RESUMO
Mutations causing amyotrophic lateral sclerosis (ALS) often affect the condensation properties of RNA-binding proteins (RBPs). However, the role of RBP condensation in the specificity and function of protein-RNA complexes remains unclear. We created a series of TDP-43 C-terminal domain (CTD) variants that exhibited a gradient of low to high condensation propensity, as observed in vitro and by nuclear mobility and foci formation. Notably, a capacity for condensation was required for efficient TDP-43 assembly on subsets of RNA-binding regions, which contain unusually long clusters of motifs of characteristic types and density. These "binding-region condensates" are promoted by homomeric CTD-driven interactions and required for efficient regulation of a subset of bound transcripts, including autoregulation of TDP-43 mRNA. We establish that RBP condensation can occur in a binding-region-specific manner to selectively modulate transcriptome-wide RNA regulation, which has implications for remodeling RNA networks in the context of signaling, disease, and evolution.
Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , RNA/metabolismo , Regiões 3' não Traduzidas/genética , Sequência de Bases , Núcleo Celular/metabolismo , Células HEK293 , Células HeLa , Homeostase , Humanos , Mutação/genética , Motivos de Nucleotídeos/genética , Transição de Fase , Mutação Puntual/genética , Poli A/metabolismo , Ligação Proteica , Multimerização Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Deleção de SequênciaRESUMO
Biomolecular condensates are reversible compartments that form through a process called phase separation. Post-translational modifications like ADP-ribosylation can nucleate the formation of these condensates by accelerating the self-association of proteins. Poly(ADP-ribose) (PAR) chains are remarkably transient modifications with turnover rates on the order of minutes, yet they can be required for the formation of granules in response to oxidative stress, DNA damage, and other stimuli. Moreover, accumulation of PAR is linked with adverse phase transitions in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In this review, we provide a primer on how PAR is synthesized and regulated, the diverse structures and chemistries of ADP-ribosylation modifications, and protein-PAR interactions. We review substantial progress in recent efforts to determine the molecular mechanism of PAR-mediated phase separation, and we further delineate how inhibitors of PAR polymerases may be effective treatments for neurodegenerative pathologies. Finally, we highlight the need for rigorous biochemical interrogation of ADP-ribosylation in vivo and in vitro to clarify the exact pathway from PARylation to condensate formation.
Assuntos
Poli Adenosina Difosfato Ribose , Poli(ADP-Ribose) Polimerases , Poli Adenosina Difosfato Ribose/metabolismo , Poli(ADP-Ribose) Polimerases/química , Poli(ADP-Ribose) Polimerases/metabolismo , Condensados Biomoleculares , Poli ADP Ribosilação , Processamento de Proteína Pós-TraducionalRESUMO
We reported previously that stem cells associated with adult rat testis seminiferous tubules are able to give rise to differentiated Leydig cells in vitro. The regulatory mechanisms by which they do so, however, are uncertain. Herein, we hypothesized that the proliferation and differentiation of Leydig cell stem cells (stem Leydig cells, SLCs) depend upon locally produced factors from the seminiferous tubules. Microarray analysis revealed that platelet-derived growth factor receptor alpha (PDGFRalpha) is up-regulated and PDGFRbeta is down-regulated with postnatal differentiation of SLCs. This suggested that their ligands, PDGF-AA and PDGF-BB, respectively, might have important roles in SLC proliferation and differentiation. To test this, we developed a unique in vitro culture system in which SLCs proliferate on the surfaces of cultured seminiferous tubules largely during Week 1 of culture and their progeny subsequently differentiate to testosterone-forming Leydig cells during Weeks 2 through 4. Using this system, seminiferous tubules from adult rat testes were cultured with PDGF-AA or PDGF-BB for up to 4 wk. Both ligands stimulated SLC proliferation during the first week of culture, with PDGF-BB significantly more potent than PDGF-AA. Furthermore, PDGF-AA had a stimulatory effect on SLC differentiation from Weeks 2 through 4 of culture. In contrast, PDGF-BB, which stimulated cell proliferation during Week 1, had a significant inhibitory effect on differentiation during Weeks 2 through 4. These findings, made possible by the development of the seminiferous tubule culture system, reveal distinct roles by locally produced PDGFs in SLC regulation.
