Peripheral administration of prokineticin 2 potently reduces food intake and body weight in mice via the brainstem.

BACKGROUND AND PURPOSE: Prokineticin 2 (PK2) has recently been shown to acutely reduce food intake in rodents. We aimed to determine the CNS sites and receptors that mediate the anorectic effects of peripherally administered PK2 and its chronic effects on glucose and energy homeostasis. EXPERIMENTAL APPROACH: We investigated neuronal activation following i.p. administration of PK2 using c-Fos-like immunoreactivity (CFL-IR). The anorectic effect of PK2 was examined in mice with targeted deletion of either prokineticin receptor 1 (PKR1) or prokineticin receptor 2 (PKR2), and in wild-type mice following administration of the PKR1 antagonist, PC1. The effect of IP PK2 administration on glucose homeostasis was investigated. Finally, the effect of long-term administration of PK2 on glucose and energy homeostasis in diet-induced obese (DIO) mice was determined. KEY RESULTS: I.p. PK2 administration significantly increased CFL-IR in the dorsal motor vagal nucleus of the brainstem. The anorectic effect of PK2 was maintained in mice lacking the PKR2 but abolished in mice lacking PKR1 and in wild-type mice pre-treated with PC1. DIO mice treated chronically with PK2 had no changes in glucose levels but significantly reduced food intake and body weight compared to controls. CONCLUSIONS AND IMPLICATIONS: Together, our data suggest that the anorectic effects of peripherally administered PK2 are mediated via the brainstem and this effect requires PKR1 but not PKR2 signalling. Chronic administration of PK2 reduces food intake and body weight in a mouse model of human obesity, suggesting that PKR1-selective agonists have potential to be novel therapeutics for the treatment of obesity.

Regional vascular response to ProAngiotensin-12 (PA12) through the rat arterial system.

ProAngiotensin-12 (PA12) is the most recent peptide to be identified as a functional component of the renin-angiotensin system (RAS). PA12 is reported to constrict rat coronary arteries and the aorta, dependent upon angiotensin II-converting enzyme 1 (ACE1) and chymase. The current study employed myography to determine the direct vascular effects of PA12 on a range of isolated rat arteries extending from the core to periphery. PA12 significantly constricted the descending thoracic aorta, right and left common carotid arteries, abdominal aorta and superior mesenteric artery, with little effect on the femoral and renal arteries. AngII was found to produce similar responses to PA12 when administered at the same dose. A potency gradient in response to PA12 was clearly apparent, with vessels in closest proximity to the heart responding with the greatest constriction; while constrictive potency was lost further form the heart. Inhibition of ACE1 and chymase both significantly attenuated PA12-induced vasoconstriction, with chymostatin displaying lesser potency. We postulate ACE1 primarily regulates RAS activity within the circulation, while chymase may have an important role in local, tissue-based RAS activity.

Urotensin II and urotensin II-related peptide (URP) in cardiac ischemia-reperfusion injury.

Circulating urotensin II (UII) concentrations and the tissue expression of its cognate receptor (UT) are elevated in patients with cardiovascular disease (CVD). The functional significance of elevated plasma UII levels in CVD is unclear. Urotensin-related peptide (URP) is a paralog of UII in that it contains the six amino acid ring structures found in UII. Although both peptides are implicated as bioactive factors capable of modulating cardiovascular status, the role of both UII and URP in ischemic injury is unknown. Accordingly, we provide here the first report describing the direct cardiac effects of UII and URP in ischemia-reperfusion injury. Isolated perfused rat hearts were subjected to no-flow global ischemia for 45 min after 30min preconditioning with either 1nM rUII or 10nM URP. Both rUII- and URP-induced significant vasodilation of coronary arteries before (both P<0.05) and after ischemia (both P<0.05). Rat UII alone lowered contractility prior to ischemia (P=0.053). Specific assay of perfusate revealed rUII and URP both significantly inhibited reperfusion myocardial creatine kinase (CK) release (P=0.012 and 0.036, respectively) and atrial natriuretic peptide (ANP) secretion (P=0.025). Antagonism of the UT receptor with 1muM palosuran caused a significant increase in perfusion pressure (PP) prior to and post-ischemia. Furthermore, palosuran significantly inhibited reductions in both PP and myocardial damage marker release induced by both rUII and URP. In conclusion, our data suggests rUII and URP reduce cardiac ischemia-reperfusion injury by increasing flow through the coronary circulation, reducing contractility and therefore myocardial energy demand, and inhibiting reperfusion myocardial damage. Thus, UII and URP present as novel peptides with potential cardioprotective actions.

