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)

RESP18 (regulated endocrine-specific protein of 18 KD) is an endoplasmic reticulum (ER) protein that was identified by coordinate dopaminergic regulation with pro-opiomelanocortin in the rat neurointermediate pituitary. Many attributes of RESP18 suggest an important function in neuroendocrine cells. Several neuropeptides, growth factors, and enzymes involved in biosynthesis of classical chemical neurotransmitters, have been identified in germ cells, Sertoli cells, and spermatozoa. In this study, screening of reproductive tissues revealed high levels of RESP18 protein and mRNA in the testes but not in ovaries or epididymis. The testes and sperm expressed 18-KD RESP18 and a unique 19-KD isoform. To better understand RESP18 expression in the testes, we have examined the stages of the cycle of the seminiferous epithelium by immunohistochemistry and Western blot analyses. Immunohistochemical analysis showed that RESP18 protein was expressed exclusively in spermatocytes and maturing spermatids. RESP18 protein was expressed at high levels in Step 1-8 round spermatids, in which the PC4 prohormone convertase, nerve growth factor, and proenkephalin are also expressed. Western blots, Northern blots, and indirect immunofluorescence staining demonstrated RESP18 expression in sperm.
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PMID:Stage-specific expression of RESP18 in the testes. 898 41

Human obesity has an inherited component, but in contrast to rodent obesity, precise genetic defects have yet to be defined. A mutation of carboxypeptidase E (CPE), an enzyme active in the processing and sorting of prohormones, causes obesity in the fat/fat mouse. We have previously described a women with extreme childhood obesity (Fig. 1), abnormal glucose homeostasis, hypogonadotrophic hypogonadism, hypocortisolism and elevated plasma proinsulin and pro-opiomelanocortin (POMC) concentrations but a very low insulin level, suggestive of a defective prohormone processing by the endopeptidase, prohormone convertase 1 (PC1; ref. 4). We now report this proband to be a compound heterozygote for mutations in PC1. Gly-->Arg483 prevents processing of proPC1 and leads to its retention in the endoplasmic reticulum (ER). A-->C+4 of the intro-5 donor splice site causes skipping of exon 5 leading to loss of 26 residues, a frameshift and creation of a premature stop codon within the catalytic domain. PC1 acts proximally to CPE in the pathway of post-translational processing of prohormones and neuropeptides. In view of the similarity between the proband and the fat/fat mouse phenotype, we infer that molecular defects in prohormone conversion may represent a generic mechanism for obesity, common to humans and rodents.
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PMID:Obesity and impaired prohormone processing associated with mutations in the human prohormone convertase 1 gene. 920 82

We examined the expression of regulated endocrine-specific protein of 18-kD (RESP18) in selected peptidergic and catecholaminergic neurons of adult rat brain. In the hypothalamic paraventricular, supraoptic, and accessory nuclei, RESP18 mRNA was highly expressed in neurons immunostained for oxytocin and vasopressin. RESP18 mRNA was also highly expressed in paraventricular nucleus neurons immunostained for corticotropin-releasing hormone, thyrotropin-releasing hormone, and somatostatin. RESP18 mRNA was expressed in POMC cells of the arcuate nucleus, in neuropeptide Y cells of the dorsal tegmental nucleus, lateral reticular nucleus, and hippocampus, and in brainstem catecholaminergic neurons. RESP18 mRNA expression was high in all paraventricular and arcuate neurons, but RESP18 protein was detectable in the perikarya of a subset of these neurons, suggesting an important post-transcriptional component to the regulation of RESP18 expression. RESP18 antisera immunostained perikarya but not axon fibers or terminals. Sub-cellular fractionation of homogenates of several hypothalamic nuclei identified RESP18 protein in fractions enriched in endoplasmic reticulum. The presence of 22- and 24-kD RESP18 isoforms in the neural lobe of the pituitary indicated that some RESP18 protein exited the endoplasmic reticulum. The post-transcriptional regulation of RESP18 expression and localization of RESP18 protein primarily to the endoplasmic reticulum suggests that RESP18 plays a regulatory role in peptidergic neurons.
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PMID:Expression of RESP18 in peptidergic and catecholaminergic neurons. 928 14

