ABSTRACT
Upon infection of mammalian cells, enterohemorrhagic E. coli (EHEC) O157:H7 utilizes a type III secretion system to translocate the effectors Tir and EspF(U) (aka TccP) that trigger the formation of F-actin-rich 'pedestals' beneath bound bacteria. EspF(U) is localized to the plasma membrane by Tir and binds the nucleation-promoting factor N-WASP, which in turn activates the Arp2/3 actin assembly complex. Although N-WASP has been shown to be required for EHEC pedestal formation, the precise steps in the process that it influences have not been determined. We found that N-WASP and actin assembly promote EHEC-mediated translocation of Tir and EspF(U) into mammalian host cells. When we utilized the related pathogen enteropathogenic E. coli to enhance type III translocation of EHEC Tir and EspF(U), we found surprisingly that actin pedestals were generated on N-WASP-deficient cells. Similar to pedestal formation on wild type cells, Tir and EspF(U) were the only bacterial effectors required for pedestal formation, and the EspF(U) sequences required to interact with N-WASP were found to also be essential to stimulate this alternate actin assembly pathway. In the absence of N-WASP, the Arp2/3 complex was both recruited to sites of bacterial attachment and required for actin assembly. Our results indicate that actin assembly facilitates type III translocation, and reveal that EspF(U), presumably by recruiting an alternate host factor that can signal to the Arp2/3 complex, exhibits remarkable versatility in its strategies for stimulating actin polymerization.
Subject(s)
Actins/metabolism , Enterohemorrhagic Escherichia coli/metabolism , Escherichia coli Infections/metabolism , Wiskott-Aldrich Syndrome Protein, Neuronal/metabolism , Animals , Carrier Proteins/metabolism , Enterohemorrhagic Escherichia coli/pathogenicity , Escherichia coli Proteins/metabolism , Gene Knockout Techniques , Humans , Immunoblotting , Intracellular Signaling Peptides and Proteins , Mice , Microscopy, Fluorescence , Protein Transport/physiology , Receptors, Cell Surface/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Signal Transduction/physiologyABSTRACT
Enterohemorrhagic Escherichia coli O157:H7 translocates 2 effectors to trigger localized actin assembly in mammalian cells, resulting in filamentous actin "pedestals." One effector, the translocated intimin receptor (Tir), is localized in the plasma membrane and clustered upon binding the bacterial outer membrane protein intimin. The second, the proline-rich effector EspF(U) (aka TccP) activates the actin nucleation-promoting factor WASP/N-WASP, and is recruited to sites of bacterial attachment by a mechanism dependent on an Asn-Pro-Tyr (NPY(458)) sequence in the Tir C-terminal cytoplasmic domain. Tir, EspF(U), and N-WASP form a complex, but neither EspF(U) nor N-WASP bind Tir directly, suggesting involvement of another protein in complex formation. Screening of the mammalian SH3 proteome for the ability to bind EspF(U) identified the SH3 domain of insulin receptor tyrosine kinase substrate (IRTKS), a factor known to regulate the cytoskeleton. Derivatives of WASP, EspF(U), and the IRTKS SH3 domain were capable of forming a ternary complex in vitro, and replacement of the C terminus of Tir with the IRTKS SH3 domain resulted in a fusion protein competent for actin assembly in vivo. A second domain of IRTKS, the IRSp53/MIM homology domain (IMD), bound to Tir in a manner dependent on the C-terminal NPY(458) sequence, thereby recruiting IRTKS to sites of bacterial attachment. Ectopic expression of either the IRTKS SH3 domain or the IMD, or genetic depletion of IRTKS, blocked pedestal formation. Thus, enterohemorrhagic E. coli translocates 2 effectors that bind to distinct domains of a common host factor to promote the formation of a complex that triggers robust actin assembly at the plasma membrane.
Subject(s)
Actins/metabolism , Carrier Proteins/metabolism , Escherichia coli O157/cytology , Escherichia coli O157/metabolism , Escherichia coli Proteins/metabolism , Microfilament Proteins/metabolism , Receptors, Cell Surface/metabolism , Amino Acid Sequence , Attachment Sites, Microbiological , Bacterial Adhesion , Carrier Proteins/chemistry , Escherichia coli Proteins/chemistry , Gene Deletion , HeLa Cells , Humans , Insulin Receptor Substrate Proteins/chemistry , Intracellular Signaling Peptides and Proteins , Microfilament Proteins/chemistry , Molecular Sequence Data , Molecular Weight , Proline-Rich Protein Domains , Protein Binding , Protein Transport , Receptors, Cell Surface/chemistry , Recombinant Fusion Proteins/metabolism , src Homology DomainsABSTRACT
OBJECTIVES: We report a positive response to electroconvulsive therapy in a severely functionally impaired adolescent with autistic disorder and classic bipolar I disorder, including an episodic pattern of decreased need for sleep, hypersexuality, expansive and agitated affect, aggression, self-injury, and property destruction. METHODS: After ineffective trials of mood stabilizers and antipsychotics as well as inability to sustain a positive response to lithium due to medication noncompliance, a course of acute and maintenance electroconvulsive therapy was attempted. RESULTS: A marked and sustained improvement across all symptom categories, as measured by directly observed frequency counts of target behaviors in an inpatient setting, was obtained. CONCLUSIONS: Electroconvulsive therapy should be considered a potentially useful intervention in cases of children with autistic disorder and a severe comorbid affective disorder.
