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1.
PLoS One ; 15(6): e0235270, 2020.
Article in English | MEDLINE | ID: mdl-32589657

ABSTRACT

Growth hormone (GH) activates multiple signal transduction pathways. To investigate these pathways, we identified novel genes whose transcription was induced by GH in the liver of hypophysectomized (HPX) rats using the suppression subtractive hybridization technique. We found that regulator of calcineurin 1 (Rcan1) mRNA was upregulated by GH administration. RCAN1 regulates the activity of calcineurin, a Ca/calmodulin-dependent phosphatase. Rcan1 encodes two major transcripts, Rcan1-1 and Rcan1-4, resulting from differential promoter use and first exon choice. We found that a single injection of GH increased the levels of Rcan1-4 mRNA and RCAN1-4 protein transiently, but did not increase Rcan1-1 mRNA in HPX rat liver. Then the molecular mechanism of GH to induce Rcan1-4 transcription was examined in rat hepatoma H4IIE cells. Experiments using inhibitors suggested that c-JUN N-terminal kinase was required for the induction of Rcan1-4 mRNA by GH. GH increased the levels of phosphorylated c-JUN protein and c-Jun mRNA in HPX rat liver. The luciferase and electrophoretic mobility shift assays showed that c-JUN upregulated Rcan1-4 mRNA by binding to the cAMP-responsive element in the upstream of Rcan1 exon 4. These results indicate that GH activates c-JUN to affect the activity of calcineurin by the induction of Rcan1-4 in rat liver.


Subject(s)
Growth Hormone/pharmacology , Intracellular Signaling Peptides and Proteins/genetics , JNK Mitogen-Activated Protein Kinases/metabolism , Liver/drug effects , Liver/metabolism , Animals , Gene Expression Regulation/drug effects , Phosphorylation/drug effects , RNA, Messenger/genetics , Rats , Signal Transduction/drug effects
2.
Endocr J ; 67(2): 185-200, 2020 Feb 28.
Article in English | MEDLINE | ID: mdl-31748431

ABSTRACT

Growth hormone (GH) has multiple physiological roles, acting on many organs. In order to investigate its roles in rat liver, we tried to identify novel genes whose transcription was regulated by GH. We identified X-box binding protein 1 (Xbp1) as a candidate gene. XBP1 is a key transcription factor activated in response to endoplasmic reticulum (ER) stress. The purpose of this study was to investigate the mode of action of GH on XBP1, including the relation with ER stress, sex-dependent expression of the mRNA, and the signaling pathway. Intravenous administration of GH rapidly and transiently increased Xbp1 mRNA in hypophysectomized rat livers. Neither phosphorylated inositol-requiring-1α (IRE1α) nor phosphorylated PKR-like ER kinase (PERK) increased, suggesting that Xbp1 expression is induced by an ER stress-independent mechanism. The active form of XBP1(S) protein was increased by GH administration and was followed by an increased ER-associated dnaJ protein 4 (ERdj4) mRNA level. XBP1(S) protein levels were predominantly identified in male rat livers with variations among individuals similar to those of phosphorylated signal transducer and activator of transcription 5B (STAT5B), suggesting that XBP1(S) protein levels are regulated by the sex-dependent secretary pattern of GH. The GH signaling pathway to induce Xbp1 mRNA was examined in rat hepatoma H4IIE cells. GH induced the phosphorylation of CCAAT/enhancer-binding protein ß (C/EBPß) following extracellular signal-regulated protein kinase (ERK) phosphorylation. Taken together, the results indicated that XBP1 is activated by GH in rat liver in a sexually dimorphic manner via ERK and C/EBPß pathway.


