Loss of p300 and CBP disrupts histone acetylation at the mouse Sry promoter and causes XY gonadal sex reversal

CREB-binding protein (CBP, CREBBP, KAT3A) and its closely related paralogue p300 (EP300, KAT3B), together termed p300/CBP, are histone/lysine acetyl-transferases that control gene expression by modifying chromatin-associated proteins. Here, we report roles for both of these chromatin-modifying enzymes in mouse sex determination, the process by which the embryonic gonad develops into a testis or an ovary. By targeting gene ablation to embryonic gonadal somatic cells using an inducible Cre line, we show that gonads lacking either gene exhibit major abnormalities of XY gonad development at 14.5 dpc, including partial sex reversal. Embryos lacking three out of four functional copies of p300/Cbp exhibit complete XY gonadal sex reversal and have greatly reduced expression of the key testis-determining genes Sry and Sox9. An analysis of histone acetylation at the Sry promoter in mutant gonads at 11.5 dpc shows a reduction in levels of the positive histone mark H3K27Ac. Our data suggest a role for CBP/p300 in testis determination mediated by control of histone acetylation at the Sry locus and reveal a novel element in the epigenetic control of Sry and mammalian sex determination. They also suggest possible novel causes of human disorders of sex development (DSD).

Design and preliminary recruitment results of the Cluster randomised triAl of PSA testing for Prostate cancer (CAP)

BACKGROUND

Screening for prostate cancer continues to generate controversy because of concerns about over-diagnosis and unnecessary treatment. We describe the rationale, design and recruitment of the Cluster randomised triAl of PSA testing for Prostate cancer (CAP) trial, a UK-wide cluster randomised controlled trial investigating the effectiveness and cost-effectiveness of prostate-specific antigen (PSA) testing.

METHODS

Seven hundred and eighty-five general practitioner (GP) practices in England and Wales were randomised to a population-based PSA testing or standard care and then approached for consent to participate. In the intervention arm, men aged 50-69 years were invited to undergo PSA testing, and those diagnosed with localised prostate cancer were invited into a treatment trial. Control arm practices undertook standard UK management. All men were flagged with the Health and Social Care Information Centre for deaths and cancer registrations. The primary outcome is prostate cancer mortality at a median 10-year-follow-up.

RESULTS

Among randomised practices, 271 (68%) in the intervention arm (198,114 men) and 302 (78%) in the control arm (221,929 men) consented to participate, meeting pre-specified power requirements. There was little evidence of differences between trial arms in measured baseline characteristics of the consenting GP practices (or men within those practices).

CONCLUSIONS

The CAP trial successfully met its recruitment targets and will make an important contribution to international understanding of PSA-based prostate cancer screening.

A specific CBP/p300-dependent gene expression programme drives the metabolic remodelling in late stages of spermatogenesis

Histone hyperacetylation is thought to drive the replacement of histones by transition proteins that occur in elongating spermatids (ElS) after a general shut down of transcription. The molecular machineries underlying this histone hyperacetylation remain still undefined. Here, we focused our attention on the role of Cbp and p300 in histone hyperacetylation and in the preceding late-gene transcriptional activity in ElS. A strategy was designed to partially deplete Cbp and p300 in ElS. These cells progressed normally through spermiogenesis and showed normal histone hyperacetylation and removal. However, a genome-wide transcriptomic analysis, performed in the round spermatids (RS) and ElS, revealed the existence of a gene regulatory circuit encompassing genes presenting high expression levels in pre-meiotic cells, undergoing a repressed state in spermatocytes and early post-meiotic cells, but becoming reactivated in ElS, just prior to the global shutdown of transcription. Interestingly, this group of genes was over-represented within the genes affected by Cbp/p300 knock down and were all involved in metabolic remodelling. This study revealed the occurrence of a tightly regulated Cbp/p300-dependent gene expression programme that drives a specific metabolic state both in progenitor spermatogenic cells and in late transcriptionally active spermatids and confirmed a special link between Cpb/p300 and cell metabolism programming previously shown in somatic cells.

