Parental Support and Adolescents' Coping with Academic Stressors: A Longitudinal Study of Parents' Influence Beyond Academic Pressure and Achievement

Adolescents face many academic pressures that require good coping skills, but coping skills can also depend on social resources, such as parental support and fewer negative interactions. The aim of this study was to determine if parental support and parental negative interactions concurrently and longitudinally relate to adolescents' ways of academic coping, above and beyond the impact of three types of academic stress, students' achievement at school (i.e., grades in school), and age. Survey data were collected from 839 Australian students in grades 5 to 10 (Mage = 12.2, SD = 1.72; 50% girls). Students completed measures of support and negative interactions with parents; academic stress from workload, external pressure (teachers/parents) to achieve, and intrapsychic pressure for high achievement; and ways of academic coping that were grouped into two positive and two negative types. Hypothesized associations were tested concurrently and from one year to the next using path modeling. Beyond the numerous significant influences of academic stress and achievement on coping, and control for age and COVID-19 timing, adolescents with more parental support reported more use of engagement coping (e.g., strategizing) and comfort-seeking, whereas those who reported more negative interactions with parents reported more use of disengagement coping (e.g., concealment) and escape. In the longitudinal model, parental support predicted an increase in engagement and comfort-seeking and a decrease in disengagement coping, whereas negative interaction with parents predicted an increase in disengagement coping. Overall, the findings support the view that coping with academic stressors will continue to depend on parent-adolescent relationships even into the teen years.

Approximating exposure therapy in the lab: Replacing the CS+ with a similar versus a different stimulus and including additional stimuli resembling the CS+ during extinction

Recent studies have shown that extinction training including the conditional stimulus (CS+) and stimuli that are similar to the CS + enhances extinction retention and generalisation to novel stimuli. However, in a clinical setting, the CS+ is rarely available for use during exposure therapy. The aim of the present study was to determine if replacing the CS+ with a similar versus different stimulus, and including other similar stimuli during extinction, could reduce fear at test on par with extinction using the original CS+ with and without other similar stimuli. In an experiment conducted in a single session, participants completed a habituation phase followed by an acquisition phase using two dog images presented with (CS+) and without (CS-) an acoustic unconditional stimulus (US). Participants were randomly allocated to four extinction conditions: similar CS + dog with novel dog images (Similar replacement extinction condition); different CS + dog with novel dog images (Different replacement extinction condition); original CS + dog with novel dog images (Multiple extinction control condition); and original CS + without novel dog images (Standard extinction control condition). All participants completed a test phase with the original CSs followed by a generalisation test with another two novel dog images. All groups acquired, and then extinguished differential skin conductance responses (SCRs) with no differences observed between groups. Whereas the Similar replacement extinction group and the Multiple and Standard extinction control groups did not exhibit significant differential SCRs when re-exposed to the original CS + relative to the CS- at test, differential responding to the CSs was significant at test in the Different replacement extinction group. There were no significant differences between groups in SCRs to the two novel dog images during the generalisation phase and in between-phase subjective ratings. Findings suggest that replacement stimuli used during extinction should be as similar as possible to the CS + to reduce physiological arousal to the original CS+.

Fear learning and extinction predicts anxiety in daily life: a study of Pavlovian conditioning and ecological momentary assessment

BACKGROUND

The association between anxious mood and aberrant fear learning mechanisms has not been fully elucidated. Studying how fear conditioning and extinction constructs relate to anxiety symptoms and reactivity to stressful and benign moments in everyday life provides a powerful addition to experimental paradigms.

METHOD

Fifty-one young adults completed laboratory-based differential conditioning and extinction tasks with (CS + ) and without (CS-) an aversive unconditional stimulus (US). Electrodermal skin conductance responses were measured during each phase, followed by ecological momentary assessment (EMA) tapping anxiety and stressors six times daily for seven days (2, 142 moments).

RESULTS

Conditioned electrodermal reactivity to the CS + and overgeneralisation to the CS- were associated with greater change in anxiety (measured via EMA), across non-stressful situations, remaining the same across stressful situations. Likewise, during extinction when the CS + is now safe, more electrodermal reactivity to the CS + was associated with more anxiety change across non-stressful situations and remained the same across stressful situations. Also, during extinction when threat is absent, more electrodermal reactivity at the late stage of the CS- was associated with less momentary anxiety change in response to stressful situations; more electrodermal activity at the late stage of the CS + was associated with more anxiety change across non-stressful situations and remained the same across stressful situations.

CONCLUSIONS

Sampling 'in vivo' emotion and stress experiences, study findings revealed links between conditioned electrodermal reactivity and overgeneralisation to safe stimuli and heightened anxious reactivity during non-stressful (i.e. safe) moments in daily life, coupled with less change in response to actual stressors.

Examining the Process of Implementing a Three-Step Mental Health and Wellbeing System of Care for Children and Adolescents Across Multiple Community Settings

Mental health problems affect large numbers of young people. Integrated systems are required that can be applied in diverse settings to reach youth 'where they are'. We evaluated the process of implementing a three-step youth mental health and wellbeing system in diverse community settings according to three implementation outcomes: feasibility, penetration and acceptability. The study describes 49 applications of the 'Life-Fit-Learning system' designed to assess the mental health and wellbeing of youth (Assess step), provide feedback on assessment results (Reflect step), and connect them to resources and services proportionate to their needs (Connect step). Within a participatory research approach, 3798 administrations were conducted with youth between 9 and 18 years and 90 administrations were conducted with adults. Implementation was based on the four phases of the Quality Implementation Framework and was staged to integrate stakeholder and consumer feedback and experience gained from focus groups and two pilot phases before full implementation. Feasibility ratings of successful implementation ranged from 86.7 to 96.4% across applications and settings. High penetration rates were achieved. The Life-Fit-Learning system successfully reached 91.9% to 96% of youth with the Assess and Reflect steps and low intensity Connect step resources. Of those, 14.7% to 23% were identified at-risk for mental health problems and 93% to 97% of those at-risk youth additionally received Connect step co-delivered group-based programs (moderate intensity care) and/or individual treatment (high intensity care). Youth and parents reported high satisfaction across all steps and delivery modes. With strong collaboration, an integrated model of care can be delivered feasibly, effectively and satisfactorily to reach large numbers of young people across settings.

