MLLT6

Gene Summary

Gene:MLLT6; MLLT6, PHD finger containing
Aliases: AF17
Location:17q12
Summary:-
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:protein AF-17
Source:NCBIAccessed: 30 August, 2019

Ontology:

What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 30 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 30 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (4)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: MLLT6 (cancer-related)

Brassesco MS, Valera ET, Meyer C, et al.
A new complex rearrangement in infant ALL: t(X;11;17)(p11.2;q23;q12).
Cancer Genet. 2018; 228-229:110-114 [PubMed] Related Publications
We present a case of an infant who developed pro-B acute lymphoblastic leukemia with a rare and complex MLL-translocation. Cytogenetic analysis of bone marrow cells at diagnosis showed a 46,XY,t(X;11)(p11.2;q23)[13]/46,XY[7] karyotype. Fluorescence in situ hybridization analysis using a break apart specific probes showed a split in the MLL gene. Long distance inverse-PCR and next generation sequencing analysis depicted a complex rearrangement t(X;11;17)(p11.2;q23;q12) involving MLL, MLLT6 and the genomic region Xp11.23, 41 bases upstream of the WDR45 gene. WDR45 encodes a beta-propeller protein essential for autophagocytosis. MLL rearrangements with involvement of Xp have not been previously described.

Yang H, Cao T, Gao L, et al.
The incidence and distribution characteristics of MLL rearrangements in Chinese acute myeloid leukemia patients by multiplex nested RT-PCR.
Technol Health Care. 2017; 25(S1):259-265 [PubMed] Related Publications
Occurrence of MLL (Mixed Lineage Leukemia) gene rearrangements indicates poor prognosis in acute myeloid leukemia (AML) patients. This is the first study to report the positive rate and distribution characteristics of MLL rearrangements in AML patients in north China. We used multiplex nested real time PCR (RT-PCR) to screen for incidence of 11 MLL rearrangements in 433 AML patients. Eleven MLL rearrangements included (MLL-PTD, MLL-AF9, MLL-ELL, MLL-AF10, MLL-AF17, MLL-AF6, MLL-ENL, MLL-AF1Q, MLL-CBP, MLL-AF1P, MLL-AFX1). There were 68 AML patients with MLL rearrangements, and the positive rate was 15.7%. MLL-PTD (4.84%) was detected in 21 patients, MLL-AF9 in 15, (3.46%), MLL-ELL in 10 (2.31%), MLL-AF10 in 8 (1.85%), MLL-AF1Q in 2 (0.46%), 3 cases each of MLL-AF17, MLL-AF6, MLL-ENL (0.69% each), a and single case each of MLL-CBP, MLL-AF1P, and MLL-AFX1 (0.23% each). The highest rate of MLL rearrangements was found in 24 patients with M5 subtype AML, occurring in 24 cases (35.3%). MLL rearrangements occurred in 21 patients with M2 subtype AML (30.9%), and in 10 patients with M4 subtype AML (14.7%). Screening fusion genes by multiplex nested RT-PCR is a convenient, fast, economical, and accurate method for diagnosis and predicting prognosis of AML.

Beronja S, Janki P, Heller E, et al.
RNAi screens in mice identify physiological regulators of oncogenic growth.
Nature. 2013; 501(7466):185-90 [PubMed] Free Access to Full Article Related Publications
Tissue growth is the multifaceted outcome of a cell's intrinsic capabilities and its interactions with the surrounding environment. Decoding these complexities is essential for understanding human development and tumorigenesis. Here we tackle this problem by carrying out the first genome-wide RNA-interference-mediated screens in mice. Focusing on skin development and oncogenic (Hras(G12V)-induced) hyperplasia, our screens uncover previously unknown as well as anticipated regulators of embryonic epidermal growth. Among the top oncogenic screen hits are Mllt6 and the Wnt effector β-catenin, which maintain Hras(G12V)-dependent hyperproliferation. We also expose β-catenin as an unanticipated antagonist of normal epidermal growth, functioning through Wnt-independent intercellular adhesion. Finally, we validate functional significance in mouse and human cancers, thereby establishing the feasibility of in vivo mammalian genome-wide investigations to dissect tissue development and tumorigenesis. By documenting some oncogenic growth regulators, we pave the way for future investigations of other hits and raise promise for unearthing new targets for cancer therapies.