Two histone/protein acetyltransferases (HATs), p300 and CBP, promote Foxp3+ T regulatory (Treg) cell production and function (179.18)

The master Treg transcription factor, Foxp3, is pivotal to the development and function of Treg cells. Foxp3 stability and function are regulated by acetylation, and we now identify p300 and CBP as controlling Treg production and function in vivo and in vitro. We found both p300 and CBP bind and acetylate Foxp3, and increase Foxp3 expression, DNA binding, and transactivation. We investigated their roles in Tregs by conditional deletion of p300, CBP, or both. While p300flflFoxp3cre and CBPflfl/Foxp3cre mice were born at the expected Mendelian ratios, p300flfl/Foxp3cre mice developed autoimmunity by several weeks of age, whereas CBPflfl/Foxp3cre mice showed long-term survival. However, p300flfl/CBPflfl/Foxp3cre mice developed severe autoimmunity and survived for only 3-4 weeks. Compared to littermate controls, both p300flflFoxp3cre and CBPflfl/Foxp3cre mice had decreased Foxp3 expression and impaired Treg suppressive function, whereas p300flfl/CBPflfl/Foxp3cre mice had even lower Foxp3 level and their Tregs essentially lacked suppression function. Additional studies showed p300 and CBP affect Foxp3 expression by regulating the Foxp3 promoter or CNS2 region, respectively. Our findings provide genetic evidence for central roles of these HATs in Treg biology, and provide a rationale for development of pharmacologic inhibitors to modulate Treg function in the context of oncology and other settings where it may be desirable to dampen but not eliminate Treg suppressive functions.

Performance of the QRISK cardiovascular risk prediction algorithm in an independent UK sample of patients from general practice: a validation study

AIM

To assess the performance of the QRISK score for predicting cardiovascular disease (CVD) in an independent UK sample from general practice and compare with the Framingham score.

DESIGN

Prospective open cohort study.

SETTING

UK general practices contributing to the THIN and QRESEARCH databases.

COHORT

The THIN validation cohort consisted of 1.07 million patients, aged 35-74 years registered at 288 THIN practices between 1 January 1995 and 1 April 2006. The QRESEARCH validation cohort consisted of 0.61 million patients from 160 practices (one-third of the full database) with data until 1 January 2007. Patients receiving statins, those with diabetes or CVD at baseline were excluded.

END POINT

First diagnosis of CVD (myocardial infarction, coronary heart disease (CHD), stroke and transient ischaemic attack) recorded on the clinical computer system during the study period.

EXPOSURES

Age, sex, smoking status, systolic blood pressure, total/high-density lipoprotein cholesterol ratio, body mass index, family history of premature CHD, deprivation and antihypertensive medication.

RESULTS

Characteristics of both cohorts were similar, except that THIN patients were from slightly more affluent areas and had lower recording of family history of CHD. QRISK performed better than Framingham for every discrimination and calibration statistic in both cohorts. Framingham overpredicted risk by 23% in the THIN cohort, while QRISK underpredicted risk by 12%.

CONCLUSION

This analysis demonstrated that QRISK is better calibrated to the UK population than Framingham and has better discrimination. The results suggest that QRISK is likely to provide more appropriate risk estimates than Framingham to help identify patients at high risk of CVD in the UK.

The detection, treatment and control of high blood pressure in older British adults: cross-sectional findings from the British Women's Heart and Health Study and the British Regional Heart Study

Among older people, the detection and control of hypertension is particularly important to reduce cardiovascular disease risk. This cross-sectional survey aimed to describe the detection, treatment and control of hypertension in older British adults. A total of 3059 women and 3007 men aged 60-79 years were randomly selected from general practice age/sex registers in 24 British towns and examined from 1998 to 2001. Of these, 52.6% women and 47.9% men had at least one indicator of hypertension (high blood pressure on examination, or taking antihypertensive medication or recalled a doctor diagnosis of high blood pressure). Among women, 50% of those with any indication of hypertension were on treatment and 29% were well controlled, and among men 45% were on treatment and 16% were well controlled. With the exception of alcohol use in men (adjusted odds ratio 0.67 (0.46, 0.98)), socioeconomic factors, area of residence and behavioural risk factors were not associated with good control among those with hypertension in either sex. Of those on treatment, 20.7% of women and 28% of men were on two classes of antihypertensive medication and 3.5 and 4.9%, respectively, were on three or more classes of antihypertensive medication. Among those with a doctor diagnosis of hypertension and taking antihypertensive medication, the proportion with well controlled blood pressure did not differ between those on more than one antihypertensive and those on just one in either sex. We conclude that targets of good control are rarely met in older individuals, who would benefit from the associated reduction in cardiovascular disease risk.

Primary prevention of cardiovascular disease: a web-based risk score for seven British black and minority ethnic groups

OBJECTIVE

To recalibrate an existing Framingham risk score to produce a web-based tool for estimating the 10-year risk of coronary heart disease (CHD) and cardiovascular disease (CVD) in seven British black and minority ethnic groups.

