Gene Summary

Gene:AFF3; AF4/FMR2 family, member 3
Aliases: LAF4, MLLT2-like
Summary:This gene encodes a tissue-restricted nuclear transcriptional activator that is preferentially expressed in lymphoid tissue. Isolation of this protein initially defined a highly conserved LAF4/MLLT2 gene family of nuclear transcription factors that may function in lymphoid development and oncogenesis. In some ALL patients, this gene has been found fused to the gene for MLL. Multiple alternatively spliced transcript variants that encode different proteins have been found for this gene. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:AF4/FMR2 family member 3
Source:NCBIAccessed: 17 August, 2015

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 17 August 2015 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.

  • Transcriptional Elongation Factors
  • Nuclear Proteins
  • KMT2A
  • HEK293 Cells
  • DNA Mutational Analysis
  • Amino Acid Sequence
  • Stomach Cancer
  • Biological Models
  • Zinc Fingers
  • Genome
  • Proto-Oncogenes
  • Transcriptional Activation
  • Transcription Factors
  • Promoter Regions
  • MLL
  • Transcription
  • Cancer DNA
  • Mll protein, mouse
  • Base Sequence
  • myc Genes
  • Messenger RNA
  • BCL2
  • Translocation
  • Chromosome 11
  • DNA Methylation
  • Molecular Sequence Data
  • Mllt2h protein, mouse
  • MLL-LAF4 fusion
  • DNA-Binding Proteins
  • DNA, Complementary
  • Oncogene Fusion Proteins
  • Histones
  • Acute Lymphocytic Leukaemia
  • Chromosome 2
  • Artificial Gene Fusion
  • Polymerase Chain Reaction
  • Chromosome 4
  • Chromosome Mapping
Tag cloud generated 17 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (2)

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: AFF3 (cancer-related)

Luo Z, Lin C, Guest E, et al.
The super elongation complex family of RNA polymerase II elongation factors: gene target specificity and transcriptional output.
Mol Cell Biol. 2012; 32(13):2608-17 [PubMed] Free Access to Full Article Related Publications
The elongation stage of transcription is highly regulated in metazoans. We previously purified the AFF1- and AFF4-containing super elongation complex (SEC) as a major regulator of development and cancer pathogenesis. Here, we report the biochemical isolation of SEC-like 2 (SEC-L2) and SEC-like 3 (SEC-L3) containing AFF2 and AFF3 in association with P-TEFb, ENL/MLLT1, and AF9/MLLT3. The SEC family members demonstrate high levels of polymerase II (Pol II) C-terminal domain kinase activity; however, only SEC is required for the proper induction of the HSP70 gene upon stress. Genome-wide mRNA-Seq analyses demonstrated that SEC-L2 and SEC-L3 control the expression of different subsets of genes, while AFF4/SEC plays a more dominant role in rapid transcriptional induction in cells. MYC is one of the direct targets of AFF4/SEC, and SEC recruitment to the MYC gene regulates its expression in different cancer cells, including those in acute myeloid or lymphoid leukemia. These findings suggest that AFF4/SEC could be a potential therapeutic target for the treatment of leukemia or other cancers associated with MYC overexpression.

