Characterization of two corneal epithelium-derived antigens associated with vasculitis

PURPOSE

In a previous investigation into corneal autoimmunity, it was demonstrated that a putative autoantigen, a protein of 66 kDa, present in bovine corneal epithelium, binds circulating autoantibodies in approximately 60% of patients with Wegener's granulomatosis (WG). The aim of the present study was to characterize and identify the 66-kDa protein.

METHODS

A purification protocol was established for the 66-kDa protein using standard chromatography techniques. During the purification procedure it became clear that the 66-kDa protein detected in patients' sera was in fact two proteins, both running at 66 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, that eluted in different fractions on DE-52 chromatography columns. These two proteins have been labeled bovine corneal epithelial antigen-A and -B (BCEA-A and BCEA-B). Further investigations of antibody binding have demonstrated that patients' sera bind to either one or the other of these proteins with no cross-reactivity between them. Separated BCEA-A and BCEA-B protein extracts were immunoblotted with 27 WG patients' sera, 10 Churg-Strauss syndrome (CSS) patients' sera, 31 rheumatoid arthritis (RA) patients' sera, and 40 healthy control subjects' sera from the blood bank.

RESULTS

Forty-six percent of WG patients' sera had antibodies to one of the 66-kDa antigens, whereas none of the healthy control subjects' sera had 66-kDa antibodies (P < 10(-5)). In the WG group, 31% were positive to BCEA-A (versus controls, P = 0.0023), and 15% were positive to BCEA-B. WG patients with peripheral ulcerative keratitis (PUK) had a significant association with anti-BCEA-A antibodies when compared with healthy control subjects (50%, P < 10(-6)). However, in the RA group with no eye disease there was an association with BCEA-A (25%, P = 0.011) but not in the RA group with PUK. The frequency of anti-BCEA-B antibodies was significantly increased in patients with CSS (60%, P < 10(-7)).

CONCLUSIONS

In summary, it has been shown that vasculitis patients have antibodies to two 66-kDa corneal antigens and that autoantibodies to these antigens are mutually exclusive. It has also been shown that antibodies to BCEA-B are associated with CSS, whereas BCEA-A antibodies are associated with WG and RA.

The Nottingham Longitudinal Study of Activity and Ageing: a methodological overview

OBJECTIVES

first, to describe the background and methodological approach to the assessment of customary physical activity, health and psycho-social status used by the Nottingham Longitudinal Study of Activity and Ageing; second, to provide information on the sampling strategy and survey response rates for three waves of data collection; and, third, to provide information on the reliability and validity of the survey assessments.

DESIGN

longitudinal study.

SUBJECTS

1042 people originally aged 65 and over, randomly sampled from general practitioner lists in Nottingham, UK.

METHODS

a descriptive overview of response rates (%), instrument reliability (alpha coefficients) and intercorrelations among measured outcomes (correlation coefficients and principal components analysis).

MAIN OUTCOME MEASURES

questionnaire-assessed levels of physical activity; instrumental measurements of handgrip strength, weight, demi-span and shoulder flexibility; brief assessments of depression, social engagement, life-satisfaction and cognitive impairment.

RESULTS

the study achieved a baseline (TI) response rate of 80%, with re-interview rates of 88% and 73% for T2 (1989) and T3 (1993) surveys respectively. For both men and women, factor scores derived from first principal components extracted from T1 survey data showed significant (r > or = 0.4; P < 0.001) product moment correlations with instrumental measurements of handgrip strength and shoulder flexibility. All the brief assessment measures showed satisfactory levels of reliability (alpha > or = 0.7).