De Braekeleer E, Meyer C, Douet-Guilbert N, et al.
Identification of MLL partner genes in 27 patients with acute leukemia from a single cytogenetic laboratory.
Mol Oncol. 2011; 5(6):555-63 [PubMed] Free Access to Full Article Related Publications
Chromosomal rearrangements involving the MLL gene have been associated with many different types of hematological malignancies. Fluorescent in situ hybridization with a panel of probes coupled with long distance inverse-PCR was used to identify chromosomal rearrangements involving the MLL gene. Between 1995 and 2010, 27 patients with an acute leukemia were found to have a fusion gene involving MLL. All seven ALL patients with B cell acute lymphoblastic leukemia were characterized by the MLL/AFF1 fusion gene resulting from a translocation (5 patients) or an insertion (2 patients). In the 19 AML patients with acute myeloblastic leukemia, 31.6% of all characterized MLL fusion genes were MLL/MLLT3, 21.1% MLL/ELL, 10.5% MLL/MLLT6 and 10.5% MLL/EPS15. Two patients had rare or undescribed fusion genes, MLL/KIAA0284 and MLL/FLNA. Seven patients (26%) had a complex chromosomal rearrangement (three-way translocations, insertions, deletions) involving the MLL gene. Splicing fusion genes were found in three patients, leading to a MLL/EPS15 fusion in two and a MLL/ELL fusion in a third patient. This study showed that fusion involving the MLL gene can be generated through various chromosomal rearrangements such as translocations, insertions and deletions, some being complex or cryptic. A systematic approach should be used in all cases of acute leukemia starting with FISH analyses using a commercially available MLL split signal probe. Then, the analysis has to be completed, if necessary, by further molecular cytogenetic and genomic PCR methods.

Meyer C, Kowarz E, Hofmann J, et al.
New insights to the MLL recombinome of acute leukemias.
Leukemia. 2009; 23(8):1490-9 [PubMed] Related Publications
Chromosomal rearrangements of the human MLL gene are associated with high-risk pediatric, adult and therapy-associated acute leukemias. These patients need to be identified, treated appropriately and minimal residual disease was monitored by quantitative PCR techniques. Genomic DNA was isolated from individual acute leukemia patients to identify and characterize chromosomal rearrangements involving the human MLL gene. A total of 760 MLL-rearranged biopsy samples obtained from 384 pediatric and 376 adult leukemia patients were characterized at the molecular level. The distribution of MLL breakpoints for clinical subtypes (acute lymphoblastic leukemia, acute myeloid leukemia, pediatric and adult) and fused translocation partner genes (TPGs) will be presented, including novel MLL fusion genes. Combined data of our study and recently published data revealed 104 different MLL rearrangements of which 64 TPGs are now characterized on the molecular level. Nine TPGs seem to be predominantly involved in genetic recombinations of MLL: AFF1/AF4, MLLT3/AF9, MLLT1/ENL, MLLT10/AF10, MLLT4/AF6, ELL, EPS15/AF1P, MLLT6/AF17 and SEPT6, respectively. Moreover, we describe for the first time the genetic network of reciprocal MLL gene fusions deriving from complex rearrangements.

Strehl S, König M, Meyer C, et al.
Molecular dissection of t(11;17) in acute myeloid leukemia reveals a variety of gene fusions with heterogeneous fusion transcripts and multiple splice variants.
Genes Chromosomes Cancer. 2006; 45(11):1041-9 [PubMed] Related Publications
The majority of translocations that involve the long arms of chromosomes 11 and 17 in acute myeloid leukemia appear identical on the cytogenetic level. Nevertheless, they are diverse on the molecular level. At present, two genes are known in 11q23 and four in 17q12-25 that generate five distinct fusion genes: MLL-MLLT6/AF17, MLL-LASP1, MLL-ACACA or MLL-SEPT9/MSF, and ZBTB16/PLZF-RARA. We analyzed 14 cases with a t(11;17) by fluorescence in situ hybridization and molecular genetic techniques and determined the molecular characteristics of their fusion genes. We identified six different gene fusions that comprised seven cases with a MLL-MLLT6/AF17, three with a MLL-SEPT9/MSF, and one each with MLL-LASP1, MLL-ACACA, and ZBTB16/PLZF-RARA fusions. In the remaining case, a MLL-SEPT6/Xq24 fusion suggested a complex rearrangement. The MLL-MLLT6/AF17 transcripts were extremely heterogeneous and the detection of seven different in-frame transcript and splice variants enabled us to predict the protein domains relevant for leukemogenesis. The putative MLL-MLLT6 consensus chimeric protein consists of the AT-hook DNA-binding, the methyltransferase, and the CXXC zinc-finger domains of MLL and the highly conserved octapeptide and the leucine-zipper dimerization motifs of MLLT6. The MLL-SEPT9 transcripts showed a similar high degree of variability. These analyses prove that the diverse types of t(11;17)-associated fusion genes can be reliably identified and delineated with a proper combination of cytogenetic and molecular genetic techniques. The heterogeneity of transcripts encountered in cases with MLL-MLLT6/AF17 and MLL-SEPT9/MSF fusions clearly demonstrates that thorough attention has to be paid to the appropriate selection of primers to cover all these hitherto unrecognized fusion variants.

