Novel Genetic Determinants of Dental Maturation in Children.

Dental occlusion requires harmonious development of teeth, jaws, and other elements of the craniofacial complex, which are regulated by environmental and genetic factors. We performed the first genome-wide association study (GWAS) on dental development (DD) using the Demirjian radiographic method. Radiographic assessments from participants of the Generation R Study (primary study population, N1 = 2,793; mean age of 9.8 y) were correlated with ~30 million genetic variants while adjusting for age, sex, and genomic principal components (proxy for population stratification). Variants associated with DD at genome-wide significant level (P < 5 × 10-8) mapped to 16q12.2 (IRX5) (lead variant rs3922616, B = 0.16; P = 2.2 × 10-8). We used Fisher's combined probability tests weighted by sample size to perform a meta-analysis (N = 14,805) combining radiographic DD at a mean age of 9.8 y from Generation R with data from a previous GWAS (N2 = 12,012) on number of teeth (NT) in infants used as proxy of DD at a mean age of 9.8 y (including the ALSPAC and NFBC1966). This GWAS meta-analysis revealed 3 novel loci mapping to 7p15.3 (IGF2BP3: P = 3.2 × 10-8), 14q13.3 (PAX9: P = 1.9 × 10-8), and 16q12.2 (IRX5: P = 1.2 × 10-9) and validated 8 previously reported NT loci. A polygenic allele score constructed from these 11 loci was associated with radiographic DD in an independent Generation R set of children (N = 703; B = 0.05, P = 0.004). Furthermore, profiling of the identified genes across an atlas of murine and human stem cells observed expression in the cells involved in the formation of bone and/or dental tissues (>0.3 frequency per kilobase of transcript per million mapped reads), likely reflecting functional specialization. Our findings provide biological insight into the polygenic architecture of the pediatric dental maturation process.

Increased cerebrospinal fluid levels of nerve cell biomarkers in narcolepsy with cataplexy.

BACKGROUND: The association between narcolepsy with cataplexy and the hypocretinergic system in the central nervous system is strong since up to 75-90% of all patients have cerebrospinal fluid (CSF) hypocretin-1 deficiency. The predominant occurrence of HLADQB1*0602 tissue type in narcolepsy patients and recent results from genome-wide association studies suggest an underlying immunological mechanism. The present study was initiated to clarify whether measurement of nerve cell biomarkers in CSF could give additional knowledge of the pathophysiological mechanisms causing narcolepsy with cataplexy. METHODS: Two patient groups with narcolepsy, comprising 18 patients with low CSF hypocretin-1 concentrations and typical cataplexy, and 18 patients with normal CSF hypocretin-1 levels and mild cataplexy-like symptoms, were compared to 17 controls. We measured the nerve cell biomarkers beta-amyloid (Aß42), total tau protein (T-tau), phosphorylated tau (P-tau) and neuron-specific enolase (NSE) in CSF. RESULTS: The concentrations of all biomarkers were significantly elevated in both patient groups compared to the controls. The concentration of beta-amyloid was significantly higher in the patient group with normal CSF hypocretin-1 concentration than in those with low concentrations, whereas the other biomarkers showed no difference between the patient groups. CONCLUSION: The findings of elevated levels of CSF biomarkers independent of CSF hypocretin-1 reduction may reflect alterations in cell metabolism. The results suggest a more extensive affection of the sleep regulating cellular network, affecting other neuronal sites important in the regulation of sleep, in addition to the hypocretin-producing neurons.

Incidence of narcolepsy in Norwegian children and adolescents after vaccination against H1N1 influenza A.