Monroe SC, Jo SY, Sanders DS, et al.
MLL-AF9 and MLL-ENL alter the dynamic association of transcriptional regulators with genes critical for leukemia.
Exp Hematol. 2011; 39(1):77-86.e1-5 [PubMed] Free Access to Full Article Related Publications
OBJECTIVE: The aim of this study was to better understand how mixed lineage leukemia (MLL) fusion proteins deregulate the expression of genes critical for leukemia.
MATERIALS AND METHODS: The transforming domain of one of the most common MLL fusion partners, AF9, was immunopurified after expression in myeloblastic M1 cells, and associating proteins were identified by mass spectrometric analysis. Chromatin immunoprecipitation followed by quantitative polymerase chain reaction was used to determine how binding of associating proteins compare across Hoxa9 and Meis1 in cell lines with and without MLL fusion proteins and how binding is altered during gene down-regulation and differentiation.
RESULTS: Consistent with earlier purifications of ENL and AF4 from 293 cells, the 90 amino acid C-terminal domain of AF9 associates with many other MLL translocation partners including Enl, Af4, Laf4, Af5q31, Ell, and Af10. This complex, termed elongation assisting proteins (EAPs), also contains the RNA polymerase II C-terminal domain kinase Cdk9/Cyclin T1/T2 (pTEFb) and the histone H3 lysine 79 methyltransferase Dot1L. Myeloid cells transformed by MLL fusions show higher levels and a broader distribution of EAP components at genes critical for leukemia. Inhibition of EAP components pTEFb and Dot1l show that both contribute significantly to activation of Hoxa9 and Meis1 expression. EAP is dynamically associated with the Hoxa9 and Meis1 loci in hematopoietic cells and rapidly dissociates during induction of differentiation. In the presence of MLL fusion proteins, its dissociation is prevented.
CONCLUSIONS: The findings suggest that MLL fusion proteins deregulate genes critical for leukemia by excessive recruitment and impaired dissociation of EAP from target loci.

Zhang L, Zhong K, Dai Y, Zhou H
Genome-wide analysis of histone H3 lysine 27 trimethylation by ChIP-chip in gastric cancer patients.
J Gastroenterol. 2009; 44(4):305-12 [PubMed] Related Publications
BACKGROUND: Trimethylation of histone H3 lysine 27 (H3K27me3) is a posttranslational modification that is highly correlated with genomic silencing. In gastric cancer (GC), global and gene-specific DNA methylation changes have been demonstrated to occur. However, to date, our understanding of the alterations in H3K27me3 in GC is incomplete. This study aimed to investigate the variations in H3K27me3 in CpG island regions between gastric cancerous and matched non-cancerous tissues.
METHODS: H3K27me3 variations were analyzed in eight pairs of GC and adjacent normal tissues, from eight GC patients, using a chromatin immunoprecipitation linked to the microarray (ChIP-chip) approach. ChIP-real time PCR was used to validate the microrray results. In addition, DNA methylation status also was further analyzed by methyl-DNA immunoprecipitation quantitative PCR.
RESULTS: One hundred twenty-eight (119 increased and 9 decreased H3K27me3) genes displaying significant H3K27me3 differences were found between GC and adjacent normal tissues. The results of ChIP-real time PCR coincided well with those of microarray. Aberrant DNA methylation can also be found on selected randomly positive genes (MMP15, UNC5B, SHH, AFF3, and RB1).
CONCLUSION: Our study indicates that there are significant alterations of H3K27me3 in gastric cancerous tissues, which may help clarify the molecular mechanisms involved in the pathogenesis of GC. Such novel findings show the significance of H3K27me3 as a potential biomarker or promising target for epigenetic-based GC therapies.

Impera L, Albano F, Lo Cunsolo C, et al.
A novel fusion 5'AFF3/3'BCL2 originated from a t(2;18)(q11.2;q21.33) translocation in follicular lymphoma.
Oncogene. 2008; 27(47):6187-90 [PubMed] Related Publications
Follicular lymphoma is the second most frequent type of non-Hodgkin's lymphoma in adults. The basic molecular defect consists of the t(14;18)(q32;q21) translocation, juxtaposing the B-cell lymphoma protein 2 gene BCL2 to the immunoglobulin heavy chain locus IGH@, and leading to the antiapoptotic BCL2 protein overproduction. Variations in the t(14;18) are rare and can be classified into two categories: (i) simple variants, involving chromosomes 18 and 2, or 22, in which the fusion partner of BCL2 is the light-chain IGK@ or IGL@; (ii) complex variant translocations occurring among chromosomes 14, 18 and other chromosomes. We report a follicular lymphoma case showing BCL2 overexpression, detected by immunohistochemistry and real-time quantitative PCR, consequently to the formation of a novel fusion gene between the 5' of the lymphoid nuclear transcriptional activator gene AFF3 at 2q11.2, and the 3' of BCL2. This case shows evidence, for the first time, of BCL2 overexpression consequently to the fusion of BCL2 to a non-IG partner locus.