Subject(s)
CCAAT-Enhancer-Binding Protein-beta/metabolism , Growth Hormone/pharmacology , Liver/drug effects , MAP Kinase Signaling System , RNA, Messenger/drug effects , X-Box Binding Protein 1/drug effects , Animals , Cell Line, Tumor , Endoplasmic Reticulum Stress/genetics , Endoribonucleases/drug effects , Endoribonucleases/metabolism , HSP40 Heat-Shock Proteins/drug effects , HSP40 Heat-Shock Proteins/genetics , Hypophysectomy , Liver/metabolism , Multienzyme Complexes/drug effects , Multienzyme Complexes/metabolism , Protein Serine-Threonine Kinases/drug effects , Protein Serine-Threonine Kinases/metabolism , RNA, Messenger/metabolism , Rats , STAT5 Transcription Factor/drug effects , STAT5 Transcription Factor/metabolism , Sex Characteristics , Signal Transduction , X-Box Binding Protein 1/genetics , eIF-2 Kinase/drug effects , eIF-2 Kinase/metabolism
3.
J Immunother Cancer ; 7(1): 219, 2019 08 14.
Article in English | MEDLINE | ID: mdl-31412935

ABSTRACT

BACKGROUND: Erythropoietin-producing hepatocellular receptor A2 (EPHA2) is overexpressed on the cell surface in many cancers and predicts poor prognosis. DS-8895a is a humanized anti-EPHA2 IgG1 monoclonal antibody afucosylated to enhance antibody-dependent cellular cytotoxicity activity. We conducted a two-step, phase I, multicenter, open-label study to determine the safety, tolerability, and pharmacokinetics of DS-8895a in patients with advanced solid tumors. METHODS: Step 1 was a dose escalation cohort in advanced solid tumor patients (six dose levels, 0.1-20 mg/kg) to determine Step 2 dosing. Step 2 was a dose expansion cohort in EPHA2-positive esophageal and gastric cancer patients. DS-8895a was intravenously administered every 2 weeks for the duration of the study, with a 28-day period to assess dose-limiting toxicity (DLT). Safety, pharmacokinetics, tumor response, and potential biomarkers were evaluated. RESULTS: Thirty-seven patients (Step 1: 22, Step 2: 15 [9: gastric cancer, 6: esophageal cancer]) were enrolled. Although one DLT (Grade 4 platelet count decreased) was observed in Step 1 (dose level 6, 20 mg/kg), the maximum tolerated dose was not reached; the highest dose (20 mg/kg) was used in Step 2. Of the 37 patients, 24 (64.9%) experienced drug-related adverse events (AEs) including three (8.1%) with Grade ≥ 3 AEs. Infusion-related reactions occurred in 19 patients (51.4%) but were manageable. All patients discontinued the study (evident disease progression, 33; AEs, 4). Maximum and trough serum DS-8895a concentrations increased dose-dependently. One gastric cancer patient achieved partial response and 13 patients achieved stable disease. Serum inflammatory cytokines transiently increased at completion of and 4 h after the start of DS-8895a administration. The proportion of CD16-positive natural killer (NK) cells (CD3-CD56+CD16+) decreased 4 h after the start of DS-8895a administration, and the ratio of CD3-CD56+CD137+ to CD3-CD56+CD16+ cells increased on day 3. CONCLUSIONS: Twenty mg/kg DS-8895a infused intravenously every 2 weeks was generally safe and well tolerated in patients (n = 21) with advanced solid tumors. The exposure of DS-8895a seemed to increase dose-dependently and induce activated NK cells. TRIAL REGISTRATION: Phase 1 Study of DS-8895a in patients with advanced solid tumors ( NCT02004717 ; 7 November 2013 to 2 February 2017); retrospectively registered on 9 December 2013.


Subject(s)
Antibodies, Monoclonal, Humanized/administration & dosage , Ephrin-A2/immunology , Esophageal Neoplasms/drug therapy , Stomach Neoplasms/drug therapy , Antibodies, Monoclonal, Humanized/adverse effects , Antibodies, Monoclonal, Humanized/pharmacokinetics , Dose-Response Relationship, Immunologic , Esophageal Neoplasms/immunology , Esophageal Neoplasms/metabolism , Female , Humans , Middle Aged , Receptor, EphA2 , Stomach Neoplasms/immunology , Stomach Neoplasms/metabolism
4.
J Reprod Dev ; 60(4): 312-6, 2014.
Article in English | MEDLINE | ID: mdl-24909600

