Rhizarthrosis in banknote processing workers: a retrospective cohort study.

BACKGROUND: Rhizarthrosis, or osteoarthritis of the base of the thumb, is a common condition affecting 10-30% of the population over the age of 60. Whether it is an occupational disease has been the subject of debate as epidemiological studies on the correlation between physical stress and the presence of rhizarthrosis have shown conflicting results. AIMS: To study the correlation between the prevalence of rhizarthrosis and the time spent by employees manually processing banknotes at the National Bank of Belgium (NBB). METHODS: We followed NBB employees currently or previously holding job titles involving the manual or automated processing of banknotes. Each participant's job history was carefully reconstructed and the number of months holding certain job titles determined. Each participant was clinically and radiologically examined for the presence of rhizarthrosis in both hands. Its presence was scored by a combination of clinical and radiological criteria. RESULTS: There were 195 participants. The prevalence of rhizarthrosis was 27% in women (mean age: 52.3 ± 4.4 years) and 17% in men (mean age: 53.2). The odds ratio (OR) for rhizarthrosis after 10 years' full-time overall exposure was significantly higher [OR 10 years: 1.53 (1.03-2.28)]. However, one particular job, 'manual counting', described by participants as highly straining and severely taxing on the thumbs, did not show a significantly higher prevalence of rhizarthrosis. CONCLUSIONS: Our study confirmed the correlation between the presence of rhizarthrosis and age, gender and general manual labour, in particular banknote processing, but found no link with one specific job-manual counting.

Influence of nucleophosmin/B23 on DNA binding and transcriptional activity of the androgen receptor in prostate cancer cell.

The promotion and progression of prostate cancer (PCa) are associated with androgen receptor (AR) signalling. AR functions are modulated by a variety of co-factors amongst which we identified the nucleophosmin (NPM/B23), a member of the histone chaperone family. Here, we show that NPM is overexpressed in PCa compared to normal adjacent tissues. AR and NPM interact in vitro and in vivo, and NPM is critical for androgen-dependent transcriptional activation in LNCaP cells as an anti-NPM siRNA downregulates transcription of a transfected androgen response element (ARE)-containing reporter promoter as well as expression of the endogenous androgen responsive prostate-specific antigen (PSA) gene. By investigating the effect of NPM on AR, we have also observed that NPM enhances AR binding to an ARE in vitro in electrophoretic gel mobility-shift assay experiments. Chromatin immunoprecipitation studies further demonstrated that both AR and NPM associate with AREs of the PSA gene in vivo. Altogether, our data suggest that the molecular histone chaperone NPM could regulate AR functions by promoting assembly of AR-containing regulatory complexes and that high levels of NPM might alter AR functions in PCa.

The androgen receptor DNA-binding domain determines androgen selectivity of transcriptional response.

The AR (androgen receptor) is a hormone-dependent transcription factor that translates circulating androgen hormone levels into a physiological cellular response by directly regulating the expression of its target genes. It is the key molecule in e.g. the development and maintenance of the male sexual characteristics, spermatocyte production and prostate gland development and growth. It is also a major factor in the onset and maintenance of prostate cancer and a first target for pharmaceutical action against the further proliferation of prostate cancer cells. The AR is a member of the steroid hormone receptors, a group of steroid-inducible transcription factors sharing an identical consensus DNA-binding motif. The problem of how specificity in gene activation is achieved among the different members of this nuclear receptor subfamily is still unclear. In this report, we describe our investigations on how the AR can specifically activate its target genes, while the other steroid hormone receptors do not, despite having the same consensus monomeric DNA-binding motif. In this respect, we describe how the AR interacts with a newly identified class of steroid-response elements to which only the AR and not, for example, the glucocorticoid receptor can bind.

Differential effect of small ubiquitin-like modifier (SUMO)-ylation of the androgen receptor in the control of cooperativity on selective versus canonical response elements.

