eEF1Bγ binds the Che-1 and TP53 gene promoters and their transcripts

Abstract

BackgroundWe have previously shown that the eukaryotic elongation factor subunit 1B gamma (eEF1Bγ) interacts with the RNA polymerase II (pol II) alpha-like subunit “C” (POLR2C), alone or complexed, in the pol II enzyme. Moreover, we demonstrated that eEF1Bγ binds the promoter region and the 3’ UTR mRNA of the vimentin gene. These events contribute to localize the vimentin transcript and consequentially its translation, promoting a proper mitochondrial network.MethodsWith the intent of identifying additional transcripts that complex with the eEF1Bγ protein, we performed a series of ribonucleoprotein immunoprecipitation (RIP) assays using a mitochondria-enriched heavy membrane (HM) fraction.ResultsAmong the eEF1Bγ complexed transcripts, we found the mRNA encoding the Che-1/AATF multifunctional protein. As reported by other research groups, we found the tumor suppressor p53 transcript complexed with the eEF1Bγ protein. Here, we show for the first time that eEF1Bγ binds not only Che-1 and p53 transcripts but also their promoters. Remarkably, we demonstrate that both the Che-1 transcript and its translated product localize also to the mitochondria and that eEF1Bγ depletion strongly perturbs the mitochondrial network and the correct localization of Che-1. In a doxorubicin (Dox)-induced DNA damage assay we show that eEF1Bγ depletion significantly decreases p53 protein accumulation and slightly impacts on Che-1 accumulation. Importantly, Che-1 and p53 proteins are components of the DNA damage response machinery that maintains genome integrity and prevents tumorigenesis.ConclusionsOur data support the notion that eEF1Bγ, besides its canonical role in translation, is an RNA-binding protein and a key player in cellular stress responses. We suggest for eEF1Bγ a role as primordial transcription/translation factor that links fundamental steps from transcription control to local translation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13046-016-0424-x) contains supplementary material, which is available to authorized users.

Non-translational Connections of eEF1B in the Cytoplasm and Nucleus of Cancer Cells

“…eEF1Bγ was one of the candidates to participate in loading of microRNAs into extracellular vesicles that may be needed to preserve microRNAs and transfer them to extracellular fluid (Hagiwara et al, 2015). eEF1Bγ interacted with components of DNA damage response machinery (Pisani et al, 2016). Yeast eEF1Bγ was found in stress granules upon heat shock (Grousl et al, 2013;Cherkasov et al, 2015).…”

Retracted: The PI3K/AKT axis modulates AATF activity in Wilms’ tumor cells

“…At the same time, AATF plays a role in such processes as proliferation, stress reactions to DNA injury, and regulation of the cell cycle [6,7]. AATF is crucial in stress reactions related to DNA injury, such as the stimulation of p53 and, possibly, p21 [5,[7][8][9]. Excessive AATF expression is present in some human leukemic cells [10,11].…”

Analysis of eEF1Bγ interactome in the nuclear fraction of A549 human lung adenocarcinoma cells

“…Cluster A comprised different polypeptides of polymerase (RNA)II (DNA directed) (POLR2B, POLR2C, POLR2D, POLR2G, POLR2E, POLR2J) involved in the transcription process. Importantly, direct interaction of eEF1Bγ with POLR2C was shown earlier [16] which presents independent evidence for eEF1Bγ contacts with the polymerase (RNA)II (DNA directed) complex. Cluster B included proteins ABCF1, EIF2B3, NMT1, EIF2B2, MRE11A, RFC4 and NELFB that are mainly involved in translation, transcription and DNA replication/reparation processes, Cluster C (TNFRSF10B, TNRFSF1A, FAS, FASLG, FADD, CASP10, CASP8, BID, MAPK8, RHOA, ARHGDIA, MSN, EZR) represented the membrane-related proteins involved in apoptosis, cell regulation and cytoskeleton-membrane interaction, Cluster D (PPP2CB , CTTNBP2NL, STRN4, PDCD10) comprised the proteins involved in cell regulation, and Cluster E (eEF1Bβ, eI-F4A3, eIF3M, PABPC1, SYNCRIP, HNRNPD, HNRNPH1, SNRNP20, MED23, SF3B1, SNRPA1, HNRNPH2, , SRSF1, TADA2A, tat, gag-pol) included the proteins involved in translation, mRNA splicing, metabolism and transport, transcription activation as well as two proteins related to HIV-1 infection.…”

“…One may suggest that eEF1Bγ can be bound to different mRNAs in nucleus contributing to their stability and transport. Notably, eEF1Bγ has been described to bind the 3' UTRs of vimentin [117] and some other mRNA [16].…”

“…HNRNPH1 and CD2AP participate in exosome trafficking [33,120]. It is worthy to mention that a role of eEF1Bγ in organelle transport has been shown [16,121]. eEF1Bγ was also co-immunoprecipitated with an essential component of ER-Golgi transport vesicles [122].…”