Identification of the multiple endocrine neoplasia type 1 (MEN1) gene. The European Consortium on MEN1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterised by tumours of the parathyroids, pancreas and anterior pituitary that represents one of the familial cancer syndromes. The MEN1 locus has been previously localised to chromosome 11q13, and a <300 kb gene-rich region flanked centromerically by PYGM and telomerically by D11S1783 defined by combined meiotic and tumour deletion mapping studies. Two candidate genes, ZFM1 and PPP2R5B, from this region have been previously excluded, and in order to identify additional candidate genes we used a BAC to isolate cDNAs from a bovine parathyroid cDNA library by direct selection. One of the novel genes that we identified, SCG2, proved to be identical to the recently published MEN1 gene, which is likely to be a tumour suppressor gene. The SCG2 transcript was 2.9 kb in all tissues with an additional 4.2 kb transcript also being present in the pancreas and thymus. Mutational analysis of SCG2 in 10 unrelated MEN1 families identified one polymorphism and nine different heterozygous mutations (one missense, four non-sense, one insertional and three deletional frameshifts) that segregated with the disease, hence providing an independent confirmation for the identification of the MEN1 gene.

Characterization of the mouse Men1 gene and its expression during development

The gene responsible for multiple endocrine neoplasia type 1 (MEN1), a heritable predisposition to endocrine tumours in man, has recently been identified. Here we have characterized the murine homologue with regard to cDNA sequence, genomic structure, expression pattern and chromosomal localisation. The murine Men1 gene spans approximately 6.7 kb of genomic DNA and is comprised of 10 exons with similar genomic structure to the human locus. It was mapped to the pericentromeric region of mouse chromosome 19, which is conserved with the human 11q13 band where MEN1 is located. The predicted protein is 611 amino acids in length and overall is 97% homologous to the human orthologue. The 45 reported MEN1 mutations which alter or delete a single amino acid in human all occur at conserved residues, thereby supporting their functional significance. Two transcripts of approximately 3.2 and 2.8 kb were detected in both embryonal and adult murine tissues, resulting from alternative splicing of intron 1. By RNA in situ hybridization and Northern analysis the spatiotemporal expression pattern of Men1 was determined during mouse development. Men1 gene activity was detected already at gestational day 7. At embryonic day 14 expression was generally high throughout the embryo, while at day 17 the thymus, skeletal muscle, and CNS showed the strongest signal. In selected tissues from postnatal mouse Men1 was detected in all tissues analysed and was expressed at high levels in cerebral cortex, hippocampus, testis, and thymus. In brain the menin protein was detected mainly in nerve cell nuclei, whereas in testis it appeared perinuclear in spermatogonia. These results show that Men1 expression is not confined to organs affected in MEN1, suggesting that Men1 has a significant function in many different cell types including the CNS and testis.

Novel mutations in the TCIRG1 gene encoding the a3 subunit of the vacuolar proton pump in patients affected by infantile malignant osteopetrosis

Fifty percent of the infantile malignant osteopetrosis (IMO) cases reported in the literature present mutations in the TCIRG1 gene encoding the 116-kDa osteoclast specific subunit of the vacuolar proton ATPase (ATP6I). In this study, we identified four novel mutations in a series of six IMO patients. All of these mutations correspond to single nucleotide changes and affect splice acceptor or donor sites, resulting in aberrant transcription products. We report also a missense mutation, G405R, previously described in several Costa Rican patients. This independent finding suggests that the highly conserved residue at amino acid 405 plays a critical role in the a3 subunit function. Finally, the results of this study were used to provide a prenatal diagnosis to one of the families.

Construction of a 1.2-Mb sequence-ready contig of chromosome 11q13 encompassing the multiple endocrine neoplasia type 1 (MEN1) gene. The European Consortium on MEN1

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant familial cancer syndrome characterized by parathyroid, pancreatic, and anterior pituitary tumors. The MEN1 locus has been previously localized to chromosome 11q13, and a 2-Mb gene-rich region flanked by D11S1883 and D11S449 has been defined. We have pursued studies to facilitate identification of the MEN1 gene by narrowing this critical region to a 900-kb interval between the VRF and D11S1783 loci through melotic mapping. This was achieved by investigating 17 cosmids for microsatellite polymorphisms, which defined two novel polymorphisms at the VRF and A0138 loci, and utilizing these to characterize recombinants in MEN1 families. In addition, we have established a 1200-kb sequence-ready contig consisting of 26 cosmids, eight BACs, and eight PACs that encompass this region. The precise locations for 19 genes and three ESTs within this contig have been determined, and three gene clusters consisting of a centromeric group (VRF, FKBP2, PNG, and PLCB3), a middle group (PYGM, ZFM1, SCG1, SCG2 (which proved to be the MEN1 gene), and PPP2R5B), and a telomeric group (H4B, ANG3, ANG2, ANG1, FON, FAU, NOF, NON, and D11S2196E) were observed. These results represent a valuable transcriptional map of chromosome 11q13 that will help in the search for disease genes in this region.

