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1.
Clinicoecon Outcomes Res ; 10: 93-103, 2018.
Article in English | MEDLINE | ID: mdl-29440920

ABSTRACT

BACKGROUND: Iron-deficiency anemia and iron deficiency are common comorbidities associated with inflammatory bowel disease (IBD) resulting in impaired quality of life and high health care costs. Intravenous iron has shown clinical benefit compared to oral iron therapy. AIM: This study aimed to compare health care outcomes and costs after oral vs intravenous iron treatment for IBD patients with iron deficiency or iron deficiency anemia (ID/A) in Germany. METHODS: IBD patients with ID/A were identified by ICD-10-GM codes and newly commenced iron treatment via ATC codes in 2013 within the InGef (formerly Health Risk Institute) research claims database. Propensity score matching was performed to balance both treatment groups. Non-observable covariates were adjusted by applying the difference-in-differences (DID) approach. RESULTS: In 2013, 589 IBD patients with ID/A began oral and 442 intravenous iron treatment. After matching, 380 patients in each treatment group were analyzed. The intravenous group had fewer all-cause hospitalizations (37% vs 48%) and ID/A-related hospitalizations (5% vs 14%) than the oral iron group. The 1-year preobservation period comparison revealed significant health care cost differences between both groups. After adjusting for cost differences by DID method, total health care cost savings in the intravenous iron group were calculated to be €367. While higher expenditure for medication (€1,876) was observed in the intravenous iron group, the inpatient setting achieved most cost savings (€1,887). CONCLUSION: IBD patients receiving intravenous iron were less frequently hospitalized and incurred lower total health care costs compared to patients receiving oral iron. Higher expenditures for pharmaceuticals were compensated by cost savings in other domains.

2.
J Med Econ ; 20(8): 832-839, 2017 Aug.
Article in English | MEDLINE | ID: mdl-28532191

ABSTRACT

OBJECTIVE: Omalizumab add-on to standard-of-care therapy has proven to be efficacious in severe asthma patients for whom exacerbations cannot be controlled otherwise. Moreover, evidence from different healthcare settings suggests reduced healthcare resource utilization with omalizumab. Based on these findings, this study aimed to assess the cost-effectiveness of the addition of omalizumab to standard-of-care therapy in patients with uncontrolled severe allergic asthma in a Brazilian healthcare setting. METHODS: A previously published Markov model was adapted using Brazil-specific unit costs to compare the costs and outcomes of the addition of omalizumab to standard-of-care therapy vs standard-of-care therapy alone. Model inputs were largely based on the eXpeRience study. Costs and health outcomes were calculated for lifetime-years and were annually discounted at 5%. Both one-way and probabilistic sensitivity analyses were performed. RESULTS: An additional cost of R$280,400 for 5.20 additional quality-adjusted life-years was estimated with the addition of omalizumab to standard-of-care therapy, resulting in an incremental cost-effectiveness ratio of R$53,890. One-way sensitivity analysis indicated that discount rates, standard-of-care therapy exacerbation rates, and exacerbation-related mortality rates had the largest impact on incremental cost-effectiveness ratios. LIMITATIONS: Assumptions of lifetime treatment adherence and rate of future exacerbations, independent of previous events, might affect the findings. The lack of Brazilian patients in the eXpeRience study may affect the findings, although sample size and baseline characteristics suggest that the modeled population closely resembles Brazilian severe allergic asthma patients. CONCLUSION: Results indicate that omalizumab as an add-on therapy is more cost-effective than standard-of-care therapy alone for Brazilian patients with uncontrolled severe allergic asthma, based on the World Health Organization's cost-effectiveness threshold of up to 3-times the gross domestic product.


Subject(s)
Anti-Asthmatic Agents/economics , Anti-Asthmatic Agents/therapeutic use , Asthma/drug therapy , Omalizumab/economics , Omalizumab/therapeutic use , Adolescent , Adult , Aged , Anti-Asthmatic Agents/administration & dosage , Asthma/physiopathology , Brazil , Child , Cost-Benefit Analysis , Drug Therapy, Combination , Female , Humans , Male , Markov Chains , Middle Aged , Models, Econometric , Observational Studies as Topic , Omalizumab/administration & dosage , Quality of Life , Quality-Adjusted Life Years , Severity of Illness Index , Young Adult
3.
Diabetes Ther ; 7(3): 439-54, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27502495