BACKGROUND: From October 2009 to January 2010, approximately 470,000 children and adolescents in Norway ages 4-19 years were vaccinated with Pandemrix® against influenza A (H1N1 subtype). The vaccination coverage in this age cohort was approximately 50%. OBJECTIVES: Our study was performed to evaluate the possible association between Pandemrix® vaccination and narcolepsy in Norway. METHODS: Children and adolescents with sudden onset of excessive daytime sleepiness (EDS) and cataplexy occurring after the 2009-2010 vaccination period were registered by the National Institute of Public Health in cooperation with the Norwegian Resource Center for AD/HD, Tourette Syndrome, and Narcolepsy. RESULTS: Fifty-eight vaccinated children and adolescents (35 girls, 23 boys) ages 4-19 years (mean age, 10.5 years) were diagnosed as new cases of confirmed narcolepsy and were included in our study during 2010 and 2011. Forty-two children had onset of symptoms within 6 months after vaccination, with 12 of them having symptoms within the first 6 weeks. All had EDS, 46 had documented cataplexy, 47 had mean sleep latency less than 8 min, and 43 had two or more sleep-onset rapid eye movement sleep (SOREM) periods in multiple sleep latency tests (MSLT). Cerebrospinal fluid (CSF) hypocretin levels were measured in 41 patients, with low levels in all. Thirty seven patients that were analyzed had tissue type HLADQB1*0602. During the same period, 10 unvaccinated cases were reported (mean age, 12.5 years). CONCLUSION: The data collected during 3 years following vaccination showed a significantly increased risk for narcolepsy with cataplexy (P<.0001) and reduced CSF hypocretin levels in vaccinated children ages 4-19 years the first year after Pandemrix® vaccination, with a minimum incidence of 10 of 100,000 individuals per year. The second year after vaccination, the incidence was 1.1 of 100,000 individuals per year, which was not significantly different from the incidence of 0.5-1 of 100,000 per year in unvaccinated children during the same period.

Distinct guanine nucleotide binding protein alpha-subunit receptor coupling in GH cell lines: effects of bromocriptine and hormones on effector enzyme modulation.

The purpose of the present study was to elucidate how the dopamine agonist bromocriptine affected receptor-effector systems in GH cells by measuring adenylate cyclase (AC) and phospholipase C (PL-C) modulation in cell membrane preparations. To perturb the interaction between the receptor and G-protein, polyclonal antibodies reacting with the predicted C-terminal amino acid sequence of G-protein alpha-subunits were used. The effect of bromocriptine on secretagogue elicited prolactin (PRL) secretion from whole cells was also monitored. Bromocriptine inhibited the basal secretion of PRL in a dose dependent manner, and completely abolished both the thyroliberin (TRH) and the vasoactive intestinal peptide (VIP) stimulated PRL secretion in GH(3) cells. Maximal inhibitory effect on PRL egress elicited by both hormones was obtained at 10-50 microM of bromocriptine. Messenger RNAs for both the short and long form of the D(2) receptor (D(2)R) were demonstrated in all three GH cell lines using the RT-PCR technique, advocating that D(2)Rs are coupled to distinct G-proteins and, thus, probably being responsible for the observed effects of bromocriptine in these cell lines. Basal AC activity, as measured in membrane preparations of GH(3) cells, remained unaffected by bromocriptine treatment (10 microM), while TRH and VIP stimulated AC activities (175% and 350% of control values, respectively) were partially inhibited (by some 50%). This inhibitory effect of bromocriptine was completely and specifically abolished in the presence of an antiserum against G(i2)alpha. Basal PL-C activity was also unaffected by bromocriptine, while TRH stimulated PL-C activity (350% of control value) was inhibited by bromocriptine (10 microM) by approximately 50%. Immunoblocking of G(q/11)alpha, however, reduced the stimulatory effect of TRH on PL-C activation by some 65%, while an antiserum against G(o)alpha partly counteracted the inhibitory effect of bromocriptine (10 microM) on TRH stimulated PL-C activity. Thus, TRH dependent AC stimulation was counteracted by bromocriptine via G(i2). TRH activation of PL-C occurs via G(q/11), while inhibition by bromocriptine appears to involve G(o). These mechanisms probably account for the major part of the actions of bromocriptine, however, other not yet recognised intermediates may be involved.

Sox-4 messenger RNA is expressed in the embryonic growth plate and regulated via the parathyroid hormone/parathyroid hormone-related protein receptor in osteoblast-like cells.