DESIGN

Risk prediction models were recalibrated against survey data on ethnic group risk factors and disease prevalence compared with the general population. Ethnic- and sex-specific 10-year risks of CHD and CVD, at the means of the risk factors for each ethnic group, were calculated from the product of the incidence rate in the general population and the prevalence ratios for each ethnic group.

SETTING

Two community-based surveys.

PARTICIPANTS

3778 men and 4544 women, aged 35-54, from the Health Surveys for England 1998 and 1999 and the Wandsworth Heart and Stroke Study.

MAIN OUTCOME MEASURES

10-year risk of CHD and CVD.

RESULTS

10-year risk of CHD and CVD for non-smoking people aged 50 years with a systolic blood pressure of 130 mm Hg and a total cholesterol to high density lipoprotein cholesterol ratio of 4.2 was highest in men for those of Pakistani and Bangladeshi origin (CVD risk 12.6% and 12.8%, respectively). CHD risk in men with the same risk factor values was lowest in Caribbeans (2.8%) and CVD risk was lowest in Chinese (5.4%). Women of Pakistani origin were at highest risk and Chinese women at lowest risk for both outcomes with CVD risks of 6.6% and 1.2%, respectively. A web-based risk calculator (ETHRISK) allows 10-year risks to be estimated in routine primary care settings for relevant risk factor and ethnic group combinations.

CONCLUSIONS

In the absence of cohort studies in the UK that include significant numbers of black and minority ethnic groups, this risk score provides a pragmatic solution to including people from diverse ethnic backgrounds in the primary prevention of CVD.

Accuracy and impact of risk assessment in the primary prevention of cardiovascular disease: a systematic review

OBJECTIVE

To determine the accuracy of assessing cardiovascular disease (CVD) risk in the primary prevention of CVD and its impact on clinical outcomes.

DESIGN

Systematic review.

DATA SOURCES

Published studies retrieved from Medline and other databases. Reference lists of identified articles were inspected for further relevant articles.

SELECTION OF STUDIES

Any study that compared the predicted risk of coronary heart disease (CHD) or CVD, with observed 10-year risk based on the widely recommended Framingham methods (review A). Randomised controlled trials examining the effect on clinical outcomes of a healthcare professional assigning a cardiovascular risk score to people predominantly without CVD (review B).

REVIEW METHODS

Data were extracted on the ratio of the predicted to the observed 10-year risk of CVD and CHD (review A), and on cardiovascular or coronary fatal or non-fatal events, risk factor levels, absolute cardiovascular or coronary risk, prescription of risk-reducing drugs and changes in health-related behaviour (review B).

RESULTS

27 studies with data from 71,727 participants on predicted and observed risk for either CHD or CVD were identified. For CHD, the predicted to observed ratios ranged from an underprediction of 0.43 (95% CI 0.27 to 0.67) in a high-risk population to an overprediction of 2.87 (95% CI 1.91 to 4.31) in a lower-risk population. In review B, four randomised controlled trials confined to people with hypertension or diabetes found no strong evidence that a cardiovascular risk assessment performed by a clinician improves health outcomes.

CONCLUSION

The performance of the Framingham risk scores varies considerably between populations and evidence supporting the use of cardiovascular risk scores for primary prevention is scarce.

Cardiovascular disease risk assessment in older women: can we improve on Framingham? British Women's Heart and Health prospective cohort study

OBJECTIVES

To develop a cardiovascular risk assessment tool that is feasible and easy to use in primary care (general practice (GP) model).

DESIGN

Prospective cohort study.

SETTING

23 towns in the United Kingdom.

PARTICIPANTS

3582 women aged 60 to 79 years who were free of coronary heart disease (CHD) at entry into the British Women's Heart and Health Study.

MAIN OUTCOME MEASURES

Predictive performance of a GP model compared with the standard Framingham model for both CHD and cardiovascular disease (CVD).

RESULTS

The Framingham tool predicted CHD events over 5 years accurately (predicted 5.7%, observed 5.5%) but overpredicted CVD events (predicted 10.5%, observed 6.8%). In higher-risk groups, Framingham overpredicted both CHD and CVD events and was poorly calibrated for this cohort. Including C-reactive protein and fibrinogen with standard Framingham risk factors did not improve discrimination of the model. The GP model, which used age, systolic blood pressure, smoking habit and self-rated health (all of which can be easily obtained in one surgery visit) performed as well as the Framingham risk tool: area under the receiver operating curve discrimination statistic was 0.66 (95% confidence interval (CI) 0.62 to 0.70) for CHD and 0.67 (95% CI 0.64 to 0.71) for CVD compared with 0.65 (95% CI 0.61 to 0.68) and 0.66 (95% CI 0.62 to 0.69) for the corresponding Framingham models.

