title: ATP Binding Cassette Transporter Mediates Both Heme and Pesticide Detoxification in Tick Midgut Cells.
abstract: In ticks, the digestion of blood occurs intracellularly and proteolytic digestion of hemoglobin takes place in a dedicated type of lysosome, the digest vesicle, followed by transfer of the heme moiety of hemoglobin to a specialized organelle that accumulates large heme aggregates, called hemosomes. In the present work, we studied the uptake of fluorescent metalloporphyrins, used as heme analogs, and amitraz, one of the most regularly used acaricides to control cattle tick infestations, by Rhipicephalus (Boophilus) microplus midgut cells. Both compounds were taken up by midgut cells in vitro and accumulated inside the hemosomes. Transport of both molecules was sensitive to cyclosporine A (CsA), a well-known inhibitor of ATP binding cassette (ABC) transporters. Rhodamine 123, a fluorescent probe that is also a recognized ABC substrate, was similarly directed to the hemosome in a CsA-sensitive manner. Using an antibody against conserved domain of PgP-1-type ABC transporter, we were able to immunolocalize PgP-1 in the digest vesicle membranes. Comparison between two R. microplus strains that were resistant and susceptible to amitraz revealed that the resistant strain detoxified both amitraz and Sn-Pp IX more efficiently than the susceptible strain, a process that was also sensitive to CsA. A transcript containing an ABC transporter signature exhibited 2.5-fold increased expression in the amitraz-resistant strain when compared with the susceptible strain. RNAi-induced down-regulation of this ABC transporter led to the accumulation of metalloporphyrin in the digestive vacuole, interrupting heme traffic to the hemosome. This evidence further confirms that this transcript codes for a heme transporter. This is the first report of heme transport in a blood-feeding organism. While the primary physiological function of the hemosome is to detoxify heme and attenuate its toxicity, we suggest that the use of this acaricide detoxification pathway by ticks may represent a new molecular mechanism of resistance to pesticides.
authors.affiliation: Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.
authors.forename: Flavio Alves
authors.initials: FA
authors.lastname: Lara
authors.affiliation: Centro de Biotecnologia e Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Paula C
authors.initials: PC
authors.lastname: Pohl
authors.affiliation: Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Ana Caroline
authors.initials: AC
authors.lastname: Gandara
authors.affiliation: Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.
authors.forename: Jessica da Silva
authors.initials: Jda S
authors.lastname: Ferreira
authors.affiliation: Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, UFRJ, Rio de Janeiro, Brazil.
authors.forename: Maria Clara
authors.initials: MC
authors.lastname: Nascimento-Silva
authors.affiliation: Departamento de Patologia Veterinária, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, Brazil.
authors.forename: Gervásio Henrique
authors.initials: GH
authors.lastname: Bechara
authors.affiliation: Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, UFRJ, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular-INCTEM, Rio de Janeiro, Brazil.
authors.forename: Marcos H F
authors.initials: MH
authors.lastname: Sorgine
authors.affiliation: The Border Biomedical Research Center, University of Texas at El Paso, El Paso, Texas, United States of America.
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.affiliation: Centro de Biotecnologia e Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular-INCTEM, Rio de Janeiro, Brazil.
authors.forename: Itabajara da Silva
authors.initials: Ida S
authors.lastname: Vaz
authors.affiliation: Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, UFRJ, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular-INCTEM, Rio de Janeiro, Brazil.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Oliveira
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry*; D056810:Acaricides / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry; D000818:Animals; D000906:Antibodies / Q000737:chemistry; D060829:Arthropod Proteins / Q000737:chemistry*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D016572:Cyclosporine / Q000737:chemistry; D005260:Female; D006418:Heme / Q000737:chemistry*; D007422:Intestines / Q000502:physiology*; D008665:Metalloporphyrins / Q000737:chemistry / Q000493:pharmacokinetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011524:Protoporphyrins / Q000737:chemistry; D034622:RNA Interference; D048494:Rhipicephalus / Q000502:physiology*; D020112:Rhodamine 123 / Q000737:chemistry / Q000493:pharmacokinetics; D013984:Tick Infestations / Q000188:drug therapy; D014052:Toluidines / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D018528:ATP-Binding Cassette Transporters; D056810:Acaricides; D000906:Antibodies; D060829:Arthropod Proteins; D008665:Metalloporphyrins; D011524:Protoporphyrins; D014052:Toluidines; D020112:Rhodamine 123; C014983:amitraz; D006418:Heme; D016572:Cyclosporine; D000255:Adenosine Triphosphate; C032628:tin protoporphyrin IX