Osteoclastic differentiation of mouse and human monocytes in a plasma clot/biphasic calcium phosphate microparticles composite

We recently demonstrated that blood clotted around biphasic calcium phosphate (BCP) microparticles constituted a composite biomaterial that could be used for bone defect filling. In addition, we showed that mononuclear cells, i.e. monocytes and lymphocytes, play a central role in the osteogenic effect of this biomaterial. Hypothesizing that osteoclast progenitors could participate to the pro-osteogenic effect of mononuclear cells we observed previously, we focus on this population through the study of mouse monocyte/macrophage cells (RAW264.7 cell line), as well as human pre-osteoclastic cells derived from mononuclear hematopoietic progenitor cells (monocytes-enriched fraction from peripheral blood). Using monocyte-derived osteoclast progenitors cultured within plasma clot/BCP microparticles composite, we aimed in the present report at the elucidation of transcriptional profiles of genes related to osteoclastogenesis and to bone remodelling. For both human and mouse monocytes, real-time PCR experiments demonstrated that plasma clot/BCP scaffold potentiated the expression of marker genes of the osteoclast differentiation such as Nfactc1, Jdp2, Fra2, Tracp and Ctsk. By contrast, Mmp9 was induced in mouse but not in human cells, and Ctr expression was down regulated for both species. In addition, for both mouse and human precursors, osteoclastic differentiation was associated with a strong stimulation of VegfC and Sdf1 genes expression. At last, using field-emission scanning electron microscopy analysis, we observed the interactions between human monocytes and BCP microparticles. As a whole, we demonstrated that plasma clot/BCP microparticles composite provided monocytes with a suitable microenvironment allowing their osteoclastic differentiation, together with the production of pro-angiogenic and chemoattractant factors.

Aromatization of testosterone and 19-nortestosterone by a single enzyme from equine testicular microsomes. Differences from human placental aromatase

A single enzyme in the stallion testis was able to aromatize both testosterone and nortestosterone. This enzyme had a much lower affinity for nortestosterone than for testosterone. In contrast to human placental estrogen synthetase, this enzyme aromatized testosterone and 19-nortestosterone with similar efficiency. The differences observed (effects of monovalent cations, inhibition of androstenedione aromatization by testosterone and 19-nortestosterone and, above all, rate of norandrogen aromatization) suggest that the aromatase in the horse testis is not the same as that in the human placenta.

RANKL treatment releases the negative regulation of the poly(ADP-ribose) polymerase-1 on Tcirg1 gene expression during osteoclastogenesis

The Tcirg1 gene encodes the osteoclast-specific a3 isoform of the V-ATPase a subunit. Using the mouse osteoclastic model RAW264.7 cells, we studied Tcirg1 gene expression, and we identified PARP-1 as a transcriptional repressor negatively regulated by RANKL during osteoclastogenesis.

INTRODUCTION

The TCIRG1 gene encodes the a3 isoform of the V-ATPase a subunit, and mutations at this locus account for approximately 60% of infantile malignant osteopetrosis cases. Using RAW264.7 cells as an osteoclastic differentiation model, we undertook a transcriptional study of the mouse Tcirg1 gene focused on the 4-kb region upstream of the transcription starting point.

MATERIALS AND METHODS

The promoter activity of serial-deletion fragments of the Tcirg1 gene promoter was monitored throughout the RAW264.7 cell differentiation process. We next performed EMSA, UV cross-linking, affinity purification, mass spectrometry analysis, gel supershift, and siRNA transfection experiments to identify the factor(s) interacting with the promoter.

RESULTS

The -3946/+113 region of the mouse Tcirg1 gene displayed a high basal promoter activity, which was enhanced by RANKL treatment of RAW264.7 cells. Constructs deleted up to -1589 retained this response to RANKL. A deletion up to -1402 induced a 3-fold enhancement of the basal activity, whereas RANKL response was not affected. EMSA experiments led us to identify within the -1589/-1402 region, a 10-nucleotide sequence, which bound a nuclear protein present in nondifferentiated RAW264.7 cells. This interaction was lost using nuclear extracts derived from RANKL-treated cells. Affinity purification followed by mass spectrometry analysis and gel supershift assay allowed the identification of poly(ADP-ribose) polymerase-1 (PARP-1) as this transcriptional repressor, whereas Western blot experiments revealed the cleavage of the DNA-binding domain of PARP-1 on RANKL treatment. Finally, both PARP-1 depletion after siRNA transfection and RAW264.7 cell treatment by an inhibitor of PARP-1 activity induced an increase of a3 mRNA expression.

