RESUMO
Iron is a critical nutrient required by hosts and pathogens. Uropathogenic Escherichia coli (UPEC), the principal causative agent of urinary tract infections (UTIs), chelate iron for their survival and persistence. Here, we demonstrate that dietary modulation of iron availability limits UPEC burden in a mouse model of UTI. Mice on a low-iron diet exhibit reduced systemic and bladder mucosal iron availability and harbor significantly lower bacterial burden, concomitant with dampened inflammation. Hepcidin is a master regulator of iron that controls iron-dependent UPEC intracellular growth. Hepcidin-deficient mice ( Hamp1-/-) exhibit accumulation of iron deposits, persistent bacterial burden in the bladder, and a heightened inflammatory response to UTI. However, a low-iron dietary regimen reversed the iron overload and increased bacterial burden phenotypes in Hamp1-/- mice. Thus modulation of iron levels via diet can reduce UPEC infection and persistence, which may have significant implications for clinical management of UTI.
Assuntos
Infecções por Escherichia coli/dietoterapia , Ferro da Dieta/metabolismo , Bexiga Urinária/microbiologia , Infecções Urinárias/dietoterapia , Escherichia coli Uropatogênica/patogenicidade , Animais , Carga Bacteriana , Modelos Animais de Doenças , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Ferritinas/metabolismo , Hepcidinas/genética , Hepcidinas/metabolismo , Interações Hospedeiro-Patógeno , Interleucina-6/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Bexiga Urinária/metabolismo , Infecções Urinárias/metabolismo , Infecções Urinárias/microbiologiaRESUMO
Although iron is essential for cell survival, dysregulated levels can contribute to cancer development or even cell death. The underlying mechanisms mediating these events remain unclear. Herein, proteomic alterations are assessed in iron-treated ovarian cell lines using reverse phase protein array (RPPA) technology and potential functional responses via ingenuity pathway analysis (IPA). Using these approaches, upregulation of pathways modulating organismal death with alterations in mTOR, MAPK, and AKT signaling in HEY ovarian cancer cells in contrast to T80 non-malignant ovarian cells is noted. Since modulation of cell death is mediated in part via microphthalmia-associated transcription factor (MiTF) family, which regulates lysosomal biogenesis and autophagosome formation by upregulating expression of coordinated lysosomal expression and regulation (CLEAR) network, expression changes in these factors in response to iron are investigated. Increased transcription factor EB (TFEB) in T80 (relative to HEY), accompanied by its nuclear translocation and increased CLEAR network gene expression with iron, is identified. Inhibition of AKT alters these responses in contrast to mTOR inhibition, which has little effect. Collectively, these findings support use of RPPA/IPA technology to predict functional responses to iron and further implicate AKT pathway and MiTF members in iron-induced cellular responses in ovarian cells.
Assuntos
Ferro/farmacologia , Neoplasias Ovarianas/metabolismo , Proteômica/métodos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Linhagem Celular Tumoral , Feminino , Humanos , Lisossomos/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Xenophagy is an autophagic phenomenon that specifically involves pathogens and other non-host entities. Although the understanding of the relationship between autophagosomes and invading organisms has grown significantly in the past decade, the exact steps to confirm xenophagy has been not been thoroughly defined. Here we describe a methodical approach to confirming autophagy, its interaction with bacterial invasion, as well as the specific type of autophagic formation (i.e. autophagosome, autolysosome, phagolysosome). Further, we argue that xenophagy is not limited to pathogen interaction with autophagosome, but also non-microbial entities such as iron.
