Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined the subcellular localization of an endopeptidase activity able to degrade gonadotropin releasing hormone (GnRH) and present in the rat adenohypophysis. After fractionation of tissue homogenates in 0.25 M sucrose by differential centrifugation, about 25% of the total cellular GnRH degrading activity was found to be sedimentable and recovered from heavy (M) and light (L) mitochondrial fractions with a distribution pattern similar to that of the mitochondrial and lysosomal reference enzymes cytochrome oxidase and beta-galactosidase. Upon further fractionation on sucrose density gradients, the activity comigrated with mitochondria. The peptidase appears endowed with a structure-linked latency; the activity is low in a freshly prepared mitochondrial fraction and increases upon treatment with membrane disrupting agents in a manner similar to that of malate dehydrogenase, a component of the mitochondrial matrix. Determination of GnRH cleavage sites was performed by amino acid analysis of the fragments obtained after incubation of the peptidase with (3H)-GnRH labelled on the pyroglutamic acid residue, in presence of carboxypeptidase and peptidyldipeptidase inhibitors. The fragments were separated by ion-exchange chromatography on an Aminex Q-15S column and purified by chromatography on silica gel plates. Fragments 1-2, 1-3, 1-4, 1-5 and 1-6 were all present as early as 1 min after the beginning of incubation. Formation of each of them was inhibited to the same extent by EDTA, mersalyl acid, dithioerythritol and Na deoxycholate. The same fragmentation pattern was observed after partial purification of the enzyme by gel filtration. These data indicate that cleavage of several peptide bonds may result from a possibly single endopeptidase located in the mitochondrial matrix space.
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PMID:Characterization of a neutral endopeptidase localized in the mitochondrial matrix of rat anterior pituitary tissue with GnRH as a substrate. 637 12

A pituitary cell population of 14-day-old female rats, containing lactotropes and somatotropes but deprived of gonadotropes, was prepared by unit gravity sedimentation through a serum albumin gradient and allowed to reaggregate either as such or after mixing this population with cells of the gonadotropic alpha T3-1 cell line. In a perifusion system gonadotropin-releasing hormone (GnRH) had no effect on prolactin (PRL) and growth hormone (GH) release in the former aggregates but stimulated PRL release in the latter. In the alpha T3-1 cell-containing aggregates GnRH showed a biphasic effect on GH release: inhibition during exposure to GnRH followed by a rebound secretion upon removal of the peptide. The aggregation capacity of alpha T3-1 cells with the normal pituitary cells was demonstrated by using an alpha T3-1 cell clone stably transfected with the reporter gene beta-galactosidase. Perifusion of the gonadotrope-deprived aggregates with medium conditioned by alpha T3-1 cell provoked a rapid stimulation of PRL release and a biphasic effect on GH release. Medium conditioned by the corticotropic cell line AtT20 also stimulated PRL release but had no concomitant effect on GH release. Medium conditioned by alpha T3-1 cells, when added for 40 h to aggregates of 14-day-old rat pituitary, provoked an increase in the number of 3H-thymidine (3H-T)-labelled lactotropes and a decreased in the number of 3H-T-labelled somatotropes. The conditioned medium was concentrated on Sep-Pak C18 and ultrafiltrated through an Amicon membrane with 3-kD molecular weight cut-off and the retained molecules separated by reversed-phase HPLC. The material stimulating 3H-T labelling of lactotropes eluted from the column with a different retention time than material inhibiting 3H-T labelling of somatotropes, suggesting that the effect on lactotropes is mediated by (a) molecule(s) different from that affecting somatotropes. The effects of alpha T3-1 cells and their secretion products on lactotropes and somatotropes were comparable to those we previously observed using enriched populations of normal gonadotropes. The HPLC elution profiles of the substances affecting 3H-T incorporation as well as the specificity of these effects were also similar to that of the substances isolated previously from gonadotrope-conditioned medium. The present data, therefore, support previous conclusions on the paracrine control of the lactotrope/somatotrope lineage by the gonadotropes. Further purification and chemical characterization of the growth factors with selective action on lactotropes and somatotropes may lead to a better understanding of the development of the latter lineage.
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PMID:Interaction of alpha T3-1 cells with lactotropes and somatotropes of normal pituitary in vitro. 789 38

Spermatogonial stem cells can be transplanted from a fertile donor mouse to the testis of an infertile recipient where they establish spermatogenesis and produce spermatozoa. In the present study we investigated whether treatment of recipient mice with the gonadotropin-releasing hormone (GnRH) agonist leuprolide acetate could alter the efficiency of colonization by donor spermatogonial stem cells in the recipient testis. Six recipient mice were treated with busulfan to destroy endogenous spermatogenesis followed by injection of leuprolide acetate to three of the mice. Testis cells from mice carrying the ZFlacZ transgene, which produces beta-galactosidase in spermatids, were used as donor cells for transplantation to allow for identification of donor spermatogenesis in the recipient testis by staining for enzyme activity. The extent of donor cell colonization was compared between leuprolide treated recipients and untreated control mice 3 months after transplantation. Efficiency of colonization by donor cells was markedly enhanced in recipient mice treated with the GnRH agonist leuprolide acetate, which makes the technique of spermatogonial transplantation applicable to a wide range of experimental situations. The present study also indicates that this technique can be used as a biological assay system to investigate factors controlling the establishment and progression of spermatogenesis.
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PMID:Leuprolide, a gonadotropin-releasing hormone agonist, enhances colonization after spermatogonial transplantation into mouse testes. 983 81

This review summarizes recent work on the use of reporter genes to label selected neuronal populations in transgenic mice, with particular emphasis on gonadotropin-releasing hormone (GnRH) neurons. Reporter genes discussed are the lacZ, green fluorescent protein (GFP), luc, and bla genes, which encode the reporter proteins beta-galactosidase, GFP, luciferase, and beta-lactamase, respectively. Targeted transgenic expression of these reporter proteins is obtained by fusing the corresponding reporter gene, with or without a subcellular localization signal, to a cell type- or brain region-specific gene promoter. Mice carrying GnRH promoter-driven reporter genes have proven useful for revealing the promoter elements required for cell type-specific expression of GnRH, the full anatomical profile of the GnRH neuronal network, and its electrophysiological activity, suggesting that similar approaches will assist in elucidating the properties of other neuronal populations as well.
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PMID:Using reporter genes to label selected neuronal populations in transgenic mice for gene promoter, anatomical, and physiological studies. 1116

The complete Serine 8-type gonadotropin releasing hormone (GnRH) coding sequence with a substantial 5-prime regulatory sequence (5 kb) has been isolated and characterised in Nile Tilapia (Oreochromis niloticus) from a relevant genomic library. The primary structure of the protein precursor was identified for this gene. The promoter efficacy has been tested using 0.6 kb of the GnRH promoter driving a lacZ reporter gene in both cultured spleen cells and transiently expressing zebrafish. In the cell transfection experiments, the average level of beta-galactosidase activity in transfected cells was more than 2.1 (P<0.05) times higher than the control promoter-less vector in five independent cultures indicating that the 0.6 GnRH/lacZ construct is able to express in spleen cells. In addition, the transient expression of the lacZ gene was detected in the brain of G0 zebrafish embryos (Danio rerio) 4 days after fertilisation following egg injection with the construct, which demonstrated the efficacy of the tilapia GnRH promoter.
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PMID:Isolation and expression of tilapia (Oreochromis niloticus) serine 8-type GnRH coding and regulatory sequences. 1256 19