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1.
BMC Prim Care ; 25(1): 12, 2024 01 05.
Article En | MEDLINE | ID: mdl-38178010

BACKGROUND: Older people with multiple long-term conditions (multimorbidity) (MLTC-M) experience difficulties accessing and interacting with health and care services. Breakdowns in communication between patients and staff can threaten patient safety. To improve communication and reduce risks to patient safety in primary care, we developed an intervention: Safer Patients Empowered to Engage and Communicate about Health (SPEECH). SPEECH comprises a booklet for patients and an associated guide for staff. The booklet is designed to provide patients with information about staff and services, skills to prepare and explain, and confidence to speak up and ask. METHODS: A single-arm mixed methods feasibility study with embedded process evaluation. General practices in the North West of England were recruited. Participating practices invited patients aged 65+ with MLTC-M who had an appointment scheduled during the study period. Patients were asked to complete questionnaires at baseline and follow-up (four to eight weeks after being sent the patient booklet), including the Consultation and Relational Empathy measure, Empowerment Scale, Multimorbidity Treatment Burden Questionnaire, and Primary Care Patient Measure of Safety. Staff completed questionnaires at the end of the study period. A sub-sample of patients and staff were interviewed about the study processes and intervention. Patients and the public were involved in all aspects of the study, from generation of the initial idea to interpretation of findings. RESULTS: Our target of four general practices were recruited within 50 days of the study information being sent out. A fifth practice was recruited later to boost patient recruitment. We received expressions of interest from 55 patients (approx. 12% of those invited). Our target of 40 patient participants completed baseline questionnaires and were sent the SPEECH booklet. Of these, 38 (95%) completed follow-up. Patients found the intervention and study processes acceptable, and staff found the intervention acceptable and feasible to deliver. CONCLUSIONS: Our findings suggest the intervention is acceptable, and it would be feasible to deliver a trial to assess effectiveness. Prior to further evaluation, study processes and the intervention will be updated to incorporate suggestions from participants. TRIAL REGISTRATION: The study was registered on the ISRCTN registry (ISRCTN13196605: https://doi.org/10.1186/ISRCTN13196605 ).


Multimorbidity , Patient Safety , Humans , Aged , Feasibility Studies , Speech , Primary Health Care
2.
BJGP Open ; 7(4)2023 Dec.
Article En | MEDLINE | ID: mdl-37295796

BACKGROUND: Treatment burden represents the work patients undertake because of their health care, and the impact of that effort on the patient. Most research has focused on older adults (aged >65 years) with multiple long-term conditions (multimorbidity) (MLTC-M), but there are now more younger adults (aged 18-65 years) living with MLTC-M and they may experience treatment burden differently. Understanding experiences of treatment burden, and identifying those most at risk of high treatment burden, are important for designing primary care services to meet their needs. AIM: To understand the treatment burden associated with MLTC-M, for people aged 18-65 years, and how primary care services affect this burden. DESIGN & SETTING: Mixed-methods study in up to 33 primary care practices in two UK regions. METHOD: The following two approaches will be used: (i) in-depth qualitative interviews with adults living with MLTC-M (approximately 40 participants) to understand their experiences of treatment burden and the impact of primary care, with a think-aloud aspect to explore face validity of a novel short treatment burden questionnaire (STBQ) for routine clinical use in the initial 15 interviews; (ii) cross-sectional patient survey (approximately 1000 participants), with linked routine medical record data to examine the factors associated with treatment burden for people living with MLTC-M, and to test the validity of STBQ. CONCLUSION: This study will generate in-depth understanding of the treatment burden experienced by people aged 18-65 years living with MLTC-M, and how primary care services affect this burden. This will inform further development and testing of interventions to reduce treatment burden, and potentially influence MLTC-M trajectories and improve health outcomes.

