1 Differential regulation of interleukin-1-receptor-associated kinase-1 (IRAK-1) and IRAK-2 by micro RNA-146a and NF-кB in stressed human astroglial cells and in Alzheimer’s disease Jian Guo Cui, Yuan Yuan Li, Yuhai Zhao, Suridypta Bhattacharjee, Walter J. Lukiw LSU Neuroscience Center and Department of Ophthalmology, Louisiana State University Health Science Center, New Orleans LA 70112, USA; University of Pittsburgh Department of Structural Biology, Pittsburgh PA 15260, USA Running Head: miRNA-146a and IRAK-2 signaling in AD brain Address correspondence to: Walter J. Lukiw, MS, PhD, LSU Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, Room 904, New Orleans LA 70112-2272 USA, e-mail: wlukiw@lsuhsc.edu Specific micro RNAs (miRNAs), small non- coding RNAs that support homeostatic gene expression, are significantly altered in abundance in human neurological disorders. In monocytes, increased expression of an NF-κB- regulated miRNA-146a down-regulates expression of the interleukin-1-receptor- associated kinase-1 (IRAK-1), an essential component of Toll-like/IL-1-receptor (TLR/IL- 1R) signaling. Here we extend those observations to the hippocampus and neocortex of Alzheimer’s disease (AD) brain, and to stressed human astroglial (HAG) cells in primary culture. In 66 control and AD samples we note a significant up-regulation of miRNA-146a coupled to down-regulation of IRAK-1, and a compensatory up-regulation of IRAK-2. Using miRNA-146a-, IRAK-1- or IRAK-2-promoter- luciferase-reporter constructs we observe decreases in IRAK-1, and increases in miRNA- 146a and IRAK-2 expression in interleukin-1beta (IL-1β)- and amyloid-beta-42 (Aβ42)-peptide- stressed HAG cells. NF-κB-mediated transcriptional control of human IRAK-2 was localized to between -119 and +12 bp of the immediate IRAK-2 promoter. The NF-κB inhibitors curcumin, pyrollidine dithiocar- bamate (PDTC) or CAY10512 abrogated both IRAK-2 and miRNA-146a expression, while IRAK-1 was up-regulated. Incubation of a protected antisense-miRNA-146a was found to inhibit miRNA-146a and restore IRAK-1 while IRAK-2 remained unaffected. These data suggest a significantly independent regulation of IRAK-1 and IRAK-2 in AD and in IL-1β+Aβ42-peptide- stressed HAG cells, and that an inducible, NF- κB-sensitive, miRNA-146a-mediated down- regulation of IRAK-1 coupled to an NF-κB- induced up-regulation of IRAK-2 expression drives an extensively sustained inflammatory response. The interactive signaling of NF-κB and miRNA-146a further illustrate interplay between inducible transcription factors and pro- inflammatory miRNAs that regulate brain IRAK expression. The combinatorial use of NF-кB inhibitors with miRNA-146a or antisense miRNA-146a may have potential as a bi-pronged therapeutic strategy directed against IRAK-2- driven pathogenic signaling. The innate immune response and inflammatory signaling play determinant roles in brain homeostasis, neuroprotection and repair, however, altered or excessive signaling in these injury defense systems contribute to the irreversible degeneration of brain cells, as typified in the common, age-related neurodegenerative disorder Alzheimer’s disease (AD). In innate immune signaling members of the Toll-like receptor (TLR) or IL-1 receptor (IL-1R) superfamily, via their common Toll and IL-1R (TIR) domains, act as extracellular sensors to detect pathogens and cytotoxic molecules. This enables http://www.jbc.org/cgi/doi/10.1074/jbc.M110.178848 The latest version is at JBC Papers in Press. Published on October 11, 2010 as Manuscript M110.178848 Copyright 2010 by The American Society for Biochemistry and Molecular Biology, Inc. by guest on August 8, 2017 http://www.jbc.org/ Downloaded from