Presentation of unpaired unconditional stimuli during extinction reduces renewal of conditional fear and slows re-acquisition

Past research has shown that presenting unconditional stimuli (US) during extinction training, either paired with the conditional stimulus (CS) or explicitly unpaired, can reduce spontaneous recovery and slow the re-acquisition of conditional fear. Whether contextual renewal of conditioned fear as indexed by electrodermal responses and self-report measures of anxiety and CS evaluations is also reduced after presentation of paired or unpaired USs during extinction training is currently unclear. Three groups of participants (Paired, Unpaired, Standard Extinction) completed a sequence of habituation, acquisition, extinction, renewal, and re-acquisition phases. During extinction, five CS-US pairings were presented in group Paired, whereas five US were presented alone in group Unpaired. No US were presented during standard extinction. For all groups, extinction was conducted in a context that was different from that of the other phases. Extinction of differential electrodermal responding was evident in groups Unpaired and Standard, but not in group Paired. Contextual renewal and fast re-acquisition, as indexed by differential electrodermal responding, were evident in group Standard, but not in group Unpaired and differential electrodermal responding persisted in group Paired. After extinction, self-reported anxiety was higher in groups Paired and Unpaired, but differential CS evaluations were evident in group Paired only. The current results suggest that presenting additional unpaired USs during extinction training strengthens extinction and protects against the renewal of differential electrodermal responding.

The effects of presenting additional stimuli resembling the CS+ during extinction on extinction retention and generalisation to novel stimuli

Recent studies have shown that extinction training including the conditional stimulus (CS+) and stimuli similar to the CS + enhances extinction retention and generalisation to novel stimuli. The aim of the present study was to confirm that these effects are specific to presenting stimuli similar to the CS+ during extinction and not merely an effect of additional trials or additional stimuli unrelated to the CS+. In an experiment conducted in a single session on the same day, participants (134 adults; 70.7% female; 17-40 years of age, M = 20.04, SD = 4.36) completed a habituation phase followed by an acquisition phase using dog images presented with (CS+) and without (CS-) a dog growl paired with a scream unconditional stimulus (US). Participants were randomly allocated to four extinction conditions: Multiple exemplar extinction comprising the CSs and two novel dog images similar to the CS+; Standard extinction control matched for the number of CS+ and CS- presentations; Extended extinction control matched for the total number extinction trials, and Other stimuli extinction control comprising the CSs and two novel stimuli unrelated to the CS+. All participants completed an extinction test with the original CSs followed by a generalisation test with two novel dog images. Multiple, Standard and Other stimuli extinction groups exhibited larger skin conductance responses (SCRs) during extinction to the CSs compared to the Extended extinction group. SCRs to the additional dog images in the Multiple group were larger than SCRs to the additional CSs in the Extended group and the novel images in the Other stimuli group. There were no group differences in responses to the CSs during extinction test. Unlike the other groups, SCRs to the first presentation of the novel generalisation dogs did not differ from those to the last CS trials in extinction in the Multiple group. However, this group difference did not persist beyond the initial generalisation trial. Finally, the Multiple, Extended, and Other stimuli groups exhibited more negative CS evaluations after extinction, extinction test, and generalisation test than the Standard extinction group. The results suggest that extinction with the original CSs and additional stimuli resembling the CS + elevated physiological responses during extinction and reduced physiological responses to novel stimuli similar to the CSs. Further studies are needed including clinical samples and trial-by-trial evaluations of the stimuli presented.

Does the assessment of different combinations of within-phase subjective measures influence electrodermal responding and between-phase subjective ratings during fear conditioning and extinction experiments?

The type and number of dependent measures assessed have varied between fear conditioning and extinction experiments and it remains unclear whether methodological differences influence results. Measuring skin conductance responses (SCRs) and between-phase subjective ratings between four conditions; Con condition had no within-phase ratings; US Exp condition included within-phase US expectancy ratings only; CS Eval condition included within-phase CS evaluations only and All Meas condition included both. All Meas condition exhibited larger SCRs compared to other conditions during acquisition, extinction, and return of differential responding at test. Differential SCRs did not extinguish in CS Eval and Con conditions, and CS Eval condition exhibited smaller CS- SCRs than other conditions throughout phases. US Exp condition revealed differential conditioning, successful extinction, and no return of differential SCRs. Between-phase ratings were not affected by within-phase ratings. Researchers should consider assessing different combinations of within-phase subjective ratings depending on the aims of their research.

Towards the enhancement of quality publication practices in clinical psychological science

Addressing the 'replication crisis' and questionable research practices are at the forefront of international research agendas in clinical psychological science. The aim of this paper is to consider how the quality of research practices can be improved by a specific focus on publication practices. Currently, the responsibility for documenting quality research practices is primarily placed on authors. However, barriers to improved quality publication practices cut across all levels of the research community and require a broader approach that shares the burden for ensuring the production of high quality publications. We describe a framework that is intended to be ambitious and aspirational and encourage discussion and adoption of strategies to improve quality publication practices (QPPs). The framework cuts across multiple stakeholders and is designed to enhance (a) the quality of reporting; (b) adherence to protocols and guidelines; (c) timely accessibility of study materials and data. We discuss how QPPs might be improved by (a) funding bodies considering formally supporting QPPs; (b) research institutions encouraging a research culture that espouses quality research practices, and internally supporting QPP review processes and professional development in QPPs; (c) journals expanding editorial teams to include reviewers with design and statistical expertise, considering strategies to enhance QPP adherence during the peer review process, and committing to ongoing assessment and development of QPP training for peer reviewers; and (d) authors and peer reviewers integrating QPPs during the manuscript preparation/peer review process, engaging in ongoing QPP training, and committing to openness and transparency initiatives. We discuss the current state and potential next steps within each stage of the framework and provide information and resources to enhance QPPs. We hope that the suggestions offered here inspire research institutions, leaders and faculty to discuss, reflect on, and take action towards, integrating these, or other, QPPs into their research practice and workplace.

Psychophysiological Markers of Fear and Anxiety

PURPOSE OF REVIEW

The purpose of this paper is to provide a current review of the recent literature (2015-2018) on psychophysiological markers of fear and anxiety.

RECENT FINDING

Relative to healthy controls, fear-based disorders are characterised by heightened physiological reactivity to circumscribe threat salient stimuli, whereas anxiety-related disorders are associated with a more blunted pattern of physiological reactivity. Fear and anxiety disorders are marked by abnormal patterns of physiological reactivity, characterised by hyper- and hypo-reactivity in response to stimuli varying in threat salience.

From Molecules to Mind: Mechanisms of Action of Electroconvulsive Therapy

(Reprinted with permission from Acta Psychatrica Scandinavica (John Wiley & Sons, Ltd.); ©John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Acta Psychiatrica Scandinavica 2018: 138:177-179).