ABSTRACT

INTRODUCTION: Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used in the management of patients with type 2 diabetes mellitus (T2DM) and renal impairment (RI). A systematic literature review was performed to compare the efficacy and safety of DPP-4 inhibitors in patients with T2DM and RI. METHODS: We searched EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials (cut-off, June 2015) to identify ≥12-week, randomized, placebo-controlled trials on DPP-4 inhibitors in ≥50 patients with T2DM and RI. Outcomes of interest included change in glycated hemoglobin (HbA1c), overall safety, and incidence of hypoglycemic events (HEs). RESULTS: Seven trials of ≤52-54 weeks duration were retrieved, which included one study each on vildagliptin, saxagliptin, and sitagliptin, two on linagliptin, and the remaining two were extension studies of vildagliptin and saxagliptin. Majority of patients were on insulin at baseline (53-86%), except in the sitagliptin study, where approximately 11% received insulin during the placebo-controlled phase. After 52 weeks, vildagliptin and saxagliptin reduced HbA1c levels by 0.6-0.7% (baseline 7.8-8.4%) versus placebo in the overall population. HbA1c reductions were similar at weeks 12 and 52. In the 12-week, placebo-controlled phase, sitagliptin and linagliptin reduced mean HbA1c by approximately 0.4% (baseline 7.7-8.1%) versus placebo. Rates of HEs with DPP-4 inhibitors were not significantly different versus placebo in any study. Rates of adverse events (AEs) and changes involving renal function were similar in the active- and placebo-treated groups. CONCLUSION: These results suggest that DPP-4 inhibitors have the potential to improve glycemic control in patients with RI without increasing the risk of HEs or overall AEs. FUNDING: Novartis Pharma AG.

4.
Am J Cancer Res ; 6(5): 878-93, 2016.
Article in English | MEDLINE | ID: mdl-27293986

ABSTRACT

Many studies are dedicated to exploring the molecular mechanisms of chemotherapy-resistance in breast cancer (BC). Some of them are focused on searching for candidate genes responsible for this process. The aim of this study was typing the candidate genes associated with the response to standard chemotherapy in the case of invasive ductal carcinoma. Frozen material from 28 biopsies obtained from IDC patients with different responses to chemotherapy were examined using gene expression microarray, Real-Time PCR (RT-PCR) and Western blot (WB). Based on the microarray results, further analysis of candidate gene expression was evaluated in 120 IDC cases by RT-PCR and in 224 IDC cases by immunohistochemistry (IHC). The results were correlated with clinical outcome and molecular subtype of the BC. Gene expression microarray revealed Prolactin-Induced Peptide (PIP) as a single gene differentially expressed in BC therapy responder or non-responder patients (p <0.05). The level of PIP expression was significantly higher in the BC therapy responder group than in the non-responder group at mRNA (p=0.0092) and protein level (p=0.0256). Expression of PIP mRNA was the highest in estrogen receptor positive (ER+) BC cases (p=0.0254) and it was the lowest in triple negative breast cancer (TNBC) (p=0.0336). Higher PIP mRNA expression was characterized by significantly longer disease free survival (DFS, p=0.0093), as well as metastasis free survival (MFS, p=0.0144). Additionally, PIP mRNA and PIP protein expression levels were significantly higher in luminal A than in other molecular subtypes and TNBC. Moreover significantly higher PIP expression was observed in G1, G2 vs. G3 cases (p=0.0027 and p=0.0013, respectively). Microarray analysis characterized PIP gene as a candidate for BC standard chemotherapy response marker. Analysis of clinical data suggests that PIP may be a good prognostic and predictive marker in IDC patients. Higher levels of PIP were related to longer DFS and MFS but not with OS.