The androgen receptor (AR) can be small ubiquitin-like modifier (SUMO)-ylated in its amino-terminal domain at lysines 385 and 511. This SUMO-ylation is responsive to several agonists, but is not induced by the pure antagonist hydroxyflutamide. We show that the main site of interaction of Ubc9, the SUMO-1 conjugating enzyme, resides in transcription activation unit 5. Overexpression of SUMO-1 represses the AR-mediated transcription, and this effect is abolished after mutating both SUMO-1 acceptor sites. On the other hand, the mutation of lysine 385 clearly affects the cooperativity of the receptor on multiple hormone response elements. Lysine 511 is not implicated in this function. Surprisingly, these effects on cooperativity clearly depend on the nature of the response elements. When selective androgen response elements, which are organized as direct repeats of 5'-TGTTCT-3'-like sequences, were tested, the lysine 385 mutation did not increase the androgen response. Point mutations changing the direct-repeat elements into inverted-repeat elements restored the effects of the lysine 385 mutation on cooperativity. In conclusion, SUMO-ylation of the AR might have a differential function in the control of cooperativity, depending on the conformation of the AR dimer bound to DNA.

Anti-androgenic properties of Compound A, an analog of a non-steroidal plant compound.

We investigated the interactions between Compound A (CpdA), an analog of a hydroxyphenyl aziridine precursor found in an African shrub, and the androgen receptor (AR). CpdA represses androgen-induced activation of both specific and non-specific androgen DNA response elements. While a similar effect was obtained for the progesterone receptor (PR) via a non-specific hormone response element, CpdA had no effect on the actions of the glucocorticoid and mineralocorticoid receptors. CpdA represses the ligand-dependent interaction between the NH(2)- and COOH-terminal domains of the AR, similar to well-characterised anti-androgens. CpdA also interferes with the interaction of steroid receptor co-activator 1 (SRC1) with the activation domain AF2 but not with AF1. However, CpdA does not compete with androgen for binding to the AR. These results demonstrate that CpdA elicits anti-androgenic actions by a mechanism other than competitive binding for the AR.

Tissue-specific androgen responses in primary cultures of lacrimal epithelial cells studied by adenoviral gene transfer.

The lacrimal gland secretes most of the water and many proteins present in tear fluid. The composition of the tear fluid is affected dramatically by androgens, an observation which has been linked to the fact that more than 90% of the patients with Sjögren syndrome are female. Although the presence of androgen receptors in the lacrimal gland has been established, the molecular biology of the protective effects of androgens remains largely unknown. Here, we report the use of primary cultures of the lacrimal gland which express endogenous proteins under androgen control, as a more homologous test system for tissue-specific transcription studies. Infection with recombinant adenoviral vectors was the most efficient method to introduce foreign gene constructs in these cultures. A thus introduced mouse mammary tumor virus promoter was inducible with androgens and this effect was independent of the sexual genotype of the infected cells. By use of two recombinant adenoviral vectors containing genomic fragments of the SC gene, which is androgen responsive in the lacrimal gland, we could demonstrate the functionality of the sc promoter as well as its androgen regulation in this culture system.

Selective DNA binding by the androgen receptor as a mechanism for hormone-specific gene regulation.

Steroid hormones control many physiological processes by activating specific receptors that act as transcription factors. In vivo, each of these receptors has a specific set of target genes, but in vitro the glucocorticoid, progesterone, mineralocorticoid and androgen receptors (class I receptors) all recognise response elements which are organised as inverted repeats of 5'-TGTTCT-3'-like sequences with a three nucleotide spacer. This poses the question how the in vivo specificity of the different steroid responses is mediated. To unravel the mechanisms involved, we have compared the structural features of the androgen-selective enhancers of the probasin, the secretory component and the sex-limited protein genes with those of non-selective enhancers in the mouse mammary tumour viral promoter and the C3(1) gene. The probasin promoter contains an androgen response element which is recognised with high affinity by the androgen receptor, but not by the other class I receptors. Swapping experiments between the DNA-binding domains of the androgen and glucocorticoid receptor revealed that it is not the first zinc finger, but rather the second zinc finger and part of the hinge region which contribute to this specificity. Three AR-specific aminoacids are involved in the probasin ARE recognition, but not in the C3(1) ARE binding by the AR. The location of these residues strongly suggests that an alternative dimerisation interface is involved in the probasin ARE binding. We could subsequently demonstrate that the AR binds direct repeats of 5'-TGTTCT-3'-like sequences in gel retardation assays as well as in transfection experiments. Moreover, the androgen-specific enhancers all contain direct repeats, and point mutations that change the nature of these elements into inverted repeats result in a change of specificity. It seems, therefore, that direct repeat elements can be the determinants of the AR-specificity. It will be exciting to learn how such DNA elements will affect the properties of the receptor dimer with respect to ligand binding, interactions between the aminoterminal domain and the ligand-binding domain, the recruitement of co-activators and cooperativity with other transcription factors.