The need for standards in the design of differential fear conditioning and extinction experiments in youth: A systematic review and recommendations for research on anxiety

Fear extinction studies in youth have yielded mixed results due to developmental processes and variations in design, methodology and dependent measures. This systematic review focused on studies with healthy youth between 2 and 17 years of age to identify experimental parameters of studies documenting extinction effects. Thirty-five studies met inclusion criteria and the following themes emerged (a) some studies employed parameters and task demands that are complex and require active participant involvement whereas others involved simple stimulus configurations and passive participant involvement, and (b) variation exists among dependent measures in units of measurement, timing and type of measurement. The review identified that studies using geometric shape conditioned stimuli (CS) paired with a tone unconditioned stimulus (US) (e.g., metal scraping on slate), as well as face CSs with a scream US produced the most reliable extinction effects, although the latter combination may be associated with higher drop-out than shape CSs and a tone US. The most commonly used and effective dependent measures for revealing extinction effects were skin conductance responses (SCR) and subjective ratings (SR) of CS valence, fearfulness and arousal. Fear potentiated startle (FPS) blink reflexes were also an effective but less commonly used measure. It is recommended that future studies use shape CSs and the metal scraping on slate US in studies involving children and either shape CSs and the metal scraping on slate US or face CSs paired with a scream US with adolescents. It is also recommended that US expectancy ratings and CS evaluations are assessed trial-by-trial and between-phase, and that startle-eliciting stimuli to measure startle blink reflexes are delivered on every second trial per CS so that SCR and FPS can be examined. However, further research is required to determine whether increased participant involvement due to providing trial-by-trial and between-phase ratings of the CSs and US differentially influences responding, particularly in children relative to adolescents and adults.

Loss of RhoA promotes skin tumor formation and invasion by upregulation of RhoB

Cellular movement is controlled by small GTPases, such as RhoA. Although migration is crucial for cancer cell invasion, the specific role of RhoA in tumor formation is unclear. Inducing skin tumors in mice with a keratinocyte-restricted loss of RhoA, we observed increased tumor frequency, growth and invasion. In vitro invasion assays revealed that in the absence of RhoA cell invasiveness is increased in a Rho-associated protein kinase (ROCK) activation and cell contraction-dependent manner. Surprisingly, loss of RhoA causes increased Rho signaling via overcompensation by RhoB because of reduced lysosomal degradation of RhoB in Gamma-aminobutyric acid receptor-associated protein (GABARAP)+ autophagosomes and endosomes. In the absence of RhoA, RhoB relocalized to the plasma membrane and functionally replaced RhoA with respect to invasion, clonogenic growth and survival. Our data demonstrate for the first time that RhoA is a tumor suppressor in 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol 13-acetate skin carcinogenesis and identify Rho signaling dependent on RhoA and RhoB as a potent driver of tumor progression.

Peripheral blood microRNA and VEGFA mRNA changes following electroconvulsive therapy: implications for psychotic depression

OBJECTIVE

MicroRNAs are short, non-coding molecules that regulate gene expression. Here, we investigate the role of microRNAs in depression and electroconvulsive therapy (ECT).

METHODS

We performed three studies: a deep sequencing discovery-phase study of miRNA changes in whole blood following ECT (n = 16), followed by a validation study in a separate cohort of patients pre-/post-ECT (n = 37) and matched healthy controls (n = 34). Changes in an experimentally validated gene target (VEGFA) were then analysed in patients pre-/post-ECT (n = 97) and in matched healthy controls (n = 53).

RESULTS

In the discovery-phase study, we found no statistically significant differences in miRNA expression from baseline to end of treatment in the group as a whole, but post hoc analysis indicated a difference in patients with psychotic depression (n = 3). In a follow-up validation study, patients with psychotic depression (n = 7) had elevated baseline levels of miR-126-3p (t = 3.015, P = 0.006) and miR-106a-5p (t = 2.598, P = 0.025) compared to healthy controls. Following ECT, these differences disappeared. Baseline VEGFA levels were significantly higher in depressed patients compared to healthy controls (F(1,144) = 27.688, P = <0.001). Following ECT, there was a significant change in VEGFA levels in the psychotic group only (t = 2.915, P = 0.010).

CONCLUSION

Molecular differences (miRNA and VEGFA) may exist between psychotic and non-psychotic depression treated with ECT.

DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose

This corrects the article DOI: 10.1038/cdd.2015.26.

Electroconvulsive therapy modulates plasma pigment epithelium-derived factor in depression: a proteomics study

Electroconvulsive therapy (ECT) is the most effective treatment for severe depression, yet its mechanism of action is not fully understood. Peripheral blood proteomic analyses may offer insights into the molecular mechanisms of ECT. Patients with a major depressive episode were recruited as part of the EFFECT-Dep trial (enhancing the effectiveness of electroconvulsive therapy in severe depression; ISRCTN23577151) along with healthy controls. As a discovery-phase study, patient plasma pre-/post-ECT (n=30) was analyzed using 2-dimensional difference in gel electrophoresis and mass spectrometry. Identified proteins were selected for confirmation studies using immunodetection methods. Samples from a separate group of patients (pre-/post-ECT; n=57) and matched healthy controls (n=43) were then used to validate confirmed changes. Target protein mRNA levels were also assessed in rat brain and blood following electroconvulsive stimulation (ECS), the animal model of ECT. We found that ECT significantly altered 121 protein spots with 36 proteins identified by mass spectrometry. Confirmation studies identified a post-ECT increase (P<0.01) in the antiangiogenic and neuroprotective mediator pigment epithelium-derived factor (PEDF). Validation work showed an increase (P<0.001) in plasma PEDF in depressed patients compared with the controls that was further increased post-ECT (P=0.03). PEDF levels were not associated with mood scores. Chronic, but not acute, ECS increased PEDF mRNA in rat hippocampus (P=0.02) and dentate gyrus (P=0.03). This study identified alterations in blood levels of PEDF in depressed patients and further alterations following ECT, as well as in an animal model of ECT. These findings implicate PEDF in the biological response to ECT for depression.

Application of CRISPR/Cas9 to Autophagy Research

The ability to efficiently modulate autophagy activity is paramount in the study of the field. Conventional broad-range autophagy inhibitors and genetic manipulation using RNA interference (RNAi), although widely used in autophagy research, are often limited in specificity or efficacy. In this chapter, we address the problems of conventional autophagy-modulating tools by exploring the use of three different CRISPR/Cas9 systems to abrogate autophagy in numerous human and mouse cell lines. The first system generates cell lines constitutively deleted of ATG5 or ATG7 whereas the second and third systems express a Tet-On inducible-Cas9 that enables regulated deletion of ATG5 or ATG7. We observed the efficiency of autophagy inhibition using the CRISPR/Cas9 strategy to surpass that of RNAi, and successfully generated cells with complete and sustained autophagy disruption through the CRISPR/Cas9 technology.

