Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adult rat adrenal cortical cells maintained in medium supplemented with horse serum (HS) from cohesive epithelial islands secrete large amounts of corticosterone. Such cells do not produce detectable extracellular material (ECM) and are not motile. Cultures exposed to fetal calf serum supplements (FCS) produce metachromatic ECM, modulate to a fibroblastic morphology, and become motile. Within 24 h, steroid production by these cells drop 100-fold. Cells now resemble myofibroblastic "stem" cells of the adrenal cortical capsule, and express structural and functional bimorphism by exhibiting a myofibroblastic phenotype while retaining responsiveness to adrenocorticotropic hormone (ACTH) and limited corticosteroid secreting capacity. Exposure of the myofibroblastic cells to ACTH in FCS overrides the effect of FSC: ECM disappears, steroid production increases several fold, and cells develop an epithelial morphology. The possibility that ECM produced in response to FCS may be responsible for the alteration from a highly differentiated, non-motile adrenocortical cell to a less differentiated, motile adrenocortical stem cell was investigated by inhibition studies using 6-diazo-5-oxo-L-nor-leucine (DON) and by exogenously added components of ECM. DON, a glutamine analogue, inhibited the synthesis of metachromatic ECM in FCS, and prevented the modulation to a fibroblastic morphology, onset of motility, and decrease in steroid production. Addition of hyaluronic acid, but not of chondroitin sulfate, to the epithelioid secretory cells promoted a drop in steroid production and slight alteration in morphology and movement. Both results are consistent with the possibility that metachromatic ECM production is responsible for the reversion of the steroid secretory to the myofibroblastic phenotype. This effect was mimicked by maintaining cells on polystyrene surfaces that were sulfonated to a negative charge density similar to that of ECM. This result implies that the negative charge of ECM may contribute to the expression of the adrenocortical stem cell phenotype, and that its effect is extracellular. A possible physiologic role for ECM-mediated control of adrenal cortical differentiation is proposed.
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PMID:The control of adrenocortical cytodifferentiation by extracellular matrix. 625 47

To elucidate the role of proteinase inhibitors in the regulation of protein breakdown in vivo, we measured the effect of leupeptin on the rate of appearance of leucine in the plasma compartment in overnight-fasted conscious dogs. Two groups of dogs were studied. The control group (I) received saline infusion, and the experimental group (II) was rendered hypercatabolic with daily administration of adrenocorticotropic hormone (ACTH) (500 U/d) for 4 d.ACTH treatment increased plasma cortisol from 2+/-0.4 to 17+/-2 mug/dl (P < 0.005). It raised plasma leucine levels (mumol/liter) from 123+/-6 in I to 206+/-5 in II (P < 0.01) and its rate of appearance into the plasma compartment (micromoles per kilogram per minute) from 3.1+/-0.1 in I to 4.6+/-0.3 in II (P < 0.01). Whole blood alanine concentration (micromoles per liter) increased by 50% (from 387+/-31 to 577+/-53, P < 0.01) and whole blood glutamine concentration (micromoles per liter) increased from 653+/-51 to 917+/-93 (P < 0.01). Leupeptin infusion in the ACTH-treated group significantly decreased both the concentration of plasma leucine and its rate of appearance. Blood glutamine declined by 30% (P < 0.05) after leupeptin, but no effect on blood alanine was observed. Leupeptin had no effect on the saline control group. These data indicate that leupeptin decreases the accelerated rate of protein breakdown induced by cortisol excess. The fact that it did not affect protein degradation in controls may indicate that control of protein breakdown in the postabsorptive state may differ from that during accelerated turnover. Thus, the antibiotic proteinase enzyme inhibitors may be potentially useful in treating conditions of inappropriate protein breakdown.
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PMID:Leupeptin inhibits adrenocorticotropic hormone-induced protein breakdown in the conscious dog. 629 1

The primary mechanism of activation of intracellular prohormones seems to involve proteolytic cleavage at sequences of consecutive basic residues. Thus, all the known biologically active peptides derived from the prohormone of corticotropin and beta-endorphin appear to be excised initially by enzymes with this specificity. The C-terminal peptide, beta-endorphin (1-31), is generated by cleavage at a lysyl arginine sequence and an additional cleavage can give rise to the related peptides, beta-endorphin (1-27) and beta-endorphin (1-26). These derivatives of beta-endorphin are released by an endopeptidase that appears to catalyse cleavage on the carboxyl side of paired lysine residues, followed by the action of a carboxypeptidase B-like enzyme (Fig. 1). The beta-endorphin fragments, beta-endorphin (1-27) and beta-endorphin (1-26), have been isolated from porcine and bovine pituitary but the C-terminal dipeptide, glycyl glutamine, has not been reported previously. Here we describe the isolation of glycyl glutamine from porcine pituitary and present evidence for its presence in sheep brain stem. When applied ionophoretically to brain stem neurones in the rat, the dipeptide exhibited an inhibitory action on cell firing.
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PMID:Glycyl glutamine, an inhibitory neuropeptide derived from beta-endorphin. 631 48