In order to define the functional importance of the conserved RRGDL motif in the P-domain of the mammalian proprotein convertases(PCs) we generated and cellularly expressed three mutant PC1 vaccinia-virus (VV) recombinants: ARGDL-PC1, RAGDL-PC1 and RRGEL-PC1. Functionally, these mutants caused a decreased level of processing of pro-opiomelanocortin (POMC) into beta-lipotropic pituitary hormone (beta-LPH), especially in the constitutively secreting BSC40 cells. Pulse-chase analyses demonstrated that, in part, this effect was due to both an increased degradation of the mutant PC1s within the endoplasmic reticulum and to a diminished level of zymogen processing in the same compartment. In addition, within cells containing secretory granules such as PC12 and GH4C1 cells, such mutations prevented the C-terminal auto-processing of PC1 into the fully mature 66 kDa form stored in the secretory granules of regulated cells. Since the 66 kDa PC1 is the most active form of the enzyme, it is proposed that the RRGDL sequence is critical for the generation of maximal intracellular PC1 activity. In regulated cells, co-expression of POMC with PC1 or its mutants together with the general PC inhibitor alpha1-antitrypsin Portland (alpha1-PDX), which acts primarily within the constitutive secretory pathway, demonstrated that the latter completely inhibited the formation of beta-LPH by PC1 mutants, whereas it only partially inhibited the ability of wild-type PC1 to process POMC. This suggests that RRGDL mutations prevent PC1 from entering secretory granules and hence the formation of the 66 kDa PC1, and result in the mis-sorting of PC1 mutants towards the constitutive secretory pathway. This conclusion was further supported by immunocytochemical data demonstrating that RRGDL mutants exhibit an intracellular localization pattern different from that of the granule-associated wild-type PC1,but similar to that of the Golgi-localized convertase PC5-B.
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PMID:The integrity of the RRGDL sequence of the proprotein convertase PC1 is critical for its zymogen and C-terminal processing and for its cellular trafficking. 930 23

We used an anti-rat adrenal cytochrome P450C17 (P450C17) antibody to perform immunofluorescence and also immunogold electron microscopic studies to determine the zonal and intracellular distribution of P450C17 in hamster adrenals. Because P450C17 activity is regulated mainly by adrenocorticotropin (ACTH), its zonal and intracellular localization was also analyzed after ACTH treatment. The effect of ACTH treatment on protein concentration was also investigated by Western blotting analysis. By immunofluorescence, we found P450C17 to be confined to the zona fasciculata (ZF) in the hamster, in contrast to other small rodents, which do not express P450C17 in their adrenals. After treatment with ACTH, the thickness of the ZF remained unchanged compared to that of control animals, whereas a marked increase in fluorescence intensity was observed. In addition, dispersed cells in the zona reticularis (ZR) showed positive staining after ACTH treatment. Immunocytochemistry with colloidal gold showed P450C17 to be localized and importantly increased only in the cytoplasmic areas between the mitochondria of ZF cells of ACTH-treated animals. These areas are predominantly occupied by elements of the endoplasmic reticulum and other unidentified organelles. Immunoblotting analysis of whole glands revealed a single protein band at approximately 55 kD, which reacted with the 450C17 antibody. After stimulation with ACTH injected at 5-hr intervals over a period of 20 hr, P450C17 protein concentrations were considerably greater than in control animals. In conclusion, P450C17 is located not over mitochondria but probably in the endoplasmic reticulum of the ZF cells in hamster adrenals. Treatment with ACTH induced expression of cytochrome P450C17 in ZF cells, increasing its production in these cells without stimulating cell proliferation.
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PMID:Immunolocalization and biochemical determination of cytochrome P450C17 in adrenals of hamsters treated with ACTH. 931 2