Founder BRCA1 and BRCA2 mutations in French Canadian breast and ovarian cancer families

We have identified four mutations in each of the breast cancer-susceptibility genes, BRCA1 and BRCA2, in French Canadian breast cancer and breast/ovarian cancer families from Quebec. To identify founder effects, we examined independently ascertained French Canadian cancer families for the distribution of these eight mutations. Mutations were found in 41 of 97 families. Six of eight mutations were observed at least twice. The BRCA1 C4446T mutation was the most common mutation found, followed by the BRCA2 8765delAG mutation. Together, these mutations were found in 28 of 41 families identified to have a mutation. The odds of detection of any of the four BRCA1 mutations was 18.7x greater if one or more cases of ovarian cancer were also present in the family. The odds of detection of any of the four BRCA2 mutations was 5.3x greater if there were at least five cases of breast cancer in the family. Interestingly, the presence of a breast cancer case <36 years of age was strongly predictive of the presence of any of the eight mutations screened. Carriers of the same mutation, from different families, shared similar haplotypes, indicating that the mutant alleles were likely to be identical by descent for a mutation in the founder population. The identification of common BRCA1 and BRCA2 mutations will facilitate carrier detection in French Canadian breast cancer and breast/ovarian cancer families.

Food safety knowledge and practice among elderly people living at home

OBJECTIVE

To assess the food storage knowledge and practice of elderly people living at home.

METHODS

Three phase survey data collection: face to face interviews; dietary diaries with a food frequency questionnaire; and follow up interviews.

SETTING

Urban Nottingham.

PARTICIPANTS

809 elderly people (aged 65+) randomly selected from general practitioner lists.

MAIN OUTCOME MEASURES

Respondent's refrigerator temperature; knowledge of freezer star rating; understanding of "use by" and "sell by" dates; reported ability to read food product safety labels.

RESULTS

From a weighted total of 645 refrigerators measured, 451 (70%) were too warm for the safe storage of food (> or = 6 degrees Celsius). Only 41% of respondents (n = 279) knew the star rating of their freezer. Within a smaller sub-sample knowledge of the "use by" and "sell by" dates was good, but 45% of these respondents reported difficulty reading food labels. The storage of foods at inappropriate temperatures was not independent of socioeconomic or demographic status, and tended to be more likely among the poorer and those not living alone.

CONCLUSIONS

Food storage practices among the majority of elderly people interviewed in this study do not meet recommended safety standards to minimise the risk of food poisoning.

Genetic mapping of X-linked loci involved in skewing of X chromosome inactivation in the human

We have analyzed X-chromosome inactivation patterns in lymphocytes of 264 females from 38 families not known to have any genetic disease. Quantitative measures of X-inactivation showed strong sister-sister correlation in the degree of departure from equal numbers of cells having each X chromosome active, suggesting heritability of this phenotype. Strong sister-sister correlation was also observed for the fraction of cells having the same parent's X chromosome active, consistent with the possibility that this trait might be controlled by a cis-acting, X-linked gene. We used a sib-pair approach to determine whether X-inactivation phenotype was linked to loci in any region of the X chromosome. Both quantitative and discrete measures of X-inactivation phenotype showed evidence of linkage to markers in the region of the X inactivation center (XIC). The quantitative measure of X-inactivation phenotype used in our study also showed linkage to loci at Xq25-q26. This study provides the first evidence for X-linked inheritance of X chromosome inactivation phenotype derived from linkage analysis in phenotypically normal human families.

Fruit and vegetable consumption in later life

OBJECTIVE

to assess levels of fruit and vegetable consumption in elderly people, and to examine the socio-economic, physical and psychological factors which influence this consumption.

METHODS

a three-phase survey: face to face interviews; self-completed dietary diaries with a food frequency questionnaire; and follow-up face-to-face interviews.

PARTICIPANTS

445 elderly people (aged 65+) randomly selected from general practitioner lists in urban Nottingham and rural Nottinghamshire, Lincolnshire and Leicestershire.

RESULTS

the recommended target of five portions of fruit and vegetables a day was achieved by less than half the respondents: 37% of those living in the urban area and 51% of those living in the rural area. Low fruit and vegetable consumption was particularly associated with being male, smoking and having low levels of social engagement.

