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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

The transcriptional activities of the nuclear receptors can be regulated by the small molecules comprised of hydrophobic compounds. Examples of such promiscuous receptors are discussed and strategies, which can be employed in shedding light on the nature of bona fide ligands for such receptors are outlined.

Research has been conducted on nuclear thyroid hormone receptor TR(beta)1.The authors report the identification of the thyroid hormone receptor's serine phosphorylation site in receptor's DNA-binding domain, and the identifications of mitogen-activated protein kinase docking site on thyroid hormone receptor induced by L-thyroxine.