3.
Schizophrenia (Heidelb) ; 8(1): 5, 2022 02 24.
Article En | MEDLINE | ID: mdl-35210430

Clinical practice guidelines (CPGs) translate evidence into recommendations to improve patient care and outcomes. To provide an overview of schizophrenia CPGs, we conducted a systematic literature review of English-language CPGs and synthesized current recommendations for the acute and maintenance management with antipsychotics. Searches for schizophrenia CPGs were conducted in MEDLINE/Embase from 1/1/2004-12/19/2019 and in guideline websites until 06/01/2020. Of 19 CPGs, 17 (89.5%) commented on first-episode schizophrenia (FES), with all recommending antipsychotic monotherapy, but without agreement on preferred antipsychotic. Of 18 CPGs commenting on maintenance therapy, 10 (55.6%) made no recommendations on the appropriate maximum duration of maintenance therapy, noting instead individualization of care. Eighteen (94.7%) CPGs commented on long-acting injectable antipsychotics (LAIs), mainly in cases of nonadherence (77.8%), maintenance care (72.2%), or patient preference (66.7%), with 5 (27.8%) CPGs recommending LAIs for FES. For treatment-resistant schizophrenia, 15/15 CPGs recommended clozapine. Only 7/19 (38.8%) CPGs included a treatment algorithm.

4.
Clin Rheumatol ; 40(12): 4829-4836, 2021 Dec.
Article En | MEDLINE | ID: mdl-34159493

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare disease associated with vascular inflammation and multisystem organ damage. The literature reporting EGPA incidence or prevalence is limited. We performed a systematic literature review and meta-analysis to describe the incidence, prevalence, and disease burden associated with EGPA. Real-world, observational, English-language studies in MEDLINE, MEDLINE In-Process, and Embase up to 6 June, 2019, were included. A single investigator screened all identified titles/abstracts and extracted data; an additional, independent investigator repeated the screening and validated the extracted data. A random-effects meta-analysis was conducted to generate pooled estimates for EGPA incidence and prevalence. Data from 100 eligible publications were extracted (32 with incidence/prevalence data, 65 with morbidity/healthcare resource data; 3 with both types of data). Significant evidence of between-study heterogeneity for reported incidence (p = 0.0013-0.0016) and prevalence (p = 0.0001-0.0006) estimates was observed. Global and European pooled estimates (95% confidence interval) of EGPA incidence were 1.22 (0.93, 1.60) and 1.07 (0.94, 1.35) cases per million person-years, respectively; global and European pooled estimates (95% confidence interval) for EGPA prevalence were 15.27 (11.89, 19.61) and 12.13 (6.98, 21.06) cases per million individuals, respectively. The proportions of patients experiencing relapses, or who had nasal polyps or severe asthma, varied considerably across studies. EGPA healthcare resource use was high, with inpatient admissions and emergency department visits reported for 17-42% and 25-42% of patients, respectively. Our results indicate that although global and European EGPA incidence and prevalence is low, the associated disease burden is substantial. Key points • We performed a systematic literature review and meta-analysis of real-world, observational studies describing the incidence, prevalence, and disease burden associated with eosinophilic granulomatosis with polyangiitis (EGPA). • Based on meta-analysis data from 35 eligible studies reporting incidence and prevalence, the incidence and prevalence of EGPA were low (globally 1.22 cases per million person-years and 15.27 cases per million individuals, respectively). • Among the 49 studies with morbidity and/or healthcare resource data, most reported a large proportion of patients with EGPA relapses and comorbidities of nasal polyps and severe asthma. • Healthcare resource use was also high among patients with EGPA in these studies, with inpatient admissions and emergency department visits reported for 17-42% and 25-42% of patients, respectively. Taken together, these data indicate the substantial disease burden associated with EGPA.


Asthma , Churg-Strauss Syndrome , Granulomatosis with Polyangiitis , Churg-Strauss Syndrome/complications , Churg-Strauss Syndrome/epidemiology , Cost of Illness , Granulomatosis with Polyangiitis/complications , Granulomatosis with Polyangiitis/epidemiology , Humans , Incidence
5.
BMJ Open ; 11(3): e044221, 2021 03 11.
Article En | MEDLINE | ID: mdl-33707271