CONCLUSIONS

most elderly people consume less than the recommended levels of fruit and vegetables. Health programmes promoting fruit and vegetable consumption may not be successfully reaching elderly people and need to target those particularly at risk of low consumption.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay

A form of autosomal recessive spastic ataxia unique to the Charlevoix-Saguenay area was clinically identified 20 years ago in patients from that region. This region of Québec, Canada, was once considered a genetic isolate. First noted at gait initiation, signs of ataxia slowly progress along with spasticity of the four limbs, slurred speech, and followed by distal amyotrophy. Early diagnosis relies on the presence of prominent myelinated fibers embedding retinal blood vessels at funduscopy and marked saccadic alteration of ocular smooth pursuit. Imaging of the posterior fossa shows cerebellar vermis atrophy and nerve conduction studies reveal loss of sensory and reduced motor conduction velocities. The clinical features are consistent with a developmental defect in myelination of both retinal and peripheral nerve fibers. The cause of this defect and the progressive axonal degeneration in the corticospinal and spinocerebellar tracts, as well as in the peripheral nerves is still unknown. Results of recent molecular genetic linkage analysis have located the gene locus to chromosome 13q12. Further research is needed to define where this hereditary spastic ataxia stands in the classification of the early onset spinocerebellar degenerations.

Association and linkage of LDLR gene variation with variation in plasma low density lipoprotein cholesterol

The role of common variation in the low density lipoprotein (LDL) receptor gene (LDLR) as a determinant of variation in plasma LDL cholesterol in normolipidemic populations is not well established. To address this question, we used both association and linkage analysis to evaluate the relationship between plasma LDL cholesterol and genetic variation in LDLR and in three other candidate genes for lipoprotein metabolism, namely, APOE, PONI, and LPL. We studied a sample of 719 normolipidemic Alberta Hutterites, who comprised 1217 sib pairs. Variation in each of the four candidate genes was significantly associated with variation in plasma LDL cholesterol, but the average effects of the alleles were small. In contrast, sib pair analysis showed that only the LDLR gene variation was linked with variation in plasma LDL cholesterol (P = 0.026). Thus, the common LDLR gene variation was both associated with and linked to variation in plasma LDL cholesterol, suggesting that there is a functional impact of structural variation in LDLR on plasma LDL cholesterol in this study sample. However, the absence of linkage of variation in LDL cholesterol with the other three candidate genes, in particular APOE, is consistent with a lower sensitivity of linkage analysis compared with association analysis for detecting modest effects on quantitative traits. Attributes such as the genetic structure of the study sample, the amount of variance attributable to the locus, and the information content of the marker appear to affect the ability to detect genotype-phenotype relationships using linkage analysis.

Aging and lymphocyte subpopulations: whole-blood analysis of immune markers in a large population sample of healthy elderly individuals

Immune status was determined in a representative sample of elderly people by measuring lymphocyte subsets in whole-blood samples as part of an epidemiological study of the population aged 65 and over. Venepuncture was undertaken in more than 500 individuals who took part in an extensive interview that focused on the lifestyle and psychosocial determinants of healthy aging. The results show that median levels of all lymphocyte subsets tend to decline as the age of the sample increases. In the total sample there were significant age effects (p < 0.05) on total lymphocytes, CD3, CD4, and CD19 (B cells); age differences did not reach significance for CD8 and CD57. There were also significant sex differences (p < 0.05) on CD3, CD4, and CD19, and in all cases women had higher values than men. When we selected a particularly healthy subsample who did not report any illness and took no medication, the findings were unchanged. We conclude that the peripheral expression of lymphocytes appears little affected by aging-related illnesses in the general population, but is affected by aging itself. The study provides reference values for the lymphocyte measures, which can be regarded as having greater validity than the values usually cited.

