The protease responsible for the cleavage of poly(ADP-ribose) polymerase and necessary for apoptosis has been purified and characterized. This enzyme, named apopain, is composed of two subunits of relative molecular mass (M(r)) 17K and 12K that are derived from a common proenzyme identified as CPP32. This proenzyme is related to interleukin-1 beta-converting enzyme (ICE) and CED-3, the product of a gene required for programmed cell death in Caenorhabditis elegans. A potent peptide aldehyde inhibitor has been developed and shown to prevent apoptotic events in vitro, suggesting that apopain/CPP32 is important for the initiation of apoptotic cell death.

No abstract

Cysteine proteases related to mammalian interleukin-1 beta converting enzyme (ICE) and to its Caenorhabditis elegans homologue, CED-3, play a critical role in the biochemical events that culminate in apoptosis. We have determined the three-dimensional structure of a complex of the human CED-3 homologue CPP32/apopain with a potent tetrapeptide-aldehyde inhibitor. The protein resembles ICE in overall structure, but its S4 subsite is strikingly different in size and chemical composition. These differences account for the variation in specificity between the ICE- and CED-3-related proteases and enable the design of specific inhibitors that can probe the physiological functions of the proteins and disease states with which they are associated.

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Prostaglandin (PG) E(2) is a potent inducer of cortical and trabecular bone formation in humans and animals. Although the bone anabolic action of PGE(2) is well documented, the cellular and molecular mechanisms that mediate this effect remain unclear. This study was undertaken to examine the effect of pharmacological inactivation of the prostanoid receptor EP(4), one of the PGE(2) receptors, on PGE(2)-induced bone formation in vivo. We first determined the ability of EP(4)A, an EP(4)-selective ligand, to act as an antagonist. PGE(2) increases intracellular cAMP and suppresses apoptosis in the RP-1 periosteal cell line. Both effects were reversed by EP(4)A, suggesting that EP(4)A acts as an EP(4) antagonist in the cells at concentrations consistent with its in vitro binding to EP(4). We then examined the effect of EP(4) on bone formation induced by PGE(2) in young rats. Five- to 6-week-old rats were treated with PGE(2) (6 mg/kg/day) in the presence or absence of EP(4)A (10 mg/kg/day) for 12 days. We found that treatment with EP(4)A suppresses the increase in trabecular bone volume induced by PGE(2). This effect is accompanied by a suppression of bone formation indices: serum osteocalcin, extent of labeled surface, and extent of trabecular number, suggesting that the reduction in bone volume is due most likely to decreased bone formation. The pharmacological evidence presented here provides strong support for the hypothesis that the bone anabolic effect of PGE(2) in rats is mediated by the EP(4) receptor.

Montelukast sodium (Singulair), also known as MK-0476 (1-(((1(R)-(3-(2-(7-chloro-2-quinolinyl)-(E)-ethenyl)phenyl)(3-2-(1- hydroxy-1-methylethyl)phenyl)propyl)thio)methyl)cyclopropane) acetic acid sodium salt, is a potent and selective inhibitor of [3H]leukotriene D4 specific binding in guinea pig lung (Ki 0.18 +/- 0.03 nM), sheep lung (Ki 4 nM), and dimethylsulfoxide-differentiated U937 cell plasma membrane preparations (Ki 0.52 +/- 0.23 nM), but it was essentially inactive versus [3H]leukotriene C4 specific binding in dimethylsulfoxide-differentiated U937 cell membranes (IC50 10 microM) and [3H]leukotriene B4 specific binding in THP-1 cell membranes (IC50 40 microM). Montelukast also inhibited specific binding of [3H]leukotriene D4 to guinea pig lung in the presence of human serum albumin, human plasma, and squirrel monkey plasma with Ki values of 0.21 +/- 0.08, 0.19 +/- 0.02, and 0.26 +/- 0.02 nM, respectively. Functionally, montelukast antagonized contractions of guinea pig trachea induced by leukotriene D4 (pA2 value 9.3; slope 0.8). In contrast, montelukast (16 microM) failed to antagonize contractions of guinea pig trachea induced by leukotriene C4 (45 mM serine-borate), serotonin, acetylcholine, histamine, prostaglandin D2, or U-44069. Intravenous montelukast antagonized bronchoconstriction induced in anesthetized guinea pigs by i.v. leukotriene D4 but did not block bronchoconstriction to arachidonic acid, histamine, serotonin, or acetylcholine. Oral administration of montelukast blocked leukotriene D4 induced bronchoconstriction in conscious squirrel monkeys, ovalbumin-induced bronchoconstriction in conscious sensitized rats (ED50 0.03 +/- 0.001 mg/kg; 4 h pretreatment), and also ascaris-induced early and late phase bronchoconstriction in conscious squirrel monkeys (0.03-0.1 mg/kg; 4 h pretreatment). A continuous i.v. infusion of montelukast (8 micrograms.kg-1.min-1) resulted in a 70% decrease in the peak early response and a 75% reduction of the late response to ascaris aerosol in allergic conscious sheep. Montelukast, a potent and selective leukotriene D4 receptor antagonist with excellent in vivo activity is currently in clinical development for the treatment of asthma and related diseases.