Genetic and molecular analysis of the central and peripheral circadian clockwork of mice.

A hierarchy of interacting, tissue-based clocks controls circadian physiology and behavior in mammals. Preeminent are the suprachiasmatic nuclei (SCN): central hypothalamic pacemakers synchronized to solar time via retinal afferents and in turn responsible for internal synchronization of other clocks present in major organ systems. The SCN and peripheral clocks share essentially the same cellular timing mechanism. This consists of autoregulatory transcriptional/posttranslational feedback loops in which the Period (Per) and Cryptochrome (Cry) "clock" genes are negatively regulated by their protein products. Here, we review recent studies directed at understanding the molecular and cellular bases to the mammalian clock. At the cellular level, we demonstrate the role of F-box protein Fbxl3 (characterized by the afterhours mutation) in directing the proteasomal degradation of Cry and thereby controlling negative feedback and circadian period of the molecular loops. Within SCN neural circuitry, we describe how neuropeptidergic signaling by VIP synchronizes and sustains the cellular clocks. At the hypothalamic level, signaling via a different SCN neuropeptide, prokineticin, is not required for pacemaking but is necessary for control of circadian behavior. Finally, we consider how metabolic pathways are coordinated in time, focusing on liver function and the role of glucocorticoid signals in driving the circadian transcriptome and proteome.

Cardiovascular effects of native and non-native urotensin II and urotensin II-related peptide on rat and salmon hearts.

Urotensin II (UII) was first discovered in the urophyses of goby fish and later identified in mammals, while urotensin II-related peptide (URP) was recently isolated from rat brain. We studied the effects of UII on isolated heart preparations of Chinook salmon and Sprague-Dawley rats. Native rat UII caused potent and sustained, dose-dependent dilation of the coronary arteries in the rat, whereas non-native UII (human and trout UII) showed attenuated vasodilation. Rat URP dilated rat coronary arteries, with 10-fold less potency compared with rUII. In salmon, native trout UII caused sustained dilation of the coronary arteries, while rat UII and URP caused significant constriction. Nomega-nitro-(l)-arginine methyl (l-NAME) and indomethacin significantly attenuated the URP and rat UII-induced vasodilation in the rat heart. We conclude that UII is a coronary vasodilator, an action that is species form specific. We also provide the first evidence for cardiac actions of URP, possibly via mechanisms common with UII.

GABA(B) receptor function in the ileum and urinary bladder of wildtype and GABA(B1) subunit null mice.

1. GABA(B1) receptor subunit knockout mice were generated and the effects of the GABA(B) receptor agonist, baclofen, were evaluated within the peripheral nervous system (PNS) of wildtype (+/+), heterozygote (+/-) and knockout (-/-) animals. For this purpose, neuronally-mediated responses were evoked in both the isolated ileum and urinary bladder, using selective electrical field stimulation (EFS). 2. In ileum resected from 4-8-week-old-mice, low frequencies of EFS (0.5 Hz) evoked irregular muscle contractions which were prevented by atropine 1 microM and reduced by baclofen (33.4 +/- 5.6%, 100 microm). The latter effect was antagonized by the GABA(B) receptor antagonist CGP54626 0.2 microm. Baclofen 100 microm did not affect contractions of similar amplitude induced by carbachol, indicating that the ability of baclofen to inhibit cholinergic function in mouse ileum may be due to an action at prejunctional GABA(B) receptors. 3. To avoid the development of grand mal seizure by GABA(B1) (-/-) mice, a behaviour observed when the mice were greater than 3 weeks old, it was necessary to study the effects of this knockout in 1-3-week-old-animals. However, at this age, EFS at 0.5 Hz did not evoke robust muscle contractions. Consequently we used EFS at 5 Hz, which did evoke cholinergically mediated contractions, found to be of similar amplitude in (+/+) and (+/-) mice, of both 1-3 weeks and 4-8 weeks of age. At this frequency of EFS, baclofen reduced the amplitude of the evoked contractions [n = 6 (+/+) and n = 5 (+/-), IC50 19.2 +/- 4.8 microm) and this effect was greatly reduced in the presence of CGP54626 0.2 microm. 4. In urinary bladder from 1-3-week-old-mice, using higher frequencies of EFS to evoke clear, nerve-mediated contractions (10 Hz), baclofen 10-300 microm concentration-dependently inhibited contractions in (+/+) mice (IC50 9.6 +/- 3.8 microm). This effect was inhibited by CGP54626 (0.2 microm, 46.2 +/- 13.6% inhibition, 300 microm baclofen n = 7) a concentration which, by itself, had no effect on the EFS-evoked contractions. 5. The effects of baclofen in both ileum and urinary bladder were absent in the GABA(B1) receptor subunit (-/-) mice; however, responses to EFS were unaffected in (-/-) when compared to the (+/+) mice. 6. Our data suggest that, as in the central nervous system (CNS), the GABA(B1) receptor subunit is an essential requirement for GABA(B) receptor function in the enteric and PNS. As such, these data do not provide a structural explanation for the existence of putative subtypes of GABA(B) receptor, suggested by studies such as those in which different rank-orders of GABA(B) agonist affinity have been reported in different tissues.