DRAM-3 modulates autophagy and promotes cell survival in the absence of glucose

Macroautophagy is a membrane-trafficking process that delivers cytoplasmic constituents to lysosomes for degradation. The process operates under basal conditions as a mechanism to turnover damaged or misfolded proteins and organelles. As a result, it has a major role in preserving cellular integrity and viability. In addition to this basal function, macroautophagy can also be modulated in response to various forms of cellular stress, and the rate and cargoes of macroautophagy can be tailored to facilitate appropriate cellular responses in particular situations. The macroautophagy machinery is regulated by a group of evolutionarily conserved autophagy-related (ATG) proteins and by several other autophagy regulators, which either have tissue-restricted expression or operate in specific contexts. We report here the characterization of a novel autophagy regulator that we have termed DRAM-3 due to its significant homology to damage-regulated autophagy modulator (DRAM-1). DRAM-3 is expressed in a broad spectrum of normal tissues and tumor cells, but different from DRAM-1, DRAM-3 is not induced by p53 or DNA-damaging agents. Immunofluorescence studies revealed that DRAM-3 localizes to lysosomes/autolysosomes, endosomes and the plasma membrane, but not the endoplasmic reticulum, phagophores, autophagosomes or Golgi, indicating significant overlap with DRAM-1 localization and with organelles associated with macroautophagy. In this regard, we further proceed to show that DRAM-3 expression causes accumulation of autophagosomes under basal conditions and enhances autophagic flux. Reciprocally, CRISPR/Cas9-mediated disruption of DRAM-3 impairs autophagic flux confirming that DRAM-3 is a modulator of macroautophagy. As macroautophagy can be cytoprotective under starvation conditions, we also tested whether DRAM-3 could promote survival on nutrient deprivation. This revealed that DRAM-3 can repress cell death and promote long-term clonogenic survival of cells grown in the absence of glucose. Interestingly, however, this effect is macroautophagy-independent. In summary, these findings constitute the primary characterization of DRAM-3 as a modulator of both macroautophagy and cell survival under starvation conditions.

p73 engages A2B receptor signalling to prime cancer cells to chemotherapy-induced death

Tumour cells often acquire the ability to escape cell death, a key event leading to the development of cancer. In almost half of all human cancers, the capability to induce cell death is reduced by the mutation and inactivation of p53, a tumour suppressor protein that is a central regulator of apoptosis. As a result, there is a crucial need to identify different cell death pathways that could be targeted in malignancies lacking p53. p73, the closely related p53 family member, can regulate many p53 target genes and therefore some of the same cellular responses as p53. Unlike p53, however, p73 is seldom mutated in cancer, making it an attractive, alternative death effector to target. We report here the ability of p73 to upregulate the expression of the A2B receptor, a recently characterized p53 target that effectively promotes cell death in response to extracellular adenosine--a metabolite that accumulates during various forms of cellular stress. Importantly, we show that p73-dependent stimulation of A2B signalling markedly enhances apoptosis in cancer cells that are devoid of p53. This mode of death is caspase- and puma-dependent, and can be prevented by the overexpression of anti-apoptotic Bcl-X(L). Moreover, treatment of p53-null cancer cells with the chemotherapeutic drug adriamycin (doxorubicin) induces A2B in a p73-dependent manner and, in combination with an A2B agonist, substantially enhances apoptotic death. We therefore propose an alternate and distinct p53-independent pathway to stimulate programmed cell death involving p73-mediated engagement of adenosine signalling.

Younger workers’ metastereotypes, workplace mood, attitudes, and behaviors

Purpose

– The purpose of this paper is to examine the influence of age-related stereotyping processes on younger workers’ mood, attitudes, and impression management behaviors at work.

Design/methodology/approach

– Using survey data from 281 younger workers, the hypothesized model was tested using structural equation modeling.

Findings

– As younger workers are more self-conscious about being age stereotyped, they are less likely to be satisfied with older co-workers, which is partly explained by negative mood associated with that metastereotype consciousness. Also, chronological age, age-group identification, and age prejudice, were critical influences on the emergence of metastereotype consciousness.

Research limitations/implications

– Unexpected findings point to: experiences of younger workers which may not follow the same patterns found with older groups and unique operation of age as a dynamic social category that may not parallel findings regarding other social categories.

Practical implications

– There is clearly potential for younger workers to be concerned they are viewed “stereotypically” and this metastereotype consciousness influences how they feel, think, and behave at work. Organizations should be aware of the potential antecedents and consequences, as well as the nature of metastereotypic perceptions, to better facilitate positive and productive interactions across age groups at work.

Originality/value

– This research contributes to an understanding of younger workers’ experiences at work, highlights the role of mood in the operation of metastereotypes on attitudes and behaviors in age-diverse contexts, and improves our understanding of social biases and inequality associated with age-based groups.

E2F1 drives chemotherapeutic drug resistance via ABCG2

Multidrug resistance is a major barrier against successful chemotherapy, and this has been shown in vitro to be often caused by ATP-binding cassette (ABC) transporters. These transporters are frequently overexpressed in human cancers and confer an adverse prognosis in many common malignancies. The genetic factors, however, that initiate their expression in cancer are largely unknown. Here we report that the major multidrug transporter ABCG2 (BCRP/MXR) is directly and specifically activated by the transcription factor E2F1--a factor perturbed in the majority of human cancers. E2F1 regulates ABCG2 expression in multiple cell systems, and, importantly, we have identified a significant correlation between elevated E2F1 and ABCG2 expression in human lung cancers. We show that E2F1 causes chemotherapeutic drug efflux both in vitro and in vivo via ABCG2. Furthermore, the E2F1-ABCG2 axis suppresses chemotherapy-induced cell death that can be restored by the inhibition of ABCG2. These findings therefore identify a new axis in multidrug resistance and highlight a radical new function of E2F1 that is relevant to tumor therapy.

When less is more--microRNAs and psychiatric disorders

OBJECTIVE

MicroRNAs are small non-coding RNA molecules that regulate gene expression, including genes involved in neuronal function and plasticity that have relevance for brain function and mental health. We therefore performed a systematic review of miRNAs in general adult psychiatric disorders.

METHOD

Systematic searches in PubMed/MEDLINE and Web of Science were conducted to identify published clinical articles on microRNAs in general adult psychiatric disorders. We also reviewed references from included articles.

RESULTS

There is mounting evidence of microRNAs' regulatory roles in a number of central nervous system processes, including neurogenesis and synaptic plasticity. The majority of clinical studies of microRNAs in psychiatric disorders are in schizophrenia, where a number of specific microRNAs have been identified in separate studies. There is some evidence of marked downregulation of some microRNAs in affective disorders. Treatment with antidepressants appears to upregulate microRNA levels. There is currently little evidence from human studies in anxiety, addiction or other psychiatric disorders.

CONCLUSION

MicroRNA research in psychiatry is currently in a nascent period, but represents an emerging and exciting area, with the potential to clarify molecular mechanisms of disease and identify novel biomarkers and therapeutic agents.