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) exert potent and diverse effects in cells of the osteoblastic and chondrocytic lineages. However, downstream mediators of these effects are characterized inadequately. We identified a complementary DNA (cDNA) clone encoding the 5' end of the transcription factor Sox-4, using a subtracted cDNA library enriched in PTH-stimulated genes from the human osteoblast-like cell line OHS. The SOX-4 gene is a member of a gene family (SOX and SRY) comprising transcription factors that bind to DNA through their high mobility group (HMG)-type binding domain, and previous reports have implicated Sox proteins in various developmental processes. In situ hybridization of fetal and neonatal mouse hindlimbs showed that Sox-4 messenger RNA (mRNA) was expressed most intensely in the zone of mineralizing cartilage where chondrocytes undergo hypertrophy, and by embryonic day 17 (ED17), after the primary ossification center was formed, its expression was detected only in the region of hypertrophic chondrocytes. Sox-4 mRNA was detected in osteoblast-like cells of both human and rodent origin. In OHS cells, physiological concentrations (10(-10)-10(-9) M) of human PTH 1-84 [hPTH(1-84)] and hPT(1-34), but not hPTH(3-84), stimulated Sox-4 mRNA expression in a time-dependent manner, indicating involvement of the PTH/PTHrP receptor. Sox-4 transcripts also were detected in various nonosteoblastic human cell lines and tissues, in a pattern similar to that previously reported in mice. The presence of Sox-4 mRNA in hypertrophic chondrocytes within the mouse epiphyseal growth plate at sites that overlap or are adjacent to target cells for PTH and PTHrP, and its strong up-regulation via activated PTH/PTHrP receptors in OHS cells, makes it a promising candidate for mediating downstream effects of PTH and PTHrP in bone.

Developmental regulation of two isoforms of Ca(2+)/calmodulin-dependent protein kinase I beta in rat brain.

Subtractive hybridization analysis of region-specific gene expression in brain has demonstrated a mRNA species enriched in rat hypothalamus [K.M. Gautvik, L. de Lecea, V.T. Gautvik, P.E. Danielson, P. Tranque, A. Dopazo, F.E. Bloom, J.G. Sutcliffe, Proc. Natl. Acad. Sci. USA 93 (1996) 8733-8738.]. We here show that this mRNA encodes a Ca(2+)/calmodulin-dependent (CaM) kinase belonging in the CaM kinase I beta subgroup. cDNA analysis showed that this enzyme was differentially spliced into two isoforms (designated beta1 and beta2) with distinct C-termini. The C-terminal of the translated CaM kinase I beta2 protein (38.5 kDa molecular size), contained 25 amino acid residues not present in the beta1 isoform. The two isoforms were differentially developmentally regulated, with the beta1 isoform being present in rat embryos from day 18 and the beta2 isoform being present from day 5 postnatally. In situ hybridization analysis of adult rat CNS showed CaM kinase I beta2 mRNA being enriched in the hypothalamus and the hippocampal formation. Expression was also observed in a number of ventral limbic structures and in the thalamus. Northern blot analysis showed additional expression of multiple beta2 isoforms in heart and skeletal muscle. The human mRNA showed a similar distribution. Our data suggest that the two isoforms of CaM kinase I beta, created by a splicing process occurring within a week around birth, may have distinct pre- and postnatal functions in a distinct set of CNS neurons and excitable tissues.

Two human osteoblast-like osteosarcoma cell lines show distinct expression and differential regulation of parathyroid hormone-related protein.