CONCLUSIONS

We provide evidence that the basal transcription activity of the Tcirg1 gene is negatively regulated by the binding of PARP-1 protein to its promoter region in mouse pre-osteoclast. On RANKL treatment, PARP-1 protein is cleaved and loses its repression effect, allowing an increase of Tcirg1 gene expression that is critical for osteoclast function.

Long-term NSAID use in primary care: changes over a decade and NICE risk factors for gastrointestinal adverse events

OBJECTIVES

To examine prescribing of non-steroidal anti-inflammatory drugs (NSAIDs) in general practice and to compare the results with a 1993 study. To assess numbers at risk of gastrointestinal adverse events using the National Institute for Clinical Excellence (NICE) guidance on the use of cyclo-oxygenase (Cox) II selective drugs.

METHODS

Patients currently prescribed a NSAID for 2 months or more were identified from practice records. Demographic information, indications, previous gastrointestinal disease, serious co-morbidity and concomitant prescriptions were recorded. Data were compared with the 1993 survey and the NICE guidance.

RESULTS

Seven thousand nine hundred and fifty-eight patients were registered with the practice in 2003. Two hundred and four patients were receiving repeat prescriptions for conventional NSAIDs and 63 for Cox II selective drugs. As in 1993 diclofenac (38%) and ibuprofen (24%) were the commonest individual agents and the main indication was regional pain. Seventy-three per cent of patients prescribed Cox II selective drugs and 64% of patients prescribed conventional NSAIDs had at least one NICE risk factor for gastrointestinal adverse events. Frequency of co-prescription of aspirin or antacids was similar for conventional NSAIDs and Cox II selective drugs, but prescription of antacids was higher with NICE risk factors.

CONCLUSION

The indications for NSAIDs have not changed since 1993. Cox II selective drug prescribing was within the NICE guidance but a substantial proportion of patients taking other NSAIDs had risk factors for gastrointestinal adverse events. Discussion with the GPs highlighted the difficulties of balancing perceived risk of gastrointestinal adverse events with cardioprotection and further guidance is urgently needed.

Testosterone and progesterone in peripheral plasma during the oestrous cycle of the mare

Measurements every day or every other day showed that testosterone levels ranging from 15 to 70 pg/ml were higher at oestrus in 4 of the 6 mares studied. In these 4 mares, another testosterone peak occurred 11--13 days before the next oestrus either before (3 mares) or after the fall in progesterone levels.

Difficulties of sex determination from forensic bone degraded DNA: A comparison of three methods

Sex determination is of paramount importance in forensic anthropology. Numerous anthropological methods have been described, including visual assessments and various measurements of bones. Nevertheless, whatever the method used, the percentage of correct classification of a single bone usually varies between 80% and 95%, due to significant intra- and inter-population variations, and sometimes variations coming from secular trends. DNA is increasingly used in a forensic context. But forensic DNA extraction from bone raises several issues, because the samples are very often badly altered and/or in very small quantity. Nuclear DNA is difficult to get from degraded samples, according to low copy number, at least in comparison with mitochondrial DNA. In a forensic context (as in a paeleoanthropological context) DNA sex determination is usually complicated by the weak amount of DNA, the degraded nature of nucleic acids, the presence of enzymatic inhibitors in DNA extracts, the possible faint amplification of Y band and the risk of contamination during either excavation or manipulation of samples. The aim of this work was to compare three methods of DNA sex determination from bones: procedure #1 using a single PCR amplification, procedure #2 using a double PCR amplification, and procedure #3 adding bleaching for decontamination of the bone, instead of simply rubbing the bone. These processes were applied to samples of bones (49 samples coming from 39 individuals) that were in various states of post mortem alteration. The main results are the following. (i) No DNA could be extracted from three skulls (parietal bones, mastoid process), the compact bone of one rib, and the diaphysis of one femur; (ii) there was a contamination in three skulls; and (iii) the Y band did not appear in two male cases, with one of the three procedures (male tibia, procedure #2) and with procedures #2 and #3 (male femur). This study emphasises the main issue while working with altered bones: the impossibility to extract DNA in some cases, and, worth of all, the contamination of the sample or the faint amplification of Y band which leads to a wrong sex answer. Multiple and significant precautions have to be taken to avoid such difficulties.