No abstract

A general approach to the synthesis of a new class of LTD 4 antagonists is presented. The key diarylpropane framework was prepared by Claisen-Schmidt condensation and selective reduction of the enone. Depending on the bridge to the 7-chloroquinaldine moiety, alkylation or Heck coupling methodology was developed. The chiral sulfides were introduced by asymmetric reduction of the diarylpropanone intermediates and subsequent inversion of the chiral center.Since the discovery of the role played by the leukotrienes in asthma and associated inflammatory diseases the search for specific antagonists or inhibitors of this portion of the aracadonic acid cascade has been intensive. 1 An early candidate for the control of asthma was the LTD 4 antagonist MK-0571/MK-0679. 2,3 Elaboration of this original structure has advanced a new class of LTD 4 antagonists with the selection of L-691,698 (1) and L-699,392 (2) as active agents. 4 Here the 3-thiapropionamide side chain has been replaced with an arylethyl group, and in the case of the former, the trans-double bond has been changed to a phenyl quinaldine ether.Our goal was the development of a general approach to this new class of LTD 4 antagonists. 4,5 By incorporating the quinaldine portion of the molecule at the later stages of the synthesis the target became the diarylpropanol 3. A classical synthesis of a 1,3-diarylpropenone is condensation of an acetophenone and a benzaldehyde, the Claisen-Schmidt reaction, producing an enone known as a chalcone; 6 selective 3,4-reduction then provides the 1,3-diarylpropanone (Scheme 1). In the synthesis of 1 and 2 coupling of the 3′-substituted acetophenone 4 with a 2-carboxybenzaldehyde 5 afforded the backbone of 3 X Abstract published in Advance ACS Abstracts, May 1, 1996. (1) (a) Young, R. N.; Guindon, T. R.; Jones, T. R.; Ford-Hutchinson, A. W.; Bellanger, P.; Champion, E.; Charette, L.; DeHaven, R. N.; Denis, D.; Fortin, R.; Frenette, R.; Gauthier, J.-Y.; Gillard, J. W.; Kakushima, M.; Letts, L. G.; Masson, P.; Maycock, A.; McFarlane, C.; Piechuta, H.; Pong, S. S.; Rosenthal, A.; Williams, H.; Zamboni, R.; Yoakim, C.; Rokach, J. Zamboni, R.; Belley, M.; Champion, E.; Charette, L.; Ford-Hutchinson, A. W.; Frenette, R.; Gauthier, J.-Y.; Leger, S.; Masson, P.; McFarlane, C. S.; Piechuta, H.; Rokach, J.; Williams, H.; Young, R. N.; DeHaven, R. N.; Pong, S. S. Can. Jones, T.; Champion, E.; Charette, L.; Dehaven, R.; Ford-Hutchinson, A. W.; Hoogsteen, K.; Lord, A.; Masson, P.; Piechuta, H.; Pong, S. S.; Springer, J. P.; Therien, M.; Zamboni, R.; Young, R. N. J. Med. Chem. 1990, 33, 2841. (b) Zamboni, R.; Belley, M.; Champion, E.; Charette, L.; DeHaven, R.; Frenette, R.; Gauthier, J. Y.; Jones, T. R.; Leger, S.; Masson, P.; McFarlane, C. S.; Metters, K.; Pong, S. S.; Piechuta, H.; Rockach, J.; Therien, M.; Williams, H. W. R.; Young, R. N. J. Med. Chem. 1992, 35, 3832. (3) McNamara, J. M.; Leazer, J. L.; Bhupathy, M.; Amato, J. S.; Reamer, R. A.; Reider, P. J.; Grabowski, E. J. J. J. Org. Chem. 1989, 54, 3718. For the preparation of the ch...