Assuntos
Autofagia/genética , Infecções/genética , Biologia Molecular/métodos , Brucella/genética , Brucella/patogenicidade , Interações Hospedeiro-Patógeno/genética , Humanos , Infecções/microbiologia , Lisossomos/metabolismo , Fagossomos/genética , Fagossomos/microbiologia , Fagossomos/patologiaRESUMO
The role of iron in the development of cancer remains unclear. We previously reported that iron reduces cell survival in a Ras/mitogen-activated protein kinase (MAPK)-dependent manner in ovarian cells; however, the underlying downstream pathway leading to reduced survival was unclear. Although levels of intracellular iron, ferritin/CD71 protein and reactive oxygen species did not correlate with iron-induced cell survival changes, we identified mitochondrial damage (via TEM) and reduced expression of outer mitochondrial membrane proteins (translocase of outer membrane: TOM20 and TOM70) in cell lines sensitive to iron. Interestingly, Ru360 (an inhibitor of the mitochondrial calcium uniporter) reversed mitochondrial changes and restored cell survival in HEY ovarian carcinoma cells treated with iron. Further, cells treated with Ru360 and iron also had reduced autophagic punctae with increased lysosomal numbers, implying cross-talk between these compartments. Mitochondrial changes were dependent on activation of the Ras/MAPK pathway since treatment with a MAPK inhibitor restored expression of TOM20/TOM70 proteins. Although glutathione antioxidant levels were reduced in HEY treated with iron, extracellular glutamate levels were unaltered. Strikingly, oxalomalate (inhibitor of aconitase, involved in glutamate production) reversed iron-induced responses in a similar manner to Ru360. Collectively, our results implicate iron in modulating cell survival in a mitochondria-dependent manner in ovarian cancer cells.
Assuntos
Antineoplásicos/farmacologia , Carcinoma/tratamento farmacológico , Compostos Férricos/farmacologia , Mitocôndrias/efeitos dos fármacos , Neoplasias Ovarianas/tratamento farmacológico , Ovário/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Compostos de Amônio Quaternário/farmacologia , Aconitato Hidratase/antagonistas & inibidores , Aconitato Hidratase/metabolismo , Antineoplásicos/química , Autofagia/efeitos dos fármacos , Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio/química , Canais de Cálcio/metabolismo , Carcinoma/metabolismo , Carcinoma/ultraestrutura , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Feminino , Compostos Férricos/antagonistas & inibidores , Glutationa/antagonistas & inibidores , Glutationa/metabolismo , Humanos , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/ultraestrutura , Ovário/metabolismo , Ovário/ultraestrutura , Compostos de Amônio Quaternário/antagonistas & inibidores , Espécies Reativas de Oxigênio/agonistas , Espécies Reativas de Oxigênio/metabolismoRESUMO
Medical schools use pre-matriculation programs consisting of knowledge-based curricula to prepare at-risk students. There is limited evidence showing the direct benefit of these programs with long-term success. We propose a pre-matriculation program focused on professional development and wellness to facilitate student acclimation and, in turn, academic success.
RESUMO
Medical education needs real-time documentation of professionalism for feedback and improvement. "ClassDojo™" is a behavioral tracking mobile app used in elementary education in USA with limited presence in medical education. A protocol adapting ClassDojo™ in pre-clerkship curriculum was developed and implemented. ClassDojo™ serves as an effective means of formative assessment of medical students' professionalism.
RESUMO
Medical school curricula integrate classroom academic teaching, hands-on clinical training, longitudinal professional development, and identity formation to prepare students to enter the healthcare workforce as residents. Mentorship, coaching, and advising are well-recognized approaches used by educators to help young learners accomplish their personal and professional goals and objectives. However, undergraduate medical education literature has not clearly articulated the distinctions between the roles and core responsibilities of each guidance approach. Attempts to describe each role and responsibility have generated ambiguity and steered institutions towards implementing their own role-specific functions. The purpose of this paper is to establish a functional framework that may be used to differentiate the principal duties of a mentor, coach, and advisor in the context of undergraduate medical education (UME). Four key components are necessary to achieve this goal: (1) adopting a singular definition for each form of guidance; (2) characterizing each role based on unique skills; (3) describing the interplay between learner needs and educator capabilities; (4) training educators on how to effectively distinguish each form of guidance. Creating clear distinctions between mentors, coaches, and advisors in medical education will bolster students' academic experience and improve the educator-learner relationship. These definitions may also benefit faculty members by providing a clear framework for their responsibilities, which can be used for evaluations or determining future promotions.
