Gap junctions and connexin hemichannels underpin hemostasis and thrombosis

BACKGROUND: Connexins are a widespread family of membrane proteins that assemble into hexameric hemichannels, also known as connexons. Connexons regulate membrane permeability in individual cells or couple between adjacent cells to form gap junctions and thereby provide a pathway for regulated intercellular communication. We have now examined the role of connexins in platelets, blood cells that circulate in isolation, but upon tissue injury adhere to each other and the vessel wall to prevent blood loss and facilitate wound repair. METHODS AND RESULTS: We report the presence of connexins in platelets, notably connexin37, and that the formation of gap junctions within platelet thrombi is required for the control of clot retraction. Inhibition of connexin function modulated a range of platelet functional responses prior to platelet-platelet contact, and reduced laser induced thrombosis in vivo in mice. Deletion of the Cx37 gene (Gja4) in transgenic mice reduced platelet aggregation, fibrinogen binding, granule secretion and clot retraction indicating an important role for Cx37 hemichannels and gap junctions in platelet thrombus function. CONCLUSIONS: Together, these data demonstrate that platelet gap junctions and hemichannels underpin the control of haemostasis and thrombosis and represent potential therapeutic targets.

'Love me or kill me’: Sarah Kane & the theatre of extremes

Monograph on the playwright Sarah Kane

'Out Vile Jelly': Sarah Kane's 'Blasted' & Shakespeare's 'King Lear'

Sarah Kane's notorious 1995 debut, Blasted, has been widely though belatedly recognized as a defining example of experiential or ‘in-yer-face’ theatre. However, Graham Saunders here argues that the best playwrights not only innovate in use of language and dramatic form, but also rewrite the classic plays of the past. He believes that too much stress has been placed on the play's radical structure and contemporary sensibility, with the effect of obscuring the influence of Shakespearean tradition on its genesis and content. He clarifies Kane's gradually dawning awareness of the influence of Shakespeare's King Lear on her work and how elements of that tragedy were rewritten in terms of dialogue, recast thematically, and reworked in terms of theatrical image. He sees Blasted as both a response to contemporary reality and an engagement with the history of drama. Graham Saunders is Senior Lecturer in Theatre Studies at the University of the West of England, Bristol, and author of the first full-length study of Kane's work: ‘Love Me or Kill Me’: Sarah Kane and the Theatre of Extremes (Manchester University Press, 2002). An earlier version of this article was given as a paper at the ‘Crucible of Cultures: Anglophone Drama at the Dawn of a New Millennium’ conference in Brussels, May 2001. Saunders is currently working on articles about Samuel Beckett and Edward Bond

Sarah Kane: Cool Britannia’s reluctant feminist

Aleks Sierz in his important survey of mid 1990s drama has identified the plays of Sarah Kane as exemplars of what he terms ‘In-Yer Face’ theatre. Sierz argues that Kane and her contemporaries such as Mark Ravenhill and Judy Upton represent a break with the ideological concerns of the previous generation of playwrights such as Doug Lucie and Stephen Lowe, whose work was shaped through recognizable political concerns, often in direct opposition to Thatcherism. In contrast Sarah Kane and her generation have frequently been seen as literary embodiments of ‘Thatcher’s Children’, whereby following the fall of the Berlin Wall and the inertia of the Major years, their drama eschews a recognizable political position, and seems more preoccupied with the plight of individuals cut adrift from society. In the case of Sarah Kane her frequently quoted statement, ‘I have no responsibility as a woman writer because I don’t believe there’s such a thing’, has compounded this perception. Moreover, its dogmatism also echoes the infamous comments attributed to Mrs Thatcher regarding the role of the individual to society. However, this article seeks to reassess Kane’s position as a woman writer and will argue that her drama is positioned somewhere between the female playwrights who emerged after 1979 such as Sarah Daniels, Timberlake Wertenbaker and Clare McIntyre, whose drama was distinguished by overtly feminist concerns, and its subsequent breakdown, best exemplified by the brief cultural moment associated with the newly elected Blair government known as ‘Cool Britannia’. Drawing on a variety of sources, including Kane’s unpublished monologues, written while she was a student just after Mrs Thatcher left office, this paper will argue that far from being an exponent of post-feminism, Kane’s drama frequently revisits and is influenced by the generation of dramatists whose work was forged out the sharp ideological positions that characterized the 1980s and a direct consequence of Thatcherism.

Randomized controlled trial of parent-enhanced CBT compared with individual CBT for obsessive-compulsive disorder in young people

Objective: Obsessive-compulsive disorder (OCD) in young people can be effectively treated with Cognitive Behavior Therapy (CBT). Practice guidelines in the United Kingdom recommend that CBT be delivered with parental or family involvement; however, there is no evidence from randomized trials that this enhances effectiveness. The aim of this trial was to assess if CBT with high parental involvement was more effective than CBT with low parental involvement (individual CBT) in reducing symptoms of OCD. Method: Fifty young people ages 12–17 years with OCD were randomly allocated to individual CBT or parent-enhanced CBT. In parent-enhanced CBT parents attended all treatment sessions; in individual CBT, parents attended only Sessions 1, 7, and the final session. Participants received up to 14 sessions of CBT. Data were analyzed using intent-to-treat and per-protocol methods. The primary outcome measure was the Children’s Yale-Brown Obsessive Compulsion Scale (Scahill et al., 1997). Results: Both forms of CBT significantly reduced symptoms of OCD and anxiety. Change in OCD symptoms was maintained at 6 months. Per-protocol analysis suggested that parent-enhanced CBT may be associated with significantly larger reductions in anxiety symptoms. Conclusions: High and low parental involvement in CBT for OCD in young people were both effective, and there was no evidence that 1 method of delivery was superior on the primary outcome measure. However, this study was small. Future trials should be adequately powered and examine interactions with the age of the young person and comorbid anxiety disorders.

