Abstract
Purpose: :
Human brain and retinal cells rely on a specific set of micro RNAs (miRNAs) to shape their gene expression patterns, and these actions are mediated through miRNA effects on messenger RNA (mRNA) complexity. The purpose of these studies was to examine (a) in short post-mortem interval (~1-2 hr) Alzheimer’s disease (AD) association neocortex and retina; (b) in cytokine- and Aβ42 peptide-stressed human neuronal-glial (HNG), astroglial (HAG) and microglial (HMG) cells in primary culture; and (c) in several murine transgenic AD (Tg-AD) models including Tg2576 and 5xFAD, the abundance of brain-and retinal-abundant miRNA species that may impact mRNA speciation, alter gene expression, and associate with neural and retinal pathology.We focused on pro-inflammatory miRNAs, that through bioinformatics analysis, showed high potential to interact stongly with the 3'-untranslated region (3'-UTR) of the mRNA encoding human complement factor H (CFH; chr 1q32).
Methods: :
Aβ42-peptide+TNFα-induced stress; bioinformatics; DNA array; DNA sequencing; human brain post-mortem tissue; human retinal tissue; human brain and retinal cells in primary culture; gel shift assay; micro-RNA array; Northern micro-dot blot analysis; RT-PCR; transfection assay; Western immunohistochemistry
Results: :
In AD neocortex and retina, in stressed human brain cells, and in aging Tg-AD models, we identified several brain-and retina-abundant miRNA species that are consistently up-regulated, including miRNA-125b, miRNA-146a and miRNA-155. Each of these inducible, NF-kB-regulated, 22 nucleotide small RNAs target the 3’-UTR of mRNA encoding the innate-immune- and inflammation-related regulatory protein, CFH, resulting in significant decreases in CFH expression (p<0.01, ANOVA). Our results further indicate that HNG, HAG and HMG cells each respond differently to Aβ42-peptide+TNFα-induced stress, in part by variation in their intrinsic miRNA-125b-, miRNA-146a-and miRNA-155-triggered responses. Both NF-kB and anti-miRNAs (AMs; antisense miRNAs; antagomirs) were found to significantly quench miRNA-125b, miRNA-146a and miRNA-155 induction, and restore CFH back to near homeostatic levels.
Conclusions: :
These data provide the first evidence of CFH expression regulation by multiple miRNAs in the human brain and retina. The combinatorial use of NF-ΚB inhibitors with antisense miRNA strategies may have potential as a multi-pronged therapeutic strategy directed against CFH-driven pathogenic signaling in both neurodegenerative and retinal disease.
Keywords: aging • gene/expression • age-related macular degeneration