RESUMO
Medical school admissions have become increasingly competitive, creating a pool of nontraditional applicants that seek postbaccalaureate training in biomedical sciences. Several postbaccalaureate and graduate programs developed curricula that, except for learning clinical skills, mirror the learning objectives of the foundational science curricula in medical schools. This education structure provides applicants with a competitive advantage when applying to medical schools. However, basic science curriculum assessments in medical schools have changed to pass/fail scoring systems. As a result, students that participate in preparatory postbaccalaureate and graduate programs cannot show their superior level of knowledge and may find some core foundational science subjects redundant during their pre-clerkship medical education. The aim of this article is to propose an innovative system for matriculation into medical school through the AdvancedMed (AMed) Track, a three-year accelerated medical curriculum in which graduate curricula adopt an advanced placement course called AMed courses. This system would mirror the structure of the high school Advanced Placement (AP) system; therefore, students would take AMed courses similar in rigor to medical school basic science courses. These courses include Anatomy, Histology, Physiology, Cellular Biology, Biochemistry, Genetics, Microbiology, Immunology, Biostatistics, and Epidemiology. All courses would require a scored national standardized test to receive medical school credit toward a three-year accelerated track curriculum. Nontraditional students could choose to study independently and take the AMed standardized examination for credit to enter the AMed Track. Medical schools have the incentive to start an AMed Track because its implementation could lessen the financial burden, reduce time spent in medical school, and increase the participation of nontraditional medical students.
RESUMO
Iron plays a unique physiological role in the maintenance of homeostasis and the pathological outcomes of the female reproductive tract. The dual nature of elemental iron has created an evolutionary need to tightly regulate its biological concentration. The female reproductive tract is particularly unique due to the constant cycle of endometrial growth and shedding, in addition to the potential need for iron transfer to a developing fetus. Here, iron regulation is explored in a number of physiologic states including the endometrial lining and placenta. While iron dysregulation is a common characteristic in many women's health pathologies there is currently a lack of targeted therapeutic options. Traditional iron therapies, including iron replacement and chelation, are common treatment options for gynecological diseases but pose long term negative health consequences; therefore, more targeted interventions directed towards iron regulation have been proposed. Recent findings show potential benefits in a therapeutic focus on ferritin-hepcidin regulation, modulation of reactive oxygen species (ROS), and iron mediated cell death (ferroptosis). These novel therapeutics are the direct result of previous research in iron's complex signaling pathway and show promise for improved therapy, diagnosis, and prognosis in women's health.
RESUMO
50% of Caucasians carry a Thr300Ala variant (T300A) in the protein encoded by the macroautophagy/autophagy gene ATG16L1. Here, we show that the T300A variant confers protection against urinary tract infections (UTIs), the most common infectious disease in women. Using knockin mice carrying the human T300A variant, we show that the variant limits the UTI-causing bacteria, uropathogenic Escherichia coli (UPEC), from establishing persistent intracellular reservoirs, which can seed UTI recurrence. This phenotype is recapitulated in mice lacking Atg16l1 or Atg7 exclusively in the urothelium. We further show that mice with the T300A variant exhibit urothelial cellular abnormalities, including vesicular congestion and aberrant accumulation of UPK (uroplakin) proteins. Importantly, presence of the T300A variant in humans is associated with similar urothelial architectural abnormalities, indicating an evolutionarily conserved impact. Mechanistically, we show that the reduced bacterial persistence is independent of basal autophagic flux or proinflammatory cytokine responses and does not involve Atg14 or Epg5. However, the T300A variant is associated with increased expression of the small GTPase Rab33b; RAB33B interacts with ATG16L1, as well as other secretory RABs, RAB27B and RAB11A, important for UPEC exocytosis from the urothelium. Finally, inhibition of secretory RABs in bladder epithelial cells increases intracellular UPEC load. Together, our results reveal that UPEC selectively utilize genes important for autophagosome formation to persist in the urothelium, and that the presence of the T300A variant in ATG16L1 is associated with changes in urothelial vesicle trafficking, which disrupts the ability of UPEC to persist, thereby limiting the risk of recurrent UTIs. Abbreviations: 3-PEHPC: 3-pyridinyl ethylidene hydroxyl phosphonocarboxylate; ATG: autophagy; ATG16L1: autophagy related 16 like 1; BECs: bladder epithelial cells; dpi: days post infection; hpi: hours post infection; IF: immunofluorescence; IL1B: interleukin 1 beta; IL6: interleukin 6; MAP1LC3B/LC3B: microtubule-associated protein 1 light chain 3 beta; MVB: multivesicular bodies; T300A: Thr300Ala; TNF: tumor necrosis factor; QIR(s): quiescent intracellular reservoir(s); siRNA: short interfering RNA; UPEC: uropathogenic Escherichia coli; UTI(s): urinary tract infection(s); TEM: transmission electron microscopy; WT: wild type.
