustly with oxidized and alkylated bases. CONCLUSIONS: AID, A3A and A3B can efficiently recognize and deaminate dC whose neighbouring nucleotides are damaged. GENERAL SIGNIFICANCE: Beyond AID/A3s initiating DNA damage, some forms of pre-existing damaged DNA can constitute favored targets of AID/A3s if encountered.


Assuntos
Citidina Desaminase/química , Dano ao DNA , Desoxicitidina/química , Antígenos de Histocompatibilidade Menor/química , Proteínas/química , Citidina Desaminase/metabolismo , Desaminação , Desoxicitidina/metabolismo , Humanos , Antígenos de Histocompatibilidade Menor/metabolismo , Oxirredução , Proteínas/metabolismo
11.
J Biol Chem ; 294(5): 1609-1617, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30538130

RESUMO

The lipoyl cofactor plays an integral role in several essential biological processes. The last step in its de novo biosynthetic pathway, the attachment of two sulfur atoms at C6 and C8 of an n-octanoyllysyl chain, is catalyzed by lipoyl synthase (LipA), a member of the radical SAM superfamily. In addition to the [4Fe-4S] cluster common to all radical SAM enzymes, LipA contains a second [4Fe-4S] auxiliary cluster, which is sacrificed during catalysis to supply the requisite sulfur atoms, rendering the protein inactive for further turnovers. Recently, it was shown that the Fe-S cluster carrier protein NfuA from Escherichia coli can regenerate the auxiliary cluster of E. coli LipA after each turnover, but the molecular mechanism is incompletely understood. Herein, using protein-protein interaction and kinetic assays as well as site-directed mutagenesis, we provide further insight into the mechanism of NfuA-mediated cluster regeneration. In particular, we show that the N-terminal A-type domain of E. coli NfuA is essential for its tight interaction with LipA. Further, we demonstrate that NfuA from Mycobacterium tuberculosis can also regenerate the auxiliary cluster of E. coli LipA. However, an Nfu protein from Staphylococcus aureus, which lacks the A-type domain, was severely diminished in facilitating cluster regeneration. Of note, addition of the N-terminal domain of E. coli NfuA to S. aureus Nfu, fully restored cluster-regenerating activity. These results expand our understanding of the newly discovered mechanism by which the auxiliary cluster of LipA is restored after each turnover.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Proteínas Ferro-Enxofre/metabolismo , Ferro/metabolismo , Enxofre/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Catálise , Proteínas de Escherichia coli/química , Ferro/química , Proteínas Ferro-Enxofre/química , Domínios Proteicos , Enxofre/química
12.
Mol Cancer Ther ; 18(2): 448-458, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30523049

RESUMO

Inhibitors of the PD-1/PD-L1/CTLA-4 immune checkpoint pathway have revolutionized cancer treatment. Indeed, some patients with advanced, refractory malignancies achieve durable responses; however, only a subset of patients benefit, necessitating new biomarkers to predict outcome. Interrogating cell-free DNA (cfDNA) isolated from plasma (liquid biopsy) provides a promising method for monitoring response. We describe the use of low-coverage, genome-wide sequencing of cfDNA, validated extensively for noninvasive prenatal testing, to detect tumor-specific copy-number alterations, and the development of a new metric-the genome instability number (GIN)-to monitor response to these drugs. We demonstrate how the GIN can be used to discriminate clinical response from progression, differentiate progression from pseudoprogression, and identify hyperprogressive disease. Finally, we provide evidence for delayed kinetics in responses to checkpoint inhibitors relative to molecularly targeted therapies. Overall, these data demonstrate a proof of concept for using this method for monitoring treatment outcome in patients with cancer receiving immunotherapy.


