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)

The gene encoding pro-opiomelanocortin (POMC) presents unique regulatory features. In particular, glucocorticoids inhibit transcription of the POMC gene in the anterior pituitary, but not in the intermediate pituitary. In order to study the mechanism leading to transcriptional inhibition of POMC by glucocorticoid and the interaction of the glucocorticoid receptor complex with specific DNA sequences along the POMC gene, we have cloned the rat POMC gene and determined its structure. The gene is composed of three exons and appears to be present at a single copy per haploid genome. Besides the usual regulatory signals like 'TATA' and 'CCAAT' boxes, the upstream region contains sequences homologous to known enhancer sequences and to the glucocorticoid receptor binding site observed in glucocorticoid-responsive genes.
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PMID:Structure of the rat pro-opiomelanocortin (POMC) gene. 299 78

The S region of the murine major histocompatibility complex contains two structurally related genes (21-OHase A and 21-OHase B) that encode 21-hydroxylase (21-OHase), an enzyme essential for the synthesis of adrenal steroids. Expression of these two genes has been analyzed by using oligonucleotide probes specific for the 21-OHase A and B genes and by DNA-mediated gene transfer. Hybridization of the oligonucleotides to blots of BALB/c adrenal RNA demonstrated that all 21-OHase mRNA is derived from the 21-OHase A gene. Cosmids bearing either the 21-OHase A or B gene were introduced into Y1 adrenocortical tumor cells by cotransfection with pSV2-neo. Cells transfected with the 21-OHase A gene expressed 21-OHase as determined by steroid metabolism and by RNA blot hybridization; 21-OHase transcripts were not detected in parent Y1 cells or in cells transfected with the 21-OHase B gene. Treatment of 21-OHase A transfectants with adrenocorticotropin increased 21-OHase mRNA levels by up to 10-fold, thus mimicking the observed effect of this hormone on 21-OHase levels in primary adrenal cultures. The regulated expression of the 21-OHase A gene in transfected Y1 cells should provide a useful system for the investigation of factors controlling the adrenal-specific regulation of 21-OHase activity.
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PMID:Expression of murine 21-hydroxylase in mouse adrenal glands and in transfected Y1 adrenocortical tumor cells. 299 80

In the steroidogenic pathway of the adrenal cortex, 17 alpha-hydroxylase cytochrome P-450 (P-450(17 alpha)) is a major regulatory enzyme. Previous studies have shown that stimulation of 17 alpha-hydroxylase activity occurs upon treatment of bovine adrenocortical cells in culture with adrenocorticotropic hormone (ACTH), via cAMP, due to an increase in the enzyme concentration. Alterations in the levels of this enzyme result in pronounced changes in the pattern of steroids produced, with the potent glucocorticoid cortisol, as well as the sex steroids, being products of 17 alpha-hydroxylated steroid precursors. In the present study, the identification and sequencing of two cloned DNA molecules, pB17 alpha-1 and pcD17 alpha-2, which are complementary to mRNA sequences encoding bovine adrenal cortex P-450(17 alpha), are reported. Clone pcD17 alpha-2 contains an open reading frame coding for the complete amino acid sequence of P-450(17 alpha) which consists of 509 amino acids and has a molecular weight of 57,251. By comparison to other forms of cytochrome P-450, we conclude that P-450(17 alpha) is a member of a previously unidentified family within the P-450 multigene superfamily. Single bovine and human mRNA species of approximately equal to 1850 bases in length hybridize to these clones. Regulation of the concentration of this RNA has been studied using bovine adrenocortical cells in culture. Treatment with ACTH or dibutyryl cAMP causes an increase in the content of P-450(17 alpha) RNA in as little as 2 h, and its concentration increases greater than 20-fold by 8 h. In contrast, other steroidogenic enzymes that have been studied respond more slowly to ACTH. Actinomycin D and cycloheximide block induction of P-450(17 alpha) RNA, indicating that regulation of 17 alpha-hydroxylase activity is controlled at the level of transcription and requires ongoing protein synthesis.
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PMID:Bovine adrenocortical cytochrome P-450(17 alpha). Regulation of gene expression by ACTH and elucidation of primary sequence. 300 17