ABSTRACT

Puberty is associated with an increase in gonadotropin secretion as a result of an increase in gonadotropin-releasing hormone (GnRH) secretion. Kisspeptin is considered to play a key role in puberty onset in many mammalian species, including rodents, ruminants and primates. The present study aimed to determine if changes in hypothalamic expression of the KISS1 gene, encoding kisspeptin, are associated with the onset of puberty in pigs. The animals (n=4 in each group) were perfused with 4% paraformaldehyde at 0, 1, 2, 3 and 4 months old, as prepubertal stages, and at 5 months old, as the peripubertal stage, following each blood sampling. KISS1 gene expressions in coronal sections of brains were visualized by in situ hybridization. Plasma luteinizing hormone (LH) was measured by radioimmunoassay. KISS1 mRNA signals were observed in the arcuate nucleus (ARC) at all ages examined without any significant difference in the number of KISS1-expressing cells, indicating that the KISS1 gene is constantly expressed in the ARC throughout pubertal development in pigs. The plasma LH concentration was the highest in 0-month-old piglets and significantly decreased in the 1- and 2 month-old groups (P<0.05), suggesting a developing negative feedback mechanism affecting gonadotropin release during the prepubertal period. Considering the potent stimulating effect of kisspeptin on gonadotropin release in prepubertal pigs, kisspeptin secretion rather than kisspeptin synthesis may be responsible for the onset of puberty in pigs.


Subject(s)
Arcuate Nucleus of Hypothalamus/metabolism , Kisspeptins/metabolism , Sexual Maturation , Animals , Arcuate Nucleus of Hypothalamus/growth & development , Estradiol/blood , Female , Follicle Stimulating Hormone/blood , Kisspeptins/genetics , Luteinizing Hormone/blood , Ovary/growth & development , Progesterone/blood , Swine
5.
Clin Calcium ; 21(7): 981-91, 2011 Jul.
Article in Japanese | MEDLINE | ID: mdl-21719978

ABSTRACT

The most recommendable MRI sequence for the morphologic assessment of the cartilage damage due to osteoarthritis (OA) is gradient echo fat suppression T1 weighted image (SPGR: Spoiled gradient recalled acquisition in the steady state, FLASH: Fast low-angle shot). For the detection of the cartilage degeneration before the morphological change, T2 mapping, dGEMRIC (delayed Gd-DTPA2-Enhanced MRI of Cartilage), and T1ρ mapping are suggested. Subchondral bone structural changes such as bone sclerosis and cyst are deeply related to the etiology of OA, and quantitative evaluation for them using MDCT (Multi-Detector row CT) and 3TMRI are suggested.


Subject(s)
Bone and Bones/pathology , Cartilage, Articular/pathology , Magnetic Resonance Imaging/methods , Osteoarthritis/diagnosis , Tomography, Spiral Computed , Bone and Bones/diagnostic imaging , Cartilage, Articular/diagnostic imaging , Humans
6.
Bone ; 48(3): 627-30, 2011 Mar 01.
Article in English | MEDLINE | ID: mdl-21087686

ABSTRACT

The geometry as well as bone mineral density (BMD) of the proximal femur contributes to fracture risk. How and the extent to which they change due to natural aging is not fully understood. We assessed BMD and geometry in the femoral neck and shaft separately, in 59 normal Japanese postmenopausal women aged 54-84 years, using clinical computed tomography (CT) and commercially available software, at baseline and 2-year follow-up. This system detected significant reductions over the 2-year interval in total BMD (%change/year = -0.900 ± 0.257, p < 0.0005), cortical cross-sectional area (CSA) (-0.800 ± 0.423%/year, p < 0.05) and cortical thickness (-1.120 ± 0.453%/year, p < 0.01) in the femoral neck. In the femoral shaft, cortical BMD decreased significantly (-0.642 ± 0.188%/year, p < 0.005). Regarding biomechanical parameters in the femoral neck, the cross-sectional moment of inertia (CSMI) and section modulus (SM) decreased (-1.38 ± 3.65%/year, p < 0.01 and -1.37 ± 2.96%/year, p < 0.005) and the buckling ratio (BR) increased significantly (1.48 ± 4.81%/year, p < 0.05), whereas no changes were found in the femoral shaft. The distinct patterns of age-related changes in the geometry and biomechanical properties in the femoral neck and shaft suggest that improved geometric measures are possible with the current non-invasive method using clinical CT.