OBJECTIVES: Primary care records have traditionally served the needs and demands of clinicians rather than those of the patient. In England, general practices must promote and offer registered patients online access to their primary care record, and research has shown benefits to both patients and clinicians of doing so. Despite this, we know little about patients' needs and expectations regarding online access to their record. This study explored what patients and carers want from online access to their electronic primary care health record, their experiences of using it, how they would like to interact with their record and what support they may need. DESIGN: Focus groups and semistructured interviews using purposive sampling to achieve a good sociodemographic spread. Interviews were digitally audiorecorded, transcribed and coded using an established thematic approach. SETTING: Focus groups and interviews were conducted in community settings in the UK. PARTICIPANTS: Fifty-four individuals who were either eligible for the National Health Service Health Check, living with more than one long-term condition or caring for someone else. RESULTS: Participants views regarding online access were categorised into four main themes: awareness, capabilities, consequences and inevitability. Participants felt online access should be better promoted, and suggested a number of additional functions, such as better integration with other parts of the healthcare system. It was felt that online access could improve quality of care (eg, through increased transparency) but also have potential negative consequences (eg, by replacing face to face contact). A move towards more online records access was considered inevitable, but participants noted a need for additional support and training in using the online record, especially to ensure that health inequalities are not exacerbated. CONCLUSIONS: Discussions with patients and carers about their views of accessing online records have provided useful insights into future directions and potential improvements for this service.


Motivation , State Medicine , England , Humans , Primary Health Care , Qualitative Research
6.
Cancer Treat Res Commun ; 24: 100200, 2020.
Article En | MEDLINE | ID: mdl-32750661

KRAS (Kirsten Rat Sarcoma) is the most common oncogenic mutation detected in patients with non-small cell lung cancer (NSCLC). However, the role of KRAS as either a prognostic factor or predictive factor (modifier of treatment effects) in NSCLC is not well established at this time. This systematic literature review (SLR) and meta-analysis synthesized the available evidence regarding the role of KRAS mutation as a predictive factor and/or prognostic factor of survival and response outcomes in patients with advanced/metastatic (stage IIIB-IV) NSCLC. Relevant clinical trials and observational studies were identified by searching MEDLINE, Embase and Cochrane Register of Controlled Trials. Meta-analyses were performed using data extracted from multivariable and univariable analyses from clinical studies to assess the empirical evidence of KRAS mutation status as a prognostic or/and predicitive factor. 43 selected studies were identified by the SLR and included in this meta-analysis. Pairwise meta-analyses of hazard ratios (HRs) reported in randomized controlled trials (RCTs) did not demonstrate a significant prognostic effect of mutant KRAS on overall survival (OS) (HR=1.10; 95% CI [0.88, 1.38]) or progression free survival (PFS) (HR=1.03; 95% CI [0.80, 1.33]). However, when conducting meta-analyses on HRs reported in observational studies, a statistically significant negative prognostic effect of mutant KRAS was observed (OS HR=1.71; 95% CI [1.07, 2.84]; PFS HR=1.18; 95% CI [1.02, 1.36]). Meta-analyses of objective response rate (ORR) in RCTs demonstrated a negative prognostic effect of mutant KRAS (RR=0.38; 95% CI [0.16, 0.63]). Limited data were available to evaluate the role of KRAS mutation as a predictive factor. In conclusion, this research offers evidence that KRAS mutation may be a negative prognostic factor for survival and response outcomes in patients with advanced/metastatic NSCLC, but further research is needed to address conflicting results on the importance of KRAS mutations as a predictive factor.


Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers, Tumor/genetics , Carcinoma, Non-Small-Cell Lung/drug therapy , Lung Neoplasms/drug therapy , Proto-Oncogene Proteins p21(ras)/genetics , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Biomarkers, Tumor/antagonists & inhibitors , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/mortality , Carcinoma, Non-Small-Cell Lung/secondary , DNA Mutational Analysis , ErbB Receptors/antagonists & inhibitors , ErbB Receptors/genetics , Humans , Lung Neoplasms/genetics , Lung Neoplasms/mortality , Lung Neoplasms/pathology , Mutation , Neoplasm Staging , Observational Studies as Topic , Prognosis , Progression-Free Survival , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Randomized Controlled Trials as Topic
7.
Appl Physiol Nutr Metab ; 43(3): 233-239, 2018 Mar.
Article En | MEDLINE | ID: mdl-29049890

