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Diuresis following blood-gorging in Rhodnius prolixus is the major process leading to the transmission of Chagas' disease. We have cloned the cDNA of the first receptor known to be involved in an antidiuretic strategy in insects, a strategy that prevents diuresis. This receptor belongs to the insect CAPA receptor family known in other insects to be activated by peptides encoded within the capability gene. We characterize the expression profile in fifth-instars and find expression is localized to the alimentary canal. Highest transcript levels are found in Malpighian tubules and the anterior midgut, which are known targets of the antidiuretic hormone, RhoprCAPA-[alpha]2. Two transcripts were identified, capa-r1 and capa-r2; however, the latter encodes an atypical G protein-coupled receptor lacking a region ranging between the first and second transmembrane domain. Our heterologous expression assay revealed the expressed capa-r1 receptor is activated by RhoprCAPA-[alpha]2 ([EC.sub.50] = 385nM) but not by RhoprCAPA-[alpha]1. Structural analogs of the inactive RhoprCAPA-[alpha]1 were capable of activating the expressed capa-r1 receptor, confirming the importance of the C-terminal consensus sequence common to CAPA-related peptides. In addition, this receptor has some sensitivity to the pyrokininrelated peptide, RhoprCAPA-[alpha]PK1, but with an efficacy [approximately equal to] 40-fold less than RhoprCAPA-[alpha]2. Other peptides belonging to the PRXa-mide superfamily were inactive on the capa-r1 receptor. Taken together, the neuroendocrinological relevance of this receptor in facilitating the antidiuretic strategy in R. prolixus may make this receptor a useful target for development of agonists or antagonists that could help influence the transmission of Chagas' disease that occurs during diuresis in this medically important insect-disease vector. CAPA | Chagas' | G protein-coupled receptor | neurohormone | neuropeptide doi/ 10.1073/pnas.1003666107

The present study was designed to determine the role of central vasopressin 1 receptors ([V.sub.1]R) in the regulation of cardiovascular parameters in chronically stressed infarcted rats and sham-operated rats under resting conditions and during exposure to acute alarming stress. The experiments were performed on four groups of conscious sham-operated and four groups of infarcted rats subjected to intraventricular infusion of either vehicle or a [V.sub.1]R antagonist ([V.sub.1]RANT). Two groups of infarcted and two groups of sham-operated rats were subjected to mild chronic stressing. Mean arterial blood pressure (MABP) and heart rate (HR) were determined under resting conditions and alter exposure to acute stress (air jet). During vehicle infusion, MABP and HR increases in response to acute stress in the infarcted rats not subjected to chronic stress, and in the infarcted and sham-operated chronically stressed rats, were significantly greater than in the sham-operated rats not exposed to chronic stress. However, MABP and HR responses to acute stress in the chronically stressed infarcted rats and chronically stressed sham-operated rats did not differ. [V.sub.1]RANT abolished differences in cardiovascular responses to acute stress between the experimental groups. Resting cardiovascular parameters were not affected by any of the experimental treatments. It is concluded that chronic stressing enhances the pressor and tachycardic responses to acute stress in the sham-operated rats but does not further intensify these responses in infarcted rats. The results provide evidence that central [V.sub.1]Rs are involved in potentiation of cardiovascular responses to acute stress in chronically stressed rats, infarcted rats, and chronically stressed infarcted rats. vasopressin 1 receptor antagonist; heart failure; tachycardia; depression doi:10.1152/ajpregu.00543.2009

Growth hormone receptor gene--disrupted (GHR-/-) mice exhibit increased life span and adipose tissue mass. Although this obese phenotype has been reported extensively for young adult male GHR-/- mice, data for females and for other ages in either gender are lacking. Thus, the purpose of this study was to evaluate body composition longitudinally in both male and female GHR-/- mice. Results show that GHR-/- mice have a greater percent fat mass with no significant difference in absolute fat mass throughout life. Lean mass shows an opposite trend with percent lean mass not significantly different between genotypes but absolute mass reduced in GHR-/- mice. Differences in body composition are more pronounced in male than in female mice, and both genders of GHR-/- mice show specific enlargement of the subcutaneous adipose depot. Along with previously published data, these results suggest a consistent and intriguing protective effect of excess fat mass in the subcutaneous region. Key Words: Body composition--Growth hormone--Obesity--Adipose depots--Gender differences. doi: 10.1093/gerona/glp175