Assuntos
Células Intersticiais do Testículo/efeitos dos fármacos , Células Intersticiais do Testículo/metabolismo , Fator de Crescimento Derivado de Plaquetas/farmacologia , Proteínas Proto-Oncogênicas c-sis/farmacologia , Túbulos Seminíferos/metabolismo , Células-Tronco Adultas/citologia , Células-Tronco Adultas/metabolismo , Fatores Etários , Animais , Becaplermina , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Células Intersticiais do Testículo/citologia , Masculino , Ratos Endogâmicos BN , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Túbulos Seminíferos/citologia , Túbulos Seminíferos/efeitos dos fármacos , Testículo/citologia , Testosterona/metabolismoRESUMO
Candida albicans is a pathogenic yeast of important public health relevance. Virulence of C. albicans requires a copper and zinc containing superoxide dismutase (SOD1), but the biology of C. albicans SOD1 is poorly understood. To this end, C. albicans SOD1 activation was examined in baker's yeast (Saccharomyces cerevisiae), a eukaryotic expression system that has proven fruitful for the study of SOD1 enzymes from invertebrates, plants, and mammals. In spite of the 80% similarity between S. cerevisiae and C. albicans SOD1 molecules, C. albicans SOD1 is not active in S. cerevisiae. The SOD1 appears incapable of productive interactions with the copper chaperone for SOD1 (CCS1) of S. cerevisiae. C. albicans SOD1 contains a proline at position 144 predicted to dictate dependence on CCS1. By mutation of this proline, C. albicans SOD1 gained activity in S. cerevisiae, and this activity was independent of CCS1. We identified a putative CCS1 gene in C. albicans and created heterozygous and homozygous gene deletions at this locus. Loss of CCS1 resulted in loss of SOD1 activity, consistent with its role as a copper chaperone. C. albicans CCS1 also restored activity to C. albicans SOD1 expressed in S. cerevisiae. C. albicans CCS1 is well adapted for activating its partner SOD1 from C. albicans, but not SOD1 from S. cerevisiae. In spite of the high degree of homology between the SOD1 and CCS1 molecules in these two fungal species, there exists a species-specific barrier in CCS-SOD interactions which may reflect the vastly different lifestyles of the pathogenic versus the noninfectious yeast.
Assuntos
Candida albicans/enzimologia , Cobre/metabolismo , Chaperonas Moleculares/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Superóxido Dismutase/metabolismo , Cobre/química , Chaperonas Moleculares/química , Ligação Proteica , Proteínas de Saccharomyces cerevisiae/química , Superóxido Dismutase/genéticaRESUMO
Recessive mutations at the mouse pirouette (pi) locus result in hearing loss and vestibular dysfunction due to neuroepithelial defects in the inner ear. Using a positional cloning strategy, we have identified mutations in the gene Grxcr1 (glutaredoxin cysteine-rich 1) in five independent allelic strains of pirouette mice. We also provide sequence data of GRXCR1 from humans with profound hearing loss suggesting that pirouette is a model for studying the mechanism of nonsyndromic deafness DFNB25. Grxcr1 encodes a 290 amino acid protein that contains a region of similarity to glutaredoxin proteins and a cysteine-rich region at its C terminus. Grxcr1 is expressed in sensory epithelia of the inner ear, and its encoded protein is localized along the length of stereocilia, the actin-filament-rich mechanosensory structures at the apical surface of auditory and vestibular hair cells. The precise architecture of hair cell stereocilia is essential for normal hearing. Loss of function of Grxcr1 in homozygous pirouette mice results in abnormally thin and slightly shortened stereocilia. When overexpressed in transfected cells, GRXCR1 localizes along the length of actin-filament-rich structures at the dorsal-apical surface and induces structures with greater actin filament content and/or increased lengths in a subset of cells. Our results suggest that deafness in pirouette mutants is associated with loss of GRXCR1 function in modulating actin cytoskeletal architecture in the developing stereocilia of sensory hair cells.
