scholarly journals Gene expression in Zymomonas mobilis: promoter structure and identification of membrane anchor sequences forming functional lacZ' fusion proteins.

1987 ◽  
Vol 169 (6) ◽  
pp. 2327-2335 ◽  
Author(s):  
T Conway ◽  
Y A Osman ◽  
L O Ingram
Keyword(s):  
Gene Expression ◽  
Fusion Proteins ◽  
Zymomonas Mobilis ◽  
Lacz Fusion ◽  
Membrane Anchor ◽  
Promoter Structure

The Development of Inhibitors Targeting the Mixed Lineage Leukemia 1 (MLL1)-WD Repeat Domain 5 Protein (WDR5) Protein- Protein Interaction

2020 ◽  
Vol 27 (33) ◽  
pp. 5530-5542
Author(s):  
Xiaoqing Ye ◽  
Gang Chen ◽  
Jia Jin ◽  
Binzhong Zhang ◽  
Yinda Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Interaction ◽  
Fusion Proteins ◽  
Recent Progress ◽  
Mixed Lineage Leukemia ◽  
Core Complex ◽  
Histone Methyltransferases ◽  
Protein Protein Interaction ◽  
Histone 3 ◽  
Repeat Domain

Mixed Lineage Leukemia 1 (MLL1), an important member of Histone Methyltransferases (HMT) family, is capable of catalyzing mono-, di-, and trimethylation of Histone 3 lysine 4 (H3K4). The optimal catalytic activity of MLL1 requires the formation of a core complex consisting of MLL1, WDR5, RbBP5, and ASH2L. The Protein-Protein Interaction (PPI) between WDR5 and MLL1 plays an important role in abnormal gene expression during tumorigenesis, and disturbing this interaction may have a potential for the treatment of leukemia harboring MLL1 fusion proteins. In this review, we will summarize recent progress in the development of inhibitors targeting MLL1- WDR5 interaction.

scholarly journals Non-coding RNAs in cancers with chromosomal rearrangements: the signatures, causes, functions and implications

2019 ◽  
Vol 11 (10) ◽  
pp. 886-898 ◽  
Author(s):  
Cai Han ◽  
Lin-Yu Sun ◽  
Wen-Tao Wang ◽  
Yu-Meng Sun ◽  
Yue-Qin Chen
Keyword(s):  
Gene Expression ◽  
Signaling Pathways ◽  
Fusion Proteins ◽  
Gene Fusion ◽  
Chromosomal Rearrangements ◽  
Chromosomal Translocation ◽  
Chromosomal Translocations ◽  
Rna Molecules ◽  
Non Coding Rnas ◽  
The Relationship

Abstract Chromosomal translocation leads to the juxtaposition of two otherwise separate DNA loci, which could result in gene fusion. These rearrangements at the DNA level are catastrophic events and often have causal roles in tumorigenesis. The oncogenic DNA messages are transferred to RNA molecules, which are in most cases translated into cancerous fusion proteins. Gene expression programs and signaling pathways are altered in these cytogenetically abnormal contexts. Notably, non-coding RNAs have attracted increasing attention and are believed to be tightly associated with chromosome-rearranged cancers. These RNAs not only function as modulators in downstream pathways but also directly affect chromosomal translocation or the associated products. This review summarizes recent research advances on the relationship between non-coding RNAs and chromosomal translocations and on diverse functions of non-coding RNAs in cancers with chromosomal rearrangements.

Translational Polarity of a Mutation in the Initiator AUG Codon of the Λ cI Gene

Genetics ◽  
1987 ◽  
Vol 117 (2) ◽  
pp. 173-179
Author(s):  
Gary N Gussin ◽  
Susan Brown ◽  
Karen Matz
Keyword(s):  
Gene Expression ◽  
Bacterial Strain ◽  
Lacz Fusion ◽  
Lacz Gene ◽  
Bacteriophage Λ ◽  
Polar Mutation ◽  
Initiator Codon ◽  
In Trans ◽  
As If

ABSTRACT A PRM-cI-lacZ fusion inserted into the b2 region of bacteriophage λ was used to isolate mutations affecting expression of both the λ cI gene and the lacZ gene. One such mutation, a change in the cI initiator codon from AUG to AUA, reduces immunity of a λ prophage to superinfection, and causes a 60-70% reduction in β-galactosidase synthesis, even when repressor is supplied in trans. The effect of the mutation on lacZ gene expression is eliminated in a rho  - bacterial strain, and the mutation has no effect on transcription initiated at PRM in vitro. Therefore, the effects of the mutation are due to premature ρ-dependent termination of transcription in the absence of translation of the cI gene, as if the mutation were a nonsense polar mutation.

