Thyrotropin-releasing hormone is inactivated in the extracellular space by a membrane-bound peptidase, pyroglutamyl aminopeptidase II (PPII), a member of the M1 family of zinc metallopeptidases. The functional significance of multiple PPII RNA species expression is unknown. We detected, in rat tissues, a RNA species derived from an alternative processing at the exon 14-intron 14 boundary. The alternatively processed RNA encoded a shorter version of PPII (PPII*), lacking part of the C-terminal domain. PPII* was expressed in COS-7 (or C6 glioma) cells but it did not exhibit any PPII activity. Co-transfection of PPII and increasing amounts of PPII* expression vectors resulted in a dose-dependent reduction in PPII activity and the formation of covalent PPII-PPII* heterodimers. PPII* is therefore a powerful dominant-negative isoform of PPII, and heterodimerization may be its mechanism of action. Natural expression of shortened versions of M1 aminopeptidases may constitute a new mode of regulation of their activity.

TRH is hydrolyzed by pyroglutamyl aminopeptidase II (PP II), a highly specific ecto-enzyme which is localized on the surface of lactotrophs. To study whether PP II activity may be rapidly regulated during a burst of prolactin secretion, we used an in vitro model in which primary cultures of adenohypophyseal cells were incubated with 500 nM dopamine (DA) for 24 h prior to treatments. We observed a rapid increase of PP II activity when 100 nM [3-Me-His2]-TRH, a TRH agonist, was added at removal of DA. PPII activity was maximal after 20 min of treatment and reduced to time 0 activity at 30 min. Dopamine withdrawal alone, slightly and transiently, modified the enzyme activity: an initial activation at 15 min was followed by a transient inhibition at 20 min. The specific contribution of [3-Me-His2]-TRH in this paradigm was a transient enhancement of PP II activity. If DA was not removed, [3-Me-His2]-TRH was ineffective. These data demonstrate that during in vitro conditions that mimic a suckling episode, adenohypophyseal PP II activity is rapidly and reversibly adjusted.

In the adenohypophysis, thyrotrophin-releasing hormone (TRH) is inactivated by pyroglutamyl peptidase II (PPII), a TRH-specific ectoenzyme localized in lactotrophs. TRH slowly downregulates surface PPII activity in adenohypophyseal cell cultures. Protein kinase C (PKC) activation mimics this effect. We tested the hypothesis that other hypothalamic factors controlling prolactin secretion could also regulate PPII activity in adenohypophyseal cell cultures. Incubation for 16 h with pituitary adenylate cyclase activator peptide 38 (PACAP; 10(-6) M) decreased PPII activity. Bromocryptine (10(-8) M), a D2 dopamine receptor agonist, or somatostatin (10(-6) M) stimulated enzyme activity and blocked the inhibitory effect of [3-Me-His2]-TRH, a TRH receptor agonist. Bromocryptine and somatostatin actions were suppressed by preincubation with pertussis toxin (400 ng ml(-1)). Because these hypophysiotropic factors transduce some of their effects using the cAMP pathway, we analysed its role on PPII regulation. Cholera toxin (400 ng ml(-1)) inhibited PPII activity. Forskolin (10(-6) M) caused a time-dependent decrease in PPII activity, with maximal inhibition at 12-16 h treatment; ED50 was 10(-7) M. 3-isobutyl-1-methylxanthine or dibutiryl cAMP, caused a dose-dependent inhibition of PPII activity. These data suggest that increased cAMP down-regulates PPII activity. The effect of PACAP was blocked by preincubation with H89 (10(-6) M), a protein kinase A inhibitor, suggesting that the cAMP pathway mediates some of the effects of PACAP. Maximal effects of forskolin and 12-O-tetradecanoylphorbol 13-acetate were additive. PPII activity, therefore, is independently regulated by the cAMP and PKC pathways. Because most treatments inhibited PPII mRNA levels similarly to PPII activity, an important level of control of PPII activity by these factors may be at the mRNA level. We suggest that PPII is subject to 'homologous' and 'heterologous' regulation by elements of the multifactorial system that controls prolactin secretion.

TRH (pGlu-His-ProNH2) inactivation in the brain and pituitary extracellular fluid is reviewed. While TRH could be eliminated by alternative mechanisms, i.e. uptake or internalization, modification, hydrolysis by broad specificity peptidases such as pyroglutamyl peptidase I and prolyl endopeptidase, evidence accumulates to support a specific neuroectopeptidase as the main mechanism responsible for its extracellular inactivation. Pyroglutamyl peptidase II (PPII; E.C. 3.4.19.6) is a narrow specificity zinc metallopeptidase hydrolyzing the pyroglutamyl-histidyl peptide bond of TRH. PPII is an integral membrane protein with a small intracellular domain, a transmembrane segment and a large extracellular domain that contains the catalytic site. It is therefore idealy situated to degrade TRH present in the extracellular space. PPII is highly enriched in brain, specifically present in neuronal cells. PPII inhibition enhances recovery of TRH released in vitro. In situ hybridization studies demonstrate that PPII mRNA colocalizes with TRH-receptor mRNA in various brain regions. However, the existence of exceptions suggest that alternative inactivation mechanisms for TRH may operate. PPII activity is regulated in various pharmacological or pathophysiological conditions which alter TRH transmission. It is also present in adenohypophysis, preferentially on lactotrophs, where its activity is stringently regulated by hormones and hypothalamic factors. PPII activity regulation may contribute to adjust TRH neural and hormonal transmissions.