Epileptogenesis and enhanced prepulse inhibition in GABA(B1)-deficient mice.

The recent cloning of two GABA(B) receptor subunits, GABA(B1) and GABA(B2), has raised the possibility that differences in GABA(B) receptor subunit composition may give rise to pharmacologically or functionally distinct receptors. If present, such molecular diversity could permit the selective targeting of GABA(B) receptor subtypes specifically involved in pathologies such as drug addiction, spasticity, pain, and epilepsy. To address these issues we have developed a GABA(B1) subunit knockout mouse using gene targeting techniques. In the brains of GABA(B1) null mice, all pre- and postsynaptic GABA(B) receptor function was absent demonstrating that the GABA(B1) subunit is essential for all GABA(B) receptor-mediated mechanisms. Despite this, GABA(B1) null mice appeared normal at birth, although by postnatal week four their growth was retarded and they developed a generalized epilepsy that resulted in premature death. In addition, GABA(B1) heterozygote animals showed enhanced prepulse inhibition responses compared to littermate controls, suggesting that GABA(B1) deficient mice exhibit increased sensorimotor gating mechanisms. These data suggest that GABA(B) receptor antagonists may be of benefit in the treatment of psychiatric and neurological disorders in which attentional processing is impaired.

Reliability and validity of the Mini PAS-ADD for assessing psychiatric disorders in adults with intellectual disability.

The Mini PAS-ADD is an assessment schedule for psychiatric disorders in people with an intellectual disability. It is designed to provide a link between the mental health expertise of psychiatrists and psychologists, and the detailed knowledge of individual service users possessed by support staff. In broad terms, the aim of the Mini PAS-ADD is to enable non-psychiatrists accurately to recognize clinically significant psychiatric disorders in the people who they care for, so that they can make informed referral decisions. The instrument comprises 86 psychiatric symptoms and generates a series of subscores on: depression, anxiety and phobias, mania, obsessive-compulsive disorder, psychosis, unspecified disorder (including dementia), and pervasive developmental disorder (autism). The present paper reports the results of a study investigating internal consistency, inter-rater agreement and validity in relation to clinical opinion, using a sample of 68 people with intellectual disability who were in contact with psychiatric services. In terms of the instrument fulfilling its main intended function, i.e. accurate case recognition, the crucial question was whether the support workers, with their lesser knowledge of psychopathology, were also able to correctly identify cases identified by expert clinicians. The validity results in this respect (81% agreement on case recognition) were sufficiently good that it is to be anticipated that the Mini PAS-ADD should have a significant impact on the identification of psychiatric disorders in the community of people with intellectual disability.

Reliability and validity of the PAS-ADD Checklist for detecting psychiatric disorders in adults with intellectual disability.

The PAS-ADD Checklist is a screening instrument specifically designed to help staff recognize mental health problems in the people with intellectual disability for whom they care, and to make informed referral decisions. The instrument consists of a life-events checklist and 29 symptom items scored on a four-point scale. Scores are combined to provide three threshold scores. The crossing of any of these thresholds indicates the need for a fuller assessment. The items are worded in everyday language, making the Checklist suitable for use by individuals who do not have a background in psychopathology. The present paper presents the results of a number of studies evaluating the reliability and validity of the Checklist. Factor analysis of Checklists completed on a community sample of 201 individuals yielded eight factors, of which seven were readily interpretable in diagnostic terms. Internal consistency of the scales was generally acceptable. Inter-rater reliability in respect to individual items gave a fairly low average Kappa of 0.42. However, agreement on case identification, the main purpose of the Checklist, was quite good, with 83% of the decision being in agreement. Validity in relation to clinical opinion was also satisfactory, case detection rising appropriately with the clinically judged severity of disorder. The PAS-ADD Checklist is published and distributed by the Hester Adrian Research Centre, Manchester, England, from where further information and order forms are available on request.