Growth response of human coronary smooth muscle cells to angiotensin II and influence of angiotensin AT1 receptor blockade

BACKGROUND

The renin-angiotensin system has been implicated in the development of vascular wall thickening in cardiovascular disease, through the growth-promoting actions of the vasoconstrictive agent, angiotensin II, on vascular smooth muscle cells.

OBJECTIVE

To investigate the effect of angiotensin II on growth of human coronary artery smooth muscle cells (cSMCs) in culture, and to identify the angiotensin receptor(s) mediating such a response.

METHODS

Human cSMCs were isolated from coronary arteries of recipient hearts obtained during transplantation, and characterized by immunohistochemistry. The effect of angiotensin II on protein synthesis by cSMCs was measured by [3H]leucine incorporation and protein concentration assays. Human cSMC proliferation was assessed by [3H]thymidine incorporation assay and cell count. Reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect angiotensin receptor expression. Transient increases in intracellular calcium concentration in cSMCs in response to angiotensin II stimulation were visualized under fura-2 fluorescence microscopy.

RESULTS

Angiotensin II (1 nmol/l-10 mumol/l) stimulated protein synthesis in cSMCs (maximum 24 +/- 2% increase in incorporation of [3H]leucine over 48 h; n = 4, P < 0.01). An increase in cellular protein content was also measured. However, angiotensin II had no effect on proliferation of quiescent cSMCs. The increased protein synthesis was completely inhibited by pretreatment with the angiotensin AT1 receptor antagonist, losartan, but not the AT2 receptor antagonist, PD123319. Expression of the angiotensin AT1 receptor subtype was detected in cSMCs by RT-PCR. Angiotensin II stimulation of cells triggered transient increases in intracellular calcium concentration, which were abolished by losartan, but were insensitive to PD123319 and pertussis toxin.

CONCLUSIONS

The results of this study in human coronary VSMCs indicate that angiotensin II and the AT1 receptor may be involved in the development of coronary artery disease in man.

A gene for autosomal recessive limb-girdle muscular dystrophy in Manitoba Hutterites maps to chromosome region 9q31-q33: evidence for another limb-girdle muscular dystrophy locus

Characterized by proximal muscle weakness and wasting, limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of clinical disorders. Previous reports have documented either autosomal dominant or autosomal recessive modes of inheritance, with genetic linkage studies providing evidence for the existence of at least 12 distinct loci. Gene products have been identified for five genes responsible for autosomal recessive forms of the disorder. We performed a genome scan using pooled DNA from a large Hutterite kindred in which the affected members display a mild form of autosomal recessive LGMD. A total of 200 markers were used to screen pools of DNA from patients and their siblings. Linkage between the LGMD locus and D9S302 (maximum LOD score 5.99 at recombination fraction .03) was established. Since this marker resides within the chromosomal region known to harbor the gene causing Fukuyama congenital muscular dystrophy (FCMD), we expanded our investigations, to include additional markers in chromosome region 9q31-q34.1. Haplotype analysis revealed five recombinations that place the LGMD locus distal to the FCMD locus. The LGMD locus maps close to D9S934 (maximum multipoint LOD score 7.61) in a region that is estimated to be approximately 4.4 Mb (Genetic Location Database composite map). On the basis of an inferred ancestral recombination, the gene may lie in a 300-kb region between D9S302 and D9S934. Our results provide compelling evidence that yet another gene is involved in LGMD; we suggest that it be named "LGMD2H."