Parathyroid hormone (PTH)-related protein (PTHrP) acts as a local regulator of osteoblast function via mechanisms that involve PTH/PTHrP receptors linked to protein kinase A (PKA) and C (PKC). However, the regulation of PTHrP production and mRNA expression in human osteoblasts is poorly understood. Here we have characterized alternative PTHrP mRNA 3' splicing variants, encoding PTHrP isoforms of 139, 141, and 173 amino acids, and studied the regulation of PTHrP and its mRNAs by activated PKA and PKC in two human osteoblast-like cell lines (KPDXM and TPXM). Using exon-specific Northern analysis and reverse transcriptase-coupled polymerase chain reaction, we identified mRNAs encoding PTHrP(1-139) and PTHrP(1-141) in both cell lines. PTHrP(1-139) mRNAs predominated in TPXM cells and PTHrP(1-173) mRNAs were only detected in TPXM cells. Activation of PKA or PKC resulted in different effects on PTHrP and its mRNAs in the two cell lines. In TPXM cells, peptide-specific immunoassays detected high basal levels of PTHrP, increasing by 2-fold in cell extracts and 4-fold in culture media at 7 h and 24 h after exposure to forskolin, respectively, paralleling changes in PTHrP mRNA expression. Phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA), a PKC activator, had no effect. In KPDXM cells, PTHrP was not detected in culture media under basal experimental conditions, and barely detectable amounts were present in cell extracts of TPA-treated cells, although the mRNA levels increased substantially in response to TPA. In the responsive cell lines, the effects on mRNA levels were dose dependent, and increased by 6.9- to 10.5-fold and 2.0- to 4.1-fold at 4 h in TPXM and KPDXM cells after exposure to 10 microM forskolin and 150 nM TPA, respectively. PTHrP mRNA levels then declined but were sustained above controls also at 12 h in both cell lines, albeit at considerably higher levels in TPXM cells. The different responsiveness to agents activating PKA- and PKC-dependent pathways may depend on the cellular state of differentiation, or alternatively, cancer cell line-specific defects. Our data demonstrating distinct differences in mRNA species and the amounts of PTHrP produced by the two cell lines as compared with roughly equivalent overall mRNA levels may suggest that post-transcriptional mechanisms play an important role in limiting the production of intracellular and secreted PTHrPs in human osteoblastic cells.

Transcription of the human thyrotropin-releasing hormone receptor gene-analysis of basal promoter elements and glucocorticoid response elements.

The gene for the human thyrotropin-releasing hormone receptor (TRHR) spans 35 kb and contains three exons and two introns (Matre et al. (1999) J. Neurochem. 72, 1-11). Despite a reported transcription start site (TSS) mapped to position -885 upstream of the translation initiation codon (Iwasaki et al. (1996) J. Biol. Chem. 271, 22183-8), we found cell type specific promoter activity directed by a fragment downstream of this site (-770 to +1). To elucidate the basis for this unexpected activity, we analyzed basal promoter elements in this region of the gene. One divergent TATA box, TTTAAA in position -759, was found by mutational analysis to be critical for promoter activity, providing a likely explanation for the basal activity observed. This proximal region apparently contains several promoter elements, including Pit-1 binding sequences within the first intron of the TRHR gene as previously reported. Here we describe the analysis of two putative glucocorticoid response elements (GREs) that we identified in this region, one (distal) half site overlapping the proposed TSS at -885 and one (proximal) full site within the first intron at position -624. Accordingly, stimulation of rat pituitary GH3 and GH4C1 cells with dexamethasone strongly enhanced transcription activity of a reporter construct containing the distal GRE half site and the proximal GRE site. Both sites bound the glucocorticoid receptor (GR) in a specific manner. Deletion of the distal GRE half site abolished the dexamethasone induction of CAT transcription, as did mutations in the proximal site. We therefore conclude that both sites are necessary for regulation of the TRHR gene transcription by glucocorticoids.

Structural and functional organization of the gene encoding the human thyrotropin-releasing hormone receptor.