A cAMP-resistant mutant (Kin-8) isolated from Y1 mouse adrenocortical tumor cells harbors a specific lesion in the regulatory subunit of the type 1 cAMP-dependent protein kinase. This mutant also is resistant to the effects of corticotropin and cAMP on steroidogenesis, growth and morphology, suggesting an obligatory role for the protein kinase in regulation of adrenocortical functions. In this study, the cAMP-resistant phenotype of the Kin-8 mutant was reverted by transformation with DNA from cAMP-responsive Y1 cells, and the biochemical basis of the transformation was explored. Initially, Y1 mouse adrenocortical tumor cells were evaluated for their competence as recipients in DNA-mediated transformation experiments, by measuring their ability to incorporate and express a bacterial gene (neo) encoding resistance to neomycin. Y1 cells were transfected with the plasmid pSV2-neo (an SV40-neo hybrid vector designed for expression in animal cells) and screened for resistance to the neomycin analog, G418. Neomycin-resistant transformants were recovered from Y1 cells at a frequency of approximately one per 10(3) cells per 10 micrograms of DNA, and had specific neo sequences integrated into their high molecular weight (mw) DNA. The Y1 mutant, Kin-8, then was transformed with pSV2-neo DNA plus high mw DNA prepared from cAMP-responsive Y1 cells. Cells competent for transformation were recovered by selective growth in the neomycin analog G418, and these transformants were screened for recovery of morphological responses to cAMP. Several colonies capable of rounding up in the presence of cAMP were recovered after transformation with DNA from Y1 cells. These transformants also recovered the ability to round up in the presence of corticotropin, and were able to respond to both corticotropin and cAMP with increased steroidogenesis. Transformants generated from either Y1 or Kin-8 cells were unstable. Y1 cells lost resistance to neomycin when grown in the absence of G418 at a frequency of 4% per generation. Similarly, Kin-8 transformants lost their sensitivity to cAMP in subsequent culture passages. In some of the cAMP-responsive transformants, cAMP-dependent protein kinase activity was recovered and approached the activity seen in cAMP-responsive Y1 cells. The recovery of a normal protein kinase by transformation appeared to have been sufficient to reverse the cAMP-resistant phenotype of Kin-8 cells. In other cAMP-responsive transformants, protein kinase activity was not appreciably affected by cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Recovery of hormonal regulation in protein kinase defective adrenal cells through DNA-mediated gene transfer. 300 21

A recombinant plasmid containing the human proenkephalin gene ligated to pBR322 was introduced into a mouse pituitary cell line (AtT-20D16v) that normally expresses pro-opiomelanocortin but not proenkephalin. The plasmid was introduced by co-transformation with the G418-selectable plasmid, pRSVneo. Stable transformants were isolated and analyzed for the presence of the human proenkephalin gene. AtT-20 transformants which had one or more copies of the human proenkephalin gene integrated stably into the mouse chromosomal DNA expressed a 1.45 kb mRNA identical in size to human proenkephalin mRNA. Primer extension analysis indicated that the human proenkephalin gene was accurately and efficiently transcribed from its own promoter. AtT-20 transformants that expressed the 1.45 kb human proenkephalin mRNA also expressed proenkephalin protein and cleaved the protein to form free Met-enkephalin. This is of particular interest because these cells do not cleave all of the available pairs of basic amino acids in the endogenous protein, pro-opiomelanocortin, the precursor to ACTH, beta-endorphin and melanocyte stimulating hormones. The release of both ACTH and Met-enkephalin from these cells is stimulated by corticotropin releasing factor, a natural secretagogue for ACTH, indicating that the two classes of peptide share a related secretory pathway.
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PMID:Expression of the human proenkephalin gene in mouse pituitary cells: accurate and efficient mRNA production and proteolytic processing. 300 33

In order to elucidate the mechanism responsible for ectopic hormone production in tumors, biosynthesis of ACHT and related peptides was studied in the pituitary and tumors at levels. In vitro biosynthesis of the ACTH/beta-LPH precursor directed by mRNA extracted from the pituitary and tumors showed no difference in translation products. It is highly likely, therefore, that different final products produced in the pituitary and tumors are caused by different posttranslational processing, such as proteolysis and glycosylation of translation products. The RNA blot analysis of tumors revealed mRNA identical to that of the pituitary. In certain tumors, however, there were larger or smaller mRNA hybridized with an ACTH/beta-LPH precursor probe, in addition to mRNA of normal size. Further studies with endonuclease S1 mapping have provided evidence suggesting that the larger one was probably produced by abnormal splicing of RNA precursor and that the smaller one was resulted possibly from aberrant transcription of the gene. The Southern blot analysis revealed no difference in restriction DNA fragments between the pituitary and tumors, indicating no evidence of gene rearrangement. From these studies, it is conceivable that ectopic ACTH production is resulted from abnormalities in the regulatory mechanism of gene expression. To further study the mechanism regulating the expression of the ACTH/beta-LPH precursor gene, human gene was transfected to mouse pituitary ACTH-producing adenoma cells (AtT-20) and fibroblasts (L-cell). The introduced human ACTH/beta-LPH precursor gene was expressed in AtT-20 cells and suppressed by glucocorticoids to an extent similar to the suppression of mouse gene. On the other hand, possible aberrant transcripts were observed in mouse L cells. It is likely, therefore, that there is a regulatory mechanism, probably "trans" acting, in the pituitary ACTH-producing producing cells and similar mechanism, though not identical, could be exerted in ectopic ACTH-producing tumors.
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PMID:[Hormone production and abnormalities in gene expression in tumors]. 300 63