The phytohormone abscisic acid (ABA) acts in seed dormancy, plant development, drought tolerance, and adaptive responses to environmental stresses. Structural mechanisms mediating ABA receptor recognition and signaling remain unknown but are essential for understanding and manipulating abiotic stress resistance. Here, we report structures of pyrabactin resistance 1 (PYR1), a prototypical PYR/PYR1-like (PYL)/regulatory component of ABA receptor (RCAR) protein that functions in early ABA signaling. The crystallographic structure reveals an [alpha]/[beta] helix--grip fold and homodimeric assembly, verified in vivo by coimmunoprecipitation. ABA binding within a large internal cavity switches structural motifs distinguishing ABA-free 'open-lid' from ABA-bound 'closed-lid' conformations. Small-angle x-ray scattering suggests that ABA signals by converting PYR1 to a more compact, symmetric closed-lid dimer. Site-directed PYR1 mutants designed to disrupt hormone binding lose ABA-triggered interactions with type 2C protein phosphatase partners in planta. doi: 10.1126/science.1181829

Hypocretins/orexins act through two receptor subtypes: [OX.sub.1] and [OX.sub.2]. Outside the brain, orexin receptors are expressed in adrenal glands, where orexins stimulate the release of glucocorticoids. To further address the regulation of steroidogenesis, we analyzed the effect of orexins on the expression of steroidogenic enzymes in human adrenocortical National Cancer Institute (NCI) H295R cells by qPCR. In NCI H295R cells, [OX.sub.2] receptors were highly expressed, as they were in human adrenal glands. After treatment of NCI H295R cells with orexin A for 12-24 h, the cortisol synthesis rate was significantly increased, whereas 30 min of treatment showed no effect. While CYP11B1 and CYP11B2 mRNA levels were increased already at earlier time points, the expression of HSD3B2 and CYP21 mRNA was significantly up-regulated after treatment with orexin A for 12 h. Likewise, orexin B increased CYP21 and HSD3B2 mRNA levels showing, however, a lower potency compared with orexin A. The mRNA levels of CYP11A and CYP17 were unaffected by orexin A. [OX.sub.2] receptor mRNA levels were down-regulated after 12 and 24 h of orexin A treatment. Orexin A increased intracellular [Ca.sup.2+] but not cAMP concentrations in NCI H295R cells. Furthermore, inhibition of PKC and MAPK kinase/ ERK kinase (MEK1/2) prevented the increase of HSD3B2 expression by orexin A. Accordingly, orexin A treatment of NCI H295R cells markedly enhanced ERK1/2 phosphorylation that was prevented by PKC and, in part, PKA inhibition. In conclusion, orexins may influence adrenal steroidogenesis by differential regulation of the expression of steroidogenic enzymes involving [Ca.sup.2+], as well as PKC-ERK1/2 signaling. hypocretin-1 and -2; [OX.sub.1] and [OX.sub.2] receptor; real-time reverse transcriptase-polymerase chain reaction; cortisol doi: 10.1152/ajpregu.91034.2008.

The glucocorticoid receptor (GR) affects the transcription of genes involved in diverse processes, including energy metabolism and the immune response, through DNA-binding dependent and independent mechanisms. The DNA-binding dependent mechanism occurs by direct binding of GR to glucocorticoid response elements (GREs) at regulatory regions of target genes. The DNA-binding independent mechanism involves binding of GR to transcription factors and coactivators that, in turn, contact DNA. A small molecule that competes with GR for binding to GREs could be expected to affect the DNA-dependent pathway selectively by interfering with the protein-DNA interface. We show that a DNA-binding polyamide that targets the consensus GRE sequence binds the glucocorticoid-induced zipper (GILZ) GRE, inhibits expression of GILZ and several other known GR target genes, and reduces GR occupancy at the GILZ promoter. Genome-wide expression analysis of the effects of this polyamide on a set of glucocorticoid-induced and -repressed genes could help to elucidate the mechanism of GR regulation for these genes. gene regulation | glucocorticoid response element | nuclear receptor | protein-DNA interface | Py-lm polyamide

