Human Dicer C-terminus functions as a 5-lipoxygenase binding domain

Abstract

SummaryDicer is a multidomain ribonuclease III enzyme involved in the biogenesis of microRNAs (miRNAs) in the vast majority of eukaryotes. In human, Dicer has been shown to interact with cellular proteins via its N-terminal domain. Here, we demonstrate the ability of Dicer C-terminus to interact with 5-lipoxygenase (5LO), an enzyme involved in the biosynthesis of inflammatory mediators, in vitro and in cultured human cells. Yeast two-hybrid and GST binding assays delineated the smallest 5-lipoxygenase binding domain (5LObd) of Dicer to its C-terminal 140 amino acids comprising the double-stranded RNA (dsRNA) binding domain (dsRBD). The Dicer 5LObd-5LO association was disrupted upon Ala substitution of Trp residues 13, 75 and 102 in 5LO, suggesting that the Dicer 5LObd may recognize 5LO via its N-terminal C2-like domain. Whereas a catalytically active 5LObd-containing Dicer fragment was found to enhance 5LO enzymatic activity in vitro, human 5LO modified the miRNA precursor processing activity of Dicer. In addition to revealing the dual RNA and protein binding properties of Dicer C-terminus, our results may provide a link between miRNA-mediated regulation of gene expression and inflammation.

An Inhibitor of Arachidonate 5-Lipoxygenase, Nordy, Induces Differentiation and Inhibits Self-Renewal of Glioma Stem-Like Cells

“…Therefore, our finding that expression of these stemness related regulators in GSLCs is modulated by Nordy further demonstrates that induced differentiation is mediated by reversion of an intrinsic developmental program. The miRNA precursor processing enzyme Dicer was found to contain an Alox-5 binding domain (5LObd) and Alox-5 directly interacted with 5LObd and regulated pre-miRNA processing of Dicer in human cells [36]. Owing to the essential role of miRNA in modulating biology of tumor stem cells [37,38], and more specifically the significance of aberrant miRNA processing in transformation and malignant progression [39], it is tempting to speculate that inhibition of Alox-5 by Nordy may regulate miRNA maturation and expression in GSLCs, thus resulting in a loss of stemness.…”

Dimerization of human 5-lipoxygenase

“…However, due to the nuclear localization of 5-LO and its association with euchromatin or to its interaction with dicer, other biological roles were proposed for 5-LO apart from leukotriene biosynthesis, such as regulation of gene expression or miRNA processing, respectively (Woods et al , 1995 ;Dincbas -Renqvist et al, 2009 ). Thus, dimerization could be of relevance for the proposed alternative 5-LO functions.…”

microRNA Regulation of Synaptic Plasticity

“…But what is the local substrate for dicer? One possibility is that dicer is not acting in its role as part of the RNA interference pathway, but instead has a role related to its interactions with 5-lipoxygenase (Dincbas-Renqvist et al 2009). Another possibility is that when dicer is released from postsynaptic densities, it becomes translocated from synapses to the cell body.…”