A MEIS1 Dependent Genetic Program in Leukemia Associated with Cell Cycle Entry and ‘Stemness’

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 746-746
Author(s):  
Ashish Kumar ◽  
Baolin Wu ◽  
John H. Kersey
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Stem Cells ◽  
Neural Stem Cells ◽  
Cell Line ◽  
Fusion Proteins ◽  
Leukemia Cells ◽  
Self Renewal ◽  
Knock Down ◽  
Cell Cycle Entry

Abstract The HOX co-factor MEIS1 is expressed in several leukemias, especially those involving MLL-gene rearrangements. Experimental data have demonstrated that MLL-fusion proteins induce the expression of MEIS1 in hematopoietic cells along with increased self-renewal and recent murine experiments indicate that MEIS1 is central to the growth-promoting effects of MLL fusion proteins. However, the cellular and molecular pathways that are regulated by MEIS1 are unknown. We studied the effect of MEIS1 knock-down in a cell line derived from a leukemic MLL-AF9 knock-in mouse. Transduction of this cell line (4166) with MEIS1-shRNA bearing lentivirus led to significant reduction in MEIS1 expression compared to cells transduced with control virus. The MEIS1 knock-down cells displayed decreased cell cycle entry, while terminal myeloid differentiation and apoptosis were enhanced. To characterize the molecular effects of MEIS1 knock-down, we performed gene expression profiling of leukemia cells with and without MEIS1 expression. We extracted RNA from 5 separate experiments where 4166 cells were transduced with vector control or MEIS1 shRNA for 48 hours and analyzed gene expression profiles using Affymetrix 430 2.0 whole genome arrays. We used a regularized two-sample paired t-test to select genes that were differentially expressed among the two groups. At a false discovery rate (FDR) of ≤ 5%, 1053 probe sets displayed decreased expression with MEIS1 knockdown, while 296 probe sets showed increased expression. Analysis of gene ontology (GO) terms by DAVID (Database for Annotation, Visualization and Integrated Discovery) revealed that the list of genes down-regulated with MEIS1 knock-down was significantly enriched in genes associated with the cell cycle and its regulation (Cdk2, Cdk6, Cdkn3, Ccna2, Cdc7, Cdc42, Rbl1, Wee1) and DNA replication (Brca1, Cdc6, Cdt1, Gmnn, Mcm4, Mcm5, Mcm8). Conversely, the genes displaying increased expression with MEIS1 knockdown were associated with inhibition of proliferation eg. Cdkn1a (p21), Btg2, Btg3 and pro-apoptotic effects such as Bax. A search of the Molecular Signatures Database for previously published profiles that overlap with our list of MEIS1-dependent genes revealed that the profile of MEIS1 knockdown in our murine leukemia cells significantly overlapped with that of neural stem cells. Specifically, of the 1838 genes expressed highly in neural stem cells compared to differentiated brain and bone marrow cells (Ramalho-Santos et al, Science 2002), 155 showed an overlap with the 594 genes in our MEIS1-dependent set (594 gene identifiers contained in 1053 probe sets; p = 3.27 e−28, hypergeometric distribution). This list of 155 genes included MEIS1 and several of the cell cycle and DNA replication-associated genes. These results reveal a core self-renewal genetic program shared by leukemia and neural stem cells that is regulated by MEIS1. Activation of MEIS1 in leukemia and possibly brain tumors could thus enhance self-renewal via the up-regulation of the above common genes. Overall, our results show that MEIS1 regulates cell cycle entry in murine MLL-AF9 leukemia, an effect that enhances self-renewal in other cells as well.

CBX8, a Polycomb-Group Protein, Is Essential for MLL-AF9-Induced Leukemogenesis

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4174-4174
Author(s):  
Jiaying Tan ◽  
Jay L. Hess
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Cell Lines ◽  
Transcriptional Activation ◽  
Fusion Proteins ◽  
Conflicts Of Interest ◽  
Leukemia Cell ◽  
Polycomb Group ◽  
Human Leukemia ◽  
Interaction Sites