The thyrotropin-releasing hormone (TRH) receptor (TRHR) is widely distributed throughout the central and peripheral nervous systems. In addition to its role in controlling the synthesis and secretion of thyroid-stimulating hormone and prolactin from the anterior pituitary, TRH is believed to act as a neurotransmitter as well as a neuromodulator. We have isolated genomic lambda and P1-derived artificial chromosome clones encoding the human TRHR. The gene was found to be 35 kb with three exons and two introns. A 541-bp intron 1 (-629 to -89 relative to the translation start site) is conserved between human and mouse. A large intron 2 of 31 kb disrupts the open reading frame (starting in position +790) in the sequence encoding the supposed junction between the third intracellular loop and the putative sixth transmembrane domain. A similar intron was found in chimpanzee and sheep but not in rat and mouse. Promoter analysis of upstream regions demonstrated cell type-specific reporter activation, and sequencing of 2.5 kb of the promoter revealed putative cis-acting regulatory elements for several transcription factors that may contribute to the regulation of the TRHR gene expression. Functional analysis of potential response elements for the anterior pituitary-specific transcription factor Pit-1 revealed cell type-specific binding that was competed out with a Pit-1 response element from the GH gene promoter.

[Medical research at Norwegian universities]. / Medisinsk forskning ved norske universiteter.

This study shows that Norwegian medical research suffers from lack of both public funds and recruitment, as well as being affected by the following major factors. Norway uses less of its GNP on R&D than other Western countries and less than the OECD average. Medical research in particular receives less financial support than in any of the other Nordic countries. Norwegian medical researchers publish less material and are cited less often than their colleagues in comparable countries. More than half of the medically trained scientific staff in Norway's four medical faculties will retire during the next decade and today there are many vacant positions in academic medicine because there are not enough competent applicants to fill them. The percentage of M.D.s among professors and lecturers has fallen, and a continued decline in preclinical and laboratory medicine and in public health is predicted. This percentage has also decreased among Ph.D. students, while the age at which medical doctors dissertate has increased and is higher than for other Ph.D.s. The number of medical students doing research has fallen in recent years, and the number of doctoral theses has not increased as much in medicine as in other fields. There are significant differences between the salaries paid in medical science and those paid in clinical medicine. Lack of resources and low salaries keep doctors from pursuing a career in academic medicine. In conclusion, if Norway is to be visible in the field of international medical science, this negative trend must be reversed and medical research and academic medicine revitalised.

The hypocretins: hypothalamus-specific peptides with neuroexcitatory activity.

We describe a hypothalamus-specific mRNA that encodes preprohypocretin, the putative precursor of a pair of peptides that share substantial amino acid identities with the gut hormone secretin. The hypocretin (Hcrt) protein products are restricted to neuronal cell bodies of the dorsal and lateral hypothalamic areas. The fibers of these neurons are widespread throughout the posterior hypothalamus and project to multiple targets in other areas, including brainstem and thalamus. Hcrt immunoreactivity is associated with large granular vesicles at synapses. One of the Hcrt peptides was excitatory when applied to cultured, synaptically coupled hypothalamic neurons, but not hippocampal neurons. These observations suggest that the hypocretins function within the CNS as neurotransmitters.

Binding and cyclic AMP stimulation by N-terminally deleted human PTHs (3-84 and 4-84) in a homologous ligand receptor system.

We have produced in yeast two human parathyroid hormone (hPTH) analogs with amino-terminal deletions, hPTH(3-84) and hPTH(4-84), employing the mating factor alpha (MF alpha) expression system. The authenticity of the polypeptides was demonstrated by amino-terminal analysis, amino acid composition, and molecular mass analysis. In cells (LLC-PK1) transfected with the human PTH/parathyroid hormone-related protein (PTHrP) receptor, using [125I-Tyr36]chickenPTHrP(1-36)NH2 as radioligand, binding studies revealed dissociation constants at equilibrium (Kd) for hPTH(3-84) and hPTH(4-84) of 4.7 and 8.0 nM, respectively, only slightly higher than natural recombinant hPTH(1-84) Kd = 2.3 nM). In comparison, [Nle8,18,Tyr34]bovinePTH(3-34)NH2 and [Tyr36]cPTHrP(1-36)NH2 showed equal Kd's of 1.9 nM. Neither of the N-terminally deleted hPTH analogs showed any detectable stimulation of cAMP production in the cells at concentrations below 20 nM. At supersaturated concentrations (500 nM) with receptor occupancy of more than 95% these hPTH analogs revealed about 15% rest agonism compared with that of hPTH(1-84). hPTH(1-84) and [Tyr36]cPTHrP(1-36)NH2 showed an equal half maximal cyclic adenosine monophosphate (cAMP) stimulation of about 0.8 and 0.7 nM, respectively. The hPTH analogs did not show any ability to antagonize cellular cAMP production induced by either hPTH or [Tyr36]cPTHrP(1-36)NH2. [Nle8,18,Tyr34]bPTH(3-34)NH2 did also not antagonize cAMP stimulation by hPTH, but inhibited [Tyr36]cPTHrP(1-36)NH2-induced cAMP production by 40% when present at a 1000 M excess. These distinct results related to PTH and PTHrP from different species are important to consider in experiments evaluating potential hPTH or PTHrP antagonism, and employment of a hPTH/PTHrP receptor model is a requirement.

