Loss of transcriptional repression contributes to the ectopic expression of the calcitonin/alpha-CGRP gene in a human lung carcinoma cell line.

The calcitonin/alpha-CGRP (CT/CGRP) gene is ectopically expressed in a wide variety of neoplasia. We have investigated the molecular mechanisms responsible for this ectopic expression in the human cell line BEN, which is derived from a poorly differentiated squamous cell lung carcinoma. We show that a trans-acting factor which represses expression of the CT/CGRP gene in HeLa cells is absent or inactive in BEN cells, and have localised the repressor binding site to a 53 bp fragment 1500 bp upstream of the transcription start site.

Ankylosing spondylitis and HLA-B27: restriction fragment length polymorphism and sequencing of an HLA-B27 allele from a patient with ankylosing spondylitis.

Two groups of patients with ankylosing spondylitis (AS) from England and Poland were examined for restriction fragment length polymorphisms (RFLPs) associated with the disease. No preferential association was found between the 9.2 kb PvuII fragment in HLA-B27 positive patients with AS compared with HLA-B27 healthy subjects as had been previously reported. In the English group, however, a 14 kb PvuII fragment was more common in HLA-B27 positive subjects with AS than in normal controls. Also 4.6 and 3.7 kb PvuII fragments were more prevalent in subjects without AS than in the group with AS, but these results were confined to the English group. Furthermore, the sequence of an HLA-B*2705 gene isolated from a patient with AS was examined, and no significant differences were found compared with the sequence isolated from a healthy subject. There do not seem to be significant genetic differences in the coding or in the regulatory region in HLA-B27 alleles, in subjects with or without AS.

Transgenic mice carrying the guinea-pig alpha-lactalbumin gene transcribe milk protein genes in their sebaceous glands during lactation.

We have generated transgenic mice carrying the entire guinea-pig alpha-lactalbumin gene. Lactating transgenic mice expressed high levels of correctly initiated and processed guinea-pig alpha-lactalbumin mRNA in the secretory epithelium of their mammary glands, and secreted guinea-pig alpha-lactalbumin in their milk. Transcripts were detectable after 7 days of pregnancy, indicating that the transgene was under correct hormonal control. Whereas no or negligible transcription was detectable in all other tissues tested, high levels of transcripts were found in the skin of lactating transgenic mice. Guinea-pig alpha-lactalbumin protein was undetectable in the skin, however. In situ hybridization analysis showed that expression was localized to the undifferentiated cells in the basal layer of the sebaceous glands. Further studies revealed high levels of endogenous beta-casein mRNA in normal lactating mouse skin, demonstrating that the transcription of milk protein genes in lactating mouse skin is a normal event, and is not peculiar to the transgene. This surprising finding highlights the developmental relationship of the mammary gland to other specialized structures of the skin, supports a role for epithelial-extracellular matrix interactions in the regulation of milk protein gene expression in vivo, and identifies the skin as a particularly accessible model system in which to study the regulation of milk protein gene expression. In addition, the guinea-pig alpha-lactalbumin gene will be a source of regulatory sequences with which to direct heterologous gene expression to the sebaceous glands of transgenic mice.

In-situ analysis of calcitonin and CGRP expression in medullary thyroid carcinoma.

A combination of immunocytochemistry (ICC) and in-situ hybridization (ISH) applied to formalin-fixed tissue sections was used to analyse the differential expression of calcitonin and CGRP genes, at both peptide and mRNA levels, in normal and neoplastic human thyroid C cells. Calcitonin peptide was readily detectable in normal C cells but its abundance in the neoplastic C cells of medullary thyroid carcinoma (MTC) was reduced in correlation with the degree of tumour differentiation. Conversely, the content of calcitonin mRNA was higher in MTC than in normal C cells and was not significantly related to tumour differentiation. Both the peptide and mRNA of CGRP were present at much lower levels than those of calcitonin in normal C cells but were increased in neoplastic C cells. We conclude that neoplasia of thyroid C cells is associated with (i) an increase in the content of CGRP mRNA and peptide relative to that of calcitonin, consistent with a defect in control of transcript processing, and (ii) a decrease in the ratio of calcitonin peptide to mRNA abundance relative to the normal, suggesting a defect in synthesis or storage of the peptide. ISH analysis of calcitonin mRNA may therefore be a very valuable addition to ICC analysis of the peptide as a diagnostic and prognostic marker for MTC.

