ABSTRACT
@#Mixed lineage leukemia 1(MLL1) is a member of the "SET" histone methyltransferases family.MLL1 methyltransferase complex, consisting of MLL1, WDR5, RbBP5, Ash2L and DPY-30, regulates methylation level of histone H3 lysine 4 and is essential for the development of human hematopoietic system and self-renewal of blood cells.As an oncogenic protein produced by the translocation of MLL1 gene, the MLL1 fusion protein has been found in some patients with leukemia.Complete MLL1 enzyme complex is required to perform histone demethylation effect, therefore, targeting the protein-protein interaction of MLL1-WDR5 has become a potential strategy for the treatment of leukemia induced by MLL1 fusion protein.This review systematically summarizes the biological mechanism, structural information and inhibitors of MLL1-WDR5 protein-protein interaction, with a perspective based on previously reported data, aiming to provide some reference for further investigation.
ABSTRACT
Mixed lineage leukemia proteins (MLL) are the key histone lysine methyltransferases that regulate expression of diverse genes. Aberrant activation of MLL promotes leukemia as well as solid tumors in humans, highlighting the urgent need for the development of an MLL inhibitor. We screened and isolated MLL1-binding ssRNAs using SELEX (Systemic Evolution of Ligands by Exponential enrichment) technology. When sequences in sub-libraries were obtained using next-generation sequencing (NGS), the most enriched aptamers—APT1 and APT2—represented about 30% and 26% of sub-library populations, respectively. Motif analysis of the top 50 sequences provided a highly conserved sequence: 5′-A[A/C][C/G][G/U][U/A]ACAGAGGG[U/A]GG[A/C] GAGUGGGU-3′. APT1, APT2, and APT5 embracing this motif generated secondary structures with similar topological characteristics. We found that APT1 and APT2 have a good binding activity and the analysis using mutated aptamer variants showed that the site information in the central region was critical for binding. In vitro enzyme activity assay showed that APT1 and APT2 had MLL1 inhibitory activity. Three-dimensional structure prediction of APT1-MLL1 complex indicates multiple weak interactions formed between MLL1 SET domain and APT1. Our study confirmed that NGS-assisted SELEX is an efficient tool for aptamer screening and that aptamers could be useful in diagnosis and treatment of MLL1-mediated diseases.