Subject(s)
Aging/physiology , Bone Density/physiology , Femur/anatomy & histology , Femur/diagnostic imaging , Hip/anatomy & histology , Postmenopause/physiology , Tomography, X-Ray Computed , Aged , Biomechanical Phenomena/physiology , Demography , Female , Follow-Up Studies , Hip/diagnostic imaging , Humans , Longitudinal Studies
7.
Planta Med ; 74(4): 413-6, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18484534

ABSTRACT

Four known friedelane-type triterpenoids, friedelin ( 1), 3-hydroxy-D:A-friedoolean-3-en-2-one ( 2), 2beta-hydroxy-D:A-friedooleanan-3-one ( 3), and 3alpha-hydroxy-D:A-friedooleanan-2-one ( 4), and two known lupane-type triterpenoids, lupeol ( 5) and betulin ( 6), were isolated from the stem bark of Mallotus philippensis. Isolates 1 - 4 and their synthetic analogues, 3-acetoxy-D:A-friedoolean-3-en-2-one ( 2A) and 3alpha-acetoxy-D:A-friedooleanan-2-one ( 4A), were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol 13-acetate (TPA). The inhibitory effect of compounds 2 (IC (50) = 292 mol ratio/32 pmol/TPA) and 4 (IC (50) = 288) was stronger than those of the other compounds tested and the positive control, curcumin (IC (50) = 343). Compound 4 strongly inhibited mouse skin tumor promotion in an IN VIVO two-stage carcinogenesis model. Studies have been conducted to identify the biologically active compounds extracted from the leaves, bark, and cones of trees that currently have no specific commercial use and are therefore treated as waste in the forestry industry.


Subject(s)
Antineoplastic Agents, Phytogenic/chemistry , Antineoplastic Agents, Phytogenic/pharmacology , Mallotus Plant/chemistry , Plant Bark/chemistry , Triterpenes/chemistry , Triterpenes/pharmacology , Animals , Cell Line , Female , Herpesvirus 4, Human , Humans , Mice , Mice, Inbred ICR , Molecular Structure , Neoplasms, Experimental/drug therapy , Plant Stems , Specific Pathogen-Free Organisms , Virus Activation/drug effects
8.
J Antibiot (Tokyo) ; 60(10): 633-9, 2007 Oct.
Article in English | MEDLINE | ID: mdl-17965479

ABSTRACT

In the course of our screening for inhibitors of hyaluronic acid (HA) binding to cellular receptor CD44, a novel inhibitor, F-19848 A, was isolated from the cultured broth of the fungus strain Dacrymyces sp. SANK 20204. This compound inhibited the binding of CD44 and HA with an IC50 value of 23.5 microM and CD44-dependent HA degradation was inhibited with an IC50 value of 98.6 microM in a cell-based assay. The structure was elucidated by physico-chemical properties, analysis of spectral data, and decomposition experiments.


Subject(s)
Hyaluronan Receptors/drug effects , Hyaluronan Receptors/metabolism , Hyaluronic Acid/antagonists & inhibitors , Hyaluronic Acid/metabolism , Oligosaccharides/chemical synthesis , Basidiomycota/chemistry , Basidiomycota/ultrastructure , Binding, Competitive/drug effects , Carbohydrate Sequence , Cell Line , Chemical Phenomena , Chemistry, Physical , Fatty Acids/chemistry , Fermentation , Glucose/chemistry , Magnetic Resonance Spectroscopy , Methylation , Molecular Sequence Data , Oligosaccharides/pharmacology , Spectrophotometry, Infrared , Spectrophotometry, Ultraviolet , Xylose/chemistry
9.
Bioorg Med Chem ; 15(1): 257-64, 2007 Jan 01.
Article in English | MEDLINE | ID: mdl-17049251