C-erbB2 mRNA expression in human breast tumours: comparison with c-erbB2 DNA amplification and correlation with prognosis.

In this study, we have investigated the expression of the proto-oncogene c-erbB2 in a total of 70 human primary breast tumours. In agreement with other workers, we observed c-erbB2 gene amplification in 17.5% of the tumours studied. In addition, we carried out a comprehensive analysis of c-erbB2 mRNA expression in the tumours using RNase mapping and in situ hybridisation techniques. Our results indicated a more frequent (30%) overexpression of c-erbB2 mRNA, which was associated only with breast carcinomas of a ductal origin. Furthermore, analysis of the c-erbB2 mRNA gene locus in the same tumours demonstrated that enhanced c-erbB2 expression could occur in the presence or absence of gene amplification, suggesting that additional molecular mechanisms may result in overexpression of c-erbB2 mRNA in human mammary tumours. In situ hybridisation showed that elevated levels of c-erbB2 mRNA were specific to malignant cells within the breast tumour. Analysis of the association between c-erbB2 mRNA overexpression and clinicopathological factors revealed a significant correlation with poor tumour grade, but not with steroid receptor status or patient menopausal status. No significant correlation was observed between overexpression of c-erbB2 mRNA and early disease recurrence in our group of patients, although there was a definite trend towards poorer prognosis.

Structure and evolutionary origin of the gene encoding a human serum mannose-binding protein.

The N-terminal sequence of the major human serum mannose-binding protein (MBP1) was shown to be identical at all positions determined with the amino acid sequence predicted from a cDNA clone of a human liver MBP mRNA. An oligonucleotide corresponding to part of the sequence of this cDNA clone was used to isolate a cosmid genomic clone containing a homologous gene. The intron/exon structure of this gene was found to closely resemble that of the gene encoding a rat liver MBP (MBP A). The nucleotide sequence of the exons differed in several places from that of the human cDNA clone published by Ezekowitz, Day & Herman [(1988) J. Exp. Med. 167, 1034-1046]. The MBP molecule comprises a signal peptide, a cysteine-rich domain, a collagen-like domain, a 'neck' region and a carbohydrate-binding domain. Each domain is encoded by a separate exon. This genomic organization lends support to the hypothesis that the gene arose during evolution by a process of exon shuffling. Several consensus sequences that may be involved in controlling the expression of human serum MBP have been identified in the promoter region of the gene. The consensus sequences are consistent with the suggestion that this mammalian serum lectin is regulated as an acute-phase protein synthesized by the liver.

Structure and methylation of the human calcitonin/alpha-CGRP gene.

We report a detailed analysis of the human calcitonin/alpha-CGRP gene locus. About 39kb of DNA containing the gene has been mapped and a common Pvu II RFLP identified downstream of the gene. DNA sequence analysis revealed an extensive CpG island containing several rare restriction enzyme sites at the 5' end of the gene. The structure of this island is unusual in that it contains two distinct CpG-rich regions, one located around exon 1 and the other about 1.5kb further upstream. Msp I sites within both CpG-rich regions were found to be unmethylated, regardless of whether the calcitonin/alpha-CGRP gene was being expressed. However, a correlation was found between demethylation of Msp I sites in intron 2, downstream of the CpG island, and calcitonin/alpha-CGRP gene expression. DNA sequence analysis also revealed the presence of several binding sites for constitutive and regulatory transcription factors in the promoter of the gene. These results suggest that both unmethylated CpG islands and specific demethylation of internal sequences may play a role in the activation of calcitonin/alpha-CGRP gene transcription.

