title: Protor-2 interacts with tristetraprolin to regulate mRNA stability during stress.
abstract: The A/U-rich RNA-binding protein tristetraprolin (TTP) is an mRNA destabilizing factor which plays a role in the regulated turnover of many transcripts encoding proteins involved in immune function and cell growth control. TTP also plays a role in stress-induced destabilization of mRNAs. Here we report the interaction of TTP with a component of the mTORC2 kinase, Protor-2 (PRR5-L, protein Q6MZQ0/FLJ14213/CAE45978). Protor-2 is structurally similar to human PRR5 and has been demonstrated to bind mTORC2 via Rictor and/or Sin1 and may signal downstream events promoting apoptosis. Protor-2 dissociates from mTORC2 upon hyperactivation of the kinase and is not required for mTORC2 integrity or activity. We identified Protor-2 in a yeast two-hybrid screen as a TTP interactor using the C-terminal mRNA decay domain of TTP as bait. The interaction of Protor-2 with TTP was also confirmed in vivo in co-immunoprecipitation experiments and Protor-2 was also detected in immunoprecipitates of Rictor. Protor-2 was shown to stimulate TTP-mediated mRNA turnover of several TTP-associated mRNAs (TNF-α, GM-CSF, IL-3 and COX-2) in Jurkat cells when overexpressed while the half-lives of transcripts which do not decay via a TTP-mediated mechanism were unaffected. Knockdown of Protor-2 via RNAi inhibited TTP-mediated mRNA turnover of these TTP-associated mRNAs and inhibited association of TTP with cytoplasmic stress granules (SG) or mRNA processing bodies (P-bodies) following induction of the integrated stress response. These results suggest that Protor-2 associates with TTP to accelerate TTP-mediated mRNA turnover and functionally links the control of TTP-regulated mRNA stability to mTORC2 activity.
authors.affiliation: Department of Research & Development, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, California 91343, USA.
authors.forename: Brent
authors.initials: B
authors.lastname: Holmes
authors.forename: Nicholas
authors.initials: N
authors.lastname: Artinian
authors.forename: Lauren
authors.initials: L
authors.lastname: Anderson
authors.forename: Jheralyn
authors.initials: J
authors.lastname: Martin
authors.forename: Janine
authors.initials: J
authors.lastname: Masri
authors.forename: Cheri
authors.initials: C
authors.lastname: Cloninger
authors.forename: Andrew
authors.initials: A
authors.lastname: Bernath
authors.forename: Tariq
authors.initials: T
authors.lastname: Bashir
authors.forename: Angelica
authors.initials: A
authors.lastname: Benavides-Serrato
authors.forename: Joseph
authors.initials: J
authors.lastname: Gera
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003594:Cytoplasmic Granules / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D034622:RNA Interference; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D051816:Tristetraprolin / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C570157:Protor-2 protein, human; D012333:RNA, Messenger; D011994:Recombinant Proteins; D051816:Tristetraprolin; C497552:ZFP36 protein, human