Overview of the most prevalent hypothalamus-specific mRNAs, as identified by directional tag PCR subtraction.

We applied the directional tag PCR subtractive hybridization method to construct a rat hypothalamic cDNA library from which cerebellar and hippocampal sequences had been depleted, enriching 20-30-fold for sequences expressed selectively in the hypothalamus. We studied a sample of 94 clones selected for enrichment in the subtracted library. These clones corresponded to 43 distinct mRNA species, about half of which were novel. Thirty-eight of these 43 mRNAs (corresponding to 85 of the clones in the sample) exhibited enrichment in the hypothalamus; 23 were highly enriched. In situ hybridization studies revealed that one novel species was restricted to cells in a small bilaterally symmetric area of the paraventricular hypothalamus. Other novel mRNAs showed substantial enrichment in basal diencephalic structures, particularly the hypothalamus, without restriction to single hypothalamic nuclei. The data suggest that the hypothalamus utilizes at least two distinct strategies for employing its selectively expressed proteins. Secretory neuropeptides utilized for intercellular communication are produced by functionally discrete nuclei, while several other proteins are shared by structures that are unrelated in their physiological roles but may share biochemical systems.

A cortical neuropeptide with neuronal depressant and sleep-modulating properties.

Acetylcholine (ACh) plays a key role in the transitions between the different phases of sleep: Slow-wave sleep requires low ACh concentrations in the brain, whereas rapid-eye-movement (REM) sleep is associated with high levels of ACh. Also, these phases of sleep are differentially sensitive to a number of endogenous neuropeptides and cytokines, including somatostatin, which has been shown to increase REM sleep without significantly affecting other phases. Here we report the cloning and initial characterization of cortistatin, a neuropeptide that exhibits strong structural similarity to somatostatin, although it is the product of a different gene. Administration of cortistatin depresses neuronal electrical activity but, unlike somatostatin, induces low-frequency waves in the cerebral cortex and antagonizes the effects of acetylcholine on hippocampal and cortical measures of excitability. This suggests a mechanism for cortical synchronization related to sleep.

High-level production of human parathyroid hormone in Bombyx mori larvae and BmN cells using recombinant baculovirus.

A full-length cDNA encoding human parathyroid hormone (hPTH) containing the prepro region was cloned into Bombyx mori baculovirus under the control of the polyhedrin promoter and polyadenylation sequences. After transfection and generation of the recombinant baculovirus, hPTH production was examined in silkworm larvae and BmN cell cultures. The larvae synthesized and efficiently secreted the correctly processed and authentic hPTH (9.4 kDa) with no sign of internal degradation. In BmN cells, the major secreted form was the correctly sized protein, but small amounts of degraded hPTH could also be detected in the medium by immunoblotting. Unlike the situation in larvae, prepro-hPTH could also be demonstrated intracellularly in BmN cells. The concentration of hPTH in the larval hemolymph was about 70 mg/l, as compared to approx. 55 micrograms/l in the medium per 7.5 x 10(6) cells. Recombinant hPTH (re-hPTH) from the hemolymph was purified by reverse-phase HPLC and subjected to chemical and biological analyses. The authenticity of the purified re-hPTH was confirmed by N-terminal sequencing, amino acid composition and a mass of 9425 Da, close to the theoretical value. The hormone showed high-affinity receptor binding and full biological potency in increasing cellular cAMP.