Physical activity confers many health benefits, but the underlying mechanisms require further exploration. In this pilot randomized controlled trial we tested the association between longitudinal measures of DNA methylation and changes in objective measures, including physical activity, weight loss, and C-reactive protein levels in community-dwelling women aged 55 to 70 years. We assessed DNA methylation from 20 healthy postmenopausal women, who did not have a mobility disability and allocated them to a group-based intervention, Everyday Activity Supports You, or a control group (monthly group-based health-related education sessions). The original randomized controlled trial was 6 months in duration and consisted of nine 2-h sessions that focused on reducing sedentary behaviour for the intervention group, or six 1-h sessions that focused on other topics for the control group. We collected peripheral blood mononuclear cells, both at baseline and 6 months later. Samples were processed using the Illumina 450k Methylation array to quantify DNA methylation at >485 000 CpG sites in the genome. There were no significant associations between DNA methylation and physical activity, but we did observe alterations at epigenetic modifications that correlated with change in percent body weight over a 6-month period at 12 genomic loci, 2 of which were located near the previously reported weight-associated genes RUNX3 and NAMPT. We also generated a potential epigenetic predictor of weight loss using baseline DNA methylation at 5 CpG sites. These exploratory findings suggest a potential biological link between body weight changes and epigenetic processes.


DNA Methylation , Leukocytes, Mononuclear/physiology , Life Style , Aged , Exercise , Female , Humans , Middle Aged , Pilot Projects , Weight Loss
8.
Br J Clin Pharmacol ; 80(4): 868-77, 2015 Oct.
Article En | MEDLINE | ID: mdl-25060532

AIM: Adverse drug events lead to increased morbidity, mortality and health care costs. Pharmacogenetic testing that guides drug prescribing has the potential to reduced adverse drug events and increase drug effectiveness. Our aim was to quantify the clinical effectiveness of genotype-guided prescribing. METHODS: Three electronic databases were searched from January 1980 through December 2013. Studies were eligible if they were RCTs comparing genotype-guided prescribing with non-genetic informed prescribing, reported drug specific adverse drug events and clinical effectiveness outcomes. Two reviewers independently screened titles and abstracts, extracted data and assessed study quality. Meta-analyses of specific outcomes were conducted where data allowed. RESULTS: Fifteen studies, involving 5688 patients and 19 drugs, met the inclusion and exclusion criteria. Eight studies had statistically significant results for their primary outcome in favour of genotype-guided prescribing. Nine studies evaluated genotype-guided warfarin dosing. Analysis of percentage of time in therapeutic international normalized ratio range (1952 individuals) showed a statistically significant benefit in favour of genotype-guided warfarin dosing (mean difference = 6.67; 95% CI 1.34, 12.0, I(2) = 80%). There was a statistically significant reduction in numbers of warfarin-related minor bleeding, major bleeding and thromboembolisms associated with genotype guided warfarin dosing, relative risk 0.57 (95% CI 0.33, 0.99; I(2) = 60%). It was not possible to meta-analyze genotype-guided dosing for other drugs. Of the six non-warfarin genotype-guided trials, two demonstrated a statistically significant benefit for their primary outcome, odds ratio 0.03 (95% CI 0.00, 0.62, P < 0.001) for abacavir. CONCLUSIONS: There is evidence of improved clinical effectiveness associated with genotype-guided warfarin dosing.


Drug Prescriptions/statistics & numerical data , Drug-Related Side Effects and Adverse Reactions/genetics , Drug-Related Side Effects and Adverse Reactions/prevention & control , Genotype , Pharmacogenetics/methods , Humans , Randomized Controlled Trials as Topic
9.
Am J Trop Med Hyg ; 86(1): 65-74, 2012 Jan.
Article En | MEDLINE | ID: mdl-22232453

Universities Allied for Essential Medicines organized its first Neglected Diseases and Innovation Symposium to address expanding roles of public sector research institutions in innovation in research and development of biomedical technologies for treatment of diseases, particularly neglected tropical diseases. Universities and other public research institutions are increasingly integrated into the pharmaceutical innovation system. Academic entities now routinely undertake robust high-throughput screening and medicinal chemistry research programs to identify lead compounds for small molecule drugs and novel drug targets. Furthermore, product development partnerships are emerging between academic institutions, non-profit entities, and biotechnology and pharmaceutical companies to create diagnostics, therapies, and vaccines for diseases of the poor. With not for profit mission statements, open access publishing standards, open source platforms for data sharing and collaboration, and a shift in focus to more translational research, universities and other public research institutions are well-placed to accelerate development of medical technologies, particularly for neglected tropical diseases.