Glucocorticoid receptor [alpha] (GR[alpha]) and peroxisome proliferator-activated receptor [alpha] (PPAR[alpha]) are transcription factors with clinically important immune-modulating properties. Either receptor can inhibit cytokine gene expression, mainly through interference with nuclear factor [kappa]B (NF-[kappa]B)-driven gene expression. The present work aimed to investigate a functional cross-talk between PPAR[alpha]- and GR[alpha]-mediated signaling pathways. Simultaneous activation of PPAR[alpha] and GR[alpha] dose-dependently enhances transrepression of NF-[kappa]B-driven gene expression and additively represses cytokine production. In sharp contrast and quite unexpectedly, PPAR[alpha] agonists inhibit the expression of classical glucocorticoid response element (GRE)-driven genes in a PPAR[alpha]-dependent manner, as demonstrated by experiments using PPAR[alpha] wild-type and knockout mice. The unclerlying mechanism for this transcriptional antagonism relies on a PPAR[alpha]-mediated interference with the recruitment of GR[alpha], and concomitantly of RNA polymerase II, to GRE-driven gene promoters. Finally, the biological relevance of this phenomenon is underscored by the observation that treatment with the PPAR[alpha] agonist fenofibrate prevents glucocorticoid-induced hyperinsulinemia of mice fed a high-fat diet. Taken together, PPAR[alpha] negatively interferes with GRE-mediated GR[alpha] activity while potentiating its antiinflammatory effects, thus providing a rationale for combination therapy in chronic inflammatory disorders. cross-talk | gluconeogenesis | inflammation | hyperinsulinema | side effects

In response to small-molecule signals such as retinoids or steroids, nuclear receptors activate gene expression to regulate development in different tissues. MicroRNAs turn off target gene expression within cells by binding complementary regions in messenger RNA transcripts, and they have been broadly implicated in development and disease. Here we show that the Caenorhabditis elegans nuclear receptor DAF-12 and its steroidal ligand directly activate promoters of let-7 microRNA family members to down-regulate the microRNA target hbl-1, which drives progression of epidermal stem cells from second to third larval stage patterns of cell division. Conversely, the receptor without the ligand represses microRNA expression during developmental arrest. These findings identify microRNAs as components of a hormone-coupled molecular switch that shuts off earlier developmental programs to allow for later ones.

The thyroid hormone receptor (TR) has been proposed to regulate expression of target genes in the absence of triiodothyronine ([T.sub.3]) through the recruitment of the corepressors, NCoR and SMRT. Thus, NCoR and SMRT may play an essential role in thyroid hormone action, although this has never been tested in vivo. To accomplish this, we developed mice that express in the liver a mutant NCoR protein (L-NCoR[DELTA]ID) that cannot interact with the TR. L-NCoR[DELTA]ID mice appear grossly normal, however, when made hypothyroid the repression of many positively regulated [T.sub.3]-target genes is abrogated, demonstrating that NCoR plays a specific and sufficient role in repression by TR in the absence of [T.sub.3]. Remarkably, in the euthyroid state, expression of many [T.sub.3]-targets is also up-regulated in L-NCoR[DELTA]ID mice, demonstrating that NCoR also determines the magnitude of the response to [T.sub.3] in euthyroid animals. Although positive [T.sub.3] targets were up-regulated in L-NCoR[DELTA]ID mice in the hypo- and euthyroid state, there was little effect seen on negatively regulated [T.sub.3] target genes. Thus, NCoR is a specific regulator of [T.sub.3]-action in vivo and mediates repression by the unliganded TR in hypothyroidism. Furthermore, NCoR appears to play a key role in determining the tissue-specific responses to similar levels of circulating [T.sub.3]. Interestingly, NCoR recruitment to LXR is also impaired in this model, leading to activation of LXR-target genes, further demonstrating that NCoR recruitment regulates multiple nuclear receptor signaling pathways. gene expression | thyroid hormone receptor

The use of glucocorticoids for treatment of sepsis has waxed and waned during the past several decades, and recent randomized controlled trials have evoked a reassessment of this therapy. Most glucocorticoid actions are mediated by its specific intracellular receptors (GRs). Thus we initially evaluated whether sepsis and high-dose corticosteroid therapy can regulate guinea pig pulmonary expression of GRs: active receptor, GR[alpha], and dominant negative receptor, GR[beta]. Sepsis induction by LPS injection (300 [micro]g/kg ip) decreased mRNA and protein levels of GR[alpha] and increased protein expression of GR[beta] in lungs. High-dose methylprednisolone (40 mg/kg ip), administered simultaneously with LPS, markedly potentiated the decrease in GR[alpha] expression but slightly affected the increase in GR[beta] expression. Consequently, this led to a significant reduction in GR[alpha] nuclear translocation. Nevertheless, methylprednisolone treatment strongly eliminated LPS induction of NF-[kappa]B activity, as determined by NF-[kappa]B nuclear translocation and by gel mobility shift assays. Furthermore, the LPS-induced increase in inflammatory cells in bronchoalveolar lavage fluid was blunted by administration of the corticosteroid. On the other hand, immunofluorescent staining for cleaved caspase-3 showed a marked increase in this proapoptotic marker in lung sections, and terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL) represented an enhanced appearance of cell apoptosis in lungs and spleen when methylprednisolone was given together with LPS. Cell apoptosis is now considered to play a role in the pathogenesis of septic syndrome. We thus suggest that the action of glucocorticoids at high doses to accelerate sepsis-induced cell apoptosis may overwhelm their therapeutic advantages in septic shock. lung inflammation; nuclear factor-[kappa]B