Yamamoto S, Nishi M, Taniguchi K, et al.
Partial tandem duplication of MLL gene in acute myeloid leukemia with translocation (11;17)(q23;q12-21).
Am J Hematol. 2005; 80(1):46-9 [PubMed] Related Publications
Translocation 11q23 and MLL gene rearrangements are commonly observed in acute myeloid leukemia (AML) in association with the myelomonocytic or monocytic feature. We describe a case involving a 15-year-old patient with AML characterized by leukemic cells exhibiting translocation (11;17)(q23;q12-21) and MLL gene rearrangement. No fusion partner gene of the MLL gene was identified, including RARalpha(17q12) or AF17 (17q21); however, a partial tandem duplication of the MLL exon 11/exon 10 was detected in leukemic cells via a 3'RACE method for detection of unknown partner genes. The patient has been in remission for more than 2 years without hematopoietic stem cell transplantation.

Suzukawa K, Shimizu S, Nemoto N, et al.
Identification of a chromosomal breakpoint and detection of a novel form of an MLL-AF17 fusion transcript in acute monocytic leukemia with t(11;17)(q23;q21).
Int J Hematol. 2005; 82(1):38-41 [PubMed] Related Publications
More than 40 genes have been reported as translocation partners of the mixed lineage leukemia gene (MLL) in hematologic malignancies. AF17 was identified earlier than most other MLL translocation partners. On the other hand, there is only 1 report of an MLL-AF17 fusion transcript in acute myeloid leukemia (AML). Here we describe a 40-year-old man with a diagnosis of AML involving t(11;17)(q23;q21). We identified a chromosomal breakpoint for t(11;17)(q23;q21) at MLL intron 6 and AF17 intron 8. Although the previously reported form of the MLL-AF17 fusion transcript was not detected by reverse transcriptase-polymerase chain reaction (PCR) analysis, a novel form of an MLL-AF17 fusion transcript joining MLL exon 6 to AF17 exon 9 was detected by complementary DNA panhandle PCR. The fact that 2 forms of MLL-AF17 retain the leucine zipper domain of AF17 suggests that the dimerization domain of AF17 is critical for leukemogenesis by the MLL-AF17 fusion gene.

Maroc N, Morel A, Beillard E, et al.
A diagnostic biochip for the comprehensive analysis of MLL translocations in acute leukemia.
Leukemia. 2004; 18(9):1522-30 [PubMed] Related Publications
Reciprocal rearrangements of the MLL gene are among the most common chromosomal abnormalities in both Acute Lymphoblastic and Myeloid Leukemia. The MLL gene, located on the 11q23 chromosomal band, is involved in more than 40 recurrent translocations. In the present study, we describe the development and validation of a biochip-based assay designed to provide a comprehensive molecular analysis of MLL rearrangements when used in a standard clinical pathology laboratory. A retrospective blind study was run with cell lines (n=5), and MLL positive and negative patient samples (n=31), to evaluate assay performance. The limits of detection determined on cell line data were 10(-1), and the precision studies yielded 100% repeatability and 98% reproducibility. The study shows that the device can detect frequent (AF4, AF6, AF10, ELL or ENL) as well as rare partner genes (AF17, MSF). The identified fusion transcripts can then be used as molecular phenotypic markers of disease for the precise evaluation of minimal residual disease by RQ-PCR. This biochip-based molecular diagnostic tool allows, in a single experiment, rapid and accurate identification of MLL gene rearrangements among 32 different fusion gene (FG) partners, precise breakpoint positioning and comprehensive screening of all currently characterized MLL FGs.