Assuntos
Orelha Interna/fisiopatologia , Loci Gênicos/genética , Glutarredoxinas/genética , Mutação/genética , Citoesqueleto de Actina , Alelos , Sequência de Aminoácidos , Animais , Sequência de Bases , Mapeamento Cromossômico , Sequência Conservada , Análise Mutacional de DNA , Evolução Molecular , Feminino , Regulação da Expressão Gênica , Glutarredoxinas/química , Perda Auditiva/genética , Perda Auditiva/fisiopatologia , Humanos , Masculino , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Linhagem , Estrutura Terciária de Proteína , Transporte ProteicoRESUMO
An intronic GGGGCC repeat expansion in C9orf72 is a common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. The repeats are transcribed in both sense and antisense directions to generate distinct dipeptide repeat proteins, of which poly(GA), poly(GR), and poly(PR) have been implicated in contributing to neurodegeneration. Poly(PR) binding to RNA may contribute to toxicity, but analysis of poly(PR)-RNA binding on a transcriptome-wide scale has not yet been carried out. We therefore performed crosslinking and immunoprecipitation (CLIP) analysis in human cells to identify the RNA binding sites of poly(PR). We found that poly(PR) binds to nearly 600 RNAs, with the sequence GAAGA enriched at the binding sites. In vitro experiments showed that poly(GAAGA) RNA binds poly(PR) with higher affinity than control RNA and induces the phase separation of poly(PR) into condensates. These data indicate that poly(PR) preferentially binds to poly(GAAGA)-containing RNAs, which may have physiological consequences.
Assuntos
Perfilação da Expressão Gênica , Transcriptoma , Humanos , Transcriptoma/genética , Proteína C9orf72/genética , Poli A , Dipeptídeos , RNA/genéticaRESUMO
RNA-binding proteins with prion-like domains, such as FUS and TDP-43, condense into functional liquids, which can transform into pathological fibrils that underpin fatal neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Here, we define short RNAs (24-48 nucleotides) that prevent FUS fibrillization by promoting liquid phases, and distinct short RNAs that prevent and, remarkably, reverse FUS condensation and fibrillization. These activities require interactions with multiple RNA-binding domains of FUS and are encoded by RNA sequence, length, and structure. Importantly, we define a short RNA that dissolves aberrant cytoplasmic FUS condensates, restores nuclear FUS, and mitigates FUS proteotoxicity in optogenetic models and human motor neurons. Another short RNA dissolves aberrant cytoplasmic TDP-43 condensates, restores nuclear TDP-43, and mitigates TDP-43 proteotoxicity. Since short RNAs can be effectively delivered to the human brain, these oligonucleotides could have therapeutic utility for ALS/FTD and related disorders.
RESUMO
Nuclear-import receptors (NIRs) engage nuclear-localization signals (NLSs) of polypeptides in the cytoplasm and transport these cargo across the size-selective barrier of the nuclear-pore complex into the nucleoplasm. Beyond this canonical role in nuclear transport, NIRs operate in the cytoplasm to chaperone and disaggregate NLS-bearing clients. Indeed, NIRs can inhibit and reverse functional and deleterious phase transitions of their cargo, including several prominent neurodegenerative disease-linked RNA-binding proteins (RBPs) with prion-like domains (PrLDs), such as TDP-43, FUS, EWSR1, TAF15, hnRNPA1, and hnRNPA2. Importantly, elevated NIR expression can mitigate degenerative phenotypes connected to aberrant cytoplasmic aggregation of RBPs with PrLDs. Here, we review recent discoveries that NIRs can also antagonize aberrant interactions and toxicity of arginine-rich, dipeptide-repeat proteins that are associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) caused by G4C2 hexanucleotide repeat expansions in the first intron of C9ORF72. We also highlight recent findings that multiple NIR family members can prevent and reverse liquid-liquid phase separation of specific clients bearing RGG motifs in an NLS-independent manner. Finally, we discuss strategies to enhance NIR activity or expression, which could have therapeutic utility for several neurodegenerative disorders, including ALS, FTD, multisystem proteinopathy, limbic-predominant age-related TDP-43 encephalopathy, tauopathies, and related diseases.
