iTRAQ-based Proteomic Analysis of APPSw,Ind Mice Provides Insights into the Early Changes in Alzheimer’s Disease

Abstract

Background: Several proteins have been identified as potential diagnostic biomarkers in imaging, genetic, or proteomic studies in Alzheimer disease (AD) patients and mouse models. However, biomarkers for presymptom diagnosis of AD are still under investigation, as are the presymptom molecular changes in AD pathogenesis.Objective: In this study, we aim to analyzed the early proteomic changes in APPSw,Ind mice and to conduct further functional studies on interesting proteins.Methods: We used the isobaric tags for relative and absolute quantitation (iTRAQ) approach combined with mass spectrometry to examine the early proteomic changes in hippocampi of APPSw,Ind mice. Quantitative reverse transcription polymerase chain reaction (RT-PCR) and immuno-blotting were performed for further validation. Finally, the functions of interesting proteins β-spectrin and Rab3a in APP trafficking and processing were tested by shRNA knockdown, in N2A cells stably expressing β-amyloid precursor protein (APP).Results: The iTRAQ and RT-PCR results revealed the detailed molecular changes in oxidative stress, myelination, astrocyte activation, mTOR signaling and Rab3-dependent APP trafficking in the early stage of AD progression. Knock down of β-spectrin and Rab3a finally led to increased APP fragment production, indicating key roles of β-spectrin and Rab3a in regulating APP processing.Conclusion: Our study provides the first insights into the proteomic changes that occur in the hippocampus in the early stages of the AD mouse model. In addition to improving the understanding of molecular alterations and functional cascades involved in early AD pathogenesis, our findings raise the possibility of developing potential biomarkers and therapeutic targets for early AD.

Age-dependent ataxia and neurodegeneration caused by an αII spectrin mutation with impaired regulation of its calpain sensitivity

“…Progressive neurodegenerative disorders share many pathologic features yet the identification of common mechanisms of cell injury remains elusive. Data revealed here and in other reports strongly implicate damage to the spectrin scaffold as a feature of both experimental models of neuronal injury 9 and an event common in Alzheimer’s disease 35 – 37 , Parkinson’s disease 38 , and several ataxias 24 . Our studies on the R1098Q variant C57BL/6J mouse advance understanding of spectrin’s role in two important respects.…”

The Pancreatic Cancer-Initiating Cell Marker CD44v6 Affects Transcription, Translation, and Signaling: Consequences for Exosome Composition and Delivery

“…A last aspect of the coimmunoprecipitation analysis, the striking differences between wt and CD44v6kd cells and TEX in the association with proteins engaged in RNA processing require further attention. The findings are in line with the reported CD44v6 association with Dicer [68] and the linkage of CD44v6 to mRNA processing proteins. The predominant recovery in TEX fits to CD44 supporting ILV loading and the cargo being transferred via MVB into TEX [69, 70].…”

“…Furthermore, Tspan8-associated CD44v6 encounters a large range of cytosolic signaling molecules, which attach to the inner membrane of TEM due to the particular lipid organization [55, 64, 65]. A few additional proteins, where pronounced coimmunoprecipitation with CD44v6 suggested facilitating signaling pathway activation, are MOV10 (Putative helicase MOV-10) engaged in EPH-Ephrin and Wnt signaling [66] as well as MYO1D (Unconventional myosin-Id) and SPTBN1 (Spectrin beta chain, nonerythrocytic 1), which both are involved in GPCR activation [67, 68]. Taken together, the association of CD44v6 with signal transducing molecules could significantly assist CIC-TEX-promoted modulation of non-CIC.…”

Proteomics Landscape of Alzheimer’s Disease

“…Hippocampus being an early region affected in AD, Li et al carried out proteome profiling of hippocampus of APP Sw,Ind J20 mouse along with control. They reported altered mTOR signaling and β-spectrin, Rab3-mediated APP trafficking and proteolysis as early molecular events associated with AD pathogenesis [ 27 ]. Systematic analysis of proteome, phosphoproteome, and sialylated N-linked glycosylation of APPswe/PS1ΔE9 mouse olfactory bulb, hippocampus, neocortex, and the brainstem revealed alteration in synaptic functions associated with dendritic spine morphology, neurite outgrowth, long-term potentiation, CREB signaling, and cytoskeletal dynamics [ 28 ].…”