title: Cellular growth and mitochondrial ultrastructure of leishmania (Viannia) braziliensis promastigotes are affected by the iron chelator 2,2-dipyridyl.
abstract: BACKGROUND
  Iron is an essential element for the survival of microorganisms in vitro and in vivo, acting as a cofactor of several enzymes and playing a critical role in host-parasite relationships. Leishmania (Viannia) braziliensis is a parasite that is widespread in the new world and considered the major etiological agent of American tegumentary leishmaniasis. Although iron depletion leads to promastigote and amastigote growth inhibition, little is known about the role of iron in the biology of Leishmania. Furthermore, there are no reports regarding the importance of iron for L. (V.) braziliensis.
  
  
  RESULTS
  In this study, the effect of iron on the growth, ultrastructure and protein expression of L. (V.) braziliensis was analyzed by the use of the chelator 2,2-dipyridyl. Treatment with 2,2-dipyridyl affected parasites' growth in a dose- and time-dependent manner. Multiplication of the parasites was recovered after reinoculation in fresh culture medium. Ultrastructural analysis of treated promastigotes revealed marked mitochondrial swelling with loss of cristae and matrix and the presence of concentric membranar structures inside the organelle. Iron depletion also induced Golgi disruption and intense cytoplasmic vacuolization. Fluorescence-activated cell sorting analysis of tetramethylrhodamine ester-stained parasites showed that 2,2-dipyridyl collapsed the mitochondrial membrane potential. The incubation of parasites with propidium iodide demonstrated that disruption of mitochondrial membrane potential was not associated with plasma membrane permeabilization. TUNEL assays indicated no DNA fragmentation in chelator-treated promastigotes. In addition, two-dimensional electrophoresis showed that treatment with the iron chelator induced up- or down-regulation of proteins involved in metabolism of nucleic acids and coordination of post-translational modifications, without altering their mRNA levels.
  
  
  CONCLUSIONS
  Iron chelation leads to a multifactorial response that results in cellular collapse, starting with the interruption of cell proliferation and culminating in marked mitochondrial impairment in some parasites and their subsequent cell death, whereas others may survive and resume proliferating.
authors.affiliation: Laboratório de Pesquisa em Leishmaniose, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil ; Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brasil.
authors.forename: Camila
authors.initials: C
authors.lastname: Mesquita-Rodrigues
authors.forename: Rubem F S
authors.initials: RF
authors.lastname: Menna-Barreto
authors.forename: Leonardo
authors.initials: L
authors.lastname: Sabóia-Vahia
authors.forename: Silvia A G
authors.initials: SA
authors.lastname: Da-Silva
authors.forename: Elen M
authors.initials: EM
authors.lastname: de Souza
authors.forename: Mariana C
authors.initials: MC
authors.lastname: Waghabi
authors.forename: Patrícia
authors.initials: P
authors.lastname: Cuervo
authors.forename: José B
authors.initials: JB
authors.lastname: De Jesus
mesh_terms: D015082:2,2'-Dipyridyl / Q000494:pharmacology*; D016923:Cell Death; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D002614:Chelating Agents / Q000494:pharmacology*; D022162:Cytoplasmic Vesicles / Q000187:drug effects / Q000648:ultrastructure; D053938:DNA Fragmentation; D015870:Gene Expression / Q000187:drug effects; D006056:Golgi Apparatus / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D020287:In Situ Nick-End Labeling; D007501:Iron / Q000378:metabolism*; D007892:Leishmania braziliensis / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure*; D015800:Protozoan Proteins / Q000096:biosynthesis
chemical_list: D002614:Chelating Agents; D015800:Protozoan Proteins; D015082:2,2'-Dipyridyl; D007501:Iron