Elevated serum levels of calcitonin gene-related peptide (CGRP) but no evidence for CGRP gene expression in non-small cell lung carcinomas.

Calcitonin gene-related peptide (CGRP) is a hormone formed by alternative post-transcriptional processing of the calcitonin gene. It is a neuropeptide localized to discrete regions of the central nervous system (CNS) and in nerve fibres associated with blood vessels. It is also expressed in medullary carcinomas of the thyroid and lung carcinoma cell lines. The latter finding suggests a possible value for CGRP as tumour marker in lung carcinomas. In this investigation of 22 patients undergoing operation for lung tumours, pre and post-operative levels of serum CGRP were measured. Preoperative as well as postoperative serum CGRP levels were significantly elevated when compared to age-matched normals. However, no evidence could be found for CGRP gene expression in tumour tissue from the same patients as judged by immunocytochemistry or in-situ hybridization using CGRP cRNA probes. CGRP has been localized to nerve fibres in relation to pulmonary blood vessels and has been shown to be a potent vasodilator. These findings, and the absence of evidence for synthesis in tumours, as opposed to cell lines derived from lung carcinomas, suggests that the lack of post-operative normalization of serum CGRP concentrations may be related to physiological changes in cardiovascular haemodynamics following surgery. Elevated pre-operative serum CGRP levels may also reflect a consequence of the lung carcinoma leading to increased release of CGRP from sites in the vasculature yet to be determined, but does not indicate synthesis de novo and secretion of CGRP by the tumours.

Human alpha-calcitonin gene-related peptide (CGRP) is a potent vasodilator in human mesenteric vasculature.

1. The effect of human alpha-calcitonin gene-related peptide (CGRP) and sodium nitroprusside have been measured on human isolated mesenteric vasculature and on rings of human superior mesenteric artery and saphenous vein. 2. When noradrenaline (10(-5) M) was used as the vasoconstrictor in preparations perfused with Krebs solution at constant flow, human alpha-CGRP was 10 times more potent than sodium nitroprusside in evoking dose-dependent falls in perfusion pressure. 3. Human alpha-CGRP and sodium nitroprusside were about equipotent at relaxing rings of superior mesenteric artery contracted by noradrenaline (10(-6) M). When the tone of saphenous vein rings was raised by noradrenaline (10(-6) M), human alpha-CGRP did not relax the vascular smooth muscle. 4. The results show that human alpha-CGRP is a potent vasodilator in human arterial preparations and may act preferentially on arterioles rather than large arteries.

Kappa/lambda immunoglobulin distribution in Graves' thyroid-stimulating antibodies. Simultaneous analysis of C lambda gene polymorphisms.

From patients with untreated Graves' disease 11 sera showing high cAMP release in the FRTL-5 cell assay were studied for relative proportions of kappa or lambda Ig molecules showing cAMP releasing activity. Immunoabsorption of gamma-globulins was performed using monoclonal murine anti-kappa or anti-lambda antibodies linked to cyanogen bromide-activated sepharose. Specific kappa- or lambda-adsorbed fractions were also eluted from immunoabsorbents using chaotrophic thiocyanate buffers and equilibrated with pH 7.4 low salt buffer by dialysis. Immunoabsorption and elution experiments showed that five Graves' sera contained predominant cAMP-releasing activity within lambda Ig fractions, whereas two Graves' sera showed predominant cAMP-releasing activity in kappa Ig fractions. Four sera showed cAMP release approximately equally divided between kappa and lambda Ig both after immunoabsorption and specific anti-kappa or anti-lambda eluates were studied. C lambda genotypes were examined by Southern blotting and restriction fragment length polymorphism analysis of Eco RI-digested genomic DNA from 158 patients with Graves' disease in parallel with 112 normal controls and 29 patients with autoimmune hypothyroidism. Notable shifts in proportions of 8/8 and 18/18 genotypes were present when Graves' patients were compared with normal controls. Allelic frequencies and ratios of genotype 8 to 18 were significantly different (P less than 0.05) when Graves' patients were compared either to normal controls or to patients with autoimmune hypothyroidism.