5.
Patient ; 9(5): 395-407, 2016 10.
Article in English | MEDLINE | ID: mdl-26970976

ABSTRACT

AIMS: The aim of this study was to evaluate the factor structure and psychometric characteristics of the Hypoglycemia Perspectives Questionnaire (HPQ) assessing experience and perceptions of hypoglycemia in patients with type 2 diabetes mellitus (T2DM). METHODS: HPQ was administered to adults with T2DM in a clinical sample from Cyprus (HYPO-Cyprus, n = 500) and a community sample in the United States (US, n = 1257) from the 2011 US National Health and Wellness Survey. Demographic and clinical data were collected. Analysis of HPQ data from two convenience samples examined item performance, factor structure, and HPQ measurement properties (reliability, convergent validity, known-groups validity). RESULTS: Analyses supported three HPQ domains: symptom concern (six items), compensatory behavior (five items), and worry (five items). Internal consistency was high for all three domains (all ≥0.75), supporting reliability. Convergent validity was supported by moderate Spearman correlations between HPQ domain scores and the Audit of Diabetes-Dependent Quality of Life (ADDQoL-19) total score. Patients with recent hypoglycemia events had significantly higher HPQ scores, supporting known-group validity. CONCLUSIONS: HPQ may be a valid and reliable measure capturing the experience and impact of hypoglycemia and useful in clinical trials and community-based settings.


Subject(s)
Diabetes Mellitus, Type 2/psychology , Hypoglycemia/psychology , Quality of Life , Humans , Psychometrics , Reproducibility of Results , Surveys and Questionnaires
6.
Clinicoecon Outcomes Res ; 7: 313-23, 2015.
Article in English | MEDLINE | ID: mdl-26089691

ABSTRACT

INTRODUCTION: Dipeptidyl peptidase-4 (DPP-4) inhibitors are a class of oral antidiabetic agents for the treatment of type 2 diabetes mellitus, which lower blood glucose without causing severe hypoglycemia. However, the first cardiovascular (CV) safety trials have only recently reported their results, and our understanding of these therapies remains incomplete. Using clinical trial simulations, we estimated the effectiveness of DPP-4 inhibitors in preventing major adverse cardiovascular events (MACE) in a population like that enrolled in the SAVOR-TIMI (the Saxagliptin Assessment of Vascular Outcomes Recorded in Patients with Diabetes Mellitus - Thrombolysis in Myocardial Infarction) 53 trial. METHODS: We used the Archimedes Model to simulate a clinical trial of individuals (N=11,000) with diagnosed type 2 diabetes and elevated CV risk, based on established disease or multiple risk factors. The DPP-4 class was modeled with a meta-analysis of HbA1c and weight change, pooling results from published trials of alogliptin, linagliptin, saxagliptin, sitagliptin, and vildagliptin. The study treatments were added-on to standard care, and outcomes were tracked for 20 years. RESULTS: The DPP-4 class was associated with an HbA1c drop of 0.66% (0.71%, 0.62%) and a weight drop of 0.14 (-0.07, 0.36) kg. These biomarker improvements produced a relative risk (RR) for MACE at 5 years of 0.977 (0.968, 0.986). The number needed to treat to prevent one occurrence of MACE at 5 years was 327 (233, 550) in the elevated CV risk population. CONCLUSION: Consistent with recent trial publications, our analysis indicates that DPP-4 inhibitors do not increase the risk of MACE relative to the standard of care. This study provides insights about the long-term benefits of DPP-4 inhibitors and supports the interpretation of the published CV safety trial results.

8.
Curr Med Res Opin ; 30(12): 2453-60, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25265131

ABSTRACT

OBJECTIVE: This study aims to develop and validate a stroke risk model incorporating pulse pressure (PP) as a potential risk factor. Recent evidence suggests that PP, defined as the difference between systolic blood pressure (SBP) and diastolic blood pressure (DBP), could be an incremental risk factor beyond SBP. METHODS: Electronic health records (EHRs) of hypertensive patients from a US integrated health delivery system were analyzed (January 2004 to May 2012). Patients with ≥ 1 PP reading and ≥ 6 months of observation prior to the first diagnosis of hypertension were randomly split into development (two-thirds of sample) and validation (one-third of sample) datasets. Stroke events were identified using ICD-9-CM 433.xx-436.xx. Cox proportional hazards models assessed time to first stroke event within 3 years of first hypertension diagnosis based on baseline risk factors, including PP, age, gender, diabetes, and cardiac comorbidities. The optimal model was selected using the least absolute shrinkage and selection operator (LASSO); performance was evaluated by the c-statistic. RESULTS: Among 34,797 patients selected (mean age 59.3 years, 48% male), 4272 patients (12.3%) had a stroke. PP was higher among patients who developed stroke (mean [SD] PP, stroke: 02.0 [15.3] mmHg; non-stroke: 58.1 [14.0] mmHg, p < 0.001). The best performing risk model (c-statistic, development: 0.730; validation: 0.729) included PP (hazard ratio per mmHg increase: 1.0037, p < 0.001) as a significant risk factor. LIMITATIONS: This study was subject to limitations similar to other studies using EHRs. Only patient encounters occurring within the single healthcare network were captured in the data source. Though the model was tested internally, external validation (using a separate data source) would help assess the model's generalizability and calibration. CONCLUSIONS: This stroke risk model shows that greater PP is a significant predictive factor for increased stroke risk, even in the presence of known risk factors. PP should be considered by practitioners along with established risk factors in stroke treatment strategies.