Two novel series of arylidenepyruvic acid thiosemicarbazone and thiazoline derivatives were synthesized and evaluated as potential antimicrobial agents. These substances did not exhibit any significant antibacterial effects when tested against a variety of microorganisms.

□ Two novel series of steroidal derivatives containing various thiourea and substituted thiazoline moieties attached to the 2- or 4- position of estrone were synthesized and examined for in vitro effect on bovine pancreatic ribonuclease activity. All compounds studied exhibited a catabolic activity. The steroidal thiazoline derivatives were more potent activators of ribonuclease than the steroidal thioureas.

AbstractBei der Kondensation des Pyridins (I) mit dem Thiouracil (II) mit KOH in möglichst wenig Wasser entsteht die Titelverbindung (III) unter weitestgehender Vermeidung einer Bildung des isomeren S‐Substitutionsprodukts.

Abstract1‐Hydrazino‐phthalazin‐hydrochlorid (I) reagiert mit Isothiocyanaten (II) in Gegenwart von Dicyclohexylcarbodiimid zu den Cyclisierungsprodukten (III); (IIIa) wird unabhängig aus (I) über die Zwischenstufe (IV) gewonnen.

AbstractDie Thioether (II) bzw. (V) werden aus dem Bromthiazol (I) dargestellt.

AbstractA novel series of 3‐substituted amino‐s‐triazolo[3,4‐a]phthalazine derivatives has been synthesized by the one‐pot cyclodesulfurization reactions utilizing 1‐hydrazinophthalazine, alkyl, aryl, or aralkylisothiocyanates and dicyclohexylcarbodiimide (DCCD) mixtures. The products did not exhibit any antihypertensive properties. Their pmr and mass spectral analysis is given.

Condensation of 2-chloro-5-nitro pyridine with propyl-thiouracil has been carried selectively on the S as well as on N(3) of propylthiouracil. The crystal structure of the latter compound (C 12 H 12 N 4 O 3 S) has been determined. Space group is P21, Z=8, a=12.476(4), b=22.625(5), c=9.878(4)Å, B=90.883(10)°. The four independent molecules have almost the same conformation with the nitro group rotated by 7° to 11° from the pyridine rings: the dihedral angles between the latter and the pyrimidine planes are included in the limits 80 to 84°.

AbstractA series of 3‐substituted aminoimidazo[1,5‐a]pyridine derivatives have been synthesized by cyclodesulfurization of a variety of N′‐substituted‐N‐(2‐pyridylmethyl)thioureas with dicyclohexylcarbodiimide (DCCD). 1H Nmr spectral analysis of all synthesized compounds is given.

Chemischer InformationsdienstVolume 11, Issue 18 Heterocyclic Compounds ChemInform Abstract: THE CYCLODESULFURIZATION OF THIO COMPOUNDS. PART XVII. SYNTHESIS OF SOME NOVEL 2-SUBSTITUTED AMINO-3,4-DIHYDRO-5H-1,3,4-BENZOTRIAZEPIN-5-ONES BY CYCLODESULFURIZATION OF THIOSEMICARBAZIDES WITH DICYCLOHEXYLCARBODIIMIDE (DCCD) A.-M. M. E. OMAR, A.-M. M. E. OMARSearch for more papers by this authorF. A. ASHOUR, F. A. ASHOURSearch for more papers by this authorJ. BOURDAIS, J. BOURDAISSearch for more papers by this author A.-M. M. E. OMAR, A.-M. M. E. OMARSearch for more papers by this authorF. A. ASHOUR, F. A. ASHOURSearch for more papers by this authorJ. BOURDAIS, J. BOURDAISSearch for more papers by this author First published: May 6, 1980 https://doi.org/10.1002/chin.198018246AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume11, Issue18May 6, 1980 RelatedInformation

AbstractNach verschiedenen Verfahren, z.B. durch Umsetzung der Pyridyl‐ Chloride (I) mit den Pyrimidinmercaptanen (II), werden die Thioether (III) erhalten.

A simple method for the synthesis of a novel series of 2‐substituted amino‐3,4‐dihydro‐5 H ‐1,3,4‐benzotriazepin‐5‐ones (11–16) has been established through two routes. The first involving the cyelodesulfurization of the thiosemicarbazides (3–8) with DCCD and the second reacting mixtures of the acid hydrazide 1 with a variety of the isothiocyanates 2 and DCCD. The structure of the cyclized products was confirmed by nmr and mass spectra.