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)

Two mammalian gene products, PC2 and PC3, have been proposed as candidate neuroendocrine-precursor processing enzymes based on the structural similarity of their catalytic domains to that of the yeast precursor-processing endoprotease Kex2. In this report we demonstrate that these two proteases can cleave proopiomelanocortin (POMC) in the secretory pathway of mammalian cells. Similarly to pituitary corticotrophs, PC3 expressed in processing-deficient BSC-40 cells cleaved native mouse POMC at the -Lys-Arg- sites flanking corticotropin. The -Lys-Arg- within beta-lipotropin was less efficiently cleaved to release beta-endorphin. Expression of PC2 together with PC3 resulted in efficient conversion of beta-lipotropin, as occurs in pituitary melanotrophs. Furthermore, coexpression of PC2 together with mouse POMC in bovine adrenomedullary chromaffin cells resulted in conversion of beta-lipotropin to gamma-lipotropin and beta-endorphin in the regulated secretory pathway. Finally, the processing selectivities of PC3 and PC2 expressed together in BSC-40 cells were determined by using a series of mutant mouse POMCs containing all possible pairs of basic residues at certain sites. The observed pattern of cleavage site selectivities mimicked that of the endogenous endoproteases of the insulinoma and bovine adrenomedullary chromaffin cells, suggesting that PC2 and PC3 may represent important core endoproteases in the catalysis of prohormone processing in many neuroendocrine cell types.
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PMID:Kex2-like endoproteases PC2 and PC3 accurately cleave a model prohormone in mammalian cells: evidence for a common core of neuroendocrine processing enzymes. 164 29

A vaccinia virus (VV) vector was used to express rat plasma kallikrein (rPK) in the constitutively secreting cells, BSC-40, and in the endocrine regulated cells, AtT-20. Using a specific rPK antibody and a fluorogenic substrate, Phe-Phe-Arg-AMC, we demonstrated that in both cell lines VV infections resulted in the synthesis of an immunoreactive enzyme predominantly present as a zymogen which can be activated with trypsin. Stimulation of VV:rPK-infected AtT-20 cells with either 5mM 8-bromo-cAMP or 56 mM KCl resulted in a different pattern of rPK and ACTH secretion, strongly suggesting that rPK follows the constitutive secretory pathway. Finally, the 10% rPK activity found within AtT-20 cell extracts had no effect on pro-opiomelanocortin (POMC) processing either intracellularly or extracellularly. The above data show that the biosynthetic machinery of both cell lines analyzed does not allow the efficient activation of plasma prekallikrein. Finally, despite the PK's demonstrated ability to cleave various hormone precursors in vitro at pairs of basic residues, in vivo, we did not obtain evidence that this hepatic enzyme can also act as an intracellular pro-protein processing enzyme.
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PMID:Expression and sorting of rat plasma kallikrein in POMC-producing AtT-20 cells. 185 25

A recombinant vaccinia virus vector was used to coexpress the two candidate mouse prohormone convertases, PC1 and PC2, together with mouse proopiomelanocortin (POMC) in the constitutively secreting cell line BSC-40 and in the endocrine tissue-derived cell lines PC12 and AtT-20, which exhibit regulated secretion. Monitoring of POMC processing demonstrated the distinct cleavage specificities of PC1 and PC2, since in the cell lines analyzed (i) PC1 cleaves POMC into corticotropin and beta-lipotropin, (ii) PC2 cleaves POMC into beta-endorphin, an N-terminally extended corticotropin containing the joining peptide, and either alpha MSH or desacetyl-alpha MSH, and (iii) PC2 cleaves POMC at the five pairs of basic residues analyzed, whereas PC1 cleaves two of them preferentially, suggesting that PC2 has a broader spectrum of activity than PC1. These data are consistent with our hypothesis on the physiological role of PC1 and PC2 as distinct proprotein convertases acting alone or together to produce a set of tissue-specific maturation products in the brain and in peripheral tissues.
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PMID:PC1 and PC2 are proprotein convertases capable of cleaving proopiomelanocortin at distinct pairs of basic residues. 202 2

Proopiomelanocortin (POMC) is a neuroendocrine precursor protein which is processed at paired basic amino acids in a tissue-specific manner. To study this phenomenon, a vaccinia virus recombinant, which directs the synthesis of mouse POMC (VV:mPOMC) was constructed and used to infect epithelial (BSC-40) and endocrine (Rin m5F) cell lines. Bona fide mPOMC was produced in both cell types and beta-endorphin immunoreactivity was secreted in a nonregulated manner from BSC-40 cells and in a regulated manner from Rin m5F cells. Although the precursor was not cleaved to smaller beta-MSH or beta-endorphin immunoreactive peptides in BSC-40 cell extracts, Rin m5F cells produced primarily authentic gamma-lipotropin and des-acetyl beta-endorphin. Furthermore, production of these peptides was restricted to the regulated secretory pathway in Rin m5F cells. Site-directed mutagenesis was then used to change the inefficiently recognized Lys-Lys potential cleavage site near the carboxyl terminus of beta-endorphin to Lys-Arg. Expression of the mutant precursor in Rin m5F cells resulted in the synthesis of both des-acetyl beta-endorphin and beta-endorphin.
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PMID:Expression of mouse proopiomelanocortin in an insulinoma cell line. Requirements for beta-endorphin processing. 253 49