ABSTRACT

Two new lanostane-type triterpenoids, inonotsuoxides A (1) and B (2) along with three known lanostane-type triterpenoids, inotodiol (3), trametenolic acid (4), and lanosterol (5), were isolated from the sclerotia of Inonotus obliquus (Pers.: Fr.) (Japanese name: Kabanoanakake) (Russian name: Chaga). Their structures were determined to be 22R,25-epoxylanost-8-ene-3beta,24S-diol (1) and 22S,25-epoxylanost-8-ene-3beta,24S-diol (2) on the basis of spectral data including single crystal X-ray analysis. These compounds except for 2 were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), as a test for potential cancer chemopreventive agents. The most abundant triterpene, inotodiol (3), was investigated for the inhibitory effect in a two-stage carcinogenesis test on mouse skin using 7,12-dimethylbenz[a]anthracene (DMBA) as an initiator and TPA as a promoter. Compound 3 was found to exhibit the potent anti-tumor promoting activity in the in vivo carcinogenesis test.


Subject(s)
Adenocarcinoma/drug therapy , Antineoplastic Agents/chemistry , Basidiomycota/chemistry , Lanosterol/analogs & derivatives , Triterpenes/chemistry , 9,10-Dimethyl-1,2-benzanthracene/chemistry , Animals , Antigens, Viral/drug effects , Antigens, Viral/metabolism , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Crystallography, X-Ray , Drug Screening Assays, Antitumor , Female , Lanosterol/chemistry , Lanosterol/pharmacology , Magnetic Resonance Spectroscopy/methods , Magnetic Resonance Spectroscopy/standards , Mice , Mice, Inbred ICR , Models, Molecular , Molecular Conformation , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Plant Extracts/pharmacology , Reference Standards , Stereoisomerism , Structure-Activity Relationship , Tetradecanoylphorbol Acetate/chemistry , Tetradecanoylphorbol Acetate/pharmacology , Triterpenes/isolation & purification , Triterpenes/pharmacology , Xenograft Model Antitumor Assays
10.
J Antibiot (Tokyo) ; 59(12): 770-6, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17323643

ABSTRACT

In an attempt to obtain inhibitors of hyaluronic acid (HA) binding to its receptor, CD44, we established an efficient assay method to detect and quantify binding using fluorescein-labeled HA and HEK293 cells stably expressing CD44. As a result of the screening of culture broths of microorganisms, we found fungus strain Gloeoporus dichrous SANK 30502 produced inhibitory activity in this new assay. Five compounds, F-16438 A, B, E, F and G, were isolated from the fermentation broths, and their IC50 values were determined to be 10.3, 13.5, 27.3, 12.0 and 13.0 microM, respectively. F-16438 A, B, E, F and G are the first reported inhibitors of binding HA to CD44. F-16438 A, B, E and F have novel structures.


Subject(s)
Hyaluronan Receptors/metabolism , Hyaluronic Acid/antagonists & inhibitors , Mannosides/pharmacology , Polyporales/metabolism , Salicylates/pharmacology , Cell Line , Endocytosis , Humans , Hyaluronic Acid/metabolism
11.
J Antibiot (Tokyo) ; 59(12): 777-84, 2006 Dec.
Article in English | MEDLINE | ID: mdl-17323644

ABSTRACT

In the course of our screening for binding inhibitors of CD44 and hyaluronic acid, five active compounds, F-16438 A, B, E, F and G were found and isolated from the cultured broth of a fungal strain, Gloeoporus dichrous SANK 30502. The structures of these compounds except for F-16438 G were elucidated by physico-chemical and spectral data to be new compounds related to caloporoside; F-16438 G was identified to be the 6'-malonylated derivative of caloporoside.