Expression of the GH receptor (GHR) gene and its binding with GH is essential for growth and fat metabolism. A GT microsatellite exists in the promoter of bovine GHR segregating short (11 bp) and long (16 to 20 bp) allele sequences. To detect SNP and complete an association study of genotype to phenotype, we resequenced a 1,195-bp fragment of DNA including the GT microsatellite and exon 1A. Resequencing was completed in 48 familialy unrelated Holstein, Jersey, Brown Swiss, Simmental, Angus, Brahman, and Brangus cattle. Nine SNP were identified. Phylogeny analyses revealed minor distance (i.e., Key words: bovine, Brangus, deoxyribonucleic acid, growth hormone receptor, single nucleotide polymorphism

The glucocorticoid receptor (GR) interacts with specific GR-binding sequences (GBSs) at glucocorticoid response elements (GREs) to orchestrate transcriptional networks. Although the sequences of the GBSs are highly variable among different GREs, the precise sequence within an individual GRE is highly conserved. In this study, we examined whether sequence conservation of sites resembling GBSs is sufficient to predict GR occupancy of GREs at genes responsive to glucocorticoids. Indeed, we found that the level of conservation of these sites at genes up-regulated by glucocorticoids in mouse C3H10T1/2 mesenchymal stem-like cells correlated directly with the extent of occupancy by GR. In striking contrast, we failed to observe GR occupancy of GBSs at genes repressed by glucocorticoids, despite the occurrence of these sites at a frequency similar to that of the induced genes. Thus, GR occupancy of the GBS motif correlates with induction but not repression, and GBS conservation alone is sufficient to predict GR occupancy and GRE function at induced genes. glucocorticoid response element (GRE) | regulation | response elements | transcription | species conservation

Apart from evaluating orbital inflammation in Graves' ophthalmopathy (GO), somatostatin (SST) analogs have been proposed as a therapy, but recent trials were disappointing. We aimed to measure somatostatin receptor (SSTR) expression in orbital tissues ex vivo and determine whether the new broad-affinity analog SOM230 might be of therapeutic use. Orbital adipose/connective tissues from 29 GO patients and 10 normal individuals were analyzed. Transcripts were quantified using SYBR Green and a light cycler. In vitro models were used to investigate whether thyrotropin receptor activation (as occurs via thyroid stimulating antibodies) or adipogenesis affected SSTR expression in primary preadipocytes and to compare the biological acuvity of octreofide and SOM230 in their modulation. The expression of SSTR 1 was significantly higher in GO patients than normal controls (P = 0.024). Although differences in the expression of SSTR2 were not significant, 39% of GO samples had levels above the 97th percentile of the controls. SSTR3, -4, and -5 were at or below the limit of detection (LOD). The lymphocyte contribution was minimal, since CD3[alpha] transcripts were at the LOD. TSH receptor activation did not modulate SSTR expression. An in vitro model of adipogenesis indicated upregulation of SSTR1 and SSTR2 during differentiation. SOM230 produced significantly greater inhibition of orbital preadipocyte proliferation than octreotide. Ex vivo analysis of orbital tissues reveals upregulation of SSTR1 and -2 in a group of GO patients. Adipogenesis, a process occurring in GO orbits, provides one possible explanation for some of the observed increase. somatostatin analogs; adipogenesis

Obesity is characterized by hyperinsulinemia, hyperleptinemia, and an increase in islet volume. While the mechanisms that hasten the onset of diabetes in obese individuals are not known, it is possible [...]

