title: Transcriptome and proteome analyses and the role of atypical calpain protein and autophagy in the spliced leader silencing pathway in Trypanosoma brucei.
abstract: Under persistent ER stress, Trypanosoma brucei parasites induce the spliced leader silencing (SLS) pathway. In SLS, transcription of the SL RNA gene, the SL donor to all mRNAs, is extinguished, arresting trans-splicing and leading to programmed cell death (PCD). In this study, we investigated the transcriptome following silencing of SEC63, a factor essential for protein translocation across the ER membrane, and whose silencing induces SLS. The proteome of SEC63-silenced cells was analyzed with an emphasis on SLS-specific alterations in protein expression, and modifications that do not directly result from perturbations in trans-splicing. One such protein identified is an atypical calpain SKCRP7.1/7.2. Co-silencing of SKCRP7.1/7.2 and SEC63 eliminated SLS induction due its role in translocating the PK3 kinase. This kinase initiates SLS by migrating to the nucleus and phosphorylating TRF4 leading to shut-off of SL RNA transcription. Thus, SKCRP7.1 is involved in SLS signaling and the accompanying PCD. The role of autophagy in SLS was also investigated; eliminating autophagy through VPS34 or ATG7 silencing demonstrated that autophagy is not essential for SLS induction, but is associated with PCD. Thus, this study identified factors that are used by the parasite to cope with ER stress and to induce SLS and PCD.
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Ronen
authors.initials: R
authors.lastname: Hope
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Katarina
authors.initials: K
authors.lastname: Egarmina
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Voloshin
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.
authors.forename: Hiba
authors.initials: H
authors.lastname: Waldman Ben-Asher
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Carmi
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Dror
authors.initials: D
authors.lastname: Eliaz
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
authors.forename: Yaron
authors.initials: Y
authors.lastname: Drori
authors.affiliation: The Mina and Everard Goodman Faculty of Life Sciences. shulamit.michaeli@biu.ac.il.|Advanced Materials and Nanotechnology Institute, Bar-Ilan University, Ramat-Gan, 5290002, Israel. shulamit.michaeli@biu.ac.il.
authors.forename: Shulamit
authors.initials: S
authors.lastname: Michaeli
mesh_terms: D017209:Apoptosis / Q000502:physiology; D001343:Autophagy / Q000502:physiology; D002154:Calpain / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020868:Gene Silencing / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D020543:Proteome; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020038:RNA, Spliced Leader / Q000037:antagonists & inhibitors / Q000378:metabolism*; D059467:Transcriptome; D014346:Trypanosoma brucei brucei / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D056811:Unfolded Protein Response
chemical_list: D026901:Membrane Transport Proteins; D020543:Proteome; D015800:Protozoan Proteins; D012333:RNA, Messenger; D020038:RNA, Spliced Leader; D002154:Calpain