Preliminary observations [Sykes & Lowry (1980) J. Endocrinol. 85, 42P-43P] had suggested that the major hypothalamic somatoliberin (growth-hormone-releasing factor) was a larger peptide than the other characterized hypothalamic factors, with an elution position on Sephadex G-50 between those of neurophysin and corticotropin. The present paper reports the isolation and preliminary characterization of pig hypothalamic somatoliberin. Acid extracts of pig stalk median eminence were purified by gel filtration and preparative and analytical high-pressure liquid chromatography to yield a preparation that was specific in the release of somatotropin (growth hormone) in vitro, giving a steep dose--response curve at doses in the range 0.20-3.0 ng. Amino acid analysis revealed a non-cysteine-containing peptide with a high number of glutamate (or glutamine) and aspartate (or asparagine) residues. The peptide had about 56-57 amino acid residues and an apparent molecular weight of 6400, in keeping with its elution position on a column of Sephadex G-50.
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PMID:Purification of a high-molecular-weight somatoliberin (growth-hormone-releasing factor) from pig hypothalami. 640 74

Glycyl-L-glutamine (Gly-L-Gln), or beta-endorphin-(30-31) [beta-End-(30-31)], is synthesized through the post-translational processing of beta-End-(1-31). Evidence that gly-L-gln is a prominent end product of beta-End-(1-31) processing in cardioregulatory regions of rat brain prompted us to investigate whether it modulates the cardiorespiratory depression induced by central beta-End-(1-31) injection. As shown previously, beta-End-(1-31) (0.5 nmol) lowered mean arterial pressure (MAP) and HR when administered i.c.v. to pentobarbital-anesthetized rats. Gly-L-gln (0.3, 0.6, 1.0 and 10.0 nmol) produced a dose-related inhibition of beta-End-(1-31)-induced hypotension, but not bradycardia, when injected i.c.v. 15 min after beta-End-(1-31). This effect was not attributable to hydrolysis, because equimolar amounts of L-glycine and L-glutamine were ineffective. A comparable response was observed when gly-L-gln was administered to urethane-anesthetized rats and when it was injected before beta-End-(1-31). Gly-L-gln also attenuated the respiratory depressant effect of beta-End-(1-31), significantly inhibiting beta-End-(1-31)-induced hypoxia and hypercapnia. Gly-L-gln (1, 10 and 100 nmol) was inactive when injected alone, however, and produced no significant variation from base-line MAP or HR values. These results demonstrate that gly-L-gln inhibits beta-End-(1-31)-induced cardiorespiratory depression, consistent with accumulating evidence that gly-L-gln functions as a neuromodulator.
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PMID:Beta-endorphin-induced cardiorespiratory depression is inhibited by glycyl-L-glutamine, a dipeptide derived from beta-endorphin processing. 796 17

The objective of this study was to determine whether glycyl-L-glutamine [beta-endorphin(30-31)] modulates the thermoregulatory actions of alpha-MSH. Microinjection of alpha-MSH (0.06 nmol) into PGE2-responsive thermogenic sites in the medial preoptic area of rats generated a hyperthermic response, inducing a 0.85 +/- 0.19 degrees C rise in colonic temperature (Tc) within 45 min. Coadministration of glycyl-L-glutamine (3.0 nmol) completely blocked the response, maintaining Tc at baseline levels. This was not attributable to glycyl-L-glutamine hydrolysis because coadministration of glycine and glutamine had no effect on alpha-MSH-induced thermogenesis. Glycyl-L-glutamine, injected alone, was similarly without effect. These data indicate that glycyl-L-glutamine inhibits alpha-MSH-induced thermogenesis but is devoid of thermoregulatory activity itself.
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PMID:Glycyl-L-glutamine antagonizes alpha-MSH-elicited thermogenesis. 828 72

A neutral endopeptidase (NEP) from Lactococcus lactis has recently been cloned and shown to contain high sequence homology with the human neutral endopeptidase, endopeptidase 24.11 (I. Mierau et al., J. Bacteriol. 175, 2087-2096, 1993). The gene for the neutral endopeptidase from L. lactis was cloned into the pQE expression vector, resulting in the fusion of a hexahistidine at the N-terminus. The recombinant enzyme was expressed to high levels in Escherichia coli (approximately 10 mg/liter of culture) and purified to homogeneity in a two-step procedure. A number of peptides were studied as substrates for the enzyme. The enzyme cleaves the following peptides at the Gly3-Phe4 bond: enkephalins, dynorphins A-6, A-8, A-9, A-10, A-13, and A-17, and alpha-neo-endorphin. In addition the enzyme hydrolyzes bradykinin, substance P, beta-endorphin, ACTH, and VIP. Although the cleavage patterns observed are similar to that seen with mammalian neutral endopeptidase, the lactococcal enzyme more efficiently cleaves larger peptide substrates. As observed with the mammalian neutral endopeptidase, the lactococcal enzyme exhibits higher kcat/K(m) values for the enkephalins than for their corresponding amides, indicating the functionality of an active-site arginine. Inactivation of the lactococcal endopeptidase by diethyl pyrocarbonate and protection afforded by the substrate dynorphin A-6 indicate the functionality of a positionally conserved active-site histidine. This was confirmed by demonstrating that conversion of this histidine, histidine 587, to glutamine generated inactive enzyme. Similarly, conversion of the putative zinc ligand glutamate 535 to glutamine led to inactive enzyme. These studies indicate a conservation of critical catalytic residues between the two enzymes and suggest that the lactococcal endopeptidase is a better model than thermolysin for the mammalian enzyme.
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PMID:Heterologous expression and characterization of recombinant Lactococcus lactis neutral endopeptidase (neprilysin). 880 62