Subject(s)
Blood Pressure/physiology , Hypertension/complications , Hypertension/physiopathology , Stroke/etiology , Aged , Electronic Health Records , Female , Humans , Male , Middle Aged , Proportional Hazards Models , Reproducibility of Results , Retrospective Studies , Risk Factors , Stroke/physiopathology
9.
J Card Fail ; 20(11): 853-63, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25152497

ABSTRACT

BACKGROUND: Current guidelines recommend the use of intravenous (IV) vasodilators in addition to IV loop diuretics for the treatment of acute heart failure (AHF) patients without hypotension. The evidence basis for these recommendations is limited. METHODS AND RESULTS: Hospital billing records for 82,808 AHF patients in the United States were analyzed. Patients receiving IV loop diuretics alone were paired with patients receiving IV loop diuretics + IV nitrates or IV nesiritide with the use of propensity score matching, excluding those with hypotension and/or evidence of cardiogenic shock, myocardial infarction, or acute coronary syndrome. Compared with paired patients receiving IV loop diuretics alone, in-hospital mortality was similar among IV loop diuretics + IV nitrates patients (n = 4,401; 1.9% vs 2.0%; P = .88) and marginally higher for IV loop diuretics + IV nesiritide patients (n = 2,254; 2.2% vs 3.1%; P = .05). Compared with paired IV loop diuretics patients, IV loop diuretics + IV nitrates or IV nesiritide had longer lengths of stay (+1.6 and +2.1 days; P < .01) and 57% higher costs (P < .01). CONCLUSIONS: Among hospitalized AHF patients, the addition of IV vasodilators to IV loop diuretics did not lower inpatient mortality or rehospitalization rates compared with loop diuretics alone, and was associated with longer lengths of stay and higher hospitalization costs. Although the lack of complete clinical, socioeconomic, and post-discharge data may have confounded these results, this analysis questions whether currently available IV vasodilators can improve outcomes in hospitalized AHF patients.


Subject(s)
Heart Failure/drug therapy , Hospitalization , Sodium Potassium Chloride Symporter Inhibitors/therapeutic use , Vasodilator Agents/therapeutic use , Acute Disease , Aged , Drug Therapy, Combination , Female , Heart Failure/mortality , Hospital Mortality/trends , Humans , Male , Retrospective Studies , Treatment Outcome , United States/epidemiology
11.
J Med Econ ; 17(7): 499-507, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24708176

ABSTRACT

OBJECTIVE: To evaluate the cost-effectiveness of vildagliptin plus metformin vs generic sulphonylurea plus metformin in patients with type 2 diabetes mellitus, not controlled with metformin, from a Portuguese healthcare system perspective. METHODS: A cost-effectiveness model was constructed using risk equations from the UK Prospective Diabetes Study Outcomes Model with a 10,000-patient cohort and a lifetime horizon. The model predicted microvascular and macrovascular complications and mortality in yearly cycles. Patients entered the model as metformin monotherapy failures and switched to alternative treatments (metformin plus basal-bolus insulin and subsequently metformin plus intensive insulin) when glycated hemoglobin A1c >7.5% was reached. Baseline patient characteristics and clinical variables were derived from a Portuguese epidemiological study. Cost estimates were based on direct medical costs only. One-way and probabilistic sensitivity analyses were conducted to test the robustness of the model. RESULTS: There were fewer non-fatal diabetes-related adverse events (AEs) in patients treated with metformin plus vildagliptin compared with patients treated with metformin plus sulphonylurea (6752 vs 6815). Addition of vildagliptin compared with sulphonylurea led to increased drug acquisition costs but reduced costs of AEs, managing morbidities, and monitoring patients. Treatment with metformin plus vildagliptin yielded a mean per-patient gain of 0.1279 quality-adjusted life years (QALYs) and a mean per-patient increase in total cost of €1161, giving an incremental cost-effectiveness ratio (ICER) of €9072 per QALY. Univariate analyses showed that ICER values were robust and ranged from €4195 to €16,052 per QALY when different parameters were varied. LIMITATIONS: The model excluded several diabetes-related morbidities, such as peripheral neuropathy and ulceration, and did not model second events. Patients were presumed to enter the model with no diabetes-related complications. CONCLUSION: Treatment with metformin plus vildagliptin compared with metformin plus sulphonylurea is expected to result in a lower incidence of diabetes-related AEs and to be a cost-effective treatment strategy.


