title: An essential nuclear protein in trypanosomes is a component of mRNA transcription/export pathway.
abstract: In eukaryotic cells, different RNA species are exported from the nucleus via specialized pathways. The mRNA export machinery is highly integrated with mRNA processing, and includes a different set of nuclear transport adaptors as well as other mRNA binding proteins, RNA helicases, and NPC-associated proteins. The protozoan parasite Trypanosoma cruzi is the causative agent of Chagas disease, a widespread and neglected human disease which is endemic to Latin America. Gene expression in Trypanosoma has unique characteristics, such as constitutive polycistronic transcription of protein-encoding genes and mRNA processing by trans-splicing. In general, post-transcriptional events are the major points for regulation of gene expression in these parasites. However, the export pathway of mRNA from the nucleus is poorly understood. The present study investigated the function of TcSub2, which is a highly conserved protein ortholog to Sub2/ UAP56, a component of the Transcription/Export (TREX) multiprotein complex connecting transcription with mRNA export in yeast/human. Similar to its orthologs, TcSub2 is a nuclear protein, localized in dispersed foci all over the nuclei -except the fibrillar center of nucleolus- and at the interface between dense and non-dense chromatin areas, proposing the association of TcSub2 with transcription/processing sites. These findings were analyzed further by BrUTP incorporation assays and confirmed that TcSub2 is physically associated with active RNA polymerase II (RNA pol II), but not RNA polymerase I (RNA pol I) or Spliced Leader (SL) transcription, demonstrating participation particularly in nuclear mRNA metabolism in T. cruzi. The double knockout of the TcSub2 gene is lethal in T. cruzi, suggesting it has an essential function. Alternatively, RNA interference assays were performed in Trypanosoma brucei. It allowed demonstrating that besides being an essential protein, its knockdown causes mRNA accumulation in the nucleus and decrease of translation levels, reinforcing that Trypanosoma-Sub2 (Tryp-Sub2) is a component of mRNA transcription/export pathway in trypanosomes.
authors.affiliation: Departamento de Biologia Celular e Molecular, Universidade Federal do Paraná, Curitiba, Brazil.
authors.forename: Mariana
authors.initials: M
authors.lastname: Serpeloni
authors.forename: Carolina Borsoi
authors.initials: CB
authors.lastname: Moraes
authors.forename: João Renato Carvalho
authors.initials: JR
authors.lastname: Muniz
authors.forename: Maria Cristina Machado
authors.initials: MC
authors.lastname: Motta
authors.forename: Augusto Savio Peixoto
authors.initials: AS
authors.lastname: Ramos
authors.forename: Rafael Luis
authors.initials: RL
authors.lastname: Kessler
authors.forename: Alexandre Haruo
authors.initials: AH
authors.lastname: Inoue
authors.forename: Wanderson Duarte
authors.initials: WD
authors.lastname: daRocha
authors.forename: Sueli Fumie
authors.initials: SF
authors.lastname: Yamada-Ogatta
authors.forename: Stenio Perdigão
authors.initials: SP
authors.lastname: Fragoso
authors.forename: Samuel
authors.initials: S
authors.lastname: Goldenberg
authors.forename: Lucio H
authors.initials: LH
authors.lastname: Freitas-Junior
authors.forename: Andréa Rodrigues
authors.initials: AR
authors.lastname: Avila
mesh_terms: D021581:Active Transport, Cell Nucleus; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D014349:Trypanosoma cruzi / Q000166:cytology / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology
chemical_list: D009687:Nuclear Proteins; D015800:Protozoan Proteins; D012333:RNA, Messenger