Assuntos
Doenças Neurodegenerativas/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Transporte Ativo do Núcleo Celular , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismo , Proteína C9orf72/genética , Proteína C9orf72/metabolismo , Demência Frontotemporal/genética , Demência Frontotemporal/metabolismo , Humanos , Doenças Neurodegenerativas/patologia , Transição de Fase , Agregação Patológica de Proteínas , Receptores Citoplasmáticos e Nucleares/genéticaRESUMO
A hexanucleotide repeat expansion GGGGCC (G4C2) within chromosome 9 open reading frame 72 (C9orf72) is the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). This seminal realization has rapidly focused our attention to the non-canonical translation (RAN translation) of the repeat expansion, which yields dipeptide-repeat protein products (DPRs). The mechanisms by which DPRs might contribute to C9-ALS/FTD are widely studied. Arginine-rich DPRs (R-DPRs) are the most toxic of the five different DPRs produced in neurons, but how do R-DPRs promote C9-ALS/FTD pathogenesis? Proteomic analyses have uncovered potential pathways to explore. For example, the vast majority of the R-DPR interactome is comprised of disease-linked RNA-binding proteins (RBPs) with low-complexity domains (LCDs), strongly suggesting a link between R-DPRs and aberrations in liquid-liquid phase separation (LLPS). In this review, we showcase several potential mechanisms by which R-DPRs disrupt various phase-separated compartments to elicit deleterious neurodegeneration. We also discuss potential therapeutic strategies to counter R-DPR toxicity in C9-ALS/FTD.
Assuntos
Esclerose Lateral Amiotrófica , Expansão das Repetições de DNA , Demência Frontotemporal , Arginina , Proteína C9orf72/genética , Dipeptídeos/genética , Demência Frontotemporal/genética , Humanos , ProteômicaRESUMO
Defective nucleocytoplasmic transport contributes to C9-ALS/FTD, but an inventory of proteins that become redistributed has remained elusive. In this issue of Neuron, Ortega et al. (2020) catalog these redistributed proteins and pinpoint nonsense-mediated decay as a therapeutic target for C9-ALS/FTD.
Assuntos
Esclerose Lateral Amiotrófica , Demência Frontotemporal , Proteína C9orf72 , Humanos , ProteômicaRESUMO
Nuclear import receptors, also called importins, mediate nuclear import of proteins and chaperone aggregation-prone cargoes (e.g., neurodegeneration-linked RNA-binding proteins [RBPs]) in the cytoplasm. Importins were identified as modulators of cellular toxicity elicited by arginine-rich dipeptide repeat proteins (DPRs), an aberrant protein species found in C9orf72-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Mechanistically, the link between importins and arginine-rich DPRs remains unclear. Here, we show that arginine-rich DPRs (poly-GR and poly-PR) bind directly to multiple importins and, in excess, promote their insolubility and condensation. In cells, poly-GR impairs Impα/ß-mediated nuclear import, including import of TDP-43, an RBP that aggregates in C9orf72-ALS/FTD patients. Arginine-rich DPRs promote phase separation and insolubility of TDP-43 in vitro and in cells, and this pathological interaction is suppressed by elevating importin concentrations. Our findings suggest that importins can decrease toxicity of arginine-rich DPRs by suppressing their pathological interactions.