Subject(s)
Autistic Disorder/therapy , Bipolar Disorder/therapy , Electroconvulsive Therapy , Adolescent , Aggression/psychology , Antimanic Agents/therapeutic use , Antipsychotic Agents/therapeutic use , Autistic Disorder/complications , Autistic Disorder/psychology , Behavior , Bipolar Disorder/complications , Bipolar Disorder/psychology , Humans , Hypnotics and Sedatives/therapeutic use , Lithium Carbonate/therapeutic use , Male , Self-Injurious Behavior/psychologyABSTRACT
Objectives: Psychotic-spectrum disorders emerge during adolescence and early adulthood, which corresponds with the peak period for substance use initiation. Clinical and epidemiological data provide support that substance use is associated with psychotic symptom onset and severity. Experience-sampling methodology (ESM) data may provide additional insight into dynamic associations between substance use and psychotic symptoms. This is one of the first efforts to characterize substance use frequency and dynamic associations with psychotic symptoms and negative affect from ESM data in both clinical high risk (CHR) and early psychosis (EP) individuals. Methods: Using ESM, 33 individuals, including 17 with CHR and 16 EP (age range: 15-24), provided information on substance use, negative affect, and psychotic symptoms 6 times a day across a 21-day data collection window. Psychotic symptoms and negative affect included multi-item variables rated on a seven-point Likert Scale. Participants reported recent substance use for 4 drug classes (nicotine, cannabis, depressants, stimulants) via a yes/no item. Descriptive information included data on substance use frequency, and momentary negative affect and psychotic symptoms. Exploratory analyses included multi-level and person-level dynamic structural equation models, which assessed contemporaneous and lagged associations between substance use and symptoms. Results: Twenty-seven individuals (82%) reported recurrent substance use including stimulants (n = 12, 46%), nicotine (n = 9, 27%), cannabis (n = 6, 18%), and depressants (n = 4, 12%). Individuals with any recurrent substance use indicated usage at 47.7% of answered prompts; stimulants at 23.6%; nicotine at 74.2%; cannabis at 39.1%; and depressants at 20.1%. A multi-level dynamic structural equation model reflected that substance use (any class) was associated with lagged negative affect (ß = -0.02, CI: -0.06, < -0.00) but no significant contemporaneous or lagged associations between substance use and psychotic symptoms. Person-level models suggest potentially meaningful inter-individual variability. Conclusions: CHR and EP individuals use a range of substances that may both reflect and influence other experiences in daily life experiences. Data reflected moderate to high rates of recurrent substance use with more consistent use within nicotine and cannabis classes. ESM data have the potential to increase our understanding of the dynamic relationships between substance use and symptoms and to inform treatment for individuals in early course psychosis.
ABSTRACT
Enterohemorrhagic Escherichia coli (EHEC) generate F-actin-rich adhesion pedestals by delivering effector proteins into mammalian cells. These effectors include the translocated receptor Tir, along with EspF(U), a protein that associates indirectly with Tir and contains multiple peptide repeats that stimulate actin polymerization. In vitro, the EspF(U) repeat region is capable of binding and activating recombinant derivatives of N-WASP, a host actin nucleation-promoting factor. In spite of the identification of these important bacterial and host factors, the underlying mechanisms of how EHEC so potently exploits the native actin assembly machinery have not been clearly defined. Here we show that Tir and EspF(U) are sufficient for actin pedestal formation in cultured cells. Experimental clustering of Tir-EspF(U) fusion proteins indicates that the central role of the cytoplasmic portion of Tir is to promote clustering of the repeat region of EspF(U). Whereas clustering of a single EspF(U) repeat is sufficient to bind N-WASP and generate pedestals on cultured cells, multi-repeat EspF(U) derivatives promote actin assembly more efficiently. Moreover, the EspF(U) repeats activate a protein complex containing N-WASP and the actin-binding protein WIP in a synergistic fashion in vitro, further suggesting that the repeats cooperate to stimulate actin polymerization in vivo. One explanation for repeat synergy is that simultaneous engagement of multiple N-WASP molecules can enhance its ability to interact with the actin nucleating Arp2/3 complex. These findings define the minimal set of bacterial effectors required for pedestal formation and the elements within those effectors that contribute to actin assembly via N-WASP-Arp2/3-mediated signaling pathways.