Zhou MI, Wang H, Foy RL, et al.
Tumor suppressor von Hippel-Lindau (VHL) stabilization of Jade-1 protein occurs through plant homeodomains and is VHL mutation dependent.
Cancer Res. 2004; 64(4):1278-86 [PubMed] Related Publications
The von Hippel-Lindau (VHL) gene is the major renal cancer gene in adults. The mechanism of renal tumor suppression by VHL protein is only partly elucidated. VHL loss increases expression of the hypoxia-inducible factor alpha transcription factors. However, clinical and biochemical data indicate that the hypoxia-inducible factors are necessary but not sufficient for renal tumorigenesis, which suggests other VHL effector pathways are involved. Jade-1 protein interacts strongly with VHL and is most highly expressed in renal proximal tubules, precursor cells of renal cancer. Short-lived Jade-1 protein contains plant homeodomain (PHD) and candidate PEST degradation motifs and is substantially stabilized by VHL. The effect of VHL on Jade-1 protein abundance and relative protein stability was further examined in immunoblots and metabolic labeling experiments using two time points. VHL-Jade-1 binding was tested in coimmunoprecipitations. In cotransfection studies with wild-type VHL, the Jade-1 PHD-extended PHD module, not the candidate PEST domain, was required for full VHL-mediated stabilization. This module is also found in leukemia transcription factors AF10 and AF17, as well as closely related Jade-like proteins, which suggests all might be VHL regulated. Intriguingly, naturally occurring truncations and mutations of VHL affected wild-type Jade-1 binding and stabilization. Although the VHL beta domain was sufficient for Jade-1 binding, both the alpha and beta domains were required for Jade-1 stabilization. Thus, truncating VHL mutations, which are severe and associated with renal cancer development, prevented Jade-1 stabilization. Moreover, well-controlled cotransfection and metabolic labeling experiments revealed that VHL missense mutations that cause VHL disease without renal cancer, such as Tyr98His and Tyr112His, stabilized Jade-1 fully. In contrast, like the VHL truncations, VHL missense mutations commonly associated with renal cancer, such as Leu118Pro or Arg167Trp, did not stabilize Jade-1 fully. Therefore, loss of Jade-1 stability may correlate with renal cancer risk. Endogenous Jade-1 in stable renal cancer lines also exhibited VHL mutation-dependent regulation. As in the cotransfections, VHL truncations did not increase endogenous Jade-1 abundance, whereas the VHL missense mutations tested partially increased Jade-1 expression. Additional studies with non-PHD proteins indicated that Jade-1 stabilization by VHL is highly specific. Fibronectin was not stabilized like Jade-1 by VHL, nor were candidate VHL interactors from a yeast screen. Thus, protein stabilization likely reflects the biological activity of largely intact VHL protein on the PHD-extended PHD module of Jade-1. Dysregulation of the VHL protein stabilization pathway or of Jade-1 itself may therefore contribute to VHL renal disease and renal cancer pathogenesis.

Strehl S, Borkhardt A, Slany R, et al.
The human LASP1 gene is fused to MLL in an acute myeloid leukemia with t(11;17)(q23;q21).
Oncogene. 2003; 22(1):157-60 [PubMed] Related Publications
The MLL gene at chromosome 11q23 is frequently rearranged in acute leukemia. Here we report the identification of a new MLL fusion partner in the case of an infant with AML-M4 and a t(11;17)(q23;q21) translocation. Fluorescence in situ hybridization (FISH) and RT-PCR analyses indicated a rearrangement of the MLL gene, but no fusion with previously identified MLL fusion partners at 17q, such as AF17 or MSF. Rapid amplification of cDNA ends (RACE) revealed an in-frame fusion of MLL to LASP1, a gene that is amplified and overexpressed in breast cancer. Retroviral transduction of myeloid progenitors demonstrated that MLL/LASP1 is the fourth known fusion of MLL with a cytoplasmic protein that has no in vitro transformation capability, thus establishing a potential subgroup among the MLL fusion proteins.