Glycyl-L-glutamine (Gly-Gln; beta-endorphin 30-31) is an endogenous dipeptide that is synthesized through the post-translational processing of beta-endorphin. Previously, we showed that Gly-Gln inhibits the hypotension and respiratory depression produced by central beta-endorphin administration. In this study, we tested whether cyclo(Gly-Gln), a non-polar, cyclic Gly-Gln derivative, was similarly effective following intracerebro-ventricular (i.c.v.) or intra-arterial (i.a.) administration to pentobarbital-anesthetized rats pretreated with beta-endorphin (0.5 nmol i.c.v.). Intracerebroventricular cyclo(Gly-Gln) (0.3, 0.6 or 1.0 nmol) injection produced a dose-dependent inhibition of beta-endorphin-induced hypotension, but not bradycardia, with a potency similar to that of Gly-Gln. Cyclo(Gly-Gln) (5 mg/kg) was also effective following i.a. injection and significantly attenuated the fall in arterial pressure elicited by i.c.v. beta-endorphin, consistent with evidence that cyclic dipeptides permeate the blood-brain barrier; i.a. Gly-Gln was ineffective. Intra-arterial cyclo(Gly-Gln) (5 mg/kg) and i.c.v. Gly-Gln (10 nmol) also attenuated the hypotension and respiratory depression induced by morphine (50 or 100 nmol i.c.v.). Cyclo(Gly-Gln) (0.5, 5.0 or 50.0 mg/kg i.a.) had no effect on arterial pressure or heart rate when given alone. These findings indicate that cyclo(Gly-Gln) is a biologically active peptide capable of reversing the cardiorespiratory depression produced by beta-endorphin or morphine.
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PMID:Cyclo(Gly-Gln) inhibits the cardiorespiratory depression produced by beta-endorphin and morphine. 904 27

Acute muscular exercise induces an increased neutrophil count concomitant with recruitment of natural killer (NK), B and T cells to the blood as reflected by an elevation in the total lymphocyte count. Meanwhile, following intense exercise of long duration the lymphocyte count declines, non-MHC-restricted cytotoxicity is suppressed, but the neutrophil concentration increases. In relation to eccentric exercise involving muscle damage, the plasma concentrations of interleukin-1, interleukin-6 and the tumor necrosis factor are elevated. In this review we will propose a model based on the possible roles that stress hormones play a mediating the exercise- related immunological changes: adrenaline and to a lesser degree noradrenaline are responsible for the immediate effects of exercise on lymphocyte subpopulations and cytotoxic activities. The increase in catecholamines and growth hormone mediate the acute effects of exercise on neutrophils, whereas cortisol may be responsible for maintaining lymphopenia and neutrocytosis after exercise of long duration. Lastly, the role of beta-endorphin is less clear, but the cytokine response is closely related to muscle damage and stress hormones do not seem to be directly involved in the elevated cytokine level. Other possible mechanisms of exercise-induced immunomodulation may include the so-called glutamine hypothesis, which is based on the fact that skeletal muscle is an important source of glutamine production and that lymphocytes are dependent on glutamine for optimal growth. Furthermore, physiological changes during exercise, e.g. increased body temperature and decreased oxygen saturation may also in theory contribute to the exercise-induced immunological changes.
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PMID:Exercise-induced immunomodulation--possible roles of neuroendocrine and metabolic factors. 912 58

The human melanocortin 5 receptor (hMC5R) in the melanocortin receptor family has been identified as the receptor with low affinity towards alpha-MSH. Here we show that the glutamine at position 235 and arginine at the position 272 in the hMC5R are contributing to the low affinity of this receptor. Glutamine235 and arginine272 in hMC5R were mutated to lysine (Q235K) and cysteine (R272C), respectively, residues which are conserved at these positions in other melanocortin receptor subtypes. Upon these mutations affinity of alpha-MSH for hMC5R was increased 10-fold for Q235K and 690-fold for R272C mutants, respectively. The results explain the unusually low affinity of the hMC5R to the melanocortic ligands and suggest the importance of these conserved residues in maintaining the high affinity form of melanocortin receptors.
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PMID:Glutamine235 and arginine272 in human melanocortin 5 receptor determines its low affinity to MSH. 924 Apr 66


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