Assuntos
Arginina/metabolismo , Dipeptídeos/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , HumanosRESUMO
TAR DNA-binding protein 43 (TDP-43) inclusions are a pathological hallmark of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), including cases caused by G4C2 repeat expansions in the C9orf72 gene (c9FTD/ALS). Providing mechanistic insight into the link between C9orf72 mutations and TDP-43 pathology, we demonstrated that a glycine-arginine repeat protein [poly(GR)] translated from expanded G4C2 repeats was sufficient to promote aggregation of endogenous TDP-43. In particular, toxic poly(GR) proteins mediated sequestration of full-length TDP-43 in an RNA-independent manner to induce cytoplasmic TDP-43 inclusion formation. Moreover, in GFP-(GR)200 mice, poly(GR) caused the mislocalization of nucleocytoplasmic transport factors and nuclear pore complex proteins. These mislocalization events resulted in the aberrant accumulation of endogenous TDP-43 in the cytoplasm where it co-aggregated with poly(GR). Last, we demonstrated that treating G4C2 repeat-expressing mice with repeat-targeting antisense oligonucleotides lowered poly(GR) burden, which was accompanied by reduced TDP-43 pathology and neurodegeneration, including lowering of plasma neurofilament light (NFL) concentration. These results contribute to clarification of the mechanism by which poly(GR) drives TDP-43 proteinopathy, confirm that G4C2-targeted therapeutics reduce TDP-43 pathology in vivo, and demonstrate that alterations in plasma NFL provide insight into the therapeutic efficacy of disease-modifying treatments.
Assuntos
Esclerose Lateral Amiotrófica , Demência Frontotemporal , Proteinopatias TDP-43 , Esclerose Lateral Amiotrófica/genética , Animais , Proteína C9orf72/genética , Expansão das Repetições de DNA/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Demência Frontotemporal/genética , CamundongosRESUMO
Testosterone and ten of its metabolites were examined as inhibitors of butyrylcholinesterase. A significant enzyme inhibition activity (IC(50) = 1.55 microM) was observed for androst-4-en-3,7-dione. The kinetic parameters of butyrylcholinesterase inhibition were determined and molecular docking was carried out in order to develop a better understanding of the inhibitor-enzyme interactions. The results showed that the inhibition was non-competitive, stabilized mainly by hydrogen bonds and hydrophobic interactions between the inhibitor and butyrylcholinesterase.
Assuntos
Androstenodiona/farmacologia , Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Inibidores Enzimáticos/farmacologia , Testosterona/farmacologia , Androstenodiona/química , Sítios de Ligação , Inibidores da Colinesterase/química , Inibidores Enzimáticos/química , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Concentração Inibidora 50 , Cinética , Modelos Moleculares , Conformação Proteica , Relação Estrutura-Atividade , Testosterona/químicaRESUMO
The National Cancer Institute conducted the Biospecimen Pre-analytical Variables (BPV) study to determine the effects of formalin fixation and delay to fixation (DTF) on the analysis of nucleic acids. By performing whole transcriptome sequencing and small RNA profiling on matched snap-frozen and FFPE specimens exposed to different delays to fixation, this study aimed to determine acceptable delays to fixation and proper workflow for accurate and reliable Next-Generation Sequencing (NGS) analysis of FFPE specimens. In comparison to snap-freezing, formalin fixation changed the relative proportions of intronic/exonic/untranslated RNA captured by RNA-seq for most genes. The effects of DTF on NGS analysis were negligible. In 80% of specimens, a subset of RNAs was found to differ between snap-frozen and FFPE specimens in a consistent manner across tissue groups; this subset was unaffected in the remaining 20% of specimens. In contrast, miRNA expression was generally stable across various formalin fixation protocols, but displayed increased variability following a 12 h delay to fixation.