Biomedical Research/trends , Developing Countries , Drug Industry/trends , Neglected Diseases/drug therapy , Technology Transfer , Universities/organization & administration , Access to Information , Animals , Anthelmintics/economics , Anthelmintics/therapeutic use , Humans , Pharmaceutical Preparations/economics , Poverty , Praziquantel/economics , Praziquantel/therapeutic use , Public Sector , Schistosomiasis/drug therapy
10.
Hum Fertil (Camb) ; 13(2): 90-7, 2010.
Article En | MEDLINE | ID: mdl-20722578

Since 1999, we have treated HIV-positive men with sperm washing as part of a risk-reduction programme with a year-on-year increase in total infectious cycles performed to over 200 in 2008. Four hundred and thirty nine cycles of IUI, 114 cycles of IVF and 117 cycles of ICSI have been performed in HIV positive men over the decade and of the 259 couples treated, a pregnancy rate and ongoing pregnancy rate per couple of 45.4% and 36.3% have been achieved with over 100 children born with no seroconversions. We outline the continued importance of such risk-reduction measures with 9.7% of samples from men with 'stable' disease on anti-retroviral treatment and undetectable viral load demonstrating detectable viral particles in seminal fluid and discuss measures to improve outcome in this patient group.


Disease Transmission, Infectious/prevention & control , HIV Seropositivity/virology , Spermatozoa , Adult , Female , Fertilization in Vitro , Humans , Male , Middle Aged , Pregnancy , Pregnancy Rate , Treatment Outcome , Viral Load
11.
Hum Reprod ; 25(8): 1869-76, 2010 Aug.
Article En | MEDLINE | ID: mdl-20534606

BACKGROUND: Since 1999, we have treated HIV-positive men with sperm washing as part of a risk-reduction programme. METHODS: Retrospective analysis of the sperm-washing database from the treatment of 245 couples with 439 cycles of intrauterine insemination assessed the effects of patient factors (age, maternal FSH, rank of attempt), markers of HIV-disease [time since diagnosis, CD4 count, viral load (VL), use of highly active antiretroviral therapy (HAART)], cycle factors (natural versus stimulated, number of follicles, fresh versus frozen sperm) and sperm parameters on clinical (CPR) and ongoing pregnancy rate (OPR). RESULTS: Overall 111-245 (45.4%) couples achieved a clinical pregnancy (CPR: 13.5% and OPR: 9.6% per insemination) with no seroconversions. The mean duration since HIV diagnosis was 5.8 years, 73% of men were on antiretroviral therapy, there was an undetectable VL in 64% and the median CD4 was 409 cells/mm(3). A significantly decreased OPR and a non-significantly increased miscarriage rate (MR) was observed after the female age of 40. Similarly, there was a significant increased OPR and decreased MR for women with a mean cycle maternal FSH of <6.4 IU/l. There was no effect of VL, CD4 count, use of HAART or time since diagnosis on the outcome. Nor was there a difference in the OPR according to paternal age, rank of attempt, cycle regime or number of follicles. Semen volume, sperm concentration, total count and progressive motility and post-wash concentration, progressive motility and total motile count inseminated were significantly higher in successful cycles. The use of frozen sperm had a significant negative impact on outcome. CONCLUSIONS: This study of the potential safe and successful reproductive options available to HIV-positive men demonstrates that maternal age and semen quality, rather than HIV factors, remain the most important determinants of cycle success.


HIV Infections/prevention & control , Insemination, Artificial, Homologous/methods , Spermatozoa/virology , Adult , Age Factors , Female , HIV Infections/virology , Humans , Male , Middle Aged , Pregnancy , Pregnancy Outcome , Pregnancy Rate , Retrospective Studies , Risk Assessment , Semen/virology , Treatment Outcome , Viral Load
13.
Biochim Biophys Acta ; 1793(3): 447-61, 2009 Mar.
Article En | MEDLINE | ID: mdl-19168098