Calcitonin gene-related peptide messenger RNA is expressed in sensory neurones of the dorsal root ganglia and also in spinal motoneurones in man and rat.

Calcitonin gene-related peptide (CGRP) mRNA was localised to neurones of the dorsal root ganglia and motoneurones of the ventral horn in man and rat. Presence of alpha- and beta-CGRP mRNA was confirmed by Northern blot analysis of rat tissues which showed alpha-CGRP was the predominant gene. The distribution of CGRP gene transcripts corresponded with neurones displaying CGRP immunoreactivity in the ganglia of both species and in the rat ventral horn. In man few motoneurones were immunoreactive despite many expressing CGRP mRNA. In situ hybridisation revealed not only sensory but also motor neurones are sites of CGRP manufacture. Thus in conjunction with other evidence the present study reinforces the proposed muscle trophic role for this peptide.

Structure and expression of the guinea-pig alpha-lactalbumin gene.

The entire guinea-pig alpha-lactalbumin gene was isolated from a genomic DNA library constructed in the bacteriophage lambda L47. The complete nucleotide sequence of the gene and its immediate 5' and 3' flanking sequences were determined and compared with those of the human and rat alpha-lactalbumin genes. This demonstrates that the size, organization and sequence of the exons is highly conserved between species, and reveals the presence of the highly conserved potential regulatory 'milk box' consensus sequence [RGAAGRAAA(N)TGGACAGAAATCAA(CG)TTTCTA] between positions -140 and -110 relative to the transcriptional start point. A guinea-pig LINE repeat sequence was also present in the 5' flanking region between positions -520 and -1195. Transfection of the alpha-lactalbumin gene cloned in a bovine papilloma virus vector into the mouse C127 and human MCF-7 mammary tumour cell-lines gave rise to stable but seemingly constitutive expression of alpha-lactalbumin. Expression was from the correct transcriptional start point, resulting in the accumulation of correctly processed mRNA and the secretion of alpha-lactalbumin into the culture medium.

In situ hybridization reveals differential spatial distribution of mRNAs for type I and type II collagen in the chick limb bud.

During limb development, type I collagen disappears from the region where cartilage develops and synthesis of type II collagen, which is characteristic of cartilage, begins. In situ hybridization using antisense RNA probes was used to investigate the spatial localization of type I and type II collagen mRNAs. The distribution of the mRNA for type II collagen corresponded well with the pattern of type II collagen synthesis, suggesting control at the level of transcription and mRNA accumulation. In contrast, the pattern of mRNA for type I collagen remained more or less uniform and did not correspond with the synthesis of the protein, suggesting control primarily at the level of translation or of RNA processing.

Detection of parvovirus DNA in human serum using biotinylated RNA hybridisation probes.

Methods were established for the detection of parvovirus DNA in human serum using single-stranded RNA probes. The sensitivity of detection of virus using 32P-radiolabelled RNA versus non-radiolabelled biotinylated RNA probes using a streptavidin-polyalkaline phosphatase detection system was compared. Virus was detected using 32P-labelled and biotinylated RNA probes at serum dilutions of 10(-3), equivalent to approx. 3 pg of viral DNA. Using biotinylated RNA probes and a dot-blot system, diagnosis of numerous serum samples could be performed within 8 h of receipt of samples, using an RNA probe which was synthesised and stored at -20 degrees C for up to 12 months without loss of sensitivity. Our work demonstrates the potential of biotinylated RNA probes in the routine analysis of viral sequences in serum.

Isolation and characterisation of a human calcitonin-gene-related-peptide receptor.