Subject(s)
Actin Cytoskeleton/metabolism , Carrier Proteins/chemistry , Carrier Proteins/metabolism , Enterohemorrhagic Escherichia coli/metabolism , Escherichia coli Proteins/chemistry , Escherichia coli Proteins/metabolism , Repetitive Sequences, Amino Acid , Wiskott-Aldrich Syndrome Protein, Neuronal/metabolism , Actin-Related Protein 2-3 Complex/metabolism , Amino Acid Sequence , Animals , Brain/metabolism , Carrier Proteins/genetics , Cytoskeletal Proteins/genetics , Cytoskeletal Proteins/metabolism , DNA, Bacterial/genetics , DNA, Bacterial/metabolism , Enterohemorrhagic Escherichia coli/genetics , Escherichia coli Proteins/genetics , GTP Phosphohydrolases/metabolism , Humans , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Molecular Sequence Data , Protein Structure, Tertiary , Receptors, Cell Surface/genetics , Receptors, Cell Surface/metabolism , Recombinant Fusion Proteins/metabolism , Signal Transduction/genetics , SwineABSTRACT
Several microbial pathogens including enteropathogenic E. coli (EPEC) exploit mammalian tyrosine-kinase signaling cascades to recruit Nck adaptor proteins and activate N-WASP-Arp2/3-mediated actin assembly. To promote localized actin "pedestal formation," EPEC translocates the bacterial effector protein Tir into the plasma membrane, where it is tyrosine-phosphorylated and binds Nck. Enterohemorrhagic E. coli (EHEC) also generates Tir-dependent pedestals, but in the absence of phosphotyrosines and Nck recruitment. To identify additional EHEC effectors that stimulate phosphotyrosine-independent actin assembly, we systematically generated EHEC mutants containing specific deletions in putative pathogenicity-islands. Among 0.33 Mb of deleted sequences, only one ORF was critical for pedestal formation. It lies within prophage-U, and encodes a protein similar to the known effector EspF. This proline-rich protein, EspFU, is the only EHEC effector of actin assembly absent from EPEC. Whereas EHEC Tir cannot efficiently recruit N-WASP or trigger actin polymerization, EspFU associates with Tir, binds N-WASP, and potently stimulates Nck-independent actin assembly.
Subject(s)
Carrier Proteins/physiology , Escherichia coli O157/metabolism , Escherichia coli Proteins/metabolism , Escherichia coli Proteins/physiology , Nerve Tissue Proteins/metabolism , Oncogene Proteins/metabolism , Receptors, Cell Surface/metabolism , Actins/chemistry , Actins/metabolism , Adaptor Proteins, Signal Transducing , Blotting, Western , Carrier Proteins/metabolism , Cell Nucleus/metabolism , Escherichia coli/metabolism , Gene Deletion , Genetic Complementation Test , Genomic Islands , HeLa Cells , Humans , Immunoblotting , Intracellular Signaling Peptides and Proteins , Microscopy, Fluorescence , Mutation , Phosphotyrosine/chemistry , Plasmids/metabolism , Precipitin Tests , Proline/chemistry , Protein Binding , Protein Structure, Tertiary , Protein Transport , Subcellular Fractions , Two-Hybrid System Techniques , Wiskott-Aldrich Syndrome Protein, NeuronalABSTRACT
The flaviviruses dengue virus (DENV) and Zika virus (ZIKV) are severe health threats with rapidly expanding ranges. To identify the host cell dependencies of DENV and ZIKV, we completed orthologous functional genomic screens using RNAi and CRISPR/Cas9 approaches. The screens recovered the ZIKV entry factor AXL as well as multiple host factors involved in endocytosis (RAB5C and RABGEF), heparin sulfation (NDST1 and EXT1), and transmembrane protein processing and maturation, including the endoplasmic reticulum membrane complex (EMC). We find that both flaviviruses require the EMC for their early stages of infection. Together, these studies generate a high-confidence, systems-wide view of human-flavivirus interactions and provide insights into the role of the EMC in flavivirus replication.