Human parathyroid hormone as a secretory peptide in milk of transgenic mice.

In a transgenic mouse model we have targeted the expression of recombinant human parathyroid hormone (hPTH) to the mammary gland yielding hPTH as a secretory, soluble peptide in milk. A 2.5 kb upstream regulatory sequence of the murine whey acidic protein (WAP) directed the expression of the hPTH cDNA in a fusion gene construct (WAPPTHSV2) containing the SV40 small t-antigen intron and polyadenylation site in the 3' end. Established lines of transgenic mice secreted hPTH to milk in concentrations up to 415 ng/ml. Recombinant hPTH recovered from the milk was purified by HPLC and shown to be identical to hPTH standard as analyzed by SDS-PAGE followed by immunoblotting. Expression of the WAPPTHSV2 was limited to the mammary gland as analyzed by polymerase chain reaction (PCR) and Southern blot of reversed transcribed mRNA from different tissues. hPTH is an important bone anabolic hormone and may be a potentially important pharmaceutical for treatment of demineralization disorders such as osteoporosis. We present the transgenic animal as a possible production system for hPTH.

Expression and characterization of a recombinant human parathyroid hormone partial agonist with antagonistic properties: Gly-hPTH(-1-->+84).

We have produced and characterized a hPTH analogue with an amino-terminal extension of glycine, Gly-hPTH(-1-->+84) (denoted Gly-hPTH). The hormone analogue was synthesized in E. coli strain BJ5183 transformed with the expression plasmid pKKPTH, extracted from the bacterial pellet and purified by reverse-phase high performance liquid chromatography. Its chemical nature, as determined by amino acid composition analysis, N-terminal amino acid analysis, and mass spectrometry, showed the 9480-Da Gly-hPTH as the predominant species. Because f-Met-Gly-hPTH was the expected form encoded by the plasmid construct, the results indicate that the f-Met residue was efficiently removed from the precurser form. The following functional characteristics of Gly-hPTH were demonstrated. 1) In cells transfected with the human PTH/PTHrP receptor, the receptor binding affinity was reduced threefold compared to the authentic hPTH(1-84) produced by Saccharomyces cerevisiae (apparent Kds: 8.4 and 2.7 nM, respectively). 2) Using the same cells, Gly-hPTH showed 27-fold reduced potency compared to hPTH(1-84) in stimulating intracellular cAMP production (EC50: 32 and 1.2 nM, respectively). 3) Gly-hPTH demonstrated antagonist activity by reducing hPTH-induced cAMP production by 33 +/- 5% (mean +/- SD) when tested at a 1:1 molar ratio. In these studies the recombinant authentic hPTH(1-84) was used as standard for comparisons, and it showed an equal receptor binding affinity and cAMP production as the chemically synthesized peptide [Nle8,18,Tyr34]bovinePTH(1-34)-NH2.

G-proteins: implications for pathophysiology and disease.

This article focuses on the involvement of G-proteins in neuroendocrine secretion, cell growth and phenotype alterations. The current concept of hormonal activation of the GTPase cycle, as well as the molecular diversity of G-proteins families and receptor*G-protein*effector coupling, are described. Also described are certain G-proteins as possible proto-oncogenes and how point mutations and frame shift mutations alter G-protein function and determine the characteristics of various endocrine diseases. The article outlines in detail how receptors and G-proteins interact in prolactin and growth-hormone-secreting pituicytes, how G-proteins are involved in the growth and differentiation of preadipocytes and osteoblasts. All in all, it seems that hormonal activation through G-proteins is modulated through direct intra- and inter-signalling system cross-talk at the plasma membrane level (short-term) and through interactions on the level of transcription (HREs) from tyrosine kinases, steroid-like hormones and metabolic pathways. Pharmacological intervention to treat diseases where G-proteins are involved should take both long and short-term regulatory phenomena into consideration.