Epitaxial growth of visible to infra-red transparent conducting In2O3 nanodot dispersions and reversible charge storage as a Li-ion battery anode

Unique bimodal distributions of single crystal epitaxially grown In2O3 nanodots on silicon are shown to have excellent IR transparency greater than 87% at IR wavelengths up to 4 μm without sacrificing transparency in the visible region. These broadband antireflective nanodot dispersions are grown using a two-step metal deposition and oxidation by molecular beam epitaxy, and backscattered diffraction confirms a dominant (111) surface orientation. We detail the growth of a bimodal size distribution that facilitates good surface coverage (80%) while allowing a significant reduction in In2O3 refractive index. This unique dispersion offers excellent surface coverage and three-dimensional volumetric expansion compared to a thin film, and a step reduction in refractive index compared to bulk active materials or randomly porous composites, to more closely match the refractive index of an electrolyte, improving transparency. The (111) surface orientation of the nanodots, when fully ripened, allows minimum lattice mismatch strain between the In2O3 and the Si surface. This helps to circumvent potential interfacial weakening caused by volume contraction due to electrochemical reduction to lithium, or expansion during lithiation. Cycling under potentiodynamic conditions shows that the transparent anode of nanodots reversibly alloys lithium with good Coulombic efficiency, buffered by co-insertion into the silicon substrate. These properties could potentially lead to further development of similarly controlled dispersions of a range of other active materials to give transparent battery electrodes or materials capable of non-destructive in situ spectroscopic characterization during charging and discharging.

New frontiers in promoting tumour cell death: targeting apoptosis, necroptosis and autophagy

Cancer is a multifaceted disease comprising a combination of genetic, metabolic and signalling aberrations, which severely disrupt the normal homeostasis of cell growth and death. Many oncogenic events while promoting tumour development also increase the sensitivity of cells to cell death stimuli including chemotherapeutic drugs. As a result, tumour cells often acquire the ability to evade death by inactivating cell death pathways that normally function to eliminate damaged and harmful cells. The impairment of cell death function is also often the reason for the development of chemotherapeutic resistance encountered during treatment. It is therefore necessary to achieve a comprehensive understanding of existing cell death pathways and the relevant regulatory components involved, with the intention of identifying new strategies to kill cancer cells. This review provides an insightful overview of the common forms of cell death signalling pathways, the interactions between these pathways and the ways in which these pathways are deregulated in cancer. We also discuss the emerging therapies targeted at activating or restoring cell death pathways to induce tumour cell death, which are currently being tested in clinical trials.

TSC-22D1 isoforms have opposing roles in mammary epithelial cell survival

Transforming growth factor beta (TGFbeta)-stimulated clone-22 domain family member 1 (TSC-22D1) has previously been associated with enhanced apoptosis in several cell systems. In an attempt to identify novel factors that are involved in the control of cell death during mammary gland involution, we found that the mRNA for isoform 2 of TSC-22D1 was highly upregulated 24 h after forced weaning, when a dramatic increase in cell death occurred, closely following the expression of the known inducer of cell death during involution, TGFbeta3. This was paralleled by strongly increased TSC-22D1 isoform 2 protein levels in the luminal epithelium. In contrast, RNA and protein expression levels of the isoform 1 of TSC-22D1 did not change during development. Whereas isoform 2 induced cell death, isoform 1 suppressed TGFbeta-induced cell death and enhanced proliferation in mammary epithelial cell lines. Furthermore, four distinct forms of isoform 2 protein were detected in the mammary gland, of which only a 15-kDa form was associated with early involution. Our data describe novel opposing functions of the two mammalian TSC-22D1 isoforms in cell survival and proliferation, and establish the TSC-22D1 isoform 2 as a potential regulator of cell death during mammary gland involution.

Acute hyperglycaemia does not alter coronary vascular function in isolated, perfused rat hearts

AIM

The purpose of this study was to evaluate the hypothesis that acute hyperglycaemia in hearts of rats without diabetes alters coronary vascular responses to nitric oxide (NO), adenosine (ADO) and phenylephrine (PHE).

METHODS

Coronary function was studied in isolated, Langendorff-perfused, non-beating rat hearts that were perfused with an oxygenated Krebs-Henseleit solution containing 40 mM KCl to arrest the hearts. Changes in coronary vascular resistance were assessed by measuring changes in coronary perfusion pressure under constant flow conditions. Coronary responses to ADO, sodium nitroprusside (SNP), PHE and L-NAME (inhibitor of NO synthase) were studied either under normoglycaemic conditions (100 mg/dl d-glucose) or after 60 min of hyperglycaemic perfusion (500 mg/dl d-glucose). d-mannitol was used as a hyperosmotic control.

RESULTS

Hyperglycaemia did not alter vasodilator responses to ADO or SNP in the presence or absence of L-NAME. Furthermore, hyperglycaemia, compared with normoglycaemia, did not alter vasoconstrictor responses induced by L-NAME or PHE.

CONCLUSIONS

Sixty minutes of exposure to 500 mg/dl of d-glucose in an isolated, non-beating, buffer-perfused rat heart did not significantly affect coronary vascular smooth muscle vasodilator responses to NO and ADO or alter alpha(1)-adrenoceptor-mediated vasoconstrictor responses to PHE. Furthermore, an unchanged vasoconstrictor response to L-NAME suggests that acute hyperglycaemia did not alter NO bioavailability.

Changes in medication use from age 26 to 32 in a representative birth cohort

BACKGROUND

To date, longitudinal studies of medications have been confined to older adults or clinical samples, with no data from prospective studies of younger adults. The aim of the study was to examine changes in medication usage between ages 26 and 32 in a prospective study of a representative birth cohort.

METHODS

Medication use during the previous 2 weeks was investigated among 960 individuals at ages 26 and 32.

RESULTS

Nearly two-thirds took at least one medication at each age, with medication prevalence higher among women than among men. Three-quarters of those taking at least one at age 26 were doing so at 32. Over-the-counter medication prevalence increased from 35 to 43% between 26 and 32 years of age. Although the prevalence of prescribed medications decreased (from just under half to just over one-third, and from two-thirds to below half among women), there was no significant difference between the ages once hormonal contraceptives were accounted for. By 32, reduced usage of hormonal contraceptives was apparent, with one-third of age-26 users still taking these at 32. Other categories showing major changes were analgesics (increased), anti-asthma drugs (decreased), antidepressants (increased) and antiulcer drugs (increased). At 32, 82% of those taking analgesics, 85% of those taking nutrient supplements, 71% of those taking antihistamines and 33% of those taking antiulcer drugs had self-prescribed them.