Subject(s)
Dengue Virus/genetics , Genomics/methods , Zika Virus/genetics , CRISPR-Cas Systems , Cell Membrane/metabolism , Endoplasmic Reticulum/metabolism , Genetic Testing , HeLa Cells , Host-Pathogen Interactions/genetics , Humans , Intracellular Membranes/metabolism , Protein Binding , Protein Interaction Maps , RNA Interference , Virus ReplicationABSTRACT
Diabetes mellitus is a common childhood illness, and its management is often complicated by mental health challenges. Psychiatric comorbidities are common, including anxiety, depression, and eating disorders. The illness can profoundly affect the developing brain and family functioning and have lifelong consequences. The child mental health provider can provide valuable assistance to support the child and family and assessment and treatment of comorbid mental health problems and to promote positive family functioning and normal developmental progress.
ABSTRACT
A cross sectional survey was performed to obtain the characteristics of specialized inpatient psychiatry units exclusively serving children with autism and other developmental disorders in the United States. Identified units were surveyed on basic demographic characteristics, clinical challenges and therapeutic modalities. Average length of stay was 42.3 days, children with autism spectrum disorders constituted the majority of the inpatient population (62.5-87.5%), and obtaining adequate post-discharge services was identified as the greatest challenge. Health policy implications and future research directions are suggested.
Subject(s)
Autistic Disorder/therapy , Developmental Disabilities/therapy , Hospitalization/statistics & numerical data , Psychiatric Department, Hospital/statistics & numerical data , Adolescent , Child , Child, Preschool , Cross-Sectional Studies , Health Care Surveys , Humans , Inpatients , Length of Stay , United States , Young AdultABSTRACT
Diabetes mellitus is a common childhood illness, and its management is often complicated by mental health challenges. Psychiatric comorbidities are common, including anxiety, depression, and eating disorders. The illness can profoundly affect the developing brain and family functioning and have lifelong consequences. The child mental health provider can provide valuable assistance to support the child and family and assessment and treatment of comorbid mental health problems and to promote positive family functioning and normal developmental progress.
ABSTRACT
Diabetes mellitus is a common childhood illness, and its management is often complicated by mental health challenges. Psychiatric comorbidities are common, including anxiety, depression, and eating disorders. The illness can profoundly affect the developing brain and family functioning and have lifelong consequences. The child mental health provider can provide valuable assistance to support the child and family and assessment and treatment of comorbid mental health problems and to promote positive family functioning and normal developmental progress.
Subject(s)
Diabetes Mellitus, Type 1/epidemiology , Diabetes Mellitus, Type 1/psychology , Mental Disorders/epidemiology , Mental Disorders/etiology , Adolescent , Anti-Anxiety Agents/therapeutic use , Antidepressive Agents, Tricyclic/therapeutic use , Child , Cognition Disorders/diagnosis , Cognition Disorders/epidemiology , Diabetes Complications/classification , Diabetes Complications/epidemiology , Family Health , Humans , Mental Disorders/drug therapy , Neuropsychological Tests , Severity of Illness IndexSubject(s)
Anticonvulsants/therapeutic use , Bipolar Disorder/drug therapy , Triazines/therapeutic use , Adolescent , Anticonvulsants/administration & dosage , Child , Delayed-Action Preparations , Drug Therapy, Combination , Humans , Lamotrigine , Retrospective Studies , Triazines/administration & dosage , Valproic Acid/therapeutic useABSTRACT
INTRODUCTION: Treatment nonresponse in adolescent mood disorders is a major public health problem, as mood disorders in youth are associated with significant mortality by suicide, protracted course of illness, and recurrence into adulthood. Three studies with small sample sizes exist for lamotrigine in youth mood disorders. However, the risk of serious rash has limited its use in youth mood disorders. OBJECTIVE: The aims of this study are to evaluate the preliminary effectiveness and safety of lamotrigine in adolescent mood disorders. METHODS: Medical charts were retrospectively reviewed at three clinical sites for 42 adolescents treated with lamotrigine for a mood disorder. The Clinical Global Impression (CGI) Severity and Improvement scores were obtained at baseline and last visit. Treatment-emergent adverse effects were also obtained. RESULTS: Improvement was seen in 22 subjects (52%). The mean daily lamotrigine dose was 114.8mg (SD 75.6), and the average duration of lamotrigine treatment was 29.1+/-31.8 weeks. The mean CGI-S score decreased from 4.9+/-1.0 at baseline to 3.5+/-1.4 at endpoint (z=3.204, p<0.002). Four subjects (10%) developed benign rash. CONCLUSIONS: This study provides preliminary data that lamotrigine may be effective in adolescents with mood disorders. However, this study revealed that lamotrigine might be associated with a significant risk of benign rash.