Assuntos
Autofagia/genética , Infecções por Escherichia coli/metabolismo , Infecções Urinárias/metabolismo , Escherichia coli Uropatogênica , Urotélio/microbiologia , Animais , Proteína 7 Relacionada à Autofagia/genética , Proteína 7 Relacionada à Autofagia/metabolismo , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/metabolismo , Linhagem Celular , Células Epiteliais/metabolismo , Infecções por Escherichia coli/genética , Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/patologia , Feminino , Variação Genética , Humanos , Macrófagos/metabolismo , Camundongos , Camundongos Knockout , Corpos Multivesiculares/genética , Corpos Multivesiculares/microbiologia , Corpos Multivesiculares/patologia , Bexiga Urinária/microbiologia , Infecções Urinárias/genética , Infecções Urinárias/microbiologia , Infecções Urinárias/patologia , Uroplaquinas/metabolismo , Urotélio/citologia , Urotélio/metabolismo , Urotélio/ultraestrutura , Proteínas de Transporte Vesicular/genética , Proteínas de Transporte Vesicular/metabolismo , Proteínas rab de Ligação ao GTP/metabolismoRESUMO
Autophagy is a cellular recycling pathway, which in many cases, protects host cells from infections by degrading pathogens. However, uropathogenic Escherichia coli (UPEC), the predominant cause of urinary tract infections (UTIs), persist within the urinary tract epithelium (urothelium) by forming reservoirs within autophagosomes. Iron is a critical nutrient for both host and pathogen, and regulation of iron availability is a key host defense against pathogens. Iron homeostasis depends on the shuttling of iron-bound ferritin to the lysosome for recycling, a process termed ferritinophagy (a form of selective autophagy). Here, we demonstrate for the first time that UPEC shuttles with ferritin-bound iron into the autophagosomal and lysosomal compartments within the urothelium. Iron overload in urothelial cells induces ferritinophagy in an NCOA4-dependent manner causing increased iron availability for UPEC, triggering bacterial overproliferation and host cell death. Addition of even moderate levels of iron is sufficient to increase and prolong bacterial burden. Furthermore, we show that lysosomal damage due to iron overload is the specific mechanism causing host cell death. Significantly, we demonstrate that host cell death and bacterial burden can be reversed by inhibition of autophagy or inhibition of iron-regulatory proteins, or chelation of iron. Together, our findings suggest that UPEC persist in host cells by taking advantage of ferritinophagy. Thus, modulation of iron levels in the bladder may provide a therapeutic avenue to controlling UPEC persistence, epithelial cell death, and recurrent UTIs.
Assuntos
Células Epiteliais/microbiologia , Bexiga Urinária/microbiologia , Escherichia coli Uropatogênica , Autofagia/genética , Células Epiteliais/metabolismo , Infecções por Escherichia coli/metabolismo , Humanos , Ferro/metabolismo , Ferro/farmacologia , Lisossomos/metabolismo , Infecções Urinárias/metabolismo , Infecções Urinárias/microbiologiaRESUMO
INTRODUCTION: Uropathogenic Escherichia coli (UPEC), the causative agent of over 85% of urinary tract infections (UTIs), elaborate a number of siderophores to chelate iron from the host. On the other hand, the host immune imperative is to limit the availability of iron to the bacteria. Little is known regarding the mechanisms underlying this host-iron-UPEC interaction. Our objective was to determine whether macrophages, in response to UPEC infection, retain extracellular siderophore-bound and free iron, thus limiting the ability of UPEC to access iron. METHODS: Quantitative PCR, immunoblotting analysis, and gene expression analysis of wild type and IL-6-deficient macrophages was performed. RESULTS: We found that (1) macrophages upon UPEC infection increased expression of lipocalin 2, a siderophore-binding molecule, of Dmt1, a molecule that facilitates macrophage uptake of free iron, and of the intracellular iron cargo molecule ferritin, and decreased expression of the iron exporter ferroportin; (2) bladder macrophages regulate expression of genes involved in iron retention upon UPEC infection; (3) IL-6, a cytokine known to play an important role in regulating host iron homeostasis as well as host defense to UPEC, regulates this process, in part by promoting production of lipocalin 2; and finally, (4) inhibition of IL-6 signaling genetically and by neutralizing antibodies against the IL-6 receptor, promoted intra-macrophagic UPEC growth in the presence of excess iron. CONCLUSIONS: Together, our study suggests that macrophages retain siderophore-bound and free iron in response to UPEC and IL-6 signaling is necessary for macrophages to limit the growth of UPEC in the presence of excess iron. IL-6 signaling and iron regulation is one mechanism by which macrophages may mediate UPEC clearance.