We describe the identification and purification of a receptor for calcitonin-gene-related peptide (CGRP) from human term placenta, using lectin and beta-CGRP-Affigel affinity chromatography. The membrane-bound receptor has an estimated Mr of 240,000, as determined by cross-linking 125I-labelled alpha-CGRP (125I-alpha-CGRP) using discuccinimidyl suberate and SDS/polyacrylamide gel electrophoresis, or of 263,000, as judged by sucrose gradient centrifugation of the soluble partially purified native receptor preparation. Cross-linking studies with disuccinimidyl suberate and N-hydroxysuccinimidyl-4-azidobenzoate using membrane-solubilised, partially purified and CGRP-affinity-purified preparations, show a number of 125I-alpha-CGRP binding subunit(s) of Mr 62,000-68,000. Silver staining of the purified CGRP receptor preparation showed two distinct doublets in this plus a number of minor doublets of lower Mr. The receptor binds human beta-CGRP with greater affinity than alpha-CGRP, and showed little affinity for human calcitonin. Adsorption isotherms and Scatchard analysis of 125I-alpha-CGRP binding to the membrane-bound or soluble purified receptor are consistent, under the conditions used, with a single binding site of high affinity. Molecular cloning at present in progress should define the amino acid sequence and subunit composition of the human placental CGRP receptor, since at present the observed heterogeneity of CGRP-binding proteins may be interpreted in a number of ways, for instance: receptor heterogeneity, variable glycosylation of one of two subunits, or limited proteolysis of a single subunit during purification.

Immunohistochemical study of calcitonin gene-related peptide in human medullary carcinoma and C cell hyperplasia.

The distribution of calcitonin and calcitonin gene-related peptide (CGRP) has been studied by immunohistochemistry in normal, hyperplastic and neoplastic C cells. Fewer normal C cells contained immunoreactive CGRP than calcitonin, though both peptides can be co-expressed by a single cell. In the hyperplastic C cells that accompany familial medullary carcinoma immunohistochemistry was strongly and diffusely positive for both CGRP and calcitonin. In contrast, in medullary carcinoma, whether sporadic or familial, little CGRP was identified; often only a few strongly positive cells were found in a negative background, while immunoreactive calcitonin was commonly present in large amounts. The findings suggest that CGRP immunohistochemistry may be of value in identifying hyperplastic C cells, and that CGRP levels should be studied in medullary carcinoma families.

The gene for human alpha-lactalbumin is assigned to chromosome 12q13.

A cDNA clone complementary to the mRNA encoding human alpha-lactalbumin (ALA) has been used as a probe in the analysis of DNA from panels of rodent/human somatic cell hybrids. The presence of the ALA gene correlates with the presence of chromosome 12. In situ hybridization localizes the ALA gene to 12q13.

Organization and sequence of the human alpha-lactalbumin gene.

A recombinant bacteriophage containing the entire alpha-lactalbumin gene was isolated from a human genomic library constructed in bacteriophage lambda L47. Within this recombinant the 2.5 kb alpha-lactalbumin gene is flanked by about 5 kb of sequence on either side. The complete nucleotide sequence of the gene and its immediate flanking sequences were determined and compared with those of the rat alpha-lactalbumin gene. These studies showed that the size, organization and sequence of the exons have been highly conserved, whereas the introns have diverged considerably. In particular, the first intron of the human gene was found to contain an Alu repetitive sequence not present in the rat. A high degree of homology (67%) was also observed in the 5' flanking regions, extending as far as 655 nucleotide residues upstream of the transcriptional initiation site. Comparison of the 5' flanking sequences of these two alpha-lactalbumin genes with those of five casein genes has revealed the presence of a highly conserved region [consensus sequence: RGAAGRAAA(N)TGGACAGAAATCAA(CG)TTTCTA], extending from position -140 to -110 in all seven sequences examined, suggesting a possible regulatory role in the hormonal control or tissue-specific expression of milk protein genes in the mammary gland.