Assuntos
Biomarcadores Tumorais/genética , Ácidos Nucleicos Livres/genética , Imunoterapia/métodos , Neoplasias/tratamento farmacológico , Sequenciamento Completo do Genoma/métodos , Antígeno B7-H1/antagonistas & inibidores , Antígeno CTLA-4/antagonistas & inibidores , Linhagem Celular Tumoral , Variações do Número de Cópias de DNA , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Neoplasias/genética , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Estudos Prospectivos , Análise de Sobrevida , Resultado do Tratamento
13.
Methods Enzymol ; 606: 217-239, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30097094

RESUMO

Lipoyl synthase (LipA in bacteria) is a radical S-adenosylmethionine (SAM) enzyme that catalyzes the second step of the de novo biosynthesis of the lipoyl cofactor: the insertion of sulfur at C6 and C8 of a pendant octanoyl chain. In addition to the [4Fe4S] cluster that is characteristic of the radical SAM (RS) enzymes, LipA contains a second [4Fe4S] cluster that, though controversial, has been proposed to be degraded during turnover to supply the inserted sulfur atoms. A consequence of this proposed role is that the destruction of its iron-sulfur cluster renders the enzyme in an inactive state. Recently, it was shown that Escherichia coli proteins NfuA or IscU can confer catalytic properties to E. coli LipA in vitro. In this chapter, we present methods for characterizing LipA and analyzing its activity in vitro, and provide strategies to monitor the pathway for the regeneration of LipA's auxiliary cluster by E. coli iron-sulfur carrier protein NfuA.


Assuntos
Proteínas de Bactérias/metabolismo , Biocatálise , Ensaios Enzimáticos/métodos , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Proteínas de Bactérias/isolamento & purificação , Proteínas de Escherichia coli/isolamento & purificação , Proteínas Ferro-Enxofre/isolamento & purificação , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , S-Adenosilmetionina/metabolismo
14.
J Acquir Immune Defic Syndr ; 78 Suppl 2: S142-S146, 2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-29994837

RESUMO

The Accelerating Children's HIV/AIDS Treatment (ACT) Initiative was an ambitious joint donor initiative to increase the number of HIV-positive children and adolescents on treatment over a 2-year period from 2014 to 2016. The funding was provided by the US Government's President's Emergency Plan for AIDS Relief (PEPFAR) and the private Children's Investment Fund Foundation (CIFF). Great gains were achieved across the 9 ACT focus countries in pediatric treatment coverage. This article assesses the status of sustainability in the ACT countries after the pediatric treatment surge using PEPFAR sustainability data and a CIFF independent evaluation of sustainability. Although a focus on treatment is critical for pediatric HIV and HIV broadly, there is also a need to support the host country ability to maintain the progress gained once donor funds and initiatives transition. It uses the case of the ACT Initiative to argue that although surge activities are successful in rapidly scaling treatment results, there are concerns related to the health system's ability to maintain the progress along the full cascade. It shares important lessons for planning for and management of transition to support future donor efforts in pediatric HIV, overall HIV programming, and broader global health initiatives.


Assuntos
Síndrome da Imunodeficiência Adquirida/tratamento farmacológico , Saúde Global , Infecções por HIV/tratamento farmacológico , HIV/isolamento & purificação , Parcerias Público-Privadas , Síndrome da Imunodeficiência Adquirida/diagnóstico , Síndrome da Imunodeficiência Adquirida/prevenção & controle , Adolescente , Criança , Programas Governamentais , Infecções por HIV/diagnóstico , Infecções por HIV/prevenção & controle , Humanos , Programas Nacionais de Saúde , Estados Unidos
15.
Biochemistry ; 57(9): 1475-1490, 2018 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-29298049