Assuntos
Infecções por Escherichia coli/imunologia , Interleucina-6/fisiologia , Ferro/fisiologia , Macrófagos/imunologia , Escherichia coli Uropatogênica/patogenicidade , Animais , Proteínas de Escherichia coli , Camundongos , Camundongos Endogâmicos C57BL , Sideróforos , Transdução de Sinais , Infecções UrináriasRESUMO
Amplification of 3q26.2, found in many cancer lineages, is a frequent and early event in ovarian cancer. We previously defined the most frequent region of copy number increase at 3q26.2 to EVI1 (ecotropic viral integration site-1) and MDS1 (myelodysplastic syndrome 1) (aka MECOM), an observation recently confirmed by the cancer genome atlas (TCGA). MECOM is increased at the DNA, RNA, and protein level and likely contributes to patient outcome. Herein, we report that EVI1 is aberrantly spliced, generating multiple variants including a Del(190-515) variant (equivalent to previously reported) expressed in >90% of advanced stage serous epithelial ovarian cancers. Although EVI1(Del190-515) lacks â¼70% of exon 7, it binds CtBP1 as well as SMAD3, important mediators of TGFß signaling, similar to wild type EVI1. This contrasts with EVI1 1-268 which failed to interact with CtBP1. Interestingly, the EVI1(Del190-515) splice variant preferentially localizes to PML nuclear bodies compared to wild type and EVI1(Del427-515). While wild type EVI1 efficiently repressed TGFß-mediated AP-1 (activator protein-1) and plasminogen activator inhibitor-1 (PAI-1) promoters, EVI1(Del190-515) elicited a slight increase in both promoter activities. Expression of EVI1 and EVI1(Del427-515) (but not EVI1(Del190-515)) in OVCAR8 ovarian cancer cells increased cyclin E1 LMW expression and cell cycle progression. Furthermore, knockdown of specific EVI1 splice variants (both MDS1/EVI1 and EVI1(Del190-515)) markedly increased claudin-1 mRNA and protein expression in HEY ovarian and MDA-MB-231 breast cancer cells. Changes in claudin-1 were associated with alterations in specific epithelial-mesenchymal transition markers concurrent with reduced migratory potential. Collectively, EVI1 is frequently aberrantly spliced in ovarian cancer with specific forms eliciting altered functions which could potentially contribute to ovarian cancer pathophysiology.
Assuntos
Proteínas de Ligação a DNA/genética , Neoplasias Epiteliais e Glandulares/genética , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Ovário/patologia , Proto-Oncogenes/genética , Fatores de Transcrição/genética , Carcinoma Epitelial do Ovário , Ciclo Celular , Linhagem Celular Tumoral , Claudina-1/genética , Ciclina E/metabolismo , Proteínas de Ligação a DNA/análise , Proteínas de Ligação a DNA/metabolismo , Transição Epitelial-Mesenquimal , Feminino , Deleção de Genes , Regulação Neoplásica da Expressão Gênica , Humanos , Proteína do Locus do Complexo MDS1 e EVI1 , Neoplasias Epiteliais e Glandulares/metabolismo , Proteínas Oncogênicas/metabolismo , Neoplasias Ovarianas/metabolismo , Ovário/metabolismo , Isoformas de Proteínas/análise , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Fatores de Transcrição/análise , Fatores de Transcrição/metabolismo , Ativação Transcricional , Fator de Crescimento Transformador beta/metabolismoRESUMO
SnoN/SkiL (TGFß regulator) is dysregulated in ovarian cancer, a disease associated with acquired drug-resistance. Arsenic trioxide (As2O3, used in treating APL) induces SnoN to oppose the apoptotic response in ovarian cancer cells. We now report that As2O3 increases phosphorylation of EGFR/p66ShcA and EGFR degradation. As2O3 activates Src(Y416) whose activity (inhibited by PP2) modulates EGFR activation, its interaction with Shc/Grb2, and p-AKT. Inhibition of PI3K reduces SnoN and cell survival. Although EGFR or MAPK1 siRNA did not alter SnoN expression, As2O3-induced cleaved PARP was reduced together with increased XIAP. Collectively, As2O3 mediates an initial rise in pY-Src(416) to regulate the PI3K/AKT pathway which increases SnoN and cell survival; these early events may counter the cell death response associated with increased pY-EGFR/MAPK activation.