Endothelins modulate hormonal secretion in the pituitary gland. Intense signaling of endothelin A receptors (ET(A)R) has been detected by in situ hybridization, binding assay and receptor autoradiography. We used light- and electron-microscopic immunohistochemistry of ET(A)R with polyclonal antibody against a synthetic peptide corresponding to the carboxyl terminus (403-427) of human ET(A)R. Immunoreactivity was observed in 6-8% of anterior pituitary cells, which were rather large polygonal or stellate cells. These cells were often clustered. Double-staining immunofluorescence showed that the ET(A)R-positive cells immunoreacted with antibody against the beta-subunit of thyroid-stimulating hormone (TSH), but not adrenocorticotropic hormone (ACTH) or lutenizing hormone beta (LHbeta). Pre- and postembedding electron-microscopic immunohistochemistry showed that ET(A)R-positive cells had vacuolated or parallel-lined rough endoplasmic reticulum (rER) and numerous round granules in their periphery and the elongated processes. By pre-embedding immunohistochemistry, diaminobenzidine tetrahydrochloride (DAB) products were shown to be mostly located around the granules and occasionally underneath the plasma membrane. By postembedding immunohistochemistry, granules in the ET(A)R-positive cells were 90-150 nm in diameter, and colloidal gold particles due to ET(A)R were associated with about 10% of these granules. These results indicate that ET(A) receptors are associated mostly with the secretory granules of TSH cells.
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PMID:Localization of endothelin A receptors in the rat pituitary TSH cells: light- and electron-microscopic immunohistochemical studies. 1107 19

Two of 420 patients with pituitary adenoma who underwent operation from 1989 to 1997 had thyroid stimulating hormone (TSH) producing adenoma. We investigated these TSH cell adenomas with immunohistochemical and ultrastructural methods and compared their ultrastructural features with brefeldin A (BFA, 0.5 mg/ml) treated pituitary adenoma cells. BFA-treated pituitary adenomas include a prolactin (PRL) cell adenoma, a growth hormone (GH) cell adenoma, an adrenocorticotropic hormone (ACTH) cell adenoma, a gonadotroph adenoma, and a plurihormonal adenoma. Immunohistochemical staining disclosed that one of the TSH cell adenomas produced only TSH-beta and that another produces both TSH-beta and FSH-beta. Ultrastructural analysis showed the abundance of oval-shaped dilated rough endoplasmic reticulum (rER). Within the dilated rER, the mistlike deposit or deposit along the inner margin of the rER membrane was observed. On the other hand, BFA-treated cultured pituitary adenoma cells showed the opening of the cavity of the rER cisterna and they enlarged to an oval form with time and revealed an accumulation of electron-dense deposits within the dilated rER. These ultrastructural similarities between TSH cell adenoma and BFA-treated pituitary adenoma cells indicate the functional disturbances in the secretory passage through the Golgi apparatus in TSH cell adenoma cells.
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PMID:Ultrastructural characteristics of TSH-producing adenomas with special reference to its close similarity to BFA-treated pituitary adenoma cells. 1108 Dec 1

Catecholamines are produced in the medulla of the adrenal gland and may participate in the intraglandular regulation of its cortex. We analyzed the adrenal structure and function of albino tyrosine hydroxylase-null (TH-null) mice that are deficient in adrenal catecholamine production. Adrenal catecholamines were markedly reduced, and catecholamine histofluorescence was abrogated in 15-day-old TH-null mice. Chromaffin cell structure was strikingly altered at the ultrastructural level with a depletion of chromaffin vesicles and an increase in rough endoplasmic reticulum compared with wild-type mice. Remaining chromaffin vesicles lined up proximally to the cell membrane in preparation for exocytosis providing a "string-of-pearls" appearance. There was a 5-fold increase in the expression of proenkephalin mRNA (502.8 +/- 142% vs. 100 +/- 17.5%, P = 0.016) and a 2-fold increase in the expression of neuropeptide Y (213.4 +/- 41.2% vs. 100 +/- 59.9%, P = 0.014) in the TH-null animals as determined by quantitative TaqMan (Perkin-Elmer) PCR. Accordingly, immunofluorescence for met-enkephalin and neuropeptide tyrosine in these animals was strongly enhanced. The expression of phenylethanolamine N-methyl transferase and chromogranin B mRNA was similar in TH-null and wild-type mice. In TH-null mice, adrenocortical cells were characterized by an increase in liposomes and by tubular mitochondria with reduced internal membranes, suggesting a hypofunctional state of these steroid-producing cells. In accordance with these findings, plasma corticosterone levels were decreased. Plasma ACTH levels were not significantly different in TH-null mice. In conclusion, both the adrenomedullary and adrenocortical systems demonstrate structural and functional changes in catecholamine-deficient TH-null mice, underscoring the great importance of the functional interdependence of these systems in vivo.
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PMID:Deletion of tyrosine hydroxylase gene reveals functional interdependence of adrenocortical and chromaffin cell system in vivo. 1112 Oct 73