CONCLUSIONS

An alternative risk assessment based on only a simple routine examination and a small number of pertinent questions may be more useful in the primary care setting. This model appears to perform well but needs to be tested in different populations.

The CREB coactivator TORC2 is a key regulator of fasting glucose metabolism

Glucose homeostasis is regulated systemically by hormones such as insulin and glucagon, and at the cellular level by energy status. Glucagon enhances glucose output from the liver during fasting by stimulating the transcription of gluconeogenic genes via the cyclic AMP-inducible factor CREB (CRE binding protein). When cellular ATP levels are low, however, the energy-sensing kinase AMPK inhibits hepatic gluconeogenesis through an unknown mechanism. Here we show that hormonal and energy-sensing pathways converge on the coactivator TORC2 (transducer of regulated CREB activity 2) to modulate glucose output. Sequestered in the cytoplasm under feeding conditions, TORC2 is dephosphorylated and transported to the nucleus where it enhances CREB-dependent transcription in response to fasting stimuli. Conversely, signals that activate AMPK attenuate the gluconeogenic programme by promoting TORC2 phosphorylation and blocking its nuclear accumulation. Individuals with type 2 diabetes often exhibit fasting hyperglycaemia due to elevated gluconeogenesis; compounds that enhance TORC2 phosphorylation may offer therapeutic benefits in this setting.

Regulation of somatostatin gene transcription by cyclic adenosine monophosphate

Cyclic adenosine monophosphate (cAMP) stimulates transcription of somatostatin and other target genes with burst-attenuation kinetics. The kinetics of protein kinase (PK-A)-dependent cAMP response element binding protein (CREB) phosphorylation closely parallel the changes in transcription of cAMP-responsive genes by run-on assay. Nuclear translocation of PK-A, visualized by microinjection of fluorescently labeled PK-A holoenzyme, appears to represent the rate-limiting step in CREB phosphorylation and transcriptional activation. We and others have recently characterized a CREB-binding protein (CBP), which specifically recognizes sequences within the Ser133 phosphorylated form of CREB. CBP does not regulate the DNA binding, dimerization, or nuclear targeting properties of CREB, but binds selectively to the kinase-inducible 60 amino acid trans-activation domain (KID) of CREB, critical for PK-A-inducible transcription. We developed an antiserum directed against amino acid 634-648 within the CREB-binding domain of CBP. We detected a 265-kd polypeptide by Western blot as predicted from the cDNA, which coincided with the predominant phospho-CREB-binding activity in Hela nuclear extracts by "Far Western" blot assay. An identical phospho-CREB-binding activity was also found in NIH-3T3 cells. This phospho-CREB-binding protein appeared to be specific for Ser133-phosphorylated CREB, because no such band was detected with CREB labeled to the same specific activity at a nonregulatory phosphoacceptor site (Ser156) by casein kinase II (CKII). Following microinjection into nuclei of NIH-3T3 cells, a cAMP response element (CRE)-lacZ reporter was markedly induced by treatment with 8-Br cAMP plus isobutyl methyl xanthine (IBMX). Coinjection of CBP antiserum with the CRE-lacZ plasmid inhibited cAMP-dependent activity in a dose-dependent manner, but control immunoglobulin G (lgG) had no effect on this response. We can now begin reconstituting PK-A-dependent transcription in vitro, using well-characterized proteins such as CREB, TAF 110, and CBP. The assembly of such factors on cAMP-regulated promoters like somatostain may enable responsiveness to a variety of hormonal stimuli that employ cAMP as their second messenger.

Multiple protein kinase A-regulated events are required for transcriptional induction by cAMP

The second messenger cAMP stimulates the expression of numerous genes via the protein kinase A-mediated phosphorylation of the cAMP response element-binding protein (CREB) at Ser-133. Ser-133 phosphorylation, in turn, appears to induce target gene expression by promoting interaction between CREB and CBP, a 265-kDa nuclear phospho-CREB-binding protein. It is unclear, however, whether Ser-133 phosphorylation per se is sufficient for CREB-CBP complex formation and for target gene induction in vivo. Here we examine CREB activity in Jurkat T cells after stimulation of the T-cell receptor (TCR), an event that leads to calcium entry and diacylglycerol production. Triggering of the TCR stimulated Ser-133 phosphorylation of CREB with high stoichiometry, but TCR activation did not promote CREB-CBP complex formation or target gene induction unless suboptimal doses of cAMP agonist were provided as a costimulus. Our results demonstrate that, in addition to mediating Ser-133 phosphorylation of CREB, protein kinase A regulates additional proteins that are required for recruitment of the transcriptional apparatus to cAMP-responsive genes.