CONCLUSION

A considerable proportion of the sample used medications by age 32, and there was considerable change between 26 and 32. The changes are likely to have been due to a mix of ageing and period effects.

p73 regulates DRAM-independent autophagy that does not contribute to programmed cell death

Evading programmed cell death is a common event in tumour development. The p53 family member, p73, is a potent inducer of death and a determinant of chemotherapeutic response, but different to p53, is rarely mutated in cancer. Understanding cell death pathways downstream of p53 and p73 is therefore pivotal to understand both the development and treatment of malignant disease. Recently, p53 has been shown to modulate autophagy--a membrane trafficking process, which degrades long-lived proteins and organelles. This requires a p53 target gene, DRAM, and both DRAM and autophagy are critical for p53-mediated death. We report here that TA-p73 also regulates DRAM and autophagy, with different TA-p73 isoforms regulating DRAM and autophagy to varying extents. RNAi knockdown of DRAM, however, revealed that p73's modulation of autophagy is DRAM-independent. Also, p73's ability to induce death, again different to p53, is neither dependent on DRAM nor autophagy. In contrast to TA-p73, deltaN-p73 is a negative regulator of p53-induced and p73-induced autophagy, but does not affect autophagy induced by amino-acid starvation. These studies, therefore, represent not only the first report that p73 modulates autophagy but also highlight important differences in the mechanism by which starvation, p53 and p73 regulate autophagy and how this contributes to programmed cell death.

DNA-binding independent cell death from a minimal proapoptotic region of E2F-1

The ability to induce cell cycle progression while evading cell death is a defining characteristic of cancer. Deregulation of E2F is a common event in most human cancers. Paradoxically, this can lead to both cell cycle progression and apoptosis. Although the way in which E2F causes cell cycle progression is well characterized, the pathways by which E2F induces cell death are less well defined. Many of the known mechanisms through which E2F induces apoptosis occur through regulation of E2F target genes. However, mutants of E2F-1 that lack the transactivation domain are still able to induce cell death. To further investigate this activity, we refined a transactivation independent mutant to identify a minimal apoptotic domain. This revealed that only 75 amino acids from within the DNA-binding domain of E2F-1 is sufficient for cell death and that this activity is also present in the DNA-binding domains of E2F-2 and E2F-3. However, analysis of this domain from E2F-1 revealed it does not bind DNA and is consequently unable to transactivate, repress or de-repress E2F target genes. This provocative observation therefore defines a potential new mechanism of death from E2F and opens up new opportunities for inducing cell death in tumours for therapeutic gain.

Life and death decisions by E2F-1

Deregulation of the transcription factor E2F-1 is a common event in most human cancers. Paradoxically, E2F-1 has been shown to have the ability to induce both cell cycle progression and programmed cell death, leading potentially to both tumour-promoting as well as tumour-suppressive effects. Although the pathway to cell cycle progression seems straightforward with a number of growth-promoting E2F target genes having been described, the pathways to apoptosis are less well defined and more complex. The discovery that E2F-1 'knockout' mice are highly tumour prone has caused a recent surge in the number of reports relating to programmed cell death. This review focuses on these recent findings, highlighting the way in which they have increased our understanding of E2F-1-induced cell death, as well as indicating the questions that remain. Insight gained as to the role of this intriguing molecule in cancer and its potential for targeted therapy will also be discussed.

Italy reforms national policy for cancer pain relief and opioids

Treatment of pain caused by cancer in Italy has been reported to be inadequate for more than a decade. The problem has been documented in the literature by International Narcotics Control Board (INCB) reports that show Italy's low consumption of morphine, and by INCB statements reflecting concern that pain medications are not adequately available to suffering cancer patients. The reasons for undertreatment include lack of physician education, low public awareness about pain management and overly restrictive regulations that inhibit the prescribing of opioid analgesics. In 1999, a workgroup appointed by the Ministry of Health began to address inadequate cancer pain management. In 2000, the workgroup issued a proposal to reform national policy, including simplification of opioid prescribing requirements. The proposal was adopted by Parliament in January 2001 and was effective from March 6th. Distribution of a new opioids prescription form to selected regions in Italy began in December 2001. The change, when fully implemented, will be an important step toward relieving cancer pain.

Asymmetric alkene epoxidation with chromium oxo salen complexes. A systematic study of salen ligand substituents

[structure: see text]. In the stoichiometric asymmetric epoxidation of E-beta-methylstyrene with cationic chromium-salen oxo complexes, enantioselectivity is increased by halo-substitution at the 3,3'- and 6,6'-positions and decreased at the 4,4'- and 5,5'-positions on the salen rings. Addition of triphenylphosphine oxide significantly increases selection with 3,3'- or 5,5'-substituents but not with 4,4'- or 6,6'-substituents. Use of nitrate counterion is beneficial in most cases. The results are discussed with respect to the mode of stereoselection in metal-salen epoxidations.

Synthesis and characterization of dimensionally ordered semiconductor nanowires within mesoporous silica

Semiconductor nanowires of silicon have been synthesized within the pores of mesoporous silica using a novel supercritical fluid solution-phase approach. Mesoporous silica, formed by the hydrolysis of tetramethoxysilane (TMOS) in the presence of a triblock copolymer surfactant, was employed for the nucleation and growth of quantum-confined nanowires. The filling of the silica mesopores with crystalline silicon and the anchoring of these nanowires to the sides of the pores were confirmed by several techniques including electron microscopy, powder X-ray diffraction, 29Si magic angle spinning nuclear magnetic resonance, infrared spectroscopy, and X-ray fluorescence. Effectively, the silica matrix provides a means of producing a high density of stable, well-ordered arrays of semiconductor nanowires in a low dielectric medium. The ordered arrays of silicon nanowires also exhibited discrete electronic and photoluminescence transitions that could be exploited in a number of applications, including nanodevices and interconnects.

Medicalization and women's knowledge: the construction of understandings of infant feeding experiences in post-WW II New Zealand

For most of the twentieth century infant feeding knowledge has been constructed by medical scientists and health professionals. However, for a short time around the 1970s, New Zealand women (re)claimed the power to author their own knowledge based upon experience. This coincided with a dramatic return to breastfeeding on a national scale. Using New Zealand women's narratives of their infant feeding experiences over the past 50 years, this article brings to the foreground the importance of women's subjective construction of knowledge, their positioning within it, and the suppression of rudimentary discourses when that power is removed or relinquished in the process of remedicalization.