Subject(s)
Adamantane/analogs & derivatives , Diabetes Complications/economics , Diabetes Mellitus, Type 2/drug therapy , Diabetes Mellitus, Type 2/economics , Metformin/economics , Nitriles/economics , Pyrrolidines/economics , Sulfonylurea Compounds/economics , Adamantane/administration & dosage , Adamantane/economics , Computer Simulation , Cost-Benefit Analysis , Diabetes Complications/prevention & control , Diabetes Mellitus, Type 2/complications , Dipeptidyl-Peptidase IV Inhibitors/administration & dosage , Dipeptidyl-Peptidase IV Inhibitors/economics , Drug Therapy, Combination/economics , Female , Humans , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/economics , Male , Metformin/administration & dosage , Metformin/therapeutic use , Middle Aged , Models, Economic , Nitriles/administration & dosage , Portugal , Prospective Studies , Pyrrolidines/administration & dosage , Quality-Adjusted Life Years , Risk Factors , Sulfonylurea Compounds/administration & dosage , Vildagliptin
12.
J Am Soc Hypertens ; 3(6): 403-15, 2009.
Article in English | MEDLINE | ID: mdl-20409983

ABSTRACT

Study quantified incremental cost of cardiovascular (CV) events in 6 high-risk and compelling indication subgroups: post-myocardial infarction (MI), diabetes, diabetic nephropathy, elderly, chronic kidney disease, and prior stroke. Based on claims data from privately insured individuals with 2+ hypertension (HTN) diagnoses in 2004-2006, we estimated regression-adjusted per-member-per-month healthcare costs after CVE. Costs were compared between patients with and without a CV events, and before and after CV events in each subgroup. The following CVevents were studied: acute MI, acute coronary syndrome, angina, ventricular arrhythmia, atrial arrhythmia, heart failure, coronary artery disease, left ventricular hypertrophy, stroke, and sinus tachycardia. Of 1,598,890 HTN patients, 510,118 had >/=1 CV event. Compared with controls, healthcare costs among patients with events were significantly greater across all cost components (inpatient, outpatient, and prescription drug). Acute MI and congestive heart failure generally had the largest incremental total healthcare costs. First-quarter post-event costs were attributable to inpatient costs. CV events are costly sequelae of hypertension in high-risk and CI subgroups.

13.
J Biol Chem ; 283(29): 20454-72, 2008 Jul 18.
Article in English | MEDLINE | ID: mdl-18448434

ABSTRACT

The Cdc42 effector IRSp53 is a strong inducer of filopodia formation and consists of an Src homology domain 3 (SH3), a potential WW-binding motif, a partial-Cdc42/Rac interacting binding region motif, and an Inverse-Bin-Amphiphysins-Rvs (I-BAR) domain. We show that IRSp53 interacts directly with neuronal Wiskott-Aldrich syndrome protein (N-WASP) via its SH3 domain and furthermore that N-WASP is required for filopodia formation as IRSp53 failed to induce filopodia formation in N-WASP knock-out (KO) fibroblasts. IRSp53-induced filopodia formation can be reconstituted in N-WASP KO fibroblasts by full-length N-WASP, by N-WASPDeltaWA (a mutant unable to activate the Arp2/3 complex), and by N-WASPH208D (a mutant unable to bind Cdc42). IRSp53 failed to induce filopodia in mammalian enabled (Mena)/VASP KO cells, and N-WASP failed to induce filopodia when IRSp53 was knocked down with RNA interference. The IRSp53 I-BAR domain alone induces dynamic membrane protrusions that lack actin and are smaller than normal filopodia ("partial-filopodia") in both wild-type N-WASP and N-WASP KO cells. We propose that IRSp53 generates filopodia by coupling membrane protrusion through its I-BAR domain with actin dynamics through SH3 domain binding partners, including N-WASP and Mena.