Chinen Y, Taki T, Nishida K, et al.
Identification of the novel AML1 fusion partner gene, LAF4, a fusion partner of MLL, in childhood T-cell acute lymphoblastic leukemia with t(2;21)(q11;q22) by bubble PCR method for cDNA.
Oncogene. 2008; 27(15):2249-56 [PubMed] Related Publications
The AML1 gene is frequently rearranged by chromosomal translocations in acute leukemia. We identified that the LAF4 gene on 2q11.2-12 was fused to the AML1 gene on 21q22 in a pediatric patient having T-cell acute lymphoblastic leukemia (T-ALL) with t(2;21)(q11;q22) using the bubble PCR method for cDNA. The genomic break points were within intron 7 of AML1 and of LAF4, resulting in the in-frame fusion of exon 7 of AML1 and exon 8 of LAF4. The LAF4 gene is a member of the AF4/FMR2 family and was previously identified as a fusion partner of MLL in B-precursor ALL with t(2;11)(q11;q23), although AML1-LAF4 was in T-ALL. LAF4 is the first gene fused with both AML1 and MLL in acute leukemia. Almost all AML1 translocations except for TEL-AML1 are associated with myeloid leukemia; however, AML1-LAF4 was associated with T-ALL as well as AML1-FGA7 in t(4;21)(q28;q22). These findings provide new insight into the common mechanism of AML1 and MLL fusion proteins in the pathogenesis of ALL. Furthermore, we successfully applied bubble PCR to clone the novel AML1-LAF4 fusion transcript. Bubble PCR is a powerful tool for detecting unknown fusion transcripts as well as genomic fusion points.

Bitoun E, Oliver PL, Davies KE
The mixed-lineage leukemia fusion partner AF4 stimulates RNA polymerase II transcriptional elongation and mediates coordinated chromatin remodeling.
Hum Mol Genet. 2007; 16(1):92-106 [PubMed] Related Publications
AF4 gene, frequently translocated with mixed-lineage leukemia (MLL) in childhood acute leukemia, encodes a putative transcriptional activator of the AF4/LAF4/FMR2 (ALF) protein family previously implicated in lymphopoiesis and Purkinje cell function in the cerebellum. Here, we provide the first evidence for a direct role of AF4 in the regulation of transcriptional elongation by RNA polymerase II (Pol II). We demonstrate that mouse Af4 functions as a positive regulator of Pol II transcription elongation factor b (P-TEFb) kinase and, in complex with MLL fusion partners Af9, Enl and Af10, as a mediator of histone H3-K79 methylation by recruiting Dot1 to elongating Pol II. These pathways are interconnected and tightly regulated by the P-TEFb-dependent phosphorylation of Af4, Af9 and Enl which controls their transactivation activity and/or protein stability. Consistently, increased levels of phosphorylated Pol II and methylated H3-K79 are observed in the ataxic mouse mutant robotic, an over-expression model of Af4. Finally, we confirm the functional relevance of Af4, Enl and Af9 to the regulation of gene transcription as their over-expression strongly stimulates P-TEFb-dependent transcription of a luciferase reporter gene. Our findings uncover a central role for these proteins in the regulation of transcriptional elongation and coordinated histone methylation, providing valuable insight into their contribution to leukemogenesis and neurodegeneration. Since these activities likely extend to the entire ALF protein family, this study also significantly inputs our understanding of the molecular basis of FRAXE mental retardation syndrome in which FMR2 expression is silenced.