A 60-year-old woman presented with a history of palpitations, headaches and severe hypertension, which was resistant to hypotensive agents. She had a 2-year history of obesity and a moon face. Her plasma adrenocorticotropic hormone level was below the limits of detection and did not respond to corticotropin-releasing hormone. Urinary-free cortisol was elevated and the circadian rhythm of serum cortisol level had completely disappeared. Imaging analysis demonstrated a unilaterally functioning mass in the left adrenal gland. Serum cortisol level in the left adrenal vein was elevated. The resected adrenal mass measured 4 x 3.5 x 2.5 cm, and ranged from yellow to tan in color. The adrenal cortex adjacent to the nodule did not demonstrate cortical atrophy. The mass was well circumscribed but not encapsulated, and consisted of multiple cortical nodules. These nodules were composed predominantly of clear cortical cells, and partly of compact cortical cells. Immunoreactivity of steroidogenic enzymes including cholesterol side-chain-cleavage P450, 3beta-hydroxysteroid dehydrogenase, 21-hydroxylase cytochrome P450, 11beta-hydroxylase cytochrome P450 and 17alpha-hydroxylase cytochrome P450 was marked in cortical nodules, but minimal in non-nodular cortex. Ultrastructural examination of nodular cortical cells also demonstrated well-developed mitochondria and smooth endoplasmic reticulum, consistent with elevated steroidogenesis in these cells.
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PMID:Adrenocorticotropin-independent unilateral adrenocortical hyperplasia with Cushing's syndrome: Immunohistochemical studies of steroidogenic enzymes, ultrastructural examination and a review of the literature. 1116 51

We observed the histopathological and physiological characteristics of adrenocorticotropic hormone (ACTH)-secreting adenoma cells derived from a rapidly growing pituitary adenoma, which have firm cell attachment and well-preserved hormonal function in a relatively longterm culture. Corticotrophs, obtained from a 43-year-old woman with Cushing's disease in whom plasma ACTH levels increased in response to 1-deamino-8-D-arginine vasopressin (DDAVP) stimulation and the proliferative potential was very high, were grown in tissue culture for up to 6 months. The morphological features were observed by phase contrast and electron microscopy. The cultured cells were incubated with corticotroph-releasing hormone (CRH), arginine vasopressin (AVP), or DDAVP, and ACTH in the medium was measured by radioimmunoassay (RIA). The morphology of the ACTH-secreting adenoma cells in culture revealed a mixed population of formed clusters and spindle-shaped fibroblast-like cells. The adenoma cells were immunohistochemically positive only for ACTH. On electron microscopic observation, pituitary tumor cells obtained 6 days after seeding demonstrated many secretory granules, well-developed rough endoplasmic reticulum, and mitochondria; fewer secretory granules were observed after cultivation for 24 days. ACTH levels in the incubation media were elevated with stimulation by DDAVP, AVP, or CRH. In this study, the establishment of relatively longterm culture of human pituitary adenoma cells seemed to be due to the high proliferative potential of this adenoma. This in vitro study may imply that DDAVP as well as AVP directly stimulates ACTH release from corticotropic adenoma cells.
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PMID:Histopathological and physiological characteristics of cultured human ACTH-secreting cells derived from a rapidly growing pituitary adenoma. 1131 Sep 20


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