The role of reciprocal fusions in MLL-r acute leukemia: studying the chromosomal translocation t(6;11)

  • Leukemia patients bearing t(6;11)(q27;q23) translocations can be divided in two subgroups: those with breakpoints in the major breakpoint cluster region of MLL (introns 9–10; associated mainly with AML M1/4/5), and others with breakpoints in the minor breakpoint cluster region (introns 21–23), associated with T-ALL. We cloned all four of the resulting fusion genes (MLL-AF6, AF6-MLL, exMLL-AF6, AF6-shMLL) and subsequently transfected them to generate stable cell culture models. Their molecular function was tested by inducing gene expression for 48 h in a Doxycycline-dependent fashion. Here, we present our results upon differential gene expression (DGE) that were obtained by the “Massive Analyses of cDNA Ends” (MACE-Seq) technology, an established 3′-end based RNA-Seq method. Our results indicate that the PHD/BD domain, present in the AF6-MLL and the exMLL-AF6 fusion protein, is responsible for chromatin activation in a genome-wide fashion. This led to strong deregulation of transcriptional processes involving protein-coding genes, pseudogenes, non-annotated genes, and RNA genes, e.g., LincRNAs and microRNAs, respectively. While cooperation between the MLL-AF6 and AF6-MLL fusion proteins appears to be required for the above-mentioned effects, exMLL-AF6 is able to cause similar effects on its own. The exMLL-AF6/AF6-shMLL co-expressing cell line displayed the induction of a myeloid-specific and a T-cell specific gene signature, which may explain the T-ALL disease phenotype observed in patients with such breakpoints. This again demonstrated that MLL fusion proteins are instructive and allow to study their pathomolecular mechanisms.
Author:Arpita Kundu, Eric KowarzORCiDGND, Rolf MarschalekORCiDGND
Parent Title (English):Oncogene
Publisher:Springer Nature
Place of publication:London
Document Type:Article
Date of Publication (online):2021/08/05
Date of first Publication:2021/08/05
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2021/10/15
Tag:Cancer; Cell biology
Page Number:11
First Page:5902
Last Page:5912
This work is funded by DFG grants Ma 1876/12-1 and Ma 1876/13-1, and grants 2018.070.1 and 2018.070.2 from the Wilhelm Sander foundation. Open Access funding enabled and organized by Projekt DEAL.
Institutes:Biochemie, Chemie und Pharmazie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Licence (German):License LogoCreative Commons - Namensnennung 4.0