Reliability of the ICD 10 version of the Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD).

The Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD) is a semi-structured clinical interview designed for use with respondents who have learning disability. The first version was based on the Present State Examination. The revised version was derived from the Schedules for Clinical Assessment in Neuropsychiatry (SCAN), and makes ICD 10 diagnoses using the SCAN diagnostic program. This current version has a 4-point scale of severity, compared with the 3-point scale of the first version. It also has a new module relating to psychotic disorders. The sample consisted of 40 individuals representing a spectrum of neurotic, depressive and psychotic disorders. Videotapes of 40 PAS-ADD interviews were re-rated by trained interviewers who had not been involved in the original study in which the videotapes were produced. The mean Kappa across all individual item codes was 0.65, ranging from 0.94 to 0.35. The mean Kappa agreement on item groups was 0.66. Correlation between total symptom scores was 0.74. Agreement on index of definition was Kappa 0.70. We concluded that, agreement was generally lower than for the ICD 9 version. This was probably due mainly to the increase in the severity categories from three to four. However, the new items (most of which related to psychosis) were of comparable reliability to other items.

Validity of the PAS-ADD for detecting psychiatric symptoms in adults with learning disability (mental retardation).

The Psychiatric Assessment Schedule for Adults with Developmental Disability (PAS-ADD) is a semi-structured interview for use with respondents who have learning disability and for key informants. This report investigates the ability of the instrument to detect symptoms that had been found to exist during routine clinical assessment of the patients. Field trials involved 95 referred patients with learning disability and a key informant for each sample member. Clinical opinions of the referring psychiatrists were sought using a symptom checklist. Referrer checklist symptoms and PAS-ADD data were both factor analysed. Validity testing involved (a) computation of correlations between PAS-ADD factors and checklist data and (b) comparison of PAS-ADD and referrers' diagnoses. Results indicated good validity for the PAS-ADD in relation to psychotic symptoms and depressive symptoms. Anxiety symptom identification was not well validated, probably due to small numbers. Expansive mood identified by the referrers was not detected by the PAS-ADD because there is currently no corresponding section in the interview. Where the PAS-ADD produced a diagnosis (in 58 members of the sample), 44 were in agreement with the referrer. Probability of diagnosis by PAS-ADD increased with the number of relevant active symptoms identified by the referrer. The PAS-ADD has been shown in a previous report to have the sensitivity to detect mental disorders not known to psychiatric services. For psychotic and depressive conditions, our results showed that symptom detection was in good agreement with the information provided by the referring psychiatrists on their patients. The PAS-ADD needs a section on hypomania and further investigation of its detection of anxiety disorders.

Respondent and informant accounts of psychiatric symptoms in a sample of patients with learning disability.

This paper investigates differences in the nature and frequency of psychiatric symptoms reported by patients with learning disability and key informants. The study involved psychiatric assessment of 100 patients with learning disabilities and key informants using the Psychiatric Assessment Schedule for Adults with a Developmental Disability (PAS-ADD), a semi-structured psychiatric interview developed specifically for people who have a learning disability. There was considerable disagreement between respondent and informant interviews: only 40.7% of cases were detected by both interviews. Respondents were more likely to report on autonomic symptoms and certain psychotic phenomena. Other anxiety and depression symptoms were more frequently reported by informants. The results indicate that it is crucial for sensitive case detection to complete both interviews where possible. If the respondent cannot be interviewed, panic disorder or phobias may be particularly difficult to detect.

Validity of the schizophrenia diagnosis of the psychiatric assessment schedule for adults with developmental disability (PAS-ADD).

BACKGROUND: First rank symptoms are central to the diagnosis of schizophrenia, but their complexity makes it difficult to validly detect them in people with learning disability. This report investigates ability of PAS-ADD to detect schizophrenia, validated against expert clinical opinion. METHOD: The sample consisted of 98 patients with learning disabilities and a key informant for each sample member. Clinical opinions of the referring psychiatrists were sought using a symptom checklist. Reportage of remission, and the number of core schizophrenia symptoms identified, were used to estimate level of symptom activity at time of interview. RESULTS: The proportion of schizophrenia cases detected by PAS-ADD increases with the number of active core symptoms identified by the referrer. Where two or more core symptoms were indicated, PAS-ADD detected 71% cases. The most frequently fulfilled criterion was third-person auditory hallucinations. Six schizophrenia diagnoses disagreed with the clinician, four of which were referred as being hypomania. Overall symptom frequency detected by PAS-ADD was positively correlated with IQ. CONCLUSIONS: Results suggest there may be scope for modifying the ICD-10 diagnostic algorithm for use with learning disability, particularly in relation to the delusions and negative symptoms criteria.