Perrin L, Bloyer S, Ferraz C, et al.
The leucine zipper motif of the Drosophila AF10 homologue can inhibit PRE-mediated repression: implications for leukemogenic activity of human MLL-AF10 fusions.
Mol Cell Biol. 2003; 23(1):119-30 [PubMed] Free Access to Full Article Related Publications
In a screen for Drosophila genes that interfere with transcriptional repression mediated by the Polycomb group of genes, we identified a dominant mutation affecting the Alhambra (Alh) gene, the fly homologue of the human AF10 gene. AF10 has been identified as a fusion partner of both MLL and CALM in infant leukemias. Both fusion proteins retain the leucine zipper domain of AF10 but not its PHD domain. We show here that, while the full-length ALH protein has no activity on Polycomb group-responsive elements (PREs), overexpression of the isolated ALH leucine zipper domain activates several PREs. Within the ALH full-length protein, the PHD domain inhibits the PRE deregulation mediated by the leucine zipper domain. This deregulation is conserved in the human AF10 leucine zipper domain, which confers the same activity on an oncogenic MLL-AF10 fusion protein expressed in Drosophila melanogaster. These data reveal new properties for the leucine zipper domain and thus might provide new clues to understanding the mechanisms by which AF10 fusion proteins in which the PHD domain is lost might trigger leukemias in humans.

Sano K
Structure of AF3p21, a new member of mixed lineage leukemia (MLL) fusion partner proteins-implication for MLL-induced leukemogenesis.
Leuk Lymphoma. 2001; 42(4):595-602 [PubMed] Related Publications
The Mixed Lineage Leukemia (MLL) gene is frequently rearranged in leukemia, especially in infantile leukemia and therapy-related leukemia. The MLL gene is localized at chromosome 11q23, and is involved in almost all of the chromosomal translocations involving 11q23. Twenty-four fusion partner genes have been identified to date, and the N-terminus of MLL fuses in-frame to the partner genes in all cases. Some of the MLL fusion partner genes encode transcription factors; others encode small GTP binding protein interacting molecules or cytoplasmic proteins, the functions of which are presently unknown. As a result of the diverse features of the MLL fusion partners, the underlying mechanism for leukemogenesis remains obscure. We cloned the MLL fusion partner gene from leukemic cells from a therapy-related leukemia patient with t(3;11)(p21;q23) and designated the gene AF3p21. This patient had a long latency period (9 years) before developing secondary leukemia. The AF3p21 gene encodes a nuclear protein with a molecular mass of 80 kDa, and this protein has SH3 and proline-rich domains. Among MLL fusion partners identified to date, only AF10 and AF17 have a homo-oligomerization domain. AF3p21 also has a homo-oligomerization domain, which was revealed by using a mammalian two-hybrid system. These results suggest that one possible role of the MLL fusion partners is to form an oligomer of truncated MLL. In this review, current knowledge about MLL-involved leukemogenesis is outlined.

Lin YM, Ono K, Satoh S, et al.
Identification of AF17 as a downstream gene of the beta-catenin/T-cell factor pathway and its involvement in colorectal carcinogenesis.
Cancer Res. 2001; 61(17):6345-9 [PubMed] Related Publications
To elucidate the molecular mechanism of colorectal carcinogenesis, we have been attempting to isolate genes involved in the beta-catenin/T-cell factor pathway. In the experiments reported here, analysis by cDNA microarray indicated that AF17, a fusion partner of the MLL gene in acute leukemias with t(11;17)(q23;q21), was transactivated according to accumulation of beta-catenin. Expression of AF17 was significantly enhanced in 8 of the 12 colorectal cancer tissues examined. Introduction of a plasmid designed to express AF17 stimulated growth of NIH3T3 cells, and fluorescence-activated cell sorter analysis indicated that the AF17 regulation of cell-cycle progression was occurring mainly at the G(2)-M transition. Our results suggest that the AF17 gene product is likely to be involved in the beta-catenin-T-cell factor/lymphoid enhancer factor signaling pathway and to function as a growth-promoting, oncogenic protein. These findings should aid development of new strategies for diagnosis, treatment, and prevention of colon cancers and acute leukemias by clarifying the pathogenesis of these conditions.