To MD, Faseruk SA, Gokgoz N, et al.
LAF-4 is aberrantly expressed in human breast cancer.
Int J Cancer. 2005; 115(4):568-74 [PubMed] Related Publications
LAF-4, which encodes a nuclear protein with transactivation potential, is fused to the MLL gene in acute lymphoblastic leukemia (ALL). We identified LAF-4 as a gene that is transcriptionally deregulated in breast tumors and thus may have a pathological role in mammary tumorigenesis. In line with the previous finding that LAF-4 expression is tissue specific, we did not detect any LAF-4 mRNA in normal mammary epithelial cell lines. However, 2 of 5 breast cancer cell lines were found to express LAF-4 at both the RNA and protein levels. In 2 of 9 primary tumor-normal pairs, the expression of LAF-4 was clearly elevated in the tumor tissue. Using RNA in situ hybridization, we demonstrated that LAF-4 is expressed in mammary tumor cells but not in normal acini. In a group of 64 primary human breast tumors, we found that LAF-4 was overexpressed in approximately 20% of the cases. Although epigenetic changes may be involved in altered expression of some genes, differences in LAF-4 expression were not associated with DNA methylation of the predicted promoter region. Our results suggest that LAF-4 may be a proto-oncogene that is transcriptionally activated in some cases of breast cancer.

Davies FE, Dring AM, Li C, et al.
Insights into the multistep transformation of MGUS to myeloma using microarray expression analysis.
Blood. 2003; 102(13):4504-11 [PubMed] Related Publications
To define specific pathways important in the multistep transformation process of normal plasma cells (PCs) to monoclonal gammopathy of uncertain significance (MGUS) and multiple myeloma (MM), we have applied microarray analysis to PCs from 5 healthy donors (N), 7 patients with MGUS, and 24 patients with newly diagnosed MM. Unsupervised hierarchical clustering using 125 genes with a large variation across all samples defined 2 groups: N and MGUS/MM. Supervised analysis identified 263 genes differentially expressed between N and MGUS and 380 genes differentially expressed between N and MM, 197 of which were also differentially regulated between N and MGUS. Only 74 genes were differentially expressed between MGUS and MM samples, indicating that the differences between MGUS and MM are smaller than those between N and MM or N and MGUS. Differentially expressed genes included oncogenes/tumor-suppressor genes (LAF4, RB1, and disabled homolog 2), cell-signaling genes (RAS family members, B-cell signaling and NF-kappaB genes), DNA-binding and transcription-factor genes (XBP1, zinc finger proteins, forkhead box, and ring finger proteins), and developmental genes (WNT and SHH pathways). Understanding the molecular pathogenesis of MM by gene expression profiling has demonstrated sequential genetic changes from N to malignant PCs and highlighted important pathways involved in the transformation of MGUS to MM.

Hiwatari M, Taki T, Taketani T, et al.
Fusion of an AF4-related gene, LAF4, to MLL in childhood acute lymphoblastic leukemia with t(2;11)(q11;q23).
Oncogene. 2003; 22(18):2851-5 [PubMed] Related Publications
We showed that the LAF4 gene on 2q11.2-12 was fused to the MLL gene on 11q23 in a pediatric patient with CD10 positive acute lymphoblastic leukemia (ALL) having t(2;11)(q11;q23). The LAF4 gene, which encodes a lymphoid nuclear protein of 1227 amino acids with transactivation potential, is thought to have a role in early lymphoid development. The LAF4 protein was homologous to AF4 and AF5q31 proteins that are fused to MLL in infant early pre-B ALL and the breakpoint of LAF4 was located within the region homologous to the transactivation domain of AF4 and AF5q31. Expression of the 8.5-kb LAF4 transcript was detected in the adult heart, brain, and placenta and in the fetal brain. LAF4 expression was found to be higher in ALL cell lines than in AML and Epstein-Barr virus-transformed B-lymphocyte cell lines. These findings suggest that LAF4, AF4 and AF5q31 might define a new family particularly involved in the pathogenesis of 11q23-associated ALL.