Subject(s)
Actins/metabolism , Cell Membrane/metabolism , Nerve Tissue Proteins/metabolism , Pseudopodia/metabolism , cdc42 GTP-Binding Protein/metabolism , Adaptor Proteins, Signal Transducing/genetics , Adaptor Proteins, Signal Transducing/metabolism , Animals , Carrier Proteins/metabolism , Cell Line, Tumor , Cricetinae , Formins , Humans , Mass Spectrometry , Nerve Tissue Proteins/genetics , Phenotype , Protein Binding , Wiskott-Aldrich Syndrome Protein/genetics , Wiskott-Aldrich Syndrome Protein/metabolism , rac1 GTP-Binding Protein/genetics , rac1 GTP-Binding Protein/metabolism
14.
Proc Natl Acad Sci U S A ; 101(43): 15358-63, 2004 Oct 26.
Article in English | MEDLINE | ID: mdl-15492213

ABSTRACT

PTEN is a tumor suppressor gene implicated in both sporadic cancers and inherited tumor-prone syndromes. Here we show that pten+/- mice display a partially penetrant embryonic lethality. This lethality is associated with defects in both neural and placental development. Notably, this lethality is completely rescued by grb2 haploinsufficiency. In contrast, grb2 heterozygosity did not alter tumorigenesis in either pten+/- or T cell-specific pten-/- mice. grb2-/hypomorph murine embryonic fibroblasts (MEFs) show decreased activation of both PKB and Erk upon stimulation with epidermal growth factor, whereas grb2-/hypomorph; pten+/- MEFs activate PKB but not Erk normally. Similarly, grb2-/hypomorph fibroblasts die in low serum, and this phenotype is rescued by pten haploinsufficiency. Activation of both PKB and Erk as well as survival in low serum-containing media are all rescued by reexpression of Grb2 containing mutations within the N-terminal Src homology 3 (SH3) domain, but not by C-terminal SH3 domain mutants. The N-terminal SH3 domain mutants fail to bind to Sos, whereas the C-terminal SH3 domain mutants fail to bind to Gab1, suggesting that Erk and PKB activation in fibroblasts in response to epidermal growth factor depends on Gab1 or other C-terminal SH3 domain-interacting proteins, but not on Sos. Thus, PTEN/phosphatidylinositol 3' kinase signaling requires Grb2 during both embryonic development and fibroblast survival, but Grb2 heterozygosity does not effect tumorigenesis in pten-deficient mice. In fibroblasts, survival signals emanating from the epidermal growth factor receptor appear to be PKB-dependent, and this activation depends on the C-terminal SH3 domain of Grb2, likely through the interaction of Grb2 with Gab1.


Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Embryo, Mammalian , Genes, Lethal , Heterozygote , Protein Tyrosine Phosphatases/physiology , Tumor Suppressor Proteins/physiology , Animals , GRB2 Adaptor Protein , Immunohistochemistry , Mice , Mice, Inbred C57BL , Neoplasms, Experimental/genetics , PTEN Phosphohydrolase , Protein Tyrosine Phosphatases/genetics , Tumor Suppressor Proteins/genetics
15.
Dev Cell ; 6(3): 383-95, 2004 Mar.
Article in English | MEDLINE | ID: mdl-15030761

ABSTRACT

Semaphorins and ephrins are axon guidance cues. In C. elegans, semaphorin-2a/mab-20 and ephrin-4/efn-4/mab-26 also regulate cell sorting to form distinct rays in the male tail. Several erf (enhancer of ray fusion) mutations were identified in a mab-20 enhancer screen. Mutants of plexin-2 (plx-2) and unc-129, which encodes an axon guiding TGF-beta, were also found to be erfs. Genetic analyses show that plx-2 and mab-20 function in the same pathway, as expected if PLX-2 is a receptor for MAB-20. Surprisingly, MAB-20 also signals in a parallel pathway that requires efn-4. This signal utilizes a non-plexin receptor. The expression of plx-2, efn-4, and unc-129 in subsets of 3-cell sensory ray clusters likely mediates the ray-specific cell sorting functions of the ubiquitously expressed mab-20. We present a model for the integrated control of TGF-beta, semaphorin, and ephrin signaling in the sorting of cell clusters into distinct rays in the developing male tail.


