Abstract
Novel insights on proteins involved in Alzheimer’s disease (AD) are needed. Since multiple cell types and matrix components are altered in AD, bulk analysis of brain tissue maybe difficult to interpret. In the current study, we isolated pyramidal cells from the cornu ammonis 1 (CA1) region of the hippocampus from five AD and five neurologically healthy donors using laser capture microdissection (LCM). The samples were analyzed by proteomics using 18O-labeled internal standard and nano-high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for relative quantification. Fold change between AD and control was calculated for the proteins that were identified in at least two individual proteomes from each group. From the 10 cases analyzed, 62 proteins were identified in at least two AD cases and two control cases. Creatine kinase B-type (CKB), 14-3-3-γ, and heat shock cognate 71 (Hsc71), which have not been extensively studied in the context of the human AD brain previously, were selected for further studies by immunohistochemistry (IHC). In hippocampus, semi-quantitative measures of IHC staining of the three proteins confirmed the findings from our proteomic analysis. Studies of the same proteins in the frontal cortex revealed that the alterations remained for CKB and 14-3-3-γ but not for Hsc71. Protein upregulation in CA1 neurons of final stage AD is either a result of detrimental, pathological effects, or from cell-specific protective response mechanisms in surviving neurons. Based on previous findings from experimental studies, CKB and Hsc71 likely exhibit protective effects, whereas 14-3-3-γ may represent a detrimental pathway. These new players could reflect pathways of importance for the development of new therapeutic strategies.
Highlights
Alzheimer’s disease (AD) is one of the most widespread public health issues in the world with around 50 million affected patients globally, and the number is expected to grow up to 75 million by the year 2030 (World Alzheimer Report, 2015)
30 proteins were found upregulated in AD and the mean ratio for all proteins in Table 2 is 1.3 indicating that for the approximate half of the proteins upregulated in AD, the mean difference between AD and control was larger than in those downregulated in AD
In the current approach of laser capture microdissection (LCM)-isolated neuronal soma proteomics, we reduce the complexity of the analyses by focusing on one cell type—the pyramidal cornu ammonis 1 (CA1) cells
Summary
Alzheimer’s disease (AD) is one of the most widespread public health issues in the world with around 50 million affected patients globally, and the number is expected to grow up to 75 million by the year 2030 (World Alzheimer Report, 2015). Pharmaceutical treatments in trials today mostly target known neuropathological hallmarks in AD (Cummings et al, 2014). One such element is the amyloid β-peptide (Aβ), which is generated physiologically by proteolytic cleavage of the amyloid precursor protein (APP) by the enzymes β- and γ-secretase (De-Paula et al, 2012). Together with neurofibrillary tangles (NFT) composed of hyperphosphorylated Tau protein, plaques composed of fibrillar Aβ is the major neuropathological hallmark of AD (Mott and Hulette, 2005). Both Aβ and Tau have major roles in AD, the fact remains that AD is a multifactorial disease and its complexity maybe due to additional, unknown key players
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