An aquaporin-2 water channel mutant which causes autosomal dominant nephrogenic diabetes insipidus is retained in the Golgi complex

Mutations in the aquaporin-2 (AQP2) water channel gene cause autosomal recessive nephrogenic diabetes insipidus (NDI). Here we report the first patient with an autosomal dominant form of NDI, which is caused by a G866A transition in the AQP2 gene of one allele, resulting in a E258K substitution in the C-tail of AQP2. To define the molecular cause of NDI in this patient, AQP2-E258K was studied in Xenopus oocytes. In contrast to wild-type AQP2, AQP2-E258K conferred a small increase in water permeability, caused by a reduced expression at the plasma membrane. Coexpression of wild-type AQP2 with AQP2-E258K, but not with an AQP2 mutant in recessive NDI (AQP2-R187C), revealed a dominant-negative effect on the water permeability conferred by wild-type AQP2. The physiologically important phosphorylation of S256 by protein kinase A was not affected by the E258K mutation. Immunoblot and microscopic analyses revealed that AQP2-E258K was, in contrast to AQP2 mutants in recessive NDI, not retarded in the endoplasmic reticulum, but retained in the Golgi compartment. Since AQPs are thought to tetramerize, the retention of AQP2-E258K together with wild-type AQP2 in mixed tetramers in the Golgi compartment is a likely explanation for the dominant inheritance of NDI in this patient.

Parental origin-dependent, male offspring-specific transmission-ratio distortion at loci on the human X chromosome

We have analyzed the transmission of maternal alleles at loci spanning the length of the X chromosome in 47 normal, genetic disease-free families. We found a significant deviation from the expected Mendelian 1:1 ratio of grandpaternal:grandmaternal alleles at loci in Xp11.4-p21.1. The distortion in inheritance ratio was found only among male offspring and was manifested as a strong bias in favor of the inheritance of the alleles of the maternal grandfather. We found no evidence for significant heterogeneity among the families, which implies that the major determinant involved in the generation of the non-Mendelian ratio is epigenetic. Our analysis of recombinant chromosomes inherited by male offspring indicates that an 11.6-cM interval on the short arm of the X chromosome, bounded by DXS538 and DXS7, contains an imprinted gene that affects the survival of male embryos.

The Drosophila esc and E(z) proteins are direct partners in polycomb group-mediated repression

The extra sex combs (esc) and Enhancer of zeste [E(z)] proteins are members of the Drosophila Polycomb group (Pc-G) of transcriptional repressors. Here we present evidence for direct physical interaction between the esc and E(z) proteins using yeast two-hybrid and in vitro binding assays. In addition, coimmunoprecipitation from embryo extracts demonstrates association of esc and E(z) in vivo. We have delimited the esc-binding domain of E(z) to an N-terminal 33-amino-acid region. Furthermore, we demonstrate that site-directed mutations in the esc protein previously shown to impair esc function in vivo disrupt esc-E(z) interactions in vitro. We also show an in vitro interaction between the heed and EZH1 proteins, which are human homologs of esc and E(z), respectively. These results suggest that the esc-E(z) molecular partnership has been conserved in evolution. Previous studies suggested that esc is primarily involved in the early stages of Pc-G-mediated silencing during embryogenesis. However, E(z) is continuously required in order to maintain chromosome binding by other Pc-G proteins. In light of these earlier observations and the molecular data presented here, we discuss how esc-E(z) protein complexes may contribute to transcriptional silencing by the Pc-G.

A salmonellosis outbreak linked to internally contaminated pork meat

In August 1995, we investigated an outbreak of salmonellosis among patrons who attended a church camp in southern Sydney. Of the 73 attendees interviewed, 22 reported a gastroenteritis illness within two days of the conclusion of the camp, with one attendee hospitalised. Two stool specimens, one from each of two attendees, were both positive for Salmonella typhimurium phage type 9. A cohort study of 68 attendees established a statistically significant association between illness and the consumption of de-boned roast pork (estimated relative risk infinite, p = 0.03) and between illness and the degree of cooking of the pork meat (chi 2 for trend 5.8, p < 0.02). The outbreak was most likely caused by consumption of roast pork that had been internally contaminated during the de-boning process. Meat and meat products that may be internally contaminated, such as de-boned meats, should be thoroughly cooked. Guidelines about minimum cooking temperatures of meats liable to internal contamination should be developed for commercial food handlers in Australia.

