The miR-15/107 miRNA group are paralogous microRNAs (miRNAs), with overlapping gene regulatory impact, that are downregulated in Alzheimer's disease (AD) brains. Our underlying hypothesis is that miR- 15/107 gene augmentation (up-regulation) will help to reduce brain cellular expression of BACE1 and tau kinases (PKA and CDK5-regulating proteins). We have strong preliminary evidence in support of this hypothesis. The overall goal of the present research proposal is to obtain information necessary to develop future miRNA-based brain therapies and to increase our knowledge about miRNAs' role in AD. Therapeutic strategies must involve either stimulating endogenous miRNA production, or, alternatively, a 'gene therapy' approach with exogenously introduced RNA or viral vectors. The key challenges, before developing brain therapies related to miR-15/107 genes, are 1> to understand upstream stimuli that alter miR-15/107 expression in human brains, and 2> define downstream genes regulated by these miRNAs, including an assessment of the potential for manipulating the 'off-target effects' of miR-15/107-related miRNAs. We thus propose novel experiments in human brain and in primary rat brain-derived cultured cells.
Specific Aims for this research project:
Specific Aim #1 : Define the specific AD-relevant signaling pathways that modulate miR-15/107 gene expression.
Aim 1 A: Perform hypothesis-based studies in cultured rat primary brain cells anchored in our preliminary results finding that glucose levels and discrete neuroinflammatory stimuli specifically alter miR-15/107 gene expression which may suggest strategies for miRNA-based therapies.
Aim 1 B: Perform comprehensive miR-15/107 expression profiling in human brain to understand how parameters linked with AD risk correlate with altered miR-15/107 gene expression because miRNA neurochemical studies need to be anchored in human brain data.
Specific Aim #2 : Define the exact 'downstream' mRNA targets regulated by miR-15/107 genes in primary cultured rat brain cells. Preliminary data indicate that miR-15/107 genes may be a key mechanistic link between metabolic changes and increased tau phosphorylation in human brains. Using methods that were developed and optimized in our laboratory, we will perform comprehensive analyses of miR-15/107 miRNA targets in primary cultured rat brain cells.
Specific Aim #3 : Manipulate and minimize 'off-target' effects of miRNAs using RNA sequence modifications in primary cultured brain cells. Cultured neurons will be transduced with lentivirus vectors harboring altered sequences related to miR-15/107 genes. We have already generated miRNA expressing lentivirus and transduced primary cultured neurons to help optimize the potential impact of miRNA-based therapies in the brain. The overall goal is to produce reagents with optimal 'on-target' and minimal 'off-target' impact, in order to maximize the potential value of small RNA- based therapeutics.
The objective of this project is to better understand the causes of Alzheimer's disease and the linkages between this disease and the metabolic changes seen in aging. We will characterize in human brains (and in primary cultured rat brain cells) a newly-discovered high impact level of gene regulation, which are called microRNAs, focusing on a key group of genes we defined as the miR-15/107 group of miRNAs. Based on our preliminary data, we think that we can produce information that directly or indirectly contributes to therapeutics for Alzheimer's disease patients.
| Wang, Wang-Xia; Danaher, Robert J; Miller, Craig S et al. (2014) Expression of miR-15/107 family microRNAs in human tissues and cultured rat brain cells. Genomics Proteomics Bioinformatics 12:19-30 |
| Hébert, Sébastien S; Wang, Wang-Xia; Zhu, Qi et al. (2013) A study of small RNAs from cerebral neocortex of pathology-verified Alzheimer's disease, dementia with lewy bodies, hippocampal sclerosis, frontotemporal lobar dementia, and non-demented human controls. J Alzheimers Dis 35:335-48 |
| Nelson, Peter T; Smith, Charles D; Abner, Erin L et al. (2013) Hippocampal sclerosis of aging, a prevalent and high-morbidity brain disease. Acta Neuropathol 126:161-77 |
| Hébert, Sébastien S; Nelson, Peter T (2012) Studying microRNAs in the brain: technical lessons learned from the first ten years. Exp Neurol 235:397-401 |