Maintenance of optimal steroidogenic capacity in the adrenal cortex is the result of a cAMP-dependent response to the peptide hormone corticotropin (ACTH). The molecular mechanism of this action of ACTH has been examined by using five recombinant DNA clones specific for enzymes of the steroidogenic pathway (P-450scc, P-45011 beta, P-450C21, P-45017 alpha, and adrenodoxin). The presence of nuclear precursors in steady-state RNA samples derived from cultured bovine adrenocortical cells and moderate increases in the number of RNA chain initiations, as determined by in vitro nuclear run-off assays, indicate that ACTH controls the expression of the gene(s) for each of these proteins at the transcriptional level. The ACTH-mediated increase in accumulation of transcripts specific for steroid hydroxylases in nuclear RNA can be specifically blocked by inhibiting protein synthesis in bovine adrenocortical cell cultures. The steady-state concentrations of nuclear RNA for control genes show no decrease upon cycloheximide treatment. These studies suggest that a primary action of ACTH in the adrenal cortex is to activate (via cAMP) the synthesis of rapidly turning over protein factors that in turn mediate increased initiation of transcription of steroid hydroxylase genes. We propose that these protein factors impart specificity of induction to genes encoding components of this pathway in steroidogenic tissues.
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PMID:Transcriptional regulation of steroid hydroxylase genes by corticotropin. 301 7

A search for the defective gene causing torsion dystonia has been carried out in a family manifesting an autosomal dominant mode of inheritance of this movement disorder. Complete neurologic examination and establishment of lymphoblast lines have been carried out for over 50 members. Linkage analysis, using cloned DNA sequences and restriction fragment length polymorphisms, was evaluated by the LOD score method with requisite assumptions for mode of inheritance, age-of-onset and incomplete gene penetrance. Genes for pro-opiomelanocortin and glutamic acid decarboxylase, which have been implicated in the etiology of the disease in rat models, were excluded as being responsible for the disease state in this family. Other regions of the genome were also excluded using DNA probes for other genes and random "unique" sequences.
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PMID:Linkage analysis in a family with dominantly inherited torsion dystonia: exclusion of the pro-opiomelanocortin and glutamic acid decarboxylase genes and other chromosomal regions using DNA polymorphisms. 301 20

We report results indicating that expression and hormonally controlled negative regulation of the human pro-opiomelanocortin (POMC) gene in mouse fibroblasts can be accomplished by the placement nearby of a simian virus 40 enhancer sequence. Expression resulting from correctly initiated transcription required the enhancer in cis both in cells stably transfected with the POMC gene and in a transient expression assay with constructs that fused that POMC promoter region to the protein-coding region of the herpes simplex virus thymidine kinase (TK) gene. Negative regulation of POMC transcription by glucocorticoids was demonstrated in transiently infected cells by assaying for TK activity encoded by the POMC-TK fusion constructs and by quantitative S1 nuclease mapping. The sequences responsible for such regulation were shown to be contained within a DNA segment that extends 670 base pairs upstream from the cap site for POMC mRNA.
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PMID:Hormonally mediated negative regulation of human pro-opiomelanocortin gene expression after transfection into mouse L cells. 301 28

The role of the second messengers cAMP and Ca++ in the control of proopiomelanocortin (POMC) gene expression was investigated with the use of hybridization with cloned complementary DNA probes. The effects of cAMP-related drugs on POMC messenger RNA (mRNA) levels were assessed in primary cultures of intermediate (IL) and anterior rat pituitary cells maintained in serum-free medium. 8-Bromo-cAMP (1 mM), but not 8-bromo-cGMP (1 mM), induced a 2-fold increase in IL and anterior lobe cell after 2 days of treatment. A similar increase was obtained with the adenylate cyclase-activating drugs forskolin (1 microM) and cholera toxin (100 ng/ml) or the phosphodiesterase inhibitor RO 20-1724 (100 microM). At 48 h, all these treatments had increased beta-endorphin accumulation in the medium and transiently decreased the cellular beta-endorphin content in IL cells, suggesting a parallel effect of cAMP-related drugs on secretion and biosynthesis. Incubating the cells with the Ca++ channel antagonists D600 (50 microM), verapamil (50 microM), and the dihydropyridine nifedipine (0.1 microM) decreased basal POMC mRNA levels, whereas the dihydropyridine BAYK 8644 (0.1 microM), which activates the Ca++ channel, increased POMC mRNA levels after 2 days. In addition, nifedipine decreased the stimulatory effect of forskolin, whereas BAYK 8644 further stimulated the forskolin-increased POMC mRNA levels in IL cells. We conclude that both Ca++ and cAMP may regulate the gene expression of POMC.
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PMID:Calcium ion and cyclic adenosine 3',5'-monophosphate regulate proopiomelanocortin messenger ribonucleic acid levels in rat intermediate and anterior pituitary lobes. 302 21


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