Lack of inducible nitric oxide synthase in bronchial epithelium: a possible mechanism of susceptibility to infection in cystic fibrosis

Cystic fibrosis (CF) is an inherited disorder associated with severe inflammation and repeated bacterial infection and colonization in the lung. Airway epithelium is involved in defence against bacteria, but this system may be defective in CF. Pro-inflammatory cytokines can stimulate the expression of inducible nitric oxide synthase (iNOS), an enzyme generating nitric oxide, which functions as an important mediator in host defence mechanisms. To understand better the poor resistance to infections in the CF lung, the expression of the iNOS gene was investigated in explanted lungs from patients with cystic fibrosis (n = 13), bronchiectasis (n = 3), emphysema (n = 14), and in normal lungs (n = 8). In addition, bronchial epithelial cell lines were examined to study iNOS gene expression in vitro. Strong immunoreactivity for iNOS was seen in inflammatory cells and bronchial epithelium in all the diseased lungs, except for bronchial epithelium in CF. Quantitative analysis showed a significant reduction in the area of epithelium immunostained in CF [CF 6.8 +/- 1.6 (% +/- SEM); emphysema 18.2 +/- 2.8; normal 9.6 +/- 0.8, P < 0.01], regardless of steroid treatment. These results were supported by in situ hybridization of iNOS mRNA, which showed a pattern of gene expression in CF, emphysema, and normal lung which paralleled that of protein immunoreactivity. Stimulation with cytokines (IL-1 beta, TNF-alpha, and IFN-gamma) increased the expression of iNOS mRNA detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in cultures of normal (16HBE14o-), but not CF (CFBE41o-, with delta F508 CFTR mutation) epithelial cells. Expression of iNOS in inflammatory cells suggests that the gene is normal in CF. Absence of iNOS from bronchial epithelium may be due to low expression of the gene resulting from abnormalities in the signalling system that normally causes induction, such as cytokine receptors, second messengers or transcription factors. The resulting deficiency of the nitric oxide defence system may be relevant to the susceptibility of CF patients to pulmonary bacterial colonization.

Gender and living alone as determinants of fruit and vegetable consumption among the elderly living at home in urban Nottingham

Consumption of fruits and vegetables by a sample of 369 elderly people living in Nottingham, England, was analysed in relation to whether or not they were eating five portions a day. Living status was only of significance to men who, if single, consumed 2.66 portions of fruits and vegetables per day compared with an overall mean of 4.1. The salient question is therefore not "Are you living alone?" but " s there a woman in the household?". Those respondents who were older and less educated ate less vegetables and those respondents who had a lower income or social grade ate less fruit. Men were less likely to be able to cook a range of meals, to have had a job that involved cooking or to watch cookery programmes on television. Single men were more likely than single women to say that eating food that was easy to cook and prepare was an important influence on their food choice. Single women on the other hand were more influenced by body image. Finding foods that were the right portion size and easy to open, prepare and cook was more important to single men than married men, as was the amount of money left after paying the bills.

Mapping of genetic modulators of natural resistance to infection with Salmonella typhimurium in wild-derived mice

Despite antibiotic therapy and vaccination programs, microbial diseases continue to be the leading cause of morbidity and mortality worldwide. The genetic basis of the host response to infection is complex, and its understanding has been facilitated through the study of mouse models of human infectious diseases. Genetic variation in resistance of mice to infection with Salmonella typhimurium has been recognized for over 50 years and shown to be a multifactorial trait. We have studied the genetic basis of resistance or susceptibility to infection with S. typhimurium in the wild-derived inbred mouse Mus musculus molossinus (MOLF/Ei). MOLF/Ei mice are extremely susceptible to infection with S. typhimurium despite the presence of resistance alleles at Nramp1 and Lps. To identify genes that modulate the expression of natural resistance or susceptibility to infection with S. typhimurium in MOLF/Ei, we have performed a genome-wide study using an F2 intercross between C56BL/6J and MOLF/Ei inbred mice. We have mapped three QTLs that significantly affect survival time following lethal infection with S. typhimurium. The Salmonella-resistant phenotype was linked to Nramp1 on proximal chromosome 1 (maximum lod score of 18.8 at D1Mcg4) and to a newly mapped region on mouse chromosome 11 (maximum lod score of 7.0 at D11Mit5). The third QTL conferred recessive susceptibility and was located on mouse chromosome 1, approximately 25 cM distal to Nramp1 (maximum lod score of 4.8 at D1Mit100).