Abstract Abstract 4174 Trithorax and Polycomb-group (Trx-G and Pc-G) proteins are antagonistic regulators of homeobox-containing (Hox) gene expression that play a major role in regulation of hematopoiesis and leukemogenesis. Mixed lineage leukemia (MLL), a mammalian Trx-G protein, is a histone methyltransferase crucial for embryonic development and hematopoiesis that is commonly altered by translocation in acute leukemia. Recent evidence suggests that transformation by MLL fusion proteins is dependent on multiple interaction complexes, including the polymerase associated factor complex (PAFc) and the elongation activating protein complex (EAPc) or a closely related AF4 family/ENL family/P-TEFb complex (AEPc). CBX8 is a human PcG protein, functioning as a transcription repressor in the polycomb repressive complex 1 (PRC1). Previous studies have shown that CBX8 also interacts with the EAPc components AF9 and ENL; however, its role in leukemogenesis is unknown. To elucidate the significance of this interaction between these two proteins thought to have antagonistic function, we generated a large series of point mutations in AF9 and identified two amino acids that are essential for CBX8 interaction but preserve the interaction with other EAP components. Mutation of the two sites reduced the transcriptional activation of the MLL-AF9 target promoters by nearly 50% and completely inhibits the ability of MLL-AF9 to immortalize bone marrow (BM) as assessed by methylcellulose replating assays. This finding suggests that CBX8 interaction is essential for MLL-AF9-induced leukemogenesis. Several lines of evidence further support this finding. First, CBX8 knockdown by siRNAs decreased MLL-AF9-induced transcriptional activation by approximately 50%. Second, the ability of MLL-AF9 to transform primary BM was markedly reduced by retroviral shCbx8 transduction. Notably, this inhibitory effect is specific for MLL-AF9 because the BM transformation ability of E2A-HLF was unaffected by Cbx8 suppression. Third, Cbx8 suppression by shCbx8 in MLL-AF9 and MLL-ENL, but not E2A-HLF transformed AML cell lines, significantly inhibited the expression of MLL-dependent target genes, as well as cell growth and colony forming ability. Fourth, inducing CBX8 knockdown in human leukemia cell lines expressing MLL-AF9 led to a marked decrease in the localization of basic transcription machinery at the Hoxa9 locus and a corresponding reduction in Hoxa9 transcription. Importantly, the observed effects of CBX8 on MLL-rearranged leukemia cells are PRC1-independent: no effects on MLL target gene expression, cell growth, or BM transformation ability were observed by suppressing other core components of PRC1. Taken together, our results indicate that CBX8, independent of its transcription repression role in PRC1, interacts with and synergizes with MLL fusion proteins to promote leukemogenesis. Defining the interaction sites between AF9/ENL and CBX8 and the dependence of other AML subtypes and normal hematopoiesis on CBX8 will be important for the further development of agents that target this mechanism in MLL-rearranged and potentially other AML subtypes. Disclosures: No relevant conflicts of interest to declare.

A Novel Ubiquitination Pathway Regulates MLL Activity During Hematopoietic Differentiation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 743-743
Author(s):  
Jingya Wang ◽  
Andrew G. Muntean ◽  
Jay L. Hess
Keyword(s):  
Gene Expression ◽  
Half Life ◽  
Fusion Proteins ◽  
Mouse Bone Marrow ◽  
Wild Type ◽  
E3 Ligases ◽  
Over Expression ◽  
Primary Mouse ◽  
Ubiquitination Pathway ◽  
Socs Box

Abstract Abstract 743 MLL gene rearrangements are among the most common chromosomal abnormalities associated with both acute lymphoid (ALL) and myeloid (AML) leukemia. Both MLL and leukemogenic MLL fusion proteins directly regulate expression of HoxA9 and the co-factor Meis1. Normally Hoxa9 and Meis1 are expressed at high levels in early hematopoietic progenitors, where they promote HSC self-renewal. MLL fusion proteins block this physiologic down regulation so that Hoxa9 and Meis1 are persistently expressed, resulting in leukemia. The mechanisms through which the activity of MLL is normally regulated are poorly understood. MLL fusion proteins include the first 1400 amino acids of MLL and invariably delete the plant homeodomain (PHD)/Bromodomain regions (including 4 PHD fingers, with bromodomain between the 3rd and 4th PHD finger) and C terminal SET domain. Previously we showed that inclusion of the MLL PHD domain in MLL fusion proteins prevents transformation. To further explore the function of this potential regulatory domain, we identified proteins that interact with the CxxC and PHD domains by immunoaffinity purification and mass spectroscopy. These studies identified subunits of the Elongin-Cullin-Socs box (ECS) complex including Elongin B, Elongin C, Cullin 5 and Ankyrin Repeat and SOCS box (ASB) E3 ligases. Biochemical experiments on a panel of ASB proteins revealed that ASB2, which functions as a substrate recognition subunit of the ECS complex specifically and potently degrades MLL. Over expression of ASB2 enhanced the degradation of MLL, while ASB2 knockdown results in MLL protein stabilization. Moreover, co-expressed ASB2 abolished MLL mediated transcriptional activation of a HoxA9 reporter. The interaction region on ASB2 maps to the five N terminal ankyrin repeats. Since the ASB2 interaction is mediated through a region of MLL invariably deleted from fusion proteins, we predicted that MLL fusions would be significantly more stable than full length MLL. Indeed, we measured the half-life of wild type MLL to be ~7hrs, and ~16hrs in the presence of MG132 proteasome inhibition. In contrast, MLL-AF9 displayed a half-life of ~60hrs, and MG132 treatment slightly increased the half-life to ~76hrs. Gene expression analysis of different hematopoietic cell populations indicates that Asb2 expression increases dramatically with differentiation. Also, All-trans retinoid acid (ATRA) induced differentiation of NB4 and K562 cells is associated with up regulation of Asb2 and decreased MLL protein level and Hox gene expression, while MLL transcription is largely unchanged. Furthermore, expression of ASB2 in primary mouse bone marrow cells results in accelerated differentiation and decreased expression of several MLL target genes compared to vector control and over expression of ASB2 in MLL-fusion transformed murine cell lines dramatically decreased colony formation, consistent with recently published data that wild type MLL is required for MLL fusion transformation. Together this work reveals a novel ubiquitination pathway that regulates MLL at the posttranslational level, which is likely to be important for both normal hematopoiesis and the dysregulated transcription that is seen in leukemias with MLL rearrangements. Disclosures: No relevant conflicts of interest to declare.

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