ELL-associated factors 1 and 2 are positive regulators of RNA polymerase II elongation factor ELL

Abstract

In human cells, the ELL family of transcription factors includes at least three members, which are all capable of stimulating the overall rate of elongation by RNA polymerase II by suppressing transient pausing by the enzyme at many sites along DNA. In this report, we identify the ELL-associated factors (EAF)1 and EAF2 as strong positive regulators of ELL elongation activity. Our findings provide insights into the structure and function of ELL family transcription factors, and they bring to light direct roles for the EAF proteins in regulation of RNA polymerase II transcription.elongation ͉ mRNA synthesis ͉ transcription ͉ transcription factor T he gene encoding the RNA polymerase II (pol II) elongation factor eleven-nineteen lysine-rich in leukemia (ELL) was first characterized as a fusion partner of the mixed lineage leukemia (MLL) gene in the (11, 19)(q23;p13.1) translocation in acute myeloid leukemia (1). The ELL protein has been shown to be capable of interacting with pol II and increasing its rate of transcript elongation in vitro by suppressing transient pausing by the enzyme (2, 3). Consistent with a role for ELL in controlling transcript elongation in vivo, Drosophila ELL colocalizes with pol II at transcriptionally active sites on polytene chromosomes, and evidence suggests that mutations in the gene encoding Drosophila ELL may preferentially affect synthesis of long transcripts (4).In addition to ELL, human cells have two ELL paralogs, ELL2 and ELL3, which can also stimulate the rate of elongation by pol II in vitro (5, 6). ELL and ELL2 are expressed in a wide variety of tissues in humans. ELL3, on the other hand, appears to be expressed predominantly in the testis (5, 6).A variety of ELL-interacting proteins have been identified through two-hybrid screens and biochemical purifications. Two of these proteins, EAF1 and EAF2 (7,8), have been shown to colocalize with ELL in the nucleus in a stippled pattern that resembles that of Cajal bodies, structures that are enriched in factors involved in transcription and mRNA processing (9). Interestingly, Cajal bodies are disrupted in cells carrying the MLL-ELL translocation (10).Suggesting that interactions between ELL and EAF1 may contribute to the leukemic phenotype of cells expressing the MLL-ELL chimera, the C-terminal domains of EAF1 and EAF2 share similarity with AF4 and ENL, other MLL translocation partners (7,8). In addition, expression of artificial MLL-EAF1 and MLL-EAF2 chimeras can immortalize hematopoetic progenitor cells and induce the development of acute myeloid leukemia in mice (7,8). Finally, and consistent with the possibility that EAF1 and EAF2 could play a role in transcriptional regulation, their C-terminal regions function as transcriptional activation domains when fused to the GAL4 DNA binding domain (7,8).In this article, we identify the EAF1 and EAF2 proteins as positive regulators of ELL elongation activity. Our findings provide insights into the mechanism of action of ELL family transcription factors, and they bring to light direct ro...

Zebrafish eaf1 and eaf2/u19 Mediate Effective Convergence and Extension Movements through the Maintenance of wnt11 and wnt5 Expression

“…It has been reported that eaf1 and eaf2/u19 could serve as regulators of transcriptional elongation by in vitro assays (7). This fact raised a question of whether the down-regulation of noncanonical Wnt ligands wnt11, wnt5, and wnt11r in eafs morphants was due to the disruption of the function of eafs in regulating transcriptional elongation.…”

“…ELL binds to RNA polymerase II and acts as a transcriptional elongation factor whose targeted deletion leads to embryonic lethality in mice (5,6). Both EAF1 and EAF2, which share significant sequence homology, stimulate ELL elongation activity (7). Studies by Luo et al (8) argued that EAF proteins are important in MLL-ELL leukemogenesis, whereas our previous studies showed that EAF2/U19 inhibits xenograft prostate tumor growth and undergoes down-regulation in prostate cancer cell lines (9).…”

Poly(ADP-ribosyl)ation directs recruitment and activation of an ATP-dependent chromatin remodeler

“…Alternatively, whole cell lysates were prepared as described in SI Methods, and Flag-Alc1 and associated proteins were immunopurified as described (34), except beads were washed with 0.2 M KCl. For expression in Sf21 insect cells, Flag-Alc1 was cloned into a pBacPAK8 (Clontech) derivative, and purified from lysates of infected cells as described (36).…”

U19/Eaf2 knockout causes lung adenocarcinoma, B-cell lymphoma, hepatocellular carcinoma and prostatic intraepithelial neoplasia

“…Eaf2 also appears to be important during embryogenesis, particularly for eye development (Li et al, 2003;Maurus et al, 2005). Both Eaf1 and U19/Eaf2 stimulate ELL elongation activity (Kong et al, 2005). In addition, ELL and Eaf1 colocalize to nuclear suborganelles called Cajal bodies thought to be involved in nucleoli formation, RNA processing and transport of small ribonucleoproteins (Gall, 2003;Cioce and Lamond, 2005).…”