RasGRP1 is an exchange factor for membrane-localized Ras GTPases. Activation of RasGRP1 requires its translocation to membranes, which can be directly mediated by either its PT or C1 domains. RasGRP1 also has a pair of EF-hands which have been proposed to regulate RasGRP1 by sensing receptor-induced calcium fluxes. We determined that one of these EF-hands, EF1, is required for receptor-induced translocation of RasGRP1 to the plasma membrane in B cell lines. EF1 enables plasma membrane targeting of RasGRP1 by counteracting the SuPT domain, a negative regulator of the PT domain. Contrary to expectations, EF1-mediated translocation of RasGRP1 does not involve antigen receptor-induced intracellular calcium flux. Instead, alternative splicing affecting EF1 serves to modulate RasGRP1 localization. Excision of an exon encoding part of EF1 selectively disables PT domain-mediated plasma membrane targeting of RasGRP1, without affecting C1 domain-mediated localization to endomembranes. While EF1 specifically controls PT-mediated plasma membrane targeting, the Ras binding site in the catalytic GEF domain of RasGRP1 is required for both PT-mediated plasma membrane targeting and C1-mediated localization to endomembranes. Positive feedback between its GEF domain and membrane-binding domains could be important for full activation of RasGRP1, with occupation of the Ras binding sites in the GEF domain resulting in functional liberation of the PT and C1 domains, and membrane binding by these domains serving to maintain the Ras-GEF interaction.


EF Hand Motifs/physiology , Guanine Nucleotide Exchange Factors/analysis , Guanine Nucleotide Exchange Factors/chemistry , Alternative Splicing , Animals , Binding Sites , Cell Membrane/metabolism , Chickens , Guanine Nucleotide Exchange Factors/metabolism , Mice , Microscopy, Fluorescence , NIH 3T3 Cells , Protein Transport , ras Guanine Nucleotide Exchange Factors/metabolism
14.
J Pharm Sci ; 98(3): 791-4, 2009 Mar.
Article En | MEDLINE | ID: mdl-18688820

The University of British Columbia (UBC) became the first university in Canada to develop a strategy for enhancing global access to its technologies. UBC's University-Industry Liaison Office, in collaboration with the UBC chapter of Universities Allied for Essential Medicines (UAEM), established a mandate and developed principles that provide the developing world with access to UBC technologies. This commentary will discuss these principles and provide examples of where they have been applied to several UBC technologies.


Biomedical Research , Developing Countries , Global Health , Technology Transfer , Universities , British Columbia , Interinstitutional Relations , International Cooperation , Patents as Topic
15.
Mol Biol Cell ; 18(8): 3156-68, 2007 Aug.
Article En | MEDLINE | ID: mdl-17567957

RasGRP1 is a Ras-activating exchange factor that is positively regulated by translocation to membranes. RasGRP1 contains a diacylglycerol-binding C1 domain, and it has been assumed that this domain is entirely responsible for RasGRP1 translocation. We found that the C1 domain can contribute to plasma membrane-targeted translocation of RasGRP1 induced by ligation of the B cell antigen receptor (BCR). However, this reflects cooperativity of the C1 domain with the previously unrecognized Plasma membrane Targeter (PT) domain, which is sufficient and essential for plasma membrane targeting of RasGRP1. The adjacent suppressor of PT (SuPT) domain attenuates the plasma membrane-targeting activity of the PT domain, thus preventing constitutive plasma membrane localization of RasGRP1. By binding to diacylglycerol generated by BCR-coupled phospholipase Cgamma2, the C1 domain counteracts the SuPT domain and enables efficient RasGRP1 translocation to the plasma membrane. In fibroblasts, the PT domain is inactive as a plasma membrane targeter, and the C1 domain specifies constitutive targeting of RasGRP1 to internal membranes where it can be activated and trigger oncogenic transformation. Selective use of the C1, PT, and SuPT domains may contribute to the differential targeting of RasGRP1 to the plasma membrane versus internal membranes, which has been observed in lymphocytes and other cell types.


Cell Membrane/metabolism , Guanine Nucleotide Exchange Factors/chemistry , Guanine Nucleotide Exchange Factors/metabolism , Receptors, Antigen, B-Cell/metabolism , Amino Acid Sequence , Animals , Cell Transformation, Neoplastic , Chickens , Fibroblasts/metabolism , Humans , Mice , Models, Biological , Molecular Sequence Data , NIH 3T3 Cells , Phospholipase C gamma/metabolism , Protein Structure, Tertiary , Protein Transport , Receptors, Antigen, T-Cell/metabolism , Recombinant Fusion Proteins/metabolism , Structure-Activity Relationship
16.
Biochem J ; 406(2): 223-36, 2007 Sep 01.
Article En | MEDLINE | ID: mdl-17523924