Assuntos
Formaldeído/efeitos adversos , MicroRNAs/genética , Neoplasias/patologia , Inclusão em Parafina/métodos , RNA/genética , Análise de Sequência de RNA/métodos , Fixação de Tecidos/métodos , Criopreservação , Fixadores/efeitos adversos , Regulação Neoplásica da Expressão Gênica , Humanos , MicroRNAs/isolamento & purificação , MicroRNAs/metabolismo , Neoplasias/genética , RNA/isolamento & purificação , RNA/metabolismo , Sequenciamento do ExomaRESUMO
BACKGROUND: Researchers and other key stakeholders in biobanking often do not have a thorough understanding of the true costs and challenges associated with initiating, running, and maintaining a biobank. The National Cancer Institute's Biorepositories and Biospecimen Research Branch (BBRB) commissioned the Biobanking Financial Sustainability survey to better understand the challenges that biobanks face in supporting ongoing operations. A series of interviews with biobanking managers and an international focus group session informed the content of the survey. METHODS: The design of the survey included five main sections, each containing questions related to primary topics as follows: general demographics, operations, funding sources, costs, and financial challenges. While the survey focused on financial issues and challenges, it also explored staffing and strategic planning as these issues relate to the sustainability of operations and financial support. U.S. and international biobanks were included in the survey. RESULTS: Biobanks in general are dependent on public funding and most biobanks do not have formal plans for the long-term stewardship of their collections. Respondents are working at a critical level of personnel and are not in a position to further reduce staffing. Smaller biobanks in particular need assistance in defining reasonable cost recovery user fees for biospecimens and related services. CONCLUSIONS: The survey results highlight several issues that are important for long-term biobank sustainability. It is critical to prepare for such issues as effective biobanking practices have increasingly been recognized as a key component for the advancement of precision medicine.
Assuntos
Bancos de Espécimes Biológicos/economia , Pesquisa Biomédica/economia , Apoio Financeiro , Humanos , National Cancer Institute (U.S.) , Estados UnidosRESUMO
CONTEXT.: Despite widespread use of formalin-fixed, paraffin-embedded (FFPE) tissue in clinical and research settings, potential effects of variable tissue processing remain largely unknown. OBJECTIVE.: To elucidate molecular effects associated with clinically relevant preanalytical variability, the National Cancer Institute initiated the Biospecimen Preanalytical Variables (BPV) program. DESIGN.: The BPV program, a well-controlled series of systematic, blind and randomized studies, investigated whether a delay to fixation (DTF) or time in fixative (TIF) affects the quantity and quality of DNA and RNA isolated from FFPE colon, kidney, and ovarian tumors in comparison to case-matched snap-frozen controls. RESULTS.: DNA and RNA yields were comparable among FFPE biospecimens subjected to different DTF and TIF time points. DNA and RNA quality metrics revealed assay- and time point-specific effects of DTF and TIF. A quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was superior when assessing RNA quality, consistently detecting differences between FFPE and snap-frozen biospecimens and among DTF and TIF time points. RNA Integrity Number and DV200 (representing the percentage of RNA fragments longer than 200 nucleotides) displayed more limited sensitivity. Differences in DNA quality (Q-ratio) between FFPE and snap-frozen biospecimens and among DTF and TIF time points were detected with a qPCR-based assay. CONCLUSIONS.: DNA and RNA quality may be adversely affected in some tumor types by a 12-hour DTF or a TIF of 72 hours. Results presented here as well as those of additional BPV molecular analyses underway will aid in the identification of acceptable delays and optimal fixation times, and quality assays that are suitable predictors of an FFPE biospecimen's fit-for-purpose.
Assuntos
DNA/análise , Fase Pré-Analítica/métodos , Controle de Qualidade , RNA/análise , Fixação de Tecidos/métodos , Neoplasias do Colo/química , Criopreservação/métodos , DNA/isolamento & purificação , Feminino , Humanos , Neoplasias Renais/química , National Cancer Institute (U.S.) , Neoplasias Ovarianas/química , Inclusão em Parafina/métodos , RNA/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real , Manejo de Espécimes/métodos , Fatores de Tempo , Estados UnidosRESUMO
Sumoylation regulates a wide range of essential cellular functions, many of which are associated with activities in the nucleus. Although there is also emerging evidence for the involvement of the small ubiquitin-related modifier (SUMO) at intracellular membranes, the mechanisms by which sumoylation is regulated at membranes is largely unexplored. In this study, we report that the SUMO-specific isopeptidase, SENP2, uniquely associates with intracellular membranes. Using in vivo analyses and in vitro binding assays, we show that SENP2 is targeted to intracellular membranes via a predicted N-terminal amphipathic α-helix that promotes direct membrane binding. Furthermore, we demonstrate that SENP2 binding to intracellular membranes is regulated by interactions with the nuclear import receptor karyopherin-α. Consistent with membrane association, biotin identification (BioID) revealed interactions between SENP2 and endoplasmic reticulum, Golgi, and inner nuclear membrane-associated proteins. Collectively, our findings indicate that SENP2 binds to intracellular membranes where it interacts with membrane-associated proteins and has the potential to regulate their sumoylation and membrane-associated functions.