Byline: Karen T. Coschigano (1) Keywords: aging; gene disruption; growth hormone receptor/binding protein; longevity; mice Abstract: Since generation of the growth hormone receptor/binding protein (GHR/BP) gene-disrupted mouse nearly 10 years ago, use of this mouse model has become widespread in the elucidation of the physiological roles of GH and insulin-like growth factor-1 (IGF-1). In particular, it serves as a useful model to study mechanisms of aging. This review highlights the evidence demonstrating that the loss of GH signaling leads to lifespan extension in mice, and presents the multiple characteristics of this mouse line that suggest the life extension is due to alteration of the aging process. Author Affiliation: (1) Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, 351 Irvine Hall, Athens, OH, 45701, USA Article History: Registration Date: 21/03/2006 Received Date: 01/11/2005 Accepted Date: 01/12/2005 Online Date: 02/06/2006

Byline: Yuji Ikeno (1,2,3), Christie M. Lew (1,2), Lisa A. Cortez (1,2), Celeste R. Webb (1,2), Shuko Lee (3), Gene B. Hubbard (4) Keywords: aging; growth hormone receptor/binding protein; knockout mouse; neoplastic disease Abstract: Rodent models are an invaluable resource for studying the mechanism of mammalian aging. In recent years, the availability of transgenic and knockout mouse models has facilitated the study of potential mechanisms of aging. Since 1996, aging studies with several long-lived mutant mice have been conducted. Studies with the long-lived mutant mice, Ames and Snell dwarf, and growth hormone receptor/binding protein knockout mice, are currently providing important clues regarding the role of the growth hormone/insulin like growth factor-1 axis in the aging process. Interestingly, these studies demonstrate that these long-lived mutant mice have physiological characteristics that are similar to the effects of calorie restriction, which has been the most effective experimental manipulation capable of extending lifespan in various species. However, a question remains to be answered: do these long-lived mutant and calorie-restricted mice extend their lifespan through a common underlying mechanism? Author Affiliation: (1) Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA (2) Barshop Institute for Longevity and Aging Studies, The University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, USA (3) Research Service, Audie Murphy VA Hospital (STVHCS), San Antonio, TX, 78229, USA (4) Southwest National Primate Research Center, Southwest Foundation for Biomedical Research, San Antonio, TX, 78245, USA Article History: Registration Date: 21/03/2006 Received Date: 01/12/2005 Accepted Date: 15/12/2005 Online Date: 02/06/2006

This study was conducted to identify polymorphisms in the promoter and coding regions of the bovine growth hormone and growth hormone receptor genes and to study association of polymorphisms identified in these genes with growth traits and serum insulin-like growth factor-I (IGF-I) concentration. The denaturing gradient gel electrophoresis method and sequencing were utilized to identify three new single nucleotide polymorphisms in the promoter region of the growth hormone gene in Angus cattle. Polymerase chain reaction-based restriction fragment length polymorphism procedures were developed for rapid determination of the single nucleotide polymorphism genotypes in the growth hormone and the growth hormone receptor genes among Angus calves from lines divergently selected for high or low blood serum IGF-I concentration. The IGF-I concentration and growth traits were analyzed using animal models. The single nucleotide polymorphism in the promoter region of the growth hormone receptor gene was associated with serum IGFI concentration on d 42 of the postweaning test and with mean IGF-I concentration. The associated effects of the markers need to be verified in other populations. Key Words: Beef Cattle, Genes, Growth, Insulin-Like Growth Factor, Receptors, Somatotropin

Alien has been described as a corepressor for the thyroid hormone receptor (TR). Corepressors are coregulators that mediate gene silencing of DNA-bound transcriptional repressors. We describe here that Alien gene expression in vivo is regulated by thyroid hormone both in the rat brain and in cultured cells. In situ hybridization revealed that Alien is widely expressed in the mouse embryo and also throughout the rat brain. Hypothyroid animals exhibit lower expression of both Alien mRNAs and protein levels as compared with normal animals. Accordingly, we show that Alien gene is inducible after thyroid hormone treatment both in vivo and in cell culture. In cultured cells, the hormonal induction is mediated by either TRa or TR[beta], while cells lacking detectable amounts of functional TR lack hormonal induction of Alien. We have detected two Alien-specific mRNAs by Northern experiments and two Alien-specific proteins in vivo and in cell lines by Western analysis, one of the two forms representing the CSN2 subunit of the COP9 signalosome. Interestingly, both Alien mRNAs and both detected proteins are regulated by thyroid hormone in vivo and in cell lines. Furthermore, we provide evidence for the existence of at least two Alien genes in rodents. Taken together, we conclude that Alien gene expression is under control of TR and thyroid hormone. This suggests a negative feedback mechanism between TR and its own corepressor. Thus, the reduction of corepressor levels may represent a control mechanism of TR-mediated gene silencing. Keywords: Corepressor; Alien; COP9 signalosome; Thyroid hormone; Brain; Hypothyroidism

We herein report on our efforts to improve the mapping resolution of a QTL with major effect on milk yield and composition that was previously mapped to bovine chromosome 20. By using a denser chromosome 20 marker map and by exploiting linkage disequilibrium using two distinct approaches, we provide strong evidence that a chromosome segment including the gene coding for the growth hormone receptor accounts for at least part of the chromosome 20 QTL effect. By sequencing individuals with known QTL genotype, we identify an F to Y substitution in the transmembrane domain of the growth hormone receptor gene that is associated with a strong effect on milk yield and composition in the general population.