Activation of cAMP and mitogen responsive genes relies on a common nuclear factor

A number of signalling pathways stimulate transcription of target genes through nuclear factors whose activities are primarily regulated by phosphorylation. Cyclic AMP regulates the expression of numerous genes, for example, through the protein kinase-A (PKA)-mediated phosphorylation of transcription factor CREB at Ser 133. Although phosphorylation may stimulate transcriptional activators by modulating their nuclear transport or DNA-binding affinity, CREB belongs to a class of proteins whose phosphorylation appears specifically to enhance their trans-activation potential. Recent work describing a phospho-CREB binding protein (CBP) which interacts specifically with the CREB trans-activation domain prompted us to examine whether CBP is necessary for cAMP regulated transcription. We report here that microinjection of an anti-CBP antiserum into fibroblasts can inhibit transcription from a cAMP responsive promoter. Surprisingly, CBP also cooperates with upstream activators such as c-Jun, which are involved in mitogen responsive transcription. We propose that CBP is recruited to the promoter through interaction with certain phosphorylated factors, and that CBP may thus play a critical role in the transmission of inductive signals from cell surface receptor to the transcriptional apparatus.

Protein-kinase-A-dependent activator in transcription factor CREB reveals new role for CREM repressors

Hormonally induced increases in cyclic AMP levels induce phosphorylation of the transcription factor CREB at a serine residue at position 133 by protein kinase A (ref. 1), enhancing its ability to activate transcription without affecting its intracellular location or DNA-binding activity. This effect is dependent on a 60-amino-acid region of CREB that contains Ser133 and is termed the kinase-inducible domain (KID)2, which also occurs in the CREB-related CREM-alpha and -beta proteins, although these are transcriptional repressors. Here we show that the KID domain confers a cAMP-inducible increase on the activity of the Q2 activation domain from CREB and the acidic activation domains from the yeast proteins GAL4 and GCN4. Remarkably, it retains this ability even when attached to a separate polypeptide bound to an adjacent site in the promoter. KID may therefore be the first of a new class of conditional activators that work through other promoter-bound factors to stimulate gene expression in response to hormonal stimuli.

Coupling of hormonal stimulation and transcription via the cyclic AMP-responsive factor CREB is rate limited by nuclear entry of protein kinase A

Cyclic AMP (cAMP) regulates a number of eukaryotic genes by mediating the protein kinase A (PKA)-dependent phosphorylation of the CREB transcription factor at Ser-133. In this study, we test the hypothesis that the stoichiometry and kinetics of CREB phosphorylation are determined by the liberation and subsequent translocation of PKA catalytic subunit (C subunit) into the nucleus. Using fluorescence imaging techniques, we observed that PKA was activated in a stimulus-dependent fashion that led to nuclear entry of C subunit over a 30-min period. The degree of CREB phosphorylation, assessed with antiserum specific for CREB phosphorylated at Ser-133, correlated with the amount of PKA liberated. The time course of phosphorylation closely paralleled the nuclear entry of the catalytic subunit. There was a linear relationship between the subsequent induction of the cAMP-responsive somatostatin gene and the degree of CREB phosphorylation, suggesting that each event--kinase activation, CREB phosphorylation, and transcriptional induction--was tightly coupled to the next. In contrast to other PKA-mediated cellular responses which are rapid and quantitative, the slow, incremental regulation of CREB activity by cAMP suggests that multifunctional kinases like PKA may coordinate cellular responses by dictating the kinetics and stoichiometry of phosphorylation for key substrates like CREB.

Transcriptional attenuation following cAMP induction requires PP-1-mediated dephosphorylation of CREB

We have examined the mechanism by which the transcriptional activity of the cAMP-responsive factor CREB is attenuated following induction with forskolin. Metabolic labeling studies reveal that, after an initial burst of phosphorylation in response to cAMP, CREB is dephosphorylated and transcription of the cAMP-responsive somatostatin gene is correspondingly reduced. The phosphatase inhibitor 1 protein and okadaic acid both prevented the dephosphorylation of CREB at Ser-133 in PC12 cells and also augmented the transcriptional response to cAMP. Of the four Ser/Thr phosphatases described to date, only PP-1 appears to be similarly inhibited by these agents. As PP-1 specifically dephosphorylates CREB at Ser-133 and inhibits cAMP-dependent transcription, we propose that this phosphatase is the major regulator of CREB activity in cAMP-responsive cells.