RasGRPs (guanine-nucleotide-releasing proteins) are exchange factors for membrane-bound GTPases. All RasGRP family members contain C1 domains which, in other proteins, bind DAG (diacylglycerol) and thus mediate the proximal signal-transduction events induced by this lipid second messenger. The presence of C1 domains suggests that all RasGRPs could be regulated by membrane translocation driven by C1-DAG interactions. This has been demonstrated for RasGRP1 and RasGRP3, but has not been tested directly for RasGRP2, RasGRP4alpha and RasGRP4beta. Sequence alignments indicate that all RasGRP C1 domains have the potential to bind DAG. In cells, the isolated C1 domains of RasGRP1, RasGRP3 and RasGRP4alpha co-localize with membranes and relocalize in response to DAG, whereas the C1 domains of RasGRP2 and RasGRP4beta do not. Only the C1 domains of RasGRP1, RasGRP3 and RasGRP4alpha recognize DAG as a ligand within phospholipid vesicles and do so with differential affinities. Other lipid second messengers were screened as ligands for RasGRP C1 domains, but none was found to serve as an alternative to DAG. All of the RasGRP C1 domains bound to vesicles which contained a high concentration of anionic phospholipids, indicating that this could provide a DAG-independent mechanism for membrane binding by C1 domains. This concept was supported by demonstrating that the C1 domain of RasGRP2 could functionally replace the membrane-binding role of the C1 domain within RasGRP1, despite the inability of the RasGRP2 C1 domain to bind DAG. The RasGRP4beta C1 domain was non-functional when inserted into either RasGRP1 or RasGRP4, implying that the alternative splicing which produces this C1 domain eliminates its contribution to membrane binding.


Cell Membrane/metabolism , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/metabolism , Diglycerides/chemistry , Diglycerides/metabolism , Guanine Nucleotide Exchange Factors/chemistry , Guanine Nucleotide Exchange Factors/metabolism , Amino Acid Sequence , Animals , Anions/chemistry , Cell Line , Humans , Mice , Models, Molecular , Molecular Sequence Data , Mutation/genetics , Phorbol Esters , Phospholipids/chemistry , Protein Structure, Tertiary , Protein Transport , Sequence Alignment , Sequence Homology , ras Proteins/genetics , ras Proteins/metabolism
17.
Oncogene ; 24(16): 2695-704, 2005 Apr 14.
Article En | MEDLINE | ID: mdl-15829980

RasGRP1 is a Ras-specific exchange factor, which is activated by T-cell receptor (TCR) and promotes TCR-dependent positive selection of thymocytes. RasGRP1 is highly expressed on most T lymphocytic leukemias and is a common site of proviral insertion in retrovirus-induced murine T-cell lymphomas. We used RasGRP1 transgenic mice to determine if deregulated expression of RasGRP1 has a causative role in the development of T-cell malignancies. Thymic lymphomas occurred in three different RasGRP1 transgenic mouse lines. Thymocyte transformation correlated with high transgene expression in early stage lymphomas, indicating that deregulated RasGRP1 expression contributed to the initiation of lymphomagenesis. Expression of the positively selectable H-Y TCR accelerated lymphomagenesis in RasGRP1 transgenic mice. However, the transformed thymocytes lacked markers of positive selection and lymphomas occurred when positive selection was precluded by negative selection of the H-Y TCR. Therefore, initiation of lymphomagenesis via RasGRP1 was not associated with TCR-dependent positive selection of thymocytes. Thymic lymphomas occurred in RasGRP1 transgenic/Rag2-/- mice, demonstrating that neither TCR nor pre-TCR were required for RasGRP1-driven lymphomagenesis. The RasGRP1 transgene conferred pre-TCR-independent survival and proliferation of immature thymocytes, suggesting that deregulated expression of RasGRP1 promotes lymphomagenesis by expanding the pool of thymocytes which are susceptible to transformation.


Gene Expression Regulation, Neoplastic , Guanine Nucleotide Exchange Factors/metabolism , Lymphoma, T-Cell/genetics , Receptors, Antigen, T-Cell/genetics , Animals , Female , Flow Cytometry , Guanine Nucleotide Exchange Factors/genetics , Humans , Leukemia/genetics , Male , Mice , Mice, Transgenic , Phenotype , Transgenes
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