Analysis of T cell repertoire and function in mice transgenic for the human V beta 3 TCR.

We have constructed mice containing the human V beta 3 TCR gene from the influenza virus haemagglutinin specific human CD4+ T cell clone HA1.7. Similar cell yields were obtained from transgenic and non-transgenic lymphoid tissue, with normal levels of T cells and with no unusual bias of the CD4 or CD8 subpopulations. Immunostaining and FACS analysis of transgenic thymocytes, spleen, and mesenteric lymph nodes revealed that the majority of T cells expressed the human V beta 3 TCR on the cell surface. Small numbers of cells expressing murine TCR beta chain were also detected. Polymerase chain reaction analysis revealed that an extensive V alpha TCR repertoire was used in the human V beta 3 transgenic mice. Lymphocytes from the spleen and mesenteric lymph nodes of transgenic mice were assessed for functional activity in vitro. Isolated cells were stimulated with mitogen or superantigen, as well as directly through the TCR-CD3 complex, and their ability to proliferate and secrete lymphokines analysed. Cells from transgenic mice responded well after stimulation with phytohaemagglutinin, concanavalin A, anti-CD3 antibody, anti-CD3 antibody with phorbol ester, and Staphylococcus aureus enterotoxin B, and also showed alloreactivity in a mixed lymphocyte reaction. Minimal levels of response were detected after stimulation with murine TCR beta antibody. Together, these data suggest that a human TCR beta chain is able to associate with a murine TCR alpha chain, to form a fully functional surface TCR-CD3 complex.

Psychiatric morbidity in older people with moderate and severe learning disability. I: Development and reliability of the patient interview (PAS-ADD).

This paper describes the development of the PAS-ADD, a semistructured clinical interview for use specifically with patients with learning disabilities, based on items drawn from the PSE. The PAS-ADD includes a number of novel features including: parallel interviewing of patient and informant; a three-tier structure to provide a flexible interview appropriate to the patient's intellectual level; use of a memorable 'anchor event' in the patient's life to improve time focus; and simplified wording, improved organisation and lay out. Inter-rater reliability was investigated using an experimental design in which two raters viewed and re-rated videotaped PAS-ADD interviews which had been conducted by an experienced clinician. Reliability results compared favourably with those obtained in a major study of PSE reliability with a sample drawn from non-learning disabled individuals. Mean kappa for all items was 0.72. Other indexes of reliability were also good. In the current phase of development, the PAS-ADD is to be expanded to include further diagnostic categories, including schizophrenia and autism. The new version will be updated for use with ICD-10 criteria.

Regulation of human T cell receptor beta gene expression by Ets-1.

Expression of the human TcR beta gene is controlled by an enhancer located 6kb 3' to the C beta 2 gene segment. The activity of this enhancer has been shown to be inducible with phorbol esters. Within the enhancer the beta E2 element is responsible for the major part of the inducibility, multimerised beta E2 alone is also highly phorbol ester inducible. The beta E2 element contains a consensus ets-binding site as well as a core motif, and we have shown that the beta E2 ets site binds both Ets-1 and Ets-2 in vitro and that purified core binding factor (CBF) can bind the core site present in beta E2. Mutations which specifically disrupt Ets-1 and Ets-2 binding abolish inducibility as well as reducing activity, whereas mutants which cannot bind CBF have only reduced basal activity. In Jurkat, which has a high level of endogenous Ets-1, multimerized beta E2 was inactive unless treated with PMA. However when transfected into cells with no detectable Ets-1 the beta E2 multimer was highly active in the absence of PMA. Co-transfection of an Ets-1 expression construct with the full enhancer into Jurkat cells led to a repression of enhancer activity, suggesting a repressive role for Ets-1. Co-transfection of Ets-1 was also able to repress strongly the activity of the beta E2 multimer. Repression of activity from both the full enhancer construct and the beta E2 multimer was most dramatic in the presence of PMA, suggesting that Ets-1 could block TcR beta activation. The Ets-1 expression construct used transactivated the HTLV-1 LTR which has also been shown to bind Ets-1. The repression of beta E2 activity by Ets-1 appears therefore to be specific. In conclusion, the combination of ets and core sites in beta E2 constitutes a novel inducible element, which is specifically transrepressed by Ets-1.