Imamura T, Morimoto A, Ikushima S, et al.
A novel infant acute lymphoblastic leukemia cell line with MLL-AF5q31 fusion transcript.
Leukemia. 2002; 16(11):2302-8 [PubMed] Related Publications
Infant acute lymphoblastic leukemia (ALL) is characterized by the presence of the proB phenotype (CD10(-)/CD19(+)), poor prognosis and frequent rearrangement of the mixed lineage leukemia (MLL) gene. The most frequent rearrangement is t(4;11)(q21;q23), the role of whose product, the MLL-AF4 fusion transcript, has been extensively studied in leukemogenesis. In a cell line of infant leukemia with MLL rearrangement denoted KP-L-RY, panhandle PCR amplification of cDNA revealed the presence of a fusion transcript, MLL-AF5q31, indicating that AF5q31 is also a partner gene of MLL. In this fusion transcript the MLL exon 6 is fused in frame to the 5' side of the putative transactivation domain of AF5q31. The AF5q31 protein is a member of the AF4/LAF4/FMR2-related family of proteins, which have been suggested to play a role in hematopoietic cell growth and differentiation. The MLL-AF5q31 fusion transcript, although probably rare, appears to be associated with the pathogenesis of infant ALL like MLL-AF4. Co-expression of HoxA9 and Meis1 genes in the KP-L-RY cell line indicated possible functional similarity between MLL-AF4 and MLL-AF5q31. Further understanding of the function of AF5q31 as well as the specific leukemogenic mechanism of MLL-AF5q31 awaits future studies.

von Bergh AR, Beverloo HB, Rombout P, et al.
LAF4, an AF4-related gene, is fused to MLL in infant acute lymphoblastic leukemia.
Genes Chromosomes Cancer. 2002; 35(1):92-6 [PubMed] Related Publications
Infant acute lymphoblastic leukemia (ALL) with MLL gene rearrangements is characterized by a proB phenotype and a poor clinical outcome. We analyzed an infant proB ALL with t(2;11)(p15;p14) and an MLL rearrangement on Southern blot analysis. Rapid amplification of cDNA ends-polymerase chain reaction (PCR) and reverse transcriptase-PCR identified the LAF4 gene mapped on chromosome region 2q11.2-q12 as a fusion partner of the MLL gene. The LAF4 gene was identified previously by its high sequence homology to the AF4 protein and encodes a protein of 1,227 amino acids. The t(4;11)(q21;q23), creating the MLL-AF4 chimeric transcripts, is the predominant 11q23 chromosome translocation in infant ALL and is associated with an extremely poor prognosis. Our findings further suggest that fusion of MLL to one of the AF4 family members (AF4/LAF4/AF5Q31) might determine a proB-cell phenotype in infant leukemia.

Taki T, Kano H, Taniwaki M, et al.
AF5q31, a newly identified AF4-related gene, is fused to MLL in infant acute lymphoblastic leukemia with ins(5;11)(q31;q13q23).
Proc Natl Acad Sci U S A. 1999; 96(25):14535-40 [PubMed] Free Access to Full Article Related Publications
Infant acute lymphoblastic leukemia (ALL) with MLL gene rearrangements is characterized by early pre-B phenotype (CD10(-)/CD19(+)) and poor treatment outcome. The t(4;11), creating MLL-AF4 chimeric transcripts, is the predominant 11q23 chromosome translocation in infant ALL and is associated with extremely poor prognosis as compared with other 11q23 translocations. We analyzed an infant early preB ALL with ins(5;11)(q31;q13q23) and identified the AF5q31 gene on chromosome 5q31 as a fusion partner of the MLL gene. The AF5q31 gene, which encoded a protein of 1,163 aa, was located in the vicinity of the cytokine cluster region of chromosome 5q31 and contained at least 16 exons. The AF5q31 gene was expressed in fetal heart, lung, and brain at relatively high levels and fetal liver at a low level, but the expression in these tissues decreased in adults. The AF5q31 protein was homologous to AF4-related proteins, including AF4, LAF4, and FMR2. The AF5q31 and AF4 proteins had three homologous regions, including the transactivation domain of AF4, and the breakpoint of AF5q31 was located within the region homologous to the transactivation domain of AF4. Furthermore, the clinical features of this patient with the MLL-AF5q31 fusion transcript, characterized by the early pre-B phenotype (CD10(-)/CD19(+)) and poor outcome, were similar to those of patients having MLL-AF4 chimeric transcripts. These findings suggest that AF5q31 and AF4 might define a new family particularly involved in the pathogenesis of 11q23-associated-ALL.