Mammalian cell lines (BSC-40, NG108-15, and GH4C1) that cannot process the murine neuroendocrine peptide precursor prepro-opiomelanocortin (mPOMC) when its synthesis is directed by a vaccinia virus vector were coinfected with a second recombinant vaccinia virus carrying the yeast KEX2 gene, which encodes an endopeptidase that cleaves at pairs of basic amino acid residues. mPOMC was cleaved intracellularly to a set of product peptides normally found in vivo, including mature gamma-lipotropin and beta-endorphin1-31. In GH4C1 cells (a rat pituitary line), product peptides were incorporated into stored secretory granules. These results suggest that the inability of any particular cell line to process a prohormone precursor is due to the absence of a suitable endogenous processing enzyme.
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PMID:Yeast KEX2 endopeptidase correctly cleaves a neuroendocrine prohormone in mammalian cells. 329 Nov 17

Stress is the most commonly reported precipitating factor for seizures. The proconvulsant actions of stress hormones are thought to mediate the effects of stress on seizure susceptibility. Interestingly, epileptic patients have increased basal levels of stress hormones, including corticotropin-releasing hormone (CRH) and corticosterone, which are further increased following seizures. Given the proconvulsant actions of stress hormones, we proposed that seizure-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis may contribute to future seizure susceptibility. Consistent with this hypothesis, our data demonstrate that pharmacological induction of seizures in mice with kainic acid or pilocarpine increases circulating levels of the stress hormone, corticosterone, and exogenous corticosterone administration is sufficient to increase seizure susceptibility. However, the mechanism(s) whereby seizures activate the HPA axis remain unknown. Here we demonstrate that seizure-induced activation of the HPA axis involves compromised GABAergic control of CRH neurons, which govern HPA axis function. Following seizure activity, there is a collapse of the chloride gradient due to changes in NKCC1 and KCC2 expression, resulting in reduced amplitude of sIPSPs and even depolarizing effects of GABA on CRH neurons. Seizure-induced activation of the HPA axis results in future seizure susceptibility which can be blocked by treatment with an NKCC1 inhibitor, bumetanide, or blocking the CRH signaling with Antalarmin. These data suggest that compromised GABAergic control of CRH neurons following an initial seizure event may cause hyperexcitability of the HPA axis and increase future seizure susceptibility.
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PMID:Seizure-induced disinhibition of the HPA axis increases seizure susceptibility. 2422 28

Several recent studies suggest that in the human population, a routine, short anesthetic in otherwise healthy infants is void of neurodevelopmental insult. On the other hand, many human retrospective epidemiological studies report evidence of cognitive abnormalities in children after testing those who had different anesthesia-requiring procedures in early childhood. We tested in a rat model whether post-anesthesia stressful environmental factors can contribute to developmental abnormalities that were initiated by a relatively short exposure to sevoflurane, the most widely used anesthetic in pediatric anesthesia, whose polyvalent actions include enhancement of gamma-aminobutyric acid type A receptor (GABAAR) activity. Postnatal day 6 (P6) male Sprague-Dawley rats were anesthetized with sevoflurane for 60min. To simulate subsequent stress, the animals were subjected to a single maternal separation for 180min at P10. To study the role of GABAAR-mediated depolarization, subgroups of P6 rats received a single injection of the Na+-K+-2Cl- (NKCC1) inhibitor, bumetanide, prior to initiation of anesthesia with sevoflurane. Rats that were exposed to sevoflurane had decreased hypothalamic K+-2Cl- (KCC2) mRNA level (F(2,13)=3.839, P=0.049), increased NKCC1/KCC2 mRNA ratio (F(2,13)=5.043, P=0.024) and increased corticotropin-releasing hormone (CRH) mRNA level (F(2,12)=9.450, P=0.003) at P10, the age at which maternal separation was imposed. Adult rats, neonatally exposed to a combination of sevoflurane and maternal separation, exhibited increases in the escape latencies greater than animals exposed to sevoflurane only (P=0.012), and only rats in the sevoflurane plus maternal separation group spent significantly less time in the target quadrant during the Morris water maze test (F(4,55)=4.856, P=0.002). Bumetanide ameliorated abnormalities induced by sevoflurane and a combination of sevoflurane plus maternal separation. Neonatal exposure to sevoflurane may sensitize to stressors later in life, and post-exposure stress may exacerbate neurodevelopmental abnormalities even after a relatively short exposure to sevoflurane in rodents. The NKCC1 downregulation prior to exposure to the anesthetic may be therapeutic.
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PMID:Subsequent maternal separation exacerbates neurobehavioral abnormalities in rats neonatally exposed to sevoflurane anesthesia. 2898 96