RESUMO

The methylation of unactivated carbon and phosphorus centers is a burgeoning area of biological chemistry, especially given that such reactions constitute key steps in the biosynthesis of numerous enzyme cofactors, antibiotics, and other natural products of clinical value. These kinetically challenging reactions are catalyzed exclusively by enzymes in the radical S-adenosylmethionine (SAM) superfamily and have been grouped into four classes (A-D). Class B radical SAM (RS) methylases require a cobalamin cofactor in addition to the [4Fe-4S] cluster that is characteristic of RS enzymes. However, their poor solubility upon overexpression and their generally poor turnover has hampered detailed in vitro studies of these enzymes. It has been suggested that improper folding, possibly caused by insufficient cobalamin during their overproduction in Escherichia coli, leads to formation of inclusion bodies. Herein, we report our efforts to improve the overproduction of class B RS methylases in a soluble form by engineering a strain of E. coli to take in more cobalamin. We cloned five genes ( btuC, btuE, btuD, btuF, and btuB) that encode proteins that are responsible for cobalamin uptake and transport in E. coli and co-expressed these genes with those that encode TsrM, Fom3, PhpK, and ThnK, four class B RS methylases that suffer from poor solubility during overproduction. This strategy markedly enhances the uptake of cobalamin into the cytoplasm and improves the solubility of the target enzymes significantly.


Assuntos
Escherichia coli/metabolismo , Metiltransferases/metabolismo , S-Adenosilmetionina/metabolismo , Vitamina B 12/metabolismo , Escherichia coli/enzimologia , Escherichia coli/genética , Metiltransferases/química , Metiltransferases/genética , S-Adenosilmetionina/química , Solubilidade
16.
Science ; 358(6361): 373-377, 2017 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-29051382

RESUMO

Lipoyl synthase (LipA) catalyzes the last step in the biosynthesis of the lipoyl cofactor, which is the attachment of two sulfhydryl groups to C6 and C8 of a pendant octanoyl chain. The appended sulfur atoms derive from an auxiliary [4Fe-4S] cluster on the protein that is degraded during turnover, limiting LipA to one turnover in vitro. We found that the Escherichia coli iron-sulfur (Fe-S) cluster carrier protein NfuA efficiently reconstitutes the auxiliary cluster during LipA catalysis in a step that is not rate-limiting. We also found evidence for a second pathway for cluster regeneration involving the E. coli protein IscU. These results show that enzymes that degrade their Fe-S clusters as a sulfur source can nonetheless act catalytically. Our results also explain why patients with NFU1 gene deletions exhibit phenotypes that are indicative of lipoyl cofactor deficiencies.


Assuntos
Proteínas de Bactérias/metabolismo , Biocatálise , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , Proteínas Ferro-Enxofre/metabolismo , Proteínas de Bactérias/química , Proteínas de Transporte/genética , Proteínas de Escherichia coli/química , Deleção de Genes , Humanos , Proteínas Ferro-Enxofre/química , Proteólise
17.
Annu Rev Biochem ; 85: 485-514, 2016 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-27145839

RESUMO

Radical S-adenosylmethionine (SAM) enzymes catalyze an astonishing array of complex and chemically challenging reactions across all domains of life. Of approximately 114,000 of these enzymes, 8 are known to be present in humans: MOCS1, molybdenum cofactor biosynthesis; LIAS, lipoic acid biosynthesis; CDK5RAP1, 2-methylthio-N(6)-isopentenyladenosine biosynthesis; CDKAL1, methylthio-N(6)-threonylcarbamoyladenosine biosynthesis; TYW1, wybutosine biosynthesis; ELP3, 5-methoxycarbonylmethyl uridine; and RSAD1 and viperin, both of unknown function. Aberrations in the genes encoding these proteins result in a variety of diseases. In this review, we summarize the biochemical characterization of these 8 radical S-adenosylmethionine enzymes and, in the context of human health, describe the deleterious effects that result from such genetic mutations.