Differential distribution of angiotensin AT2 receptors in the normal and failing human heart

Cardiac expression of angiotensin II (Ang II) AT1 and AT2 receptor subtypes is species dependent, and changes in their relative proportion may influence myocardial hypertrophy and fibrosis. Regional differences in the distribution of Ang II receptors in the normal and failing human heart were assessed using 125I-(Sar1,Ile8)Ang II binding and quantitative autoradiography. Receptor subtypes were distinguished by their affinity for selective nonpeptide antagonists (losartan and PD123319) and sensitivity to dithiothreitol. Ventricular and atrial tissues displayed a heterogeneous distribution of ligand binding sites. AT2 receptors predominated, representing 70% to 77% of the sites in normal and noninfarcted myocardium. Endocardial, interstitial, perivascular and infarcted regions in the ventricles of patients with end-stage ischemic heart disease or dilated cardiomyopathy exhibited a significantly greater density (P < .001) of high affinity AT2 binding sites (Kd = 0.57 nmol/liter) compared with adjacent noninfarcted myocardium. Regions displaying the relative increase in AT2 binding sites corresponded to areas of fibroblast proliferation and collagen deposition, shown by picrosirius red staining. AT1 binding sites were localized to nerves, occurred at relatively low density in coronary vessels and represented only 23% to 29% of myocardial 125I-(Sar1,Ile8)Ang II binding sites. The border zone between infarcted and noninfarcted myocardium characteristically contained numerous microvessels, exhibiting perivascular AT2 receptors and endothelial angiotensin converting enzyme activity, as demonstrated by binding of 125I-351A. Specific myocardial AT2 receptor mRNA transcripts (approximately 3 kb) were identified and exhibited alternative splicing of untranslated 5' exons. The differential distribution of cardiac Ang II receptor subtypes and selective increase in binding to AT2 sites in the diseased heart suggest that cells bearing the AT2 receptor represent a significant target for Ang II, possibly contributing to its growth-related actions.

Regulation of the serine proteinase inhibitor (SERPIN) gene alpha 1-antitrypsin: a paradigm for other SERPINs

alpha 1-antitrypsin (AAT) is the archetypal member of the serine proteinase inhibitor (SERPIN) gene family. AAT is an acute-phase reactant and the plasma concentration increases three- to four-fold during the inflammatory response. In hepatocytes this increase is mediated primarily by the cytokine interleukin-6 (IL-6) via the transcription factor NF-IL6. The AAT gene contains at least two enhancer elements, one at the 5' end of the gene and the other at the 3' end. Functional studies performed in mammalian hepatoma cells (Hep G2) using constructs containing these AAT enhancer regions linked to a reporter gene have demonstrated that the 5' enhancer is dominant under basal conditions and that, following stimulation with IL-6, both enhancers are essential and the 3' enhancer plays a major role. We have identified a mutation associated with lung disease which occurs in the 3' AAT enhancer; the mutation occurs at a binding site for the ubiquitous transcription factor Oct-1. The functional significance of this mutation is a deficient IL-6 response. Using the AAT gene as a model, we describe the interactions which occur between transcription factors within the 3' enhancer and also those which take place between the 5' and 3' enhancers. These studies shed light on the molecular mechanism of the acute-phase response which could possibly be extended to other members of the SERPIN gene family.