McCullagh P, Chaplin T, Meerabux J, et al.
The cloning, mapping and expression of a novel gene, BRL, related to the AF10 leukaemia gene.
Oncogene. 1999; 18(52):7442-52 [PubMed] Related Publications
The MLL gene is reciprocally translocated with one of a number of different partner genes in a proportion of human acute leukaemias. The precise mechanism of oncogenic transformation is unclear since most of the partner genes encode unrelated proteins. However, two partner genes, AF10 and AF17 are related through the presence of a cysteine rich region and a leucine zipper. The identification of other proteins with these structures will aid our understanding of their role in normal and leukaemic cells. We report the cloning of a novel human gene (BRL) which encodes a protein containing a cysteine rich region related to that of AF10 and AF17 and is overall most closely related to the previously known protein BR140. BRL maps to chromosome 22q13 and shows high levels of expression in testis and several cell lines. The deduced protein sequence also contains a bromodomain, four potential LXXLL motifs and four predicted nuclear localization signals. A monoclonal antibody raised to a BRL peptide sequence confirmed its widespread expression as a 120 Kd protein and demonstrated localization to the nucleus within spermatocytes.

Taki T, Ohnishi H, Shinohara K, et al.
AF17q25, a putative septin family gene, fuses the MLL gene in acute myeloid leukemia with t(11;17)(q23;q25).
Cancer Res. 1999; 59(17):4261-5 [PubMed] Related Publications
The t(11;17) has been described in patients with acute myeloid leukemia (AML), and the AF17 gene was previously cloned as a fusion partner of the MLL gene in t(11;17)(q23;q21)-AML. We analyzed one patient with de novo AML and one with therapy-related AML with t(11;17)(q23;q25) and identified the AF17q25 gene on chromosome 17q25, a putative septin family gene, fused with MLL. AF17q25 encoded at least three kinds of proteins [type I (568 a.a.), type II (594 a.a.), and type III (574 a.a.)] that contained two kinds of different amino acid sequences at the COOH terminus. The MLL-AF17q25 fusion transcript consisted of type I AF17q25 transcript. The AF17q25 protein is homologous to septin family proteins, including H5, NEDD5, CDC10, and hCDCrel, which is one of the fusion partners of MLL in t(11;22)(q23;q11)-AML. These results suggest that AF17q25 and hCDCrel might define a new septin family particularly involved in the pathogenesis of 11q23-associated leukemia.

Prasad R, Yano T, Sorio C, et al.
Domains with transcriptional regulatory activity within the ALL1 and AF4 proteins involved in acute leukemia.
Proc Natl Acad Sci U S A. 1995; 92(26):12160-4 [PubMed] Free Access to Full Article Related Publications
The ALLI gene, located at chromosome band 11q23, is involved in acute leukemia through a series of chromosome translocations and fusion to a variety of genes, most frequently to A4 and AF9. The fused genes encode chimeric proteins proteins. Because the Drosophila homologue of ALL1, trithorax, is a positive regulator of homeotic genes and acts at the level of transcription, it is conceivable that alterations in ALL1 transcriptional activity may underlie its action in malignant transformation. To begin studying this, we examined the All1, AF4, AF9, and AF17 proteins for the presence of potential transcriptional regulatory domains. This was done by fusing regions of the proteins to the yeast GAL4 DNA binding domain and assaying their effect on transcription of a reporter gene. A domain of 55 residues positioned at amino acids 2829-2883 of ALL1 was identified as a very strong activator. Further analysis of this domain by in vitro mutagenesis pointed to a core of hydrophobic and acidic residues as critical for the activity. An ALL1 domain that repressed transcription of the reporter gene coincided with the sequence homologous to a segment of DNA methyltransferase. An AF4 polypeptide containing residues 480-560 showed strong activation potential. The C-terminal segment of AF9 spanning amino acids 478-568 transactivated transcription of the reporter gene in HeLa but not in NIH 3T3 cells. These results suggest that ALL1, AF4, and probably AF9 interact with the transcriptional machinery of the cell.

