title: Poisoning of mitochondrial topoisomerase I by lamellarin D.
abstract: Lamellarin D (Lam-D) is a hexacyclic pyrole alkaloid isolated from marine invertebrates, whose biologic properties have been attributed to mitochondrial targeting. Mitochondria contain their own DNA (mtDNA), and the only specific mitochondrial topoisomerase in vertebrates is mitochondrial topoisomerase I (Top1mt). Here, we show that Top1mt is a direct mitochondrial target of Lam-D. In vitro Lam-D traps Top1mt and induces Top1mt cleavage complexes (Top1mtcc). Using single-molecule analyses, we also show that Lam-D slows down supercoil relaxation of Top1mt and strongly inhibits Top1mt religation in contrast to the inefficacy of camptothecin on Top1mt. In living cells, we show that Lam-D accumulates rapidly inside mitochondria, induces cellular Top1mtcc, and leads to mtDNA damage. This study provides evidence that Top1mt is a direct mitochondrial target of Lam-D and suggests that developing Top1mt inhibitors represents a novel strategy for targeting mitochondrial DNA.
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Salim
authors.initials: S
authors.lastname: Khiati
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Yeonee
authors.initials: Y
authors.lastname: Seol
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Keli
authors.initials: K
authors.lastname: Agama
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Dalla Rosa
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Agrawal
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Katherine
authors.initials: K
authors.lastname: Fesen
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland.
authors.forename: Keir C
authors.initials: KC
authors.lastname: Neuman
authors.affiliation: Developmental Therapeutics Branch and Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute (S.K., K.A., I.D.R., S.A., K.F., H.Z., Y.P.) and Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute (Y.S., K.C.N.), National Institutes of Health, Bethesda, Maryland pommier@nih.gov.
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
mesh_terms: D045744:Cell Line, Tumor; D003374:Coumarins / Q000494:pharmacology*; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology*; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*
chemical_list: D003374:Coumarins; D004272:DNA, Mitochondrial; D006576:Heterocyclic Compounds, 4 or More Rings; D007546:Isoquinolines; C455554:lamellarin D; D004264:DNA Topoisomerases, Type I