Assuntos
Cisteína Endopeptidases/química , Cisteína Endopeptidases/metabolismo , Membranas Intracelulares/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sequência de Aminoácidos , Núcleo Celular/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Células HeLa , Humanos , Proteínas de Membrana/metabolismo , Modelos Biológicos , Sinais de Localização Nuclear , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Ligação Proteica , Isoformas de Proteínas/metabolismo , Estrutura Secundária de Proteína , Relação Estrutura-Atividade , alfa Carioferinas/metabolismoRESUMO
BACKGROUND: Biospecimens are essential resources for advancing basic and translational research. However, there are little data available regarding the costs associated with operating a biobank, and few resources to enable their long-term sustainability. To support the research community in this effort, the National Institutes of Health, National Cancer Institute's Biorepositories and Biospecimen Research Branch has developed the Biobank Economic Modeling Tool (BEMT). The tool is accessible at http://biospecimens.cancer.gov/resources/bemt.asp. METHODS: To obtain market-based cost information and to inform the development of the tool, a survey was designed and sent to 423 biobank managers and directors across the world. The survey contained questions regarding infrastructure investments, salary costs, funding options, types of biospecimen resources and services offered, as well as biospecimen pricing and service-related costs. RESULTS: A total of 106 responses were received. The data were anonymized, aggregated, and used to create a comprehensive database of cost and pricing information that was integrated into the web-based tool, the BEMT. The BEMT was built to allow the user to input cost and pricing data through a seven-step process to build a cost profile for their biobank, define direct and indirect costs, determine cost recovery fees, perform financial forecasting, and query the anonymized survey data from comparable biobanks. CONCLUSION: A survey was conducted to obtain a greater understanding of the costs involved in operating a biobank. The anonymized survey data was then used to develop the BEMT, a cost modeling tool for biobanks. Users of the tool will be able to create a cost profile for their biobanks' specimens, products and services, establish pricing, and allocate costs for biospecimens based on percent cost recovered, and perform project-specific cost analyses and financial forecasting.
Assuntos
Bancos de Espécimes Biológicos/economia , Bancos de Espécimes Biológicos/organização & administração , Administração Financeira , Modelos Econômicos , Academias e Institutos/economia , Análise Custo-Benefício , Custos e Análise de Custo , Bases de Dados Factuais , Internet , National Cancer Institute (U.S.) , Software , Inquéritos e Questionários , Pesquisa Translacional Biomédica , Estados UnidosRESUMO
Although androgen receptor (AR) function has been extensively studied, regulation of the AR gene itself has been much less characterized. In this study, we observed a dramatic reduction in the expression of androgen receptor mRNA and protein in hyperproliferative prostate epithelium of keratin 5 promoter driven E2F1 transgenic mice. To confirm an inhibitory function for E2F1 on AR transcription, we showed that E2F1 inhibited the transcription of endogenous AR mRNA, subsequent AR protein, and AR promoter activity in both human and mouse epithelial cells. E2F1 also inhibited androgen-stimulated activation of two AR target gene promoters. To elucidate the molecular mechanism of E2F-mediated inhibition of AR, we evaluated the effects of two functional E2F1 mutants on AR promoter activity and found that the transactivation domain appears to mediate E2F1 repression of the AR promoter. Because DNMT1 is a functional intermediate of E2F1 we examined DNMT1 function in AR repression. Repression of endogenous AR in normal human prostate epithelial cells was relieved by DNMT1 shRNA knock down. DNMT1 was shown to be physically associated within the AR minimal promoter located 22 bps from the transcription start site; however, methylation remained unchanged at the promoter regardless of DNMT1 expression. Taken together, our results suggest that DNMT1 operates either as a functional intermediary or in cooperation with E2F1 inhibiting AR gene expression in a methylation independent manner.