Generation of monoclonal antibodies against a human T cell receptor beta chain expressed in transgenic mice.

The generation of a panel of monoclonal antibodies specific for different variable (V) regions of human T cell receptors will be of great importance in the study of T cell-mediated diseases. However, relatively few such reagents exist, due in part to the poor immunogenicity of TcRs on the surface of human T cells. We have employed a strategy in which T cells from a transgenic mouse line expressing a human V beta 3 C beta 1 TcR were used to immunise syngeneic conventional mice to generate two monoclonal antibodies specific for human T cell receptors. Binding of antibody JOVI.3, which stained approximately 5% of human peripheral blood CD3 positive T cells, correlated with the expression of the human TcR V beta 3 gene segment. Antibody JOVI.1 recognised a determinant on the majority of TcRs, staining 50-75% of peripheral blood T cells and T cell lines expressing different V beta regions. Some TcRs, however, failed to react with this antibody. Both antibodies immunoprecipitated detergent-solubilised TcR molecules and were capable of inducing proliferation of peripheral blood T cells.

A phorbol ester response element within the human T-cell receptor beta-chain enhancer.

The activity of the T-cell receptor beta-chain gene enhancer is increased by activators of the protein kinase C pathway during T-cell activation. Analysis of mutant enhancer constructs identified two elements, beta E2 and beta E3, conferring phorbol ester inducibility. Multimerized beta E2 acted in isolation as a phorbol ester-responsive element. Both beta E2 and beta E3, which contain a consensus Ets-binding site, were shown to bind directly to the product of the c-ets-1 protooncogene. Both regions also bound a second factor, core-binding factor. Mutation of the beta E2 Ets site abolished the inducibility of the beta E2 multimer. beta E2 and beta E3 Ets site mutations also profoundly affected activity and inducibility of the enhancer. In contrast, enhancer activity but not its inducibility was affected by mutation of the beta E2 core-binding factor site. Cotransfection studies showed that Ets-1 specifically repressed activity of the multimerized beta E2 element and the complete T-cell receptor beta-chain enhancer. These data show that the T-cell receptor beta-chain enhancer responds to protein kinase C-mediated activation signals via a functional domain, composed of two elements, which contains binding sites for Ets transcription factors and which is negatively regulated by Ets-1.

TCF-1, a T cell-specific transcription factor of the HMG box family, interacts with sequence motifs in the TCR beta and TCR delta enhancers.

We have recently identified and cloned TCF-1, a T cell-specific transcription factor with specificity for the AACAAAG motif in the CD3 epsilon enhancer and for the TTCAAAG motif in the TCR alpha enhancer. TCF-1 belongs to the family of transcription-regulating proteins which share a region of homology termed the HMG-box. Here, we show by gel retardation analysis that TCF-1 specifically recognizes the T beta 5 element of the TCR beta enhancer and the T delta 7 element of the TCR delta enhancer. Comparison of the sequences of all elements recognized by TCF-1 defines a consensus motif A/T A/T C A A/G A G. These observations imply that TCF-1 is involved in the control of several T cell-specific genes and might thus play an important role in the establishment and maintenance of the mature T cell phenotype.

Identification and functional analysis of the transcriptional enhancer of the human T cell receptor beta gene.

The productive rearrangement and transcription of T cell receptor (TcR) beta genes is confined to T lymphocytes and is subject to both tissue-specific and developmental regulation. In addition to their function in transcriptional control, cis-acting elements are likely to play a role in the regulation of the rearrangement process. In this report we describe the location of a strong and inducible transcriptional enhancer 3' to the human TcR C beta 2 gene segment. The core enhancer, defined by deletion analysis using a transient transfection assay, resided within 362 bp of DNA. This enhancer core was able to activate transcription from a heterologous promoter and functioned well in T and B lymphocytes, but only minimally in HeLa cells. In contrast, a longer fragment containing the enhancer core showed marked T cell specificity. The enhancer was highly inducible by phorbol esters, the molecular basis for the inducibility residing within a 118-bp region of the enhancer core. This inducibility may be important in modulation of TcR beta gene expression during T cell differentiation and/or activation.