Assuntos
Diabetes Mellitus Tipo 2/genética , Cardiopatias Congênitas/genética , Erros Inatos do Metabolismo dos Metais/genética , Mutação , Doenças Neurodegenerativas/genética , S-Adenosilmetionina/metabolismo , Carbono-Carbono Liases , Diabetes Mellitus Tipo 2/enzimologia , Diabetes Mellitus Tipo 2/patologia , Expressão Gênica , Cardiopatias Congênitas/enzimologia , Cardiopatias Congênitas/patologia , Histona Acetiltransferases/genética , Histona Acetiltransferases/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Ferro-Enxofre/genética , Proteínas Ferro-Enxofre/metabolismo , Erros Inatos do Metabolismo dos Metais/enzimologia , Erros Inatos do Metabolismo dos Metais/patologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Doenças Neurodegenerativas/enzimologia , Doenças Neurodegenerativas/patologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Oxirredutases/genética , Oxirredutases/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-CH , Proteínas/genética , Proteínas/metabolismo , Ácido Tióctico/metabolismo , tRNA Metiltransferases/genética , tRNA Metiltransferases/metabolismo
18.
J Am Soc Cytopathol ; 5(6): 331-338, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-31042544

RESUMO

INTRODUCTION: Cervical screening has undergone significant changes in recent years, with molecular human papillomavirus (HPV) testing for HPV 16 and 18 at the forefront of clinical practice. But is molecular testing more effective than morphologic testing for cervical screening? Does current information on HPV hold true across all populations? As a public health laboratory serving high-risk, underserved populations, these remain important considerations for our practice. MATERIALS AND METHODS: The subject population largely consisted of young women within 200% or less of the poverty line. Correlation of Papanicolaou and HPV results was performed via retrospective review, focusing on Papanicolaou cases with high-grade diagnoses and an associated HPV test using the cobas 4800 HPV test. Secondary HPV testing and typing was performed via PCR at an outside laboratory for 205 cases with sufficient residual material and negative for HPV 16/18 by cobas. RESULTS: Of 20,211 cytology tests reviewed from July 2013 to May 2015, 521 were diagnosed as high-grade; 387 had concurrent HPV tests. Of those with concurrent HPV tests, 58% (225 of 387) of the high-grade Papanicolaou cases were not HPV 16/18 positive; furthermore, no HPV was detected in 14% (55 of 387) of these cases. Secondary testing revealed the presence of 25 unique genotypes. CONCLUSIONS: With recent emphasis on molecular HPV testing, the results of this review are concerning. As we move forward with evolution of cervical screening practices, it will be important to explore these questions for the continued quality and integrity of women's health services.

19.
Elife ; 42015 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-26350572

RESUMO

The cellular machinery that incorporates iron-sulfur clusters into proteins is directed to particular targets by adaptor proteins.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Transporte/metabolismo , Ferro/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Enxofre/metabolismo , Humanos
20.
Diagn Cytopathol ; 43(1): 3-7, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24819853

RESUMO

Implementing new technology in the laboratory can improve processes and patient care, but compliance with regulatory requirements can be a significant hurdle to clear. This study provides a detailed procedure to address user training, competency assessment, and internal validation of telecytopathology simultaneously, while fulfilling regulatory requirements set forth by the College of American Pathologists and CLIA '88. Six pathologists participated in this study. Methods and materials used included a blind correlation study between diagnoses rendered via telecytopathology and via direct microscopy on 10 finalized fine needle aspiration (FNA) cases. The first step of this procedure involved each pathologist to render a diagnosis for each specimen using telecytopathology. The second step was to allow each pathologist to diagnose each specimen via direct microscopic review after a wait period of at least 6 weeks. The diagnoses rendered via telecytopathology were then compared to both the established final diagnoses and the secondary direct microscopic review diagnoses to examine interpathologist and intrapathologist reproducibility with a passing rate of 90% or better. Results of the study yielded an average concordance rate of 96.67% for interpathologist reproducibility and 95% for intrapathologist reproducibility across all participating pathologists. All participants passed the assessment with a rate of 90% or better, proving evidence of competency. This study confirmed user competency and validated telecytopathology as an effective tool for examining and diagnosing cytology FNA specimens remotely. It also satisfied regulatory compliance requirements to ensure high quality of diagnostic testing and patient care.


Assuntos
Telepatologia/métodos , Biópsia por Agulha Fina/métodos , Humanos , Telepatologia/instrumentação
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