Subject(s)
Fermentation , Hyaluronan Receptors/metabolism , Hyaluronic Acid/antagonists & inhibitors , Mannosides/isolation & purification , Polyporales/metabolism , Salicylates/isolation & purification , Hyaluronic Acid/metabolism , Magnetic Resonance Spectroscopy , Mannosides/chemistry , Molecular Conformation , Salicylates/chemistry
12.
Endocr J ; 51(2): 145-54, 2004 Apr.
Article in English | MEDLINE | ID: mdl-15118263

ABSTRACT

The activation of the growth hormone (GH) receptor is followed by activation of the JAK2-STAT system in peripheral tissues, which in turn induces the expression of suppressors of cytokine signaling (SOCS) and/or cytokine-inducible SH2 protein (CIS) to achieve the attenuation of the signaling. To examine whether GH involves the SOCS/CIS system as intracellular negative regulators in the hypothalamus, we observed the effects of human GH on the gene expression of SOCS/CIS in the rat hypothalamus. The mRNAs of CIS, SOCS2, and SOCS3 in the hypothalamus of hypophysectomized male rats were examined by Northern analysis following the intravenous administration of recombinant human GH (hGH), 50 microg/100 g BW. The SOCS3 and CIS mRNAs were increased transiently with maximum expression at 1 h after hGH administration. The intravenous hGH did not induce SOCS2 mRNA expression in the hypothalamus. In situ hybridization demonstrated the increase of SOCS3 and CIS mRNAs in the arcuate nucleus after hGH administration, and the increase of SOCS3 mRNA in the periventricular nucleus. The hGH applied to primary cultured hypothalamic neurons at 500 ng/ml induced transient increase of SOCS3 and CIS mRNAs, but not SOCS2 mRNA. The results show that hGH acts directly on the neurons in the hypothalamus, and increases SOCS3 and CIS mRNAs, suggesting that these negative regulators may be involved in the mechanism that turns off the hGH action in the hypothalamic neurons.


Subject(s)
Human Growth Hormone/pharmacology , Hypothalamus/metabolism , Immediate-Early Proteins/genetics , Neurons/metabolism , RNA, Messenger/metabolism , Repressor Proteins/genetics , Transcription Factors/genetics , Animals , Blotting, Northern , Cells, Cultured , Hypophysectomy , In Situ Hybridization , Male , Neurons/drug effects , RNA, Messenger/drug effects , Rats , Rats, Wistar , Recombinant Proteins/pharmacology , Son of Sevenless Proteins/genetics , Suppressor of Cytokine Signaling 3 Protein , Suppressor of Cytokine Signaling Proteins
13.
Jpn J Ophthalmol ; 48(1): 34-6, 2004.
Article in English | MEDLINE | ID: mdl-14767648

ABSTRACT

PURPOSE: The purpose of this study was to compare the binding affinity of bunazosin and dorzolamide to synthetic melanin relative to that of timolol. METHODS: Synthetic melanin was prepared from dopa by the action of tyrosinase. Timolol, dorzolamide, and bunazosin were incubated separately at a concentration of 10(-4) M in 2 ml of 0.066 M phosphate buffer containing 5 mg of synthetic melanin. After centrifugation, the absorbance of each free drug in the supernatant was measured at its optimum wavelength. The percentage of each drug bound to melanin was calculated directly from the change in absorbance relative to the initial value. RESULTS: The increase in the binding rates of all three drugs seemed to reach a plateau after 30 min. After incubating for 60 min, the binding rate of timolol was 22.2% +/- 4.9%, bunazosin 36.3% +/- 2.5%, and dorzolamide 8.5% +/- 1.9%. There were statistically significant differences between the binding rates of each drug. CONCLUSIONS: Under our study conditions, the order of binding affinity of these ocular hypotensive agents to synthetic melanin seems to be as follows: bunazosin>timolol>dorzolamide.


Subject(s)
Antihypertensive Agents/metabolism , Melanins/metabolism , Quinazolines/metabolism , Sulfonamides/metabolism , Thiophenes/metabolism , Timolol/metabolism , Melanins/chemical synthesis , Protein Binding
14.
Genes Chromosomes Cancer ; 35(1): 30-7, 2002 Sep.
Article in English | MEDLINE | ID: mdl-12203787