Saha V, Chaplin T, Gregorini A, et al.
The leukemia-associated-protein (LAP) domain, a cysteine-rich motif, is present in a wide range of proteins, including MLL, AF10, and MLLT6 proteins.
Proc Natl Acad Sci U S A. 1995; 92(21):9737-41 [PubMed] Free Access to Full Article Related Publications
We have identified and further characterized a Caenorhabditis elegans gene, CEZF, that encodes a protein with substantial homology to the zinc finger and leucine zipper motifs of the human gene products AF10, MLLT6, and BR140. The first part of the zinc finger region of CEZF has strong similarity to the corresponding regions of AF10 (66%) and MLLT6 (64%) at the cDNA level. As this region is structurally different from previously described zinc finger motifs, sequence homology searches were done. Twenty-five other proteins with a similar motif were identified. Because the functional domain of this motif is potentially disrupted in leukemia-associated chromosomal translocations, we propose the name of leukemia-associated protein (LAP) finger. On the basis of these comparisons, the LAP domain consensus sequence is Cys1-Xaa1-2-Cys2-Xaa9-21-Cys3-Xaa2-4 -Cys4-Xaa4-5-His5-Xaa2-Cys6-Xaa12-46 - Cys7-Xaa2-Cys8, where subscripted numbers represent the number of amino acid residues. We review the evidence that this motif binds zinc, is the important DNA-binding domain in this group of regulatory proteins, and may be involved in leukemogenesis.

Chaplin T, Bernard O, Beverloo HB, et al.
The t(10;11) translocation in acute myeloid leukemia (M5) consistently fuses the leucine zipper motif of AF10 onto the HRX gene.
Blood. 1995; 86(6):2073-6 [PubMed] Related Publications
The gene on chromosome 10 at band p12 (AF10), involved in the t(10;11) translocation in acute myeloid leukemia, has been identified and shown to contain conserved zinc finger and leucine zipper domains. These regions are highly homologous to the equivalent regions on AF17, the gene involved in the t(11;17) translocations. A series of adult, childhood, and infant leukemias with either simple or complex versions of the t(10;11) has been examined by Southern analysis and shown to involve rearrangement to the HRX locus. Reverse transcriptase-polymerase chain reaction from either bone marrow or peripheral blood cells showed that HRX sequence was fused to AF10 sequence in all 8 cases and subsequent sequence analysis showed an in-frame fusion between the HRX and AF10 sequence. A consistent feature of these fusions was the juxtaposition of the leucine dimerization motif of AF10 onto the NH2-terminal region of HRX. The published data suggest that a similar conclusion can be drawn about the t(11;17) translocation, implying a critical role for this motif in the chimaeric HRX protein.

Chaplin T, Ayton P, Bernard OA, et al.
A novel class of zinc finger/leucine zipper genes identified from the molecular cloning of the t(10;11) translocation in acute leukemia.
Blood. 1995; 85(6):1435-41 [PubMed] Related Publications
A novel class of conserved transcription factors has been identified from the molecular cloning of AF10, the gene involved in the t(10;11)(p12;q23) translocation of acute myeloid leukemias. AF10 encodes a 109-kD protein of 1,027 amino acids and contains an N-terminal zinc finger region and a C-terminal leucine zipper. These structures have been found to be conserved in sequence and position in three other proteins, AF17, BR140, and a previously unrecognized Caenorhabditis elegans gene, provisionally named CEZF. The overall structure, level of sequence conservation, and expression pattern suggest that these genes encode a new class of transcription factors, some of which are targets for chromosomal translocation in acute leukemia.

Prasad R, Leshkowitz D, Gu Y, et al.
Leucine-zipper dimerization motif encoded by the AF17 gene fused to ALL-1 (MLL) in acute leukemia.
Proc Natl Acad Sci U S A. 1994; 91(17):8107-11 [PubMed] Free Access to Full Article Related Publications
Chromosome region 11q23 is involved in reciprocal chromosome translocations associated with human acute leukemias. These aberrations fuse the ALL-1 gene located at 11q23 to a series of partner genes positioned on a variety of human chromosomes. The fused genes encode chimeric proteins. Here we report the cloning and characterization of the ALL-1 partner at 17q21, the AF17 gene. The AF17 gene encodes a protein of 1093 amino acids, containing a leucine-zipper dimerization motif located 3' of the fusion point and a cysteine-rich domain at the N terminus. The latter can be arranged in three zinc fingers and shows homology to a domain within the protein Br140 (peregrin). AF17 contains stretches of amino acids previously associated with domains involved in transcriptional repression or activation. Based on features of AF17 and of the proteins encoded by the other partner genes analyzed and in conjunction with other recent studies, we propose a model in which ALL-1 rearrangements result in loss of function of the gene. In this model, the partner polypeptide plays an accessory role either by repressing activity of the truncated ALL-1 protein or by blocking the function of the normal protein presumably present in the leukemic cells.

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