Expression and chromosomal localization of the Requiem gene

Apoptosis in murine myeloid cell lines requires the expression of the Requiem gene, which encodes a putative zinc finger protein. We detected the protein in both cytoplasmic and nuclear subcellular fractions of murine myeloid cells and human K562 leukemia cells, which suggests that the protein might have a function distinct from a transcription factor. This distribution did not alter upon apoptosis induction by IL-3 deprivation. As an approach to investigate its role in development, we determined the spatio-temporal expression pattern in the mouse. Expression was detected in various tissues in earlier gestational age; however, confined to testes, spleen, thymus, and part of the hippocampus in the adult mouse. The expression profile is consistent with a functional role during rapid growth and cell turnover, and in agreement with a regulatory function for hematopoietic cells. The human cDNA clone sequenced showed high homology to its murine counterpart and extended the open reading frame by 20 codons upstream. The gene is located in the proximal region of mouse Chromosome (Chr) 19. In the homologous human region at 11q13, it is located at about 150 kb centromeric from MLK3.

Interleukin-7 partially rescues B-lymphopoiesis in osteopetrotic oc/oc mice through the engagement of B220+ CD11b+ progenitors

OBJECTIVE

We recently identified in the mouse bone marrow a B-lymphoid/myeloid B220+ CD11b+ progenitor population. This population is accumulated in the osteopetrotic oc/oc mouse, which suggests that it could be controlled by bone marrow factors whose expression varies in this pathologic bone environment. Among the possible factors, interleukin (IL)-7 is involved in the control of B lymphopoiesis and osteoclastogenesis. Therefore, we hypothesized that IL-7 could regulate the accumulation of the B220+ CD11b+ population in oc/oc mice.

METHODS

B220+ CD11b+ cells sorted from oc/oc mice were treated with IL-7 and their phenotype was analyzed by flow cytometry and real-time reverse transcriptase polymerase chain reaction (RT-PCR). In vivo, IL-7 was injected in oc/oc mice, and B220+ CD11b+ and B cells, as well as B-cell proliferation and apoptosis, were analyzed by flow cytometry. The expression of B lymphopoiesis and myelopoiesis markers was analyzed by real-time RT-PCR.

RESULTS

In vitro, IL-7 induced the differentiation of B220+ CD11b+ cells into B lymphocytes through the induction of Pax5 and the inhibition of myeloid markers. In vivo, IL-7 injections in oc/oc mice induced a decrease of the B220+ CD11b+ population and the partial restoration of B-cell population, which was reduced in oc/oc mice. In parallel, upon IL-7 injections, Pax5 expression was induced in B220+ cells and B-cell apoptosis was reduced.

CONCLUSIONS

Our results demonstrate that IL-7 injection can partially rescue B lymphopoiesis in oc/oc mice through the engagement of the B220+ CD11b+ population in the B-lymphoid pathway. Therefore, IL-7 delivery could represent a new therapeutic perspective to circumvent the lymphopenia observed in infantile malignant osteopetrosis patients.

Establishment and characterization of new osteoclast progenitor cell lines derived from osteopetrotic and wild type mice

Malignant infantile osteopetrosis is a rare and lethal disease characterized by the absence of bone resorption due to inactive osteoclasts (OCLs). Among the murine models of osteopetrosis, the Tcirg1oc/oc mouse is the most resembling to the human pathology. In the majority of patients as in Tcirg1oc/oc mouse, the gene involved is the Tcirg1 gene, encoding the a3 subunit of the vacuolar proton pump. However, to date, no osteoclastic cell lines from osteopetrotic mice are available to facilitate the study of either OCL differentiation in osteopetrosis or the factors involved in the control of Tcirg1 gene expression. Heterozygotes Tcirg1+/oc mice were crossed with p53+/- mice to obtain homozygotes p53-/-Tcirg1oc/oc and p53-/-Tcirg1+/+ animals. The p53-/-Tcirg1oc/oc mice display the same bone and hematological phenotype as the original Tcirg1oc/oc mice. From the bone marrow of these mice, we have derived cell lines named POC-MGoc/oc and POC-MG+/+. These cell lines express standard osteoclastogenic markers and differentiate into OCLs in the presence of RANK-L and M-CSF. Furthermore, both cell lines can be transduced by a lentiviral vector with a high efficiency and without alteration of their OCL differentiation potential. Therefore, these cell lines provide valuable new tools to study the differentiation and function of osteoclasts in normal and resorption defective conditions.