Subject(s)
Caenorhabditis elegans Proteins/physiology , Caenorhabditis elegans/metabolism , Ephrin-A4/physiology , Membrane Proteins/physiology , Nerve Tissue Proteins/physiology , Sense Organs/physiology , Signal Transduction/physiology , Transforming Growth Factor beta/physiology , Animals , Animals, Genetically Modified , Caenorhabditis elegans/embryology , Caenorhabditis elegans/genetics , Caenorhabditis elegans Proteins/genetics , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Chi-Square Distribution , Chromosome Mapping/methods , Cloning, Molecular , DNA Mutational Analysis , Enhancer Elements, Genetic , Ephrin-A4/genetics , Ephrins/physiology , Gene Expression Regulation, Developmental , Green Fluorescent Proteins , Immunohistochemistry/methods , Luminescent Proteins/metabolism , Male , Membrane Proteins/genetics , Models, Molecular , Mutagenesis, Insertional/methods , Mutation , Nerve Tissue Proteins/genetics , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , Sequence Analysis, DNA , Transforming Growth Factor beta/genetics , Xenopus Proteins/genetics , Xenopus Proteins/metabolism
16.
Nat Cell Biol ; 4(12): 970-5, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12447388

ABSTRACT

WAVE-1, which is also known as Scar, is a scaffolding protein that directs actin reorganization by relaying signals from the GTPase Rac to the Arp2/3 complex. Although the molecular details of WAVE activation by Rac have been described, the mechanisms by which these signals are terminated remain unknown. Here we have used tandem mass spectrometry to identify previously unknown components of the WAVE signalling network including WRP, a Rac-selective GTPase-activating protein. WRP binds directly to WAVE-1 through its Src homology domain 3 and specifically inhibits Rac function in vivo. Thus, we propose that WRP is a binding partner of WAVE-1 that functions as a signal termination factor for Rac.


Subject(s)
Microfilament Proteins/physiology , rac GTP-Binding Proteins/physiology , Amino Acid Sequence , Animals , Binding Sites , Molecular Sequence Data , Protein Binding , Rats , Rats, Sprague-Dawley , Sequence Alignment , Wiskott-Aldrich Syndrome Protein Family
17.
J Biol Chem ; 277(5): 3195-201, 2002 Feb 01.
Article in English | MEDLINE | ID: mdl-11698404

ABSTRACT

Several genetic studies in Drosophila have shown that the dSprouty (dSpry) protein inhibits the Ras/mitogen-activated protein (MAP) kinase pathway induced by various activated receptor tyrosine kinase receptors, most notably those of the epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor (FGFR). Currently, the mode of action of dSpry is unknown, and the point of inhibition remains controversial. There are at least four mammalian Spry isoforms that have been shown to co-express preferentially with FGFRs as compared with EGFRs. In this study, we investigated the effects of the various mammalian Spry isoforms on the Ras/MAP kinase pathway in cells overexpressing constitutively active FGFR1. hSpry2 was significantly more potent than mSpry1 or mSpry4 in inhibiting the Ras/MAP kinase pathway. Additional experiments indicated that full-length hSpry2 was required for its full potency. hSpry2 had no inhibitory effect on either the JNK or the p38 pathway and displayed no inhibition of FRS2 phosphorylation, Akt activation, and Ras activation. Constitutively active mutants of Ras, Raf, and Mek were employed to locate the prospective point of inhibition of hSpry2 downstream of activated Ras. Results from this study indicated that hSpry2 exerted its inhibitory effect at the level of Raf, which was verified in a Raf activation assay in an FGF signaling context.


Subject(s)
Fibroblast Growth Factors/antagonists & inhibitors , MAP Kinase Signaling System/physiology , Nerve Tissue Proteins/metabolism , Proto-Oncogene Proteins c-raf/antagonists & inhibitors , Animals , Cell Line , Cloning, Molecular , Drosophila , Humans , Mitogen-Activated Protein Kinases/antagonists & inhibitors , Mitogen-Activated Protein Kinases/metabolism , Nerve Tissue Proteins/genetics , Plasmids , Recombinant Fusion Proteins/metabolism , Recombinant Proteins/metabolism , Transfection
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