Inhibition of HIF-1- and wild-type p53-stimulated transcription by codon Arg175 p53 mutants with selective loss of functions

Overexpression of ectopic mutant p53 represses wild-type p53-stimulated transcription, known as a dominant negative effect. On the other hand, overexpression of wild-type p53 can repress transcription stimulated by several transcription factors, including hypoxia-inducible factor-1 (HIF-1). Using a panel of well-characterized Arg175 p53 mutants we found that only mutants (Tyr175, Trp175, Asp175 and Phe175) which have completely lost their ability to transactivate repress wild-type p53-stimulated Bax, p21 and PG13 promoter constructs. In contrast, Asn175, Gln175, Leu175 and Pro175 mutants which partially retained transactivating functions did not exert dominant negative effects against PG13 and p21 promoter constructs. However, these latter mutants failed to activate Bax and, instead, exerted a dominant negative effect on a Bax-Luc promoter construct. We conclude that a dominant negative effect is promoter selective as a consequence of selective loss of transactivating function. Albeit less potent than wild-type p53, all Arg175 p53 mutants retained partial ability to repress HIF-1-stimulated transcription. We propose that transrepression and the dominant negative effect have similar mechanisms and may involve competition with transcription factors (wild-type p53, HIF-1, etc.) for cofactors such as p300. Thus, a p53(22/23) mutant, which is deficient in p300 binding, did not exert dominant negative effects. Like transrepression, the dominant negative effect required overexpression of mutant p53 and, therefore, is not dominant. In the presence of a wild-type p53 allele, levels of endogenous mutant p53 protein were low in heterozygous cells. Endogenous mutant p53 became overexpressed only after loss of the second p53 allele. Therefore, endogenous mutant p53s are unable to display a dominant negative effect. This explains why loss of the second p53 allele is required to eliminate p53 functions in cancer cells.

Regulation and function of the p53 tumor suppressor protein

Loss of the p53 tumor suppressor pathway contributes to the development of most human cancers. p53 is a nuclear protein that functions as a regulator of transcription. Significant advances have been made recently in our understanding of how p53 function is regulated and the mechanisms by which p53 mediates its effects.

Differentiating embryonal stem cells are a rich source of haemopoietic gene products and suggest erythroid preconditioning of primitive haemopoietic stem cells

The difficulties associated with studying molecular mechanisms important in hemopoietic stem cell (HSC) function such as the problems of purifying homogeneous stem cell populations, have prompted us to adapt the murine ES cell system as an in vitro model of HSC generation and function. We now report that careful analysis of the time course of HSC generation in differentiating ES cells allows them to be used as a source of known and novel hemopoietic gene products. We have generated a subtracted library using cDNA from ES cells collected just prior to and just following the emergence of HSCs. Analysis of this library shows it to be a rich source of known hemopoietic and hemopoietic related gene products with 44% of identifiable cDNAs falling into these camps. We have demonstrated the value of this system as a source of novel genes of relevance to HSC function by characterizing a novel membrane protein encoding cDNA that is preferentially expressed in primitive hemopoietic cells. Intriguingly, further analysis of the known components of the subtracted library is suggestive of erythroid preconditioning of the ES cell-derived HSC. We have used dot-blot and in situ analysis to indicate that this erythroid preconditioning is probably restricted to primitive but not definitive HSC.

Role of NF-kappaB in p53-mediated programmed cell death

The tumour suppressor p53 inhibits cell growth through activation of cell-cycle arrest and apoptosis, and most cancers have either mutation within the p53 gene or defects in the ability to induce p53. Activation or re-introduction of p53 induces apoptosis in many tumour cells and may provide effective cancer therapy. One of the key proteins that modulates the apoptotic response is NF-kappaB, a transcription factor that can protect or contribute to apoptosis. Here we show that induction of p53 causes an activation of NF-kappaB that correlates with the ability of p53 to induce apoptosis. Inhibition or loss of NF-kappaB activity abrogated p53-induced apoptosis, indicating that NF-kappaB is essential in p53-mediated cell death. Activation of NF-kappaB by p53 was distinct from that mediated by tumour-necrosis factor-alpha and involved MEK1 and the activation of pp90rsk. Inhibition of MEK1 blocked activation of NF-kappaB by p53 and completely abrogated p53-induced cell death. We conclude that inhibition of NF-kappaB in tumours that retain wild-type p53 may diminish, rather than augment, a therapeutic response.

Trends in medical use and abuse of opioid analgesics

CONTEXT

Pain often is inadequately treated due in part to reluctance about using opioid analgesics and fear that they will be abused. Although international and national expert groups have determined that opioid analgesics are essential for the relief of pain, little information has been available about the health consequences of the abuse of these drugs.

OBJECTIVE

To evaluate the proportion of drug abuse related to opioid analgesics and the trends in medical use and abuse of 5 opioid analgesics used to treat severe pain: fentanyl, hydromorphone, meperidine, morphine, and oxycodone.

DESIGN AND SETTING

Retrospective survey of medical records from 1990 to 1996 stored in the databases of the Drug Abuse Warning Network (source of abuse data) and the Automation of Reports and Consolidated Orders System (source of medical use data).

PATIENTS

Nationally representative sample of hospital emergency department admissions resulting from drug abuse.

MAIN OUTCOME MEASURES

Medical use in grams and grams per 100,000 population and mentions of drug abuse by number and percentage of the population.

RESULTS

From 1990 to 1996, there were increases in medical use of morphine (59%; 2.2 to 3.5 million g), fentanyl (1168%; 3263 to 41,371 g), oxycodone (23%; 1.6 to 2.0 million g), and hydromorphone (19%; 118,455 to 141,325 g), and a decrease in the medical use of meperidine (35%; 5.2 to 3.4 million g). During the same period, the total number of drug abuse mentions per year due to opioid analgesics increased from 32,430 to 34,563 (6.6%), although the proportion of mentions for opioid abuse relative to total drug abuse mentions decreased from 5.1% to 3.8%. Reports of abuse decreased for meperidine (39%; 1335 to 806), oxycodone (29%; 4526 to 3190), fentanyl (59%; 59 to 24), and hydromorphone (15%; 718 to 609), and increased for morphine (3%; 838 to 865).

CONCLUSIONS

The trend of increasing medical use of opioid analgesics to treat pain does not appear to contribute to increases in the health consequences of opioid analgesic abuse.

DNA probe for beta-hemolytic group B Streptococcus. Diagnostic accuracy in threatened preterm labor

OBJECTIVE

To determine the diagnostic accuracy of a DNA probe for beta-hemolytic group B Streptococcus (GBS) in women with threatened preterm labor.

STUDY DESIGN

Two identical vaginal/perianal samples were collected from 75 pregnant women who were being evaluated for threatened preterm labor. One sample was managed in the traditional manner, with direct plating onto blood agar followed by plating after 8 and 24 hours of LIM broth enhancement. The "gold standard" was 24 hours of LIM broth enhancement followed by blood agar plating. The second sample was placed in LIM broth, and DNA probe testing was performed after incubation for 8 and 24 hours.