Distribution, composition and image analysis of plasma lipoproteins in steroid-treated calves

Six 8-day-old female calves were treated with a subcutaneous implant of 200 mg testosterone + 20 mg estradiol-17 beta. Thirty-five days following implantation, plasma lipoproteins were compared to those in control calves of the same age. The LDL exhibited a slight change in protein and lipid concentrations and no change in particle size. The effects of steroid therapy on HDL and particularly on the lighter density HDL were characterized by a reduction of densities associated with a decrease in protein content, and by a rise in lipids and an increase in particle size. The changes in HDL composition but not in LDL alterations were consistent with those associated with sexual maturation described previously. Although testosterone is the predominant component of our combined preparation, the effects of our treatment on young female calves is not consistent with the data reported for human lipoproteinemia. The high levels of urinary estradiol in treated calves suggest that these effects result more likely from the aromatization of the injected testosterone.

A putative human zinc-finger gene (ZFPL1) on 11q13, highly conserved in the mouse and expressed in exocrine pancreas. The European Consortium on MEN 1

In the process of identification of the multiple endocrine neoplasia type 1 gene, which was recently published, we isolated a novel gene in the 11q13 region. This gene (named ZFPL1, for zinc-finger protein-like 1) is expressed strongly in the exocrine pancreas as a 1.4-kb polyadenylated RNA encoding a putative protein of 310 amino acids. A mouse EST contig predicts an equally sized murine protein with 91% amino acid sequence identity to the human protein. No significant homology with known proteins could be found through database screening. However, zinc-finger-like domains and leucine-zipper-like motifs in the predicted ZFPL1 protein were identified, suggesting the presence of DNA-binding and dimerization domains possibly involved in transcription regulation. This notion is supported by the presence of a putative bipartite nuclear localization signal. This paper presents the full-length cDNA sequence for this gene, its genomic structure and chromosomal orientation, and expression studies by Northern blot hybridization and RNA in situ hybridization.

Qualitative and quantitative alterations of bovine serum lipoproteins with ageing

1. Plasma lipoproteins from six calves at 8, 43 and 118 days old, six heifers and six cows were separated by density gradient ultracentrifugation. For each sample lipoproteins bands were visualized by prestained control and characterized by electrophoretic, chemical and morphological analysis. 2. Two resolved bands were detected in the low density lipoprotein fraction (LDL). At an early stage of development, LDLI and LDLII were present with almost equal concentration. With ageing, LDLII became the major fraction of LDL lipoproteins. 3. HDL were isolated as a single band distributed over the range 1.064-1.166 mg/ml in young calf and 1.050-1.152 mg/ml in adult. This progressive decrease of density limits with ageing, associated with a decrease of protein content and an increase of phospholipids and cholesteryl esters content, was consistent with higher HDL particle diameters in adult. 4. With ageing, free cholesterol/esterified cholesterol ratio decreased in LDL fractions and increased in HDL fractions.

Monocytes differentiation upon treatment with a peptide corresponding to the C-terminus of activated T cell-expressed Tirc7 protein

Atp6v0a3 gene encodes for two alternative products, Tirc7 and a3 proteins, which are differentially expressed in activated T cells and resorbing osteoclasts, respectively. Tirc7 plays a central role in T cell activation, while a3 protein is critical for osteoclast-mediated bone matrix resorption. Based on the large body of evidences documenting the relationships between T cells and osteoclasts, we hypothesized that the extracellular C-terminus of Tirc7 protein could directly interact with osteoclast precursor cells. To address this issue, we performed the molecular cloning of a mouse Atp6v0a3 cDNA segment encoding the last 40 amino acids of Tirc7 protein, and we used this peptide as a ligand added to mouse osteoclast precursor cells. We evidenced that Tirc7-Cter peptide induced the differentiation of RAW264.7 cells into osteoclast-like cells, stimulated an autocrine/paracrine regulatory loop potentially involved in osteoclastic differentiation control, and strongly up-regulated F4/80 protein expression within multinucleated osteoclast-like cells. Using a mouse bone marrow-derived CD11b(+) cell line, or total bone marrow primary cells, we observed that similarly to Rankl, Tirc7-Cter peptide induced the formation of TRACP-positive large multinucleated cells. At last, using mouse primary monocytes purified from total bone marrow, we determined that Tirc7-Cter peptide induced the appearance of small multinucleated cells (3-4 nuclei), devoid of resorbing activity, and which displayed modulations of dendritic cell marker genes expression. In conclusion, we report for the first time on biological effects mediated by a peptide corresponding to the C-terminus of Tirc7 protein, which interfere with monocytic differentiation pathways.