The author reviews the publications on macromolecular transcription complexes. The topics of interest include the role of molecular chaperones in the intracellular hormone receptors and heat shock transcription factor.

Research has been conducted on the human melanine-concentrating hormone receptors. The syntheses and biological evaluation of the cyclic peptide human melanine-concentrating hormone receptors have been carried out and the details are presented.

Research has been conducted on the RXR, a nuclear hormone receptor activated by the vitamin A metabolite retionic acid. Results indicate that helix 11 phenylalanine residue mutation diminishes the RXR ability to associate with the coactivators.

This article discusses the crucial role of the gamma2 isoform of the peroxisome proliferator activated receptor gamma, a member of the nuclear hormone receptors family, in regulating adipogenesis. A rational intervention calls for understanding the adipocyte genes, development, and function with gamma2 receptor serving as a target in adipogenesis.

Research has been conducted on the mammalian hairless gene which is important for the hair growth maintenance. Results indicate that the gene functions as a transcriptional corepressor for the thyroid hormone receptors.

Polyglutamine diseases, inherited neurodegenerative deseases, come from a mutational mechanism altering the sequence of a protein so that glutamines are added to a polyglutamine tract in the androgen receptor via one of two possible mechanisms discussed in this review article with information on the effects of polyglutamine expansion at the protein level. Evidence that a polyglutamine tract can itself be toxic exists. Another mechanism would depend on change in the function of the full-length protein. Lessons from Huntington's, and from spinocerebellar ataxia types 1 and 2 are discussed.

A case study of a female patient with complete androgen-insensitivity syndrome in the absence of androgen receptor gene mutations is presented. The activation function 1 domain of her androgen receptor was disrupted, with a missing intermediary coactivator that links the domain to target genes.

Candidate gene analysis has been carried out in metamorphosing salamander thyroid hormone receptors (TRs). The hypothesis was that TR variation is associated with alternate life cycles modes in ambystomatid salamanders. It does not appear that TRs are candidate loci in maintenance or evolution in the past of alternate life cycle modes in the tiger salamander complex.

In Caenorhabditis elegans, the daf-12 gene has been found to encode a nuclear receptor that regulates the dauer diapause and developmental age. The gene acts at the convergence of pathways regulating these things. DAF-12 likely integrates hormonal signals in cellular targets to coordinate traits that are important in life history.

Transcription of GH receptor (GHR) mRNA is initiated from multiple promoters. Most GHR mRNA arise from GHR Promoter 1 (GHR P1) and GHR P2, which transcribe GHR 1A and GHR 1B mRNA, respectively. Our objective was to characterize the expression of GHR 1A and GHR 1B mRNA in liver of neonatal intact (1 d of age) and castrated (14, 28, and 42 d of age) male pigs (Exp. 1; n = 6 per age group), intact male pigs treated with recombinant porcine ST (rpST) or control (Exp. 2; 21, 42, and 77 d of age; n = 4 pigs per treatment per age), and pregnant gilts treated with rpST (n = 6) or control (n = 7) (Exp. 3). Tissue samples were collected at slaughter for mRNA analyses. The porcine GHR 1A and GHR 1B cDNA were cloned and were homologous to GHR cDNA isolated from other species. Ribonuclease protection assays were used to measure GHR 1A and GHR 1B mRNA. Liver expressed GHR 1A and GHR 1B mRNA, whereas muscle, uterus, and ovary expressed GHR 1B mRNA. The GHR 1A mRNA in the liver of neonatal intact and castrated male pigs (Exp. 1) was expressed at very low levels on d 1, 14, and 28, and two of six pigs expressed a high level of GHR 1A on d 42. The GHR 1B mRNA, however, was detected at all ages (d I through 42), and the amount of GHR 1B increased (P < .05) on d 42. The liver of intact male pigs (Exp. 2) expressed GHR 1B mRNA by 21 d, whereas a high level of GHR 1A mRNA was not detected until d 42 (P < .10). Administration of rpST had no effect on expression of GHR 1A or GHR 1B mRNA in pigs younger than 77 d (Exp. 2), but it tended to decrease (P < .10) GHR 1A mRNA but not GHR 1B mRNA in pregnant gilts (Exp. 3). In conclusion, GHR mRNA in porcine liver was composed of at least two variants (GHR 1A and GHR 1B). The GHR 1B mRNA was the major GHR mRNA in pig liver before 77 d of age. The GHR 1A mRNA increased after 42 d of age and tended to undergo specific down-regulation in response to rpST in pregnant gilts. Key Words: Pigs, Somatotropin, Hormone Receptors, Development