Androgen-receptor-specific DNA binding to an element in the first exon of the human secretory component gene.

Androgens and glucocorticoids are steroid hormones, which exert their effects in vivo by binding and activating their cognate receptors. These intracellular receptors are transcription factors that can bind specific DNA sequences, called hormone response elements, located near the target genes. Although the androgen receptor (AR) and the glucocorticoid receptor (GR) bind the same consensus DNA sequence, androgen-specific responses can be achieved by non-conventional androgen response elements (AREs). Here we determine the specificity mechanism of such a selective element recently identified in the first exon of the human gene for secretory component (sc ARE). This sc ARE consists of two receptor-binding hexamers separated by three nucleotides. The DNA-binding domains of the AR and GR both bind the sc ARE, but, although the AR fragment dimerizes on the element, the GR fragment does not. Comparing the affinities of the DNA-binding domains for mutant forms of the sc ARE revealed that dimeric GR binding is actively excluded by the left hexamer and more precisely by the presence of a G residue at position -3, relative to the central spacer nucleotide. Inserting a G at this position changed a non-selective element into an androgen-selective one. We postulate that the AR recognizes the sc ARE as a direct repeat of two 5'-TGTTCT-3'-like core sequences instead of the classical inverted repeat. Direct repeat binding is not possible for the GR, thus explaining the selectivity of the sc ARE. This alternative dimerization by the AR on the sc ARE is also indicated by the DNA-binding characteristics of receptor fragments in which the dimerization interfaces were swapped. In addition, the flanking and spacer sequences seem to affect the functionality of the sc ARE.

Differences in DNA binding characteristics of the androgen and glucocorticoid receptors can determine hormone-specific responses.

The basis for specificity of gene regulation by steroid hormone receptors remains an important problem in the study of steroid hormone action. One possible mechanism for steroid specificity is the difference in DNA binding characteristics of the receptors, although they share a high homology in their DNA-binding domains. Indeed, the androgen-specific expression of, for example, the probasin (PB) gene can be explained by the presence of an androgen response element (ARE) in its promoter (PB-ARE-2), specifically recognized by the androgen and not by the glucocorticoid receptor. Three residues in the DNA-binding domain of the AR were identified as main determinants for its high affinity for the PB-ARE-2. In addition, the direct repeat nature of this ARE seems to prohibit high affinity binding by the glucocorticoid receptor. This is confirmed by the fact that several imperfect direct repeats of the 5'-TGTTCT-3' core recognition sequence are recognized by the androgen receptor and not by the glucocorticoid receptor. Up to now, only differences between the androgen and glucocorticoid receptor in the transcription activation functions were invoked to explain the specificity of their genomic actions. In the present study, we describe the influence of the DNA-binding domain on the specificity of androgen action. The novelty of our working hypothesis resides in the demonstration of the capacity of the AR-DNA-binding domain to recognize elements with a direct repeat structure.

Change of specificity mutations in androgen-selective enhancers. Evidence for a role of differential DNA binding by the androgen receptor.

The androgen and glucocorticoid receptors recognize identical DNA motifs, leaving unanswered the question of how steroid specificity of transcriptional regulation is established in cells containing both receptors. Here, we provide evidence that subtle differences in low affinity DNA recognition might be a crucial element in the generation of steroid-specific responses. Here we identify simple hormone response elements in the mouse sex-limited protein enhancer and the human secretory component androgen response unit to be essential for the androgen specificity of both enhancers. We describe specific in vitro binding to these motifs by the DNA-binding domain of the androgen but not the glucocorticoid receptor. Both elements can be considered partial direct repeats of the 5'-TGTTCT-3' core binding motif. In addition, we show that specific point mutations in their left half-sites, essentially changing the nature of the repeats, strongly enhance the glucocorticoid sensitivity of the respective enhancers, whereas they have no effect on their androgen responsiveness. Accordingly, these mutations allow specific binding of the glucocorticoid receptor DNA-binding domain to both elements in vitro. With these experiments, we demonstrate that differential recognition by the androgen receptor of nonconventional steroid response elements is, at least in some cases, an important mechanism in androgen-specific transcriptional regulation.

Androgen specificity of a response unit upstream of the human secretory component gene is mediated by differential receptor binding to an essential androgen response element.