ABSTRACT

A novel gene, ELKS, whose 5' portion was fused to the RET gene, was found in a papillary thyroid carcinoma. A cDNA of this gene obtained from a human-brain cDNA library revealed that it encoded a peptide of 948 amino acids, termed ELKSalpha. We identified four other isoforms, which encoded ELKSbeta, ELKSgamma, ELKSdelta, and ELKSepsilon proteins consisting, respectively, of 992, 720, 1088, and 1116 amino acid residues. Analysis of the gene structure revealed that the isoforms were generated by alternative splicing. Isoforms beta, gamma, delta, and epsilon all contain an optional exon (exon14a), but ELKSgamma, -delta, and -epsilon lack exon 1b. ELKSgamma lacks exons 3 to 6. ELKSdelta and -epsilon lack exons 12 and 17; ELKSepsilon contains an optional exon (exon 6a). Analysis by RT-PCR suggested that ELKSalpha and ELKSbeta mRNAs are abundant in the brain, ELKSdelta and ELKSepsilon mRNAs predominate in testis and thyroid, and ELKSepsilon mRNA predominates in other tissues. To prove whether the fusion of different ELKS isoforms to RET (between ELKS coiled-coil domains and the RET kinase domain) could produce chimeric proteins that could be autophosphorylated, we synthesized ELKSgamma-RET, ELKSdelta-RET, and ELKSepsilon-RET fusion proteins in vitro. Immunoblotting with anti-ELKS, anti-RET, and anti-phosphotyrosine antibodies demonstrated that the chimeric proteins were constitutively phosphorylated at tyrosine residues, whereas native RET protein was not. These results indicate that the ELKS gene is alternatively spliced, and that every type of ELKS-RET chimeric protein having oligomerization domains can activate RET's cytoplasmic tyrosine kinase.


Subject(s)
Carcinoma, Papillary/genetics , Drosophila Proteins , Proto-Oncogene Proteins/biosynthesis , Proto-Oncogene Proteins/genetics , RNA, Messenger/biosynthesis , Thyroid Neoplasms/genetics , Adaptor Proteins, Signal Transducing , Adolescent , Adult , Alternative Splicing/genetics , Amino Acid Sequence , Cytoskeletal Proteins , DNA, Neoplasm/genetics , Female , Gene Expression Profiling , Gene Expression Regulation, Neoplastic/genetics , Humans , Male , Middle Aged , Molecular Sequence Data , Oncogene Proteins, Fusion/genetics , Oncogene Proteins, Fusion/metabolism , Organ Specificity/genetics , Phosphorylation , Protein Isoforms/biosynthesis , Protein Isoforms/genetics , Protein Structure, Quaternary/genetics , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins c-ret , Receptor Protein-Tyrosine Kinases/genetics , Receptor Protein-Tyrosine Kinases/metabolism , Sequence Analysis, DNA/methods
15.
Neuroendocrinology ; 75(6): 384-91, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12065891

ABSTRACT

The pattern of growth hormone (GH) secretion is sexually dimorphic in rats. We have previously shown that the secretory pattern in adult ovariectomized (OVX) female rats is masculinized by the administration of a single dose of dihydrotestosterone (DHT), a nonaromatizable androgen. To investigate the primary site of action of DHT in the brain, a small amount of DHT was injected directly into a defined area of the brain, and the blood GH profile was observed for 18 h in conscious adult OVX female rats. The bilateral direct injection of 1 microg DHT into the medial preoptic area (MPA) produced a male-like secretory pattern of GH in OVX rats. The masculinizing effects became apparent at 9 h after injection, from which time the episodic GH secretion was produced regularly at intervals of about 150 min, the amplitude of the peak increased and baseline levels were lowered. These parameters, analyzed during 9-18 h after DHT injection, were not different from those in adult male rats. On the contrary, microinjection of DHT into the bed nucleus of the stria terminalis, the hypothalamic periventricular nucleus, or the hypothalamic arcuate-ventromedial nucleus did not affect the secretory pattern of GH. The data indicate that DHT primarily acts on cells in the MPA through androgen receptors and modulates the secretion of somatostatin and/or GH-releasing hormone secondarily to masculinize the GH secretory pattern in OVX rats.


Subject(s)
Dihydrotestosterone/pharmacology , Growth Hormone/metabolism , Ovariectomy , Preoptic Area/drug effects , Sex Characteristics , Animals , Dihydrotestosterone/administration & dosage , Female , Kinetics , Male , Microinjections , Preoptic Area/physiology , Rats , Rats, Sprague-Dawley
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