Dysregulation of REST-regulated coding and non-coding RNAs in a cellular model of Huntington's disease

Huntingtin (Htt) protein interacts with many transcriptional regulators, with widespread disruption to the transcriptome in Huntington's disease (HD) brought about by altered interactions with the mutant Htt (muHtt) protein. Repressor Element-1 Silencing Transcription Factor (REST) is a repressor whose association with Htt in the cytoplasm is disrupted in HD, leading to increased nuclear REST and concomitant repression of several neuronal-specific genes, including brain-derived neurotrophic factor (Bdnf). Here, we explored a wide set of HD dysregulated genes to identify direct REST targets whose expression is altered in a cellular model of HD but that can be rescued by knock-down of REST activity. We found many direct REST target genes encoding proteins important for nervous system development, including a cohort involved in synaptic transmission, at least two of which can be rescued at the protein level by REST knock-down. We also identified several microRNAs (miRNAs) whose aberrant repression is directly mediated by REST, including miR-137, which has not previously been shown to be a direct REST target in mouse. These data provide evidence of the contribution of inappropriate REST-mediated transcriptional repression to the widespread changes in coding and non-coding gene expression in a cellular model of HD that may affect normal neuronal function and survival.

Rescue of gene expression by modified REST decoy oligonucleotides in a cellular model of Huntington's disease

Transcriptional dysfunction is a prominent hallmark of Huntington's disease (HD). Several transcription factors have been implicated in the aetiology of HD progression and one of the most prominent is repressor element 1 (RE1) silencing transcription factor (REST). REST is a global repressor of neuronal gene expression and in the presence of mutant Huntingtin increased nuclear REST levels lead to elevated RE1 occupancy and a concomitant increase in target gene repression, including brain-derived neurotrophic factor. It is of great interest to devise strategies to reverse transcriptional dysregulation caused by increased nuclear REST and determine the consequences in HD. Thus far, such strategies have involved RNAi or mutant REST constructs. Decoys are double-stranded oligodeoxynucleotides corresponding to the DNA-binding element of a transcription factor and act to sequester it, thereby abrogating its transcriptional activity. Here, we report the use of a novel decoy strategy to rescue REST target gene expression in a cellular model of HD. We show that delivery of the decoy in cells expressing mutant Huntingtin leads to its specific interaction with REST, a reduction in REST occupancy of RE1s and rescue of target gene expression, including Bdnf. These data point to an alternative strategy for rebalancing the transcriptional dysregulation in HD.

The role of REST in transcriptional and epigenetic dysregulation in Huntington's disease

Huntington's disease (HD) is a devastating disorder that affects approximately 1 in 10,000 people and is accompanied by neuronal dysfunction and neurodegeneration. HD manifests as a progressive chorea, a decline in mental abilities accompanied by behavioural, emotional and psychiatric problems followed by, dementia, and ultimately, death. The molecular pathology of HD is complex but includes widespread transcriptional dysregulation. Although many transcriptional regulatory molecules have been implicated in the pathogenesis of HD, a growing body of evidence points to the pivotal role of RE1 Silencing Transcription Factor (REST). In HD, REST, translocates from the cytoplasm to the nucleus in neurons resulting in repression of key target genes such as BDNF. Since these original observations, several thousand direct target genes of REST have been identified, including numerous non-coding RNAs including both microRNAs and long non-coding RNAs, several of which are dysregulated in HD. More recently, evidence is emerging that hints at epigenetic abnormalities in HD brain. This in turn, promotes the notion that targeting the epigenetic machinery may be a useful strategy for treatment of some aspects of HD. REST also recruits a host of histone and chromatin modifying activities that can regulate the local epigenetic signature at REST target genes. Collectively, these observations present REST as a hub that coordinates transcriptional, posttranscriptional and epigenetic programmes, many of which are disrupted in HD. We identify several spokes emanating from this REST hub that may represent useful sites to redress REST dysfunction in HD.

Transcriptional dysregulation of coding and non-coding genes in cellular models of Huntington's disease

HD (Huntington's disease) is a late onset heritable neurodegenerative disorder that is characterized by neuronal dysfunction and death, particularly in the cerebral cortex and medium spiny neurons of the striatum. This is followed by progressive chorea, dementia and emotional dysfunction, eventually resulting in death. HD is caused by an expanded CAG repeat in the first exon of the HD gene that results in an abnormally elongated polyQ (polyglutamine) tract in its protein product, Htt (Huntingtin). Wild-type Htt is largely cytoplasmic; however, in HD, proteolytic N-terminal fragments of Htt form insoluble deposits in both the cytoplasm and nucleus, provoking the idea that mutHtt (mutant Htt) causes transcriptional dysfunction. While a number of specific transcription factors and co-factors have been proposed as mediators of mutHtt toxicity, the causal relationship between these Htt/transcription factor interactions and HD pathology remains unknown. Previous work has highlighted REST [RE1 (repressor element 1)-silencing transcription factor] as one such transcription factor. REST is a master regulator of neuronal genes, repressing their expression. Many of its direct target genes are known or suspected to have a role in HD pathogenesis, including BDNF (brain-derived neurotrophic factor). Recent evidence has also shown that REST regulates transcription of regulatory miRNAs (microRNAs), many of which are known to regulate neuronal gene expression and are dysregulated in HD. Thus repression of miRNAs constitutes a second, indirect mechanism by which REST can alter the neuronal transcriptome in HD. We will describe the evidence that disruption to the REST regulon brought about by a loss of interaction between REST and mutHtt may be a key contributory factor in the widespread dysregulation of gene expression in HD.