Multiple repression domains (RDs) seen in certain corepressors that mediate transcriptional repression have been shown to be nonredundant. One RD conserved in N-coR and SMRT represses transcription by interacting directly with class II HDAC4/5. Endogenous N-CoR and SMRT associate with HDAC4 in a complex that does not have HDAC1 or mSin3A. The first instance of one corepressor using definite domains to engage multiple HDAC complexes has been seen. Alternative HDAC complexes may mediate specific repression pathways in leukemic and normal cells.

Mice lacking the known thyroid hormone (T3) receptors are viable but show disorders of growth, the pituitary-thyroid axis, and bone maturation. Receptor pathways by which the diversity in T3 functions arise are not well understood. The mice in the study had a novel array of phenotypes not seen in single- receptor-deficient mice. Results show major T3 functions are mediated by common pathways in which TR(beta) and TR(alpha)1 or substitute for or cooperate with one another. No evidence for any previously unidentified T3 receptors was found. It appears that T3-independent actions of T3 receptors, seen in vitro in the past, maybe be a signification function in vivo.

The length of a polymorphic CAG repeat sequence, occurring in the androgen receptor gene, is inversely correlated with transcriptional activity by the androgen receptor. Because heightened androgenic stimulation may increase risk of prostate cancer development and progression, we examined whether shorter CAG repeats in the androgen receptor gene are related to higher risk of prostate cancer. We conducted a nested case-control study of 587 newly diagnosed cases of prostate cancer detected between 1982 and 1995, and 588 controls without prostate cancer, within the Physician's Health Study. An association existed between fewer androgen receptor gene CAG repeats and higher risk of total prostate cancer [relative risk (RR) = 1.52; 95% confidence interval (CI) = 0.92-2.49; P trend = 0.04; for men with CAG repeat lengths [less than or equal to]18 relative to [greater than or equal to]26 repeats]. In particular, a shorter CAG repeat sequence was associated with cancers characterized by extraprostatic extension or distant metastases (stage C or D) or high histologic grade (RR = 2.14; CI = 1.14-4.01; P trend = 0.001). This association was observed individually both for high stage (RR = 2.23) and high grade prostate cancer (RR = 1.89). Men with shorter repeats were at particularly high risk for distant metastatic and fatal prostate cancer. Variability in the CAG repeat length was not associated with low grade or low stage disease. These results demonstrate that a shorter CAG repeat sequence in the androgen receptor gene predicts higher grade and advanced stage of prostate cancer at diagnosis, and metastasis and mortality from the disease. The clinical implications of these results should be evaluated further.

Two isoforms of the human growth hormone receptor (hGHR), which differ in the presence (hGHRwt) or absence (hGHRd3) of exon 3, are expressed in the placenta. Specifically, three expression patterns are observed: only hGHRwt, only hGHRd3, or an approximately 1:1 combination of both isoforms. We investigated several potential regulatory mechanisms which might account for the expression of the hGHR isoforms. The frequency of hGHRd3 expression did not change when placentas from differing stages of gestation were examined, suggesting splicing was not developmentally regulated. However, when hGHR isoform expression patterns were examined in each component of a given placenta, it was evident that alternative splicing of exon 3 is individual-specific. Surprisingly, the individual-specific regulation of hGHR isoforms appears to be the result of a polymorphism in the hGHR gene. We analyzed hGHRwt and hGHRd3 expression in Hutterite pedigrees, and our results are consistent with a simple Mendelian inheritance of two differing alleles in which exon 3 is spliced in an 'all-or-none' fashion. We conclude the alternative splicing of exon 3 in hGHR transcripts is the result of an unusual polymorphism which significantly alters splicing of the hGHR transcript and that the relatively high frequency ([approximately equal to]10%) of homozygous hGHRd3 expression suggests the possibility it may play a role in polygenic determined events.

