Aberrant alterations of the expressions and S-nitrosylation of calmodulin and the downstream factors in the brains of the rodents during scrapie infection

Abstract

The aberrant alterations of calmodulin (CaM) and its downstream substrates have been reported in some neurodegenerative diseases, but rarely described in prion disease. In this study, the potential changes of Ca/CaM and its associated agents in the brains of scrapie agent 263K-infected hamsters and the prion infected cell line SMB-S15 were evaluated by various methodologies. We found that the level of CaM in the brains of 263K-infected hamsters started to increase at early stage and maintained at high level till terminal stage. The increased CaM mainly accumulated in the regions of cortex, thalamus and cerebellum of 263K-infected hamsters and well localization of CaM with NeuN positive cells. However, the related kinases such as total and phosphorylated forms of CaMKII and CaMKIV, as well as the downstream proteins such as CREB and BDNF in the brain of 263K-infected hamsters were decreased. Further analysis showed a remarkable increase of S-nitrosylated (SNO) form of CaM in the brains of 263K-infected hamsters. Dynamic analysis of S-nitrosylated CaM showed the SNO form of CaM abnormally increases in a time-dependent manner during prion infection. Compared with that of the normal partner cell line SMB-PS, the CaM level in SMB-S15 cells was increased, meanwhile, the downstream proteins, such as CaMKII, p-CaMKII, CREB, as well as BDNF, were also increased, especially in the nucleic fraction. No SNO-CaM was detected in the cell lines SMB-S15 and SMB-PS. Our data indicate an aberrant increase of CaM during prion infection in vivo and in vitro.

Calmodulin level is significantly increased in the cerebrospinal fluid of patients with sporadic Creutzfeldt‐Jakob disease

“…Our previous dynamic studies suggest that CaM levels in the brain tissues of scrapie‐infected rodents rise rapidly then plateau at a relatively early stage of the disease [10]. In line with this observation, we also identified a significant association between the interval from onset to sampling and the rate of CSF CaM positivity via a single‐factor analysis.…”

“…Our previous study demonstrated that brain CaM levels in scrapie‐infected mouse models are markedly increased [10]. To assess the potential changes in CSF CaM levels in probable sCJD, two types of pooled CSF samples from three patients with probable sCJD and three patients with non‐PrDs were subjected to CaM‐specific Western blot analysis.…”

“…An abnormal increase in CaM level has been reported in the brain tissues of patients with AD and in AD animal models, as well as in the relevant cell lines [14–16]. Our recent studies also highlighted an aberrant increase in CaM level in the brains of prion‐infected rodents and sCJD patients [10,17]. However, an abnormal change in CSF CaM has rarely been addressed in neurodegenerative diseases, including AD and PrDs.…”

“…An aberrant increase in CaM has been described in prion‐infected cell lines and the brain tissues of scrapie‐infected rodent models [9,10]. Further analysis has revealed a remarkable increase in the S‐nitrosylated form of CaM in brains during prion infection, which might play a role in inhibiting the activation of the downstream signaling pathway, impairing nerve repair, and enhancing the neuropathological effect [10]. However, the presence of CaM in CSF specimens of human PrDs, particularly in sCJD patients, has not been addressed.…”

Decrease of RyR2 in the prion infected cell line and in the brains of the scrapie infected mice models and the patients of human prion diseases

“…As the representive biomarkers of ER stress, the levels of protein disulfide isomerase (PDI) and Grp78 abnormally up-regulated in the cells expressing PrP mutants and in the brains of scrapie-infected rodents, accompanying with aberrant S-nitrosylated modification [26]. A number of factors involving in Ca 2+ homeostasis, such as calmodulin (CaM) [27] and calpain [28], are also abnormally changed in the brain tissues of prion infection and in the cells expressing PrP mutants. In this study, we provide the evidence that RyR2, the ER-resident Ca 2+ channel, decreases remarkably in the cell line supporting prion replication and in the brain collected from scrapie infected mice and the patients of various types of human prion diseases.…”