RESULTS

The prevalence of GBS colonization by the gold standard culture was 32%. After 8 hours of incubation in LIM broth, the DNA probe had poor sensitivity (79%); however, after 24 hours of incubation in LIM broth the DNA probe sensitivity rose to 96%. The DNA probe demonstrated only one false negative result after 24 hours of LIM broth enhancement. All DNA probe results were known 25 hours after sample collection.

CONCLUSION

This DNA probe gave results nearly identical to those of standard cultures and allowed a substantial saving of time.

Hemizygosity of the MAX gene locus in HL60 cells

The oncogenic activity of c-MYC is well known, and genetic aberrations in this locus are associated with a variety of human neoplasms. Because the encoded MYC protein has transcriptional activity only when dimerized with MAX, it is possible that mutations of MAX also could have phenotypic consequences. We have now found, by fluorescence in situ hybridization and quantified Southern blot analyses, that the MAX gene has been reduced to hemizygosity in HL60 cells. Although the sequence of the coding region of the remaining allele of the MAX gene is not mutated, this reduction in gene dosage may be the cause of a lower abundance of MAX protein in these cells that could result in an imbalance in the complex transcription factor network in which MAX has a pivotal role.

Cell cycle arrest and DNA endoreduplication following p21Waf1/Cip1 expression

p21Waf1/Cip1 is a major transcriptional target of p53 and has been shown to be one of the principal mediators of the p53 induced G1 cell cycle arrest. We show that in addition to the G1 block, p21Waf1/Cip1 can also contribute to a delay in G2 and expression of p21Waf1/Cip1 gives rise to cell cycle profiles essentially indistinguishable from those obtained following p53 expression. Arrest of cells in G2 likely reflects an inability to induce cyclin B1/cdc2 kinase activity in the presence of p21Waf1/Cip1, although the inefficient association of p21Waf1/Cip1 and cyclin B1 suggests that the mechanism of inhibition is indirect. Cells released from an S-phase block were not retarded in their ability to progress through S-phase by the presence of p21Waf1/Cip1, despite efficient inhibition of cyclin E, A and B1 dependent kinase activity, suggesting that p21Waf1/Cip1 is inefficient at inhibiting replicative DNA synthesis in vivo. Interestingly, significant numbers of cells released from the p21Waf1/Cip1 activated G2 block undergo endoreduplication, passing through another S-phase before undergoing mitosis. This supports a function of the mitotic kinases in both entry into mitosis, and also in preventing re-replication of DNA following S-phase and suggests a role for p21Waf1/Cip1 in coupling DNA synthesis and mitosis. Unlike p53, which induces apoptosis in these cells, extended expression of p21Waf1/Cip1 resulted in the expression of a senescent-like phenotype in these p53 null, pRB null tumor cells.

Characterization of structural p53 mutants which show selective defects in apoptosis but not cell cycle arrest

Suppression of tumor cell growth by p53 results from the activation of both apoptosis and cell cycle arrest, functions which have been shown to be separable activities of p53. We have characterized a series of p53 mutants with amino acid substitutions at residue 175 and show that these mutants fall into one of three classes: class I, which is essentially wild type for apoptotic and cell cycle arrest functions; class II, which retains cell cycle arrest activity but is impaired in the induction of apoptosis; and class III, which is defective in both activities. Several residue 175 mutants which retain cell cycle arrest function have been detected in cancers, and we show that these have lost apoptotic function. Furthermore, several class II mutants have been found to be temperature sensitive for apoptotic activity while showing constitutive cell cycle arrest function. Taken together, these mutants comprise an excellent system with which to investigate the biochemical nature of p53-mediated apoptosis, the function of principal importance in tumor suppression. All of the mutants that showed loss of apoptotic function also showed defects in the activation of promoters from the potential apoptotic targets Bax and the insulin-like growth factor-binding protein 3 gene (IGF-BP3), and a correlation between full apoptotic activity and activation of both of these promoters was also seen with the temperature-sensitive mutants. However, a role for additional apoptotic activities of p53 was suggested by the observation that some mutants retained significant apoptotic function despite being impaired in the activation of Bax- and IGF-BP3-derived promoters. In contrast to the case of transcriptional activation, a perfect correlation between transcriptional repression of the c-fos promoter and the ability to induce apoptosis was seen, although the observation that Bax expression induced a similar repression of transcription from this promoter suggests that this may be a consequence, rather than a cause, of apoptotic death.

Induction of DNA synthesis and apoptosis are separable functions of E2F-1

The family of E2F transcription factors have an essential role in mediating cell cycle progression, and recently, one of the E2F protein family, E2F-1, has been shown to participate in the induction of apoptosis. Cooperation between E2F and the p53 tumor suppressor protein in this apoptotic response had led to the suggestion that cell cycle progression induced by E2F-1 expression provides an apoptotic signal when placed in conflict with an arrest to cell cycle progression, such as provided by p53. We show here that although apoptosis is clearly enhanced by p53, E2F-1 can induce significant apoptosis in the absence of p53. Furthermore, this apoptotic function of E2F-1 is separable from the ability to accelerate entry into DNA synthesis. Analysis of E2F-1 mutants indicates that although DNA-binding is required, transcriptional transactivation is not necessary for the induction of apoptosis by E2F-1, suggesting that it may be mediated through alleviation of E2F-dependent transcriptional repression. These results indicate that E2F-1 can show independent cell cycle progression and apoptotic functions, consistent with its putative role as a tumor suppressor.

Analysis of E-box DNA binding during myeloid differentiation reveals complexes that contain Mad but not Max

It has been shown that during myeloid differentiation the levels of mad1 mRNA are induced before the loss of c-Myc protein. This suggests that inactivation of the differentiation-blocking activity of c-Myc might not occur primarily through the loss of Myc protein, but through an increase in the levels of its antagonist, Mad1. To investigate this question we have analysed the levels of mad1 mRNA during differentiation of myeloid leukaemic HL60 cells. Although levels of mad1 mRNA were moderately increased after induction with phorbol ester, we also found that differentiation could be achieved with other inducers without any concomitant up-regulation of mad1 mRNA. In addition, analysis of E-box DNA binding revealed that, although Myc-Max complexes were lost rapidly after differentiation induction, formation of Mad1-containing complexes only occurred during the later stages of the differentiation programme. Further analysis of these Mad-containing complexes revealed that they were also unlikely to have the capacity to antagonize c-Myc function, as they did not contain Max. Therefore these data suggest that an increase in the levels of mad1 mRNA or the formation of a Mad-Max complex are unlikely to be essential or determining events for myeloid differentiation. In addition, the discovery of DNA-binding complexes that contain Mad1, but not Max, opens up this transcription factor network to include other Max-like proteins or proteins of an unrelated nature.