Jansen's metaphyseal chondrodysplasia appears to be caused by a mutation in the gene for the receptor for parathyroid hormone and parathyroid hormone-related peptide. This bone disease is characterized by short stature and elevated blood calcium levels. Researchers found a previously reported mutation in three patients with Jansen's metaphyseal chondrodysplasia but not in their healthy relatives or 45 unrelated volunteers. One other patient had a different mutation in the receptor gene that has not been described before. These mutations cause the receptor to be constantly active, even in the absence of the hormones.

The reaction rates of protein-protein and protein-DNA interactions by the human 1,25-dihydroxyvitamin D3 receptor (VDR) and 9-cis-retinoic acid receptor (RXR) with or without their cognate ligands was characterized by surface plasmon resonance. Results showed that 1,25 dihydroxyvitamin D3 binding enhances VDR-RXR heterodimerization. As a consequence, the amount of VDR-RXR heterodimers in solution is increased which in turn results to an enlarged VDR-RXR complex formation on DNA.

A study was conducted to compare the roles of the heat shock protein 70 (hsp70) from wheat germ lysate and hsp90 from rabbit reticulocyte lysate in the assembly of high-affinity glucocorticoid receptors (GR). Previous studies have shown that hsp90 binds with the hormone-binding domain of GR to form a heterocomplex with high-affinity for steroids. The results show that components of hsp70 interact with the protein-folding system of rabbit hsp90, indicating that the components of the protein-folding system in the assembly of functional GR heterocomplex were preserved during the evolution of plants and animals.

A study was conducted to characterize the receptor-binding and tyrosine kinase activities of insulin and insulin-like growth factor-I (IGF-I) in the cardiac and skeletal muscles of trout, carp, frog, turtle, pigeon and rat. The results show that receptor-binding by insulin and IGF-I in cardiac and skeletal muscles are quantitatively and qualitatively different in different vertebrate species.

The V1b (Arg8)vasopressin (AVP) receptor of rat is a protein containing 421 amino acids and is almost 50% similar to the V1a and V2 receptors. The similarity is significant in the seven putative membrane-spanning domains of the receptors. In mammals V1b mRNA is also expressed in the brain and peripheral tissues such as kidney, thymus, heart, lung and spleen. However, V1b mRNA expression is not seen in the liver, adrenal, seminal vesicles or the testis. Thus it is possible that V1b receptor may control the AVP effect in tissues other than the pituitary.

Polymerase chain reaction helps to clone three unique members of steroid thyroid hormone receptor (STR) gene family from the nematode Caenorhabditis elegans and these three members belong to the retinoic acid receptor (RAR), thyroid hormone receptor gene subfamily. Northern blot analysis reveals the differing expression of these genes in the larval and adult stages of nematode development. The ancestor of the nematode representing the STR gene family originated before the division that gave rise to the Arthropoda and Chordata.

A human EMBL phage library was screened with a DNA segment of partial length, located on canine gastrin receptor's nucleotide sequence to isolate genomic clones in which human gastrin/CCKB receptors are encoded. A 1356-bp open reading frame having five exons intervened by four introns existed in the gene, and was given to the human chromosome 11p15.4. Two types of mRNAs were produced when an area of exon four in which a segment of the putative third intracellular loop is encoded. Variations in signal transduction functions, intervened by gastrin and CCK, may be caused by the two receptor isoforms.

The molecular bases for the pigmentation phenotypes of variant extension locus alleles in mice was investigated. The results showed that the murine extension locus encodes the melanocyte-stimulating hormone (MSH) receptor. The recessive yellow allele is a frameshift mutation causing a prematurely terminated, nonfuntional receptor. The sombre and tobacco-darkening alleles, which have dominant melanizing effects, produce hyperactive receptors. These results suggest that point mutations alter MSH receptor function, thus producing pigmentation phenotypes of variant extension locus alleles.

The role of serotonin (5-HT) in the modulation of renal function was investigated by testing for the presence of 5HT-1A, a receptor sybtype of 5-HT. Antibodies raised against two peptides from the third intracellular loop of human 5-HT-1A receptor in the human kidney were used to identify immunoreactive cells in rat and human kidney tissues. Radioligand binding assays revealed the presence of 5-HT-1A receptors in medullary thick ascending limbs, the distal convoluted tubule, connecting tubule cells and principal cells in the initial collecting tubule. These results indicate a possible role for 5-HT in mammalian kidney salt and water transport.