Nilson I, Reichel M, Ennas MG, et al.
Exon/intron structure of the human AF-4 gene, a member of the AF-4/LAF-4/FMR-2 gene family coding for a nuclear protein with structural alterations in acute leukaemia.
Br J Haematol. 1997; 98(1):157-69 [PubMed] Related Publications
The AF-4 gene on human chromosome 4q21 is involved in reciprocal translocations to the ALL-1 gene on chromosome 11q23, which are associated with acute lymphoblastic leukaemias. A set of recombinant phage carrying genomic fragments for the coding region and flanking sequences of the AF-4 gene were isolated. Phage inserts were assembled into four contigs with 21 exons, and an intron phase map was produced enabling the interpretation of translocation-generated fusion proteins. The gene contains two alternative first exons, 1a and 1b, both including a translation initiation codon. The translocation breakpoint cluster region is flanked by exons 3 and 6 and two different polyadenylation signals were identified. Polyclonal antisera directed against three different portions of the AF-4 protein were produced and used to detect a 116 kD protein in cellular extracts of human B-lymphoblastoid and proB cell lines. In mitogen-stimulated human peripheral blood mononuclear cells the AF-4 antigen was predominantly located in the nucleus. The AF-4 gene is a member of the AF-4, LAF-4 and FMR-2 gene family. The members of this family encode serine-proline-rich proteins with properties of nuclear transcription factors. Comparison of AF-4 protein coding sequences with the LAF-4 and FMR-2 sequences revealed five highly conserved domains of potential functional relevance.

Ma C, Staudt LM
LAF-4 encodes a lymphoid nuclear protein with transactivation potential that is homologous to AF-4, the gene fused to MLL in t(4;11) leukemias.
Blood. 1996; 87(2):734-45 [PubMed] Related Publications
A novel human gene, LAF-4, was isolated from a subtracted cDNA library that showed strong sequence similarity to AF-4, a gene that is translocated in t(4;11)(q21;q23) acute lymphoblastic leukemias (ALLs). In t(4;11) ALL, the AF-4 gene at 4q21 is translocated into the MLL locus at 11q23, resulting in the expression of an MLL/AF-4 fusion protein that is the presumptive oncoprotein. AF-4 and LAF-4 are homologous throughout their coding regions, yet neither protein is related to previously cloned genes. Human LAF-4 readily hybridized with genes in mouse and chicken, thus showing that this gene family has been highly conserved during vertebrate evolution. In mouse tissues, LAF-4 mRNA was found to be present at highest levels in lymphoid tissues, present at lower levels in brain and lung, and absent from other tissues. In human and mouse lymphoid cell lines, LAF-4 expression was highest in pre-B cells, intermediate in mature B cells, and absent in plasma cells, thus pointing to a potential regulatory role for LAF-4 in lymphoid development. Antibodies to LAF-4 showed it to be a nuclear protein that showed an uneven, granular immunofluorescence pattern. In vitro-translated LAF-4 was able to bind strongly to double-stranded DNA cellulose. Furthermore, both LAF-4 and AF-4 had domains that activated transcription strongly when fused to the GAL4 DNA-binding domain. Interestingly, the AF-4 transactivation domain is retained in the MLL/AF-4 fusion protein; thus, it may contribute to the transforming potential of the oncoprotein. Therefore, the cloning of LAF-4 has defined a new family of potential regulatory proteins that may function in lymphoid development and oncogenesis.

Disclaimer: This site is for educational purposes only; it can not be used in diagnosis or treatment.

Cite this page: Cotterill SJ. LAF4, Cancer Genetics Web: Accessed:

Creative Commons License
This page in Cancer Genetics Web by Simon Cotterill is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Note: content of abstracts copyright of respective publishers - seek permission where appropriate.

 [Home]    Page last revised: 17 August, 2015     Cancer Genetics Web, Established 1999