title: Metalloporphyrins inactivate caspase-3 and -8.
abstract: Activation of caspases represents one of the earliest biochemical indicators for apoptotic cell death. Therefore, measurement of caspase activity is a widely used and generally accepted method to determine apoptosis in a wide range of in vivo and in vitro settings. Numerous publications characterize the role of the heme-catabolizing enzyme heme oxygenase-1 (HO-1) in regulating apoptotic processes. Different metalloporphyrins representing inducers and inhibitors of this enzyme are often used, followed by assessment of apoptotic cell death. In the present work, we found that caspase-3-like activity, as well as activity of caspase-8 measured in either Fas (CD95) ligand-treated Jurkat T-lymphocytes or by the use of recombinant caspase-3 or -8, was inhibited by different metalloporphyrins (cobalt(III) protoporphyrin IX, tin and zinc(II) protoporphyrin-IX). Moreover, employing the mouse model of Fas-induced liver apoptosis these properties of porphyrins could also be demonstrated in vivo. The metalloporphyrins were shown to inhibit caspase-3-mediated PARP cleavage. Molecular modeling studies demonstrated that porphyrins can occupy the active site of caspase-3 in an energetically favorable manner and in a binding mode similar to that of known inhibitors. The data shown here introduce metalloporphyrins as direct inhibitors of caspase activity. This finding points to the need for careful employment of metalloporphyrins as modulators of HO-1.
authors.affiliation: Department of Pharmacy, Center of Drug Research, University of Munich, Germany.
authors.forename: Signe B
authors.initials: SB
authors.lastname: Blumenthal
authors.forename: Alexandra K
authors.initials: AK
authors.lastname: Kiemer
authors.forename: Gisa
authors.initials: G
authors.lastname: Tiegs
authors.forename: Stefan
authors.initials: S
authors.lastname: Seyfried
authors.forename: Monika
authors.initials: M
authors.lastname: Höltje
authors.forename: Birte
authors.initials: B
authors.lastname: Brandt
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Höltje
authors.forename: Stefan
authors.initials: S
authors.lastname: Zahler
authors.forename: Angelika M
authors.initials: AM
authors.lastname: Vollmar
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D053181:Caspase 8; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D053222:Fas Ligand Protein; D051547:Heme Oxygenase-1 / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D008562:Membrane Glycoproteins / Q000494:pharmacology; D008665:Metalloporphyrins / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D048069:Tumor Necrosis Factors / Q000494:pharmacology
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D008665:Metalloporphyrins; D048069:Tumor Necrosis Factors; D051547:Heme Oxygenase-1; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases