Analysis of ER stress in developing rice endosperm accumulating β‐amyloid peptide

Abstract

SummaryThe common neurodegenerative disorder known as Alzheimer's disease is characterized by cerebral neuritic plaques of amyloid b (Ab) peptide. Plaque formation is related to the highly aggregative property of this peptide, because it polymerizes to form insoluble plaques or fibrils causing neurotoxicity. Here, we expressed Ab peptide as a new causing agent to endoplasmic reticulum (ER) stress to study ER stress occurred in plant. When the dimer of Ab 1-42 peptide was expressed in maturing seed under the control of the 2.3-kb glutelin GluB-1 promoter containing its signal peptide, a maximum of about 8 lg peptide per grain accumulated and was deposited at the periphery of distorted ER-derived PB-I protein bodies. Synthesis of Ab peptide in the ER lumen severely inhibited the synthesis and deposition of seed storage proteins, resulting in the generation of many small and abnormally appearing PB bodies. This ultrastructural change was accounted for by ER stress leading to the accumulation of aggregated Ab peptide in the ER lumen and a coordinated increase in ER-resident molecular chaperones such as BiPs and PDIs in Ab-expressing plants. Microarray analysis also confirmed that expression of several BiPs, PDIs and OsbZIP60 containing putative transmembrane domains was affected by the ER stress response. Ab-expressing transgenic rice kernels exhibited an opaque and shrunken phenotype. When grain phenotype and expression levels were compared among transgenic rice grains expressing several different recombinant peptides, such detrimental effects on grain phenotype were correlated with the expressed peptide causing ER stress rather than expression levels.

Functional analysis of Hsp70 superfamily proteins of rice (Oryza sativa)

“…However, a definite interpretation in this regard can be only drawn after larger number of genomes are sequenced and analyzed. This is the first comprehensive study of rice Hsp70 superfamily, though isolated studies on mitochondrial Hsp70 and BiPs of Hsp70 family of rice are published (Qi et al 2011;Oono et al 2010). Multiple Hsp70 members were identified in various cellular compartments in rice in our analysis.…”

“…Under heat stress, nuclear localized Hsp70 prevented fragmentation of DNA and provided thermotolarance (Cho and Choi 2009). Qi et al (2011) reported two mtHsp70 proteins and Oono et al (2010) reported ten BiPs proteins in rice. In this study, we found that these ten BiPs consist of six Hsp70 and four Hsp110 proteins.…”

Mini Review Roles of the bZIP gene family in rice

“…While OsbZIP60 is also affected by ER stress (Oono et al, 2010;Yu et al, 2011), the roles of OsbZIP60 in the ER stress response are not as well documented as those of OsbZIP50 and OsbZIP39. Several studies have predicted that OsbZIP60 has similar functions to that of OsbZIP50 in the response to ER stress (Oono et al, 2010;Yu et al, 2011).…”

Aβ induces oxidative stress in senescence-accelerated (SAMP8) mice

“…Because of this gut immunity, not only IgG but also IgA is produced. 16) We previously developed a rice vaccine, 17,18) and immunized familial AD model mice (Tg2576); as a result, the antibody titer increased and Aβ accumulation in the mouse brain was prevented compared with Tg2576-fed wild type (WT) rice. 19) In this study, we immunized senescence-accelerated mouse prone 8 (SAMP) mice, a sporadic AD model, 20) with the rice vaccine.…”

“…Thus, we quantified the accumulation of Aβ40. A standard peptide and the samples were incubated in microplates coated with the monoclonal antibody BNT77, which recognizes human and rat Aβ (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), for 1 h at 4°C. After washing five times, the plates were incubated with an HRP-conjugated antibody raised against the C-terminus of Aβ40 for 1 h at 4°C.…”