The expression of secretory component (SC), the epithelial receptor for poly-immunoglobulins, is regulated in a highly tissue-specific manner. In several tissues, e.g. lacrimal gland and prostate, SC synthesis is enhanced by androgens at the transcriptional level. In this study, we describe the presence of an androgen response unit, located 3.3 kb upstream of the sc transcription initiation site and containing several 5'-TGTTCT-3'-like motifs. Although each of these elements is implicated in the enhancer function, one element, the ARE1.2 motif, is found to be the main interaction site for the androgen receptor as demonstrated in in vitro binding assays as well as in transient transfection assays. A high-affinity binding site for nuclear factor I, adjacent to this ARE, is also involved in the correct functioning of the sc upstream enhancer. The ARE1.2 motif consists of an imperfect direct repeat of two core binding elements with a three-nucleotide spacer and therefore constitutes a nonconventional ARE. We demonstrate that this element displays selectivity for the androgen receptor as opposed to glucocorticoid receptor both in in vitro binding assays and in transfection experiments. Mutational analysis suggests that the direct nature of the half-site repeat is responsible for this selectivity. We have thus determined a complex and androgen-specific response unit in the far upstream region of the human SC gene, which we believe to be involved in its androgen responsiveness in epithelial cells of different organs such as prostate and lacrimal gland. We were also able to demonstrate that the primary sequence of a single nonconventional ARE motif within the enhancer is responsible for its androgen specificity.

The first exon of the human sc gene contains an androgen responsive unit and an interferon regulatory factor element.

Secretory component (SC) plays a key role in the transport of IgA and IgM to the lumina of many glands. The gene is constitutively expressed, but can be modulated by hormonal and immunological stimuli. Recently, the promoter and the first exon of the human sc gene have been cloned. The first exon contains a putative androgen/glucocorticoid response element (ARE/GRE) and an Interferon Regulatory Factor Element (IRF-E). Here we show that the ARE/GRE can bind the DNA-binding domain (DBD) of both the androgen (AR) and glucocorticoid receptor (GR) with a preference for the AR-DBD. In transient transfection experiments, this element confers higher responsiveness to androgens than to glucocorticoids. The IRF-E can function as an IRF-2, but surprisingly not as an IRF-I responsive element. We postulate that these two regulatory elements play a key role in the complex regulation of the sc gene in vivo.

Differential DNA binding by the androgen and glucocorticoid receptors involves the second Zn-finger and a C-terminal extension of the DNA-binding domains.

The androgen and glucocorticoid hormones evoke specific in vivo responses by activating different sets of responsive genes. Although the consensus sequences of the glucocorticoid and androgen response elements are very similar, this in vivo specificity can in some cases be explained by differences in DNA recognition between both receptors. This has clearly been demonstrated for the androgen response element PB-ARE-2 described in the promoter of the rat probasin gene. Swapping of different fragments between the androgen- and glucocorticoid-receptor DNA-binding domains demonstrates that (i) the first Zn-finger module is not involved in this sequence selectivity and (ii) that residues in the second Zn-finger as well as a C-terminal extension of the DNA-binding domain from the androgen receptor are required. For specific and high-affinity binding to response elements, the DNA-binding domains of the androgen and glucocorticoid receptors need a different C-terminal extension. The glucocorticoid receptor requires 12 C-terminal amino acids for high affinity DNA binding, while the androgen receptor only involves four residues. However, for specific recognition of the PB-ARE-2, the androgen receptor also requires 12 C-terminal residues. Our data demonstrate that the mechanism by which the androgen receptor binds selectively to the PB-ARE-2 is different from that used by the glucocorticoid receptor to bind a consensus response element. We would like to suggest that the androgen receptor recognizes response elements as a direct repeat rather than the classical inverted repeat.

Characterization of the human secretory component gene promoter.

Secretory Component (SC) is a receptor molecule implicated in the transepithelial transport of polymeric immunoglobulins. We have cloned and characterized the first exon, part of the first intron and 3500 bp of the upstream region of the gene and determined the transcription initiation region. A GC rich region immediately upstream of the transcription start region is interrupted by a potential TATA-box (TTTAA) at position -28. Promoter activity was demonstrated in transient transfection experiments in HepG2 and HeLa cells. The smallest fragment still showing transcriptional activity contains 48 bp of SC promoter. A number of putative recognition sites for transcription factors possibly involved in the regulation of SC transcription by steroids, peptide hormones and cytokines were found in the upstream region.