ABSTRACT
Seeding and spread of beta-amyloid (Aß) pathologies have been considered to be based on prion-like mechanisms. However, limited transmissibility of Aß seeding activity upon peripheral exposure would represent a key difference to prions, not only in terms of pathogenesis but also in terms of potential transmission of disease. We partially characterized the seeded Aß amyloidosis after intracerebral injection of various brain homogenates in APP/PS1 mice. One particularly seed-laden homogenate was selected to investigate the development of Aß pathologies after intravenous exposure. We report here that a single intravenous injection of an Alzheimer disease patient's-brain extract into APP/PS1 recipient mice led to cerebral amyloid angiopathy within 180 days post injection. Thus, vascular proteinopathies such as CAA are transmissible in mice via the intravenous route of peripheral exposure.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/administration & dosage , Amyloid beta-Peptides/metabolism , Brain/metabolism , Cerebral Amyloid Angiopathy/etiology , Cerebral Amyloid Angiopathy/metabolism , Aged , Amyloid beta-Peptides/genetics , Animals , Brain/pathology , Cerebral Amyloid Angiopathy/pathology , Disease Models, Animal , Female , Humans , Injections, Intravenous , Male , Mice, Inbred C57BL , Mice, Transgenic , Middle Aged , Presenilin-1/genetics , Presenilin-1/metabolismABSTRACT
Alzheimer's disease (AD) and prion diseases carry a significant inflammatory component. The astrocytic overexpression of CCAAT/enhancer-binding protein delta (C/EBPD) in prion- and AD-affected brain tissue prompted us to study the role of this transcription factor in murine model systems of these diseases. Ablation of C/EBPD had neither in the AD model (APP/PS1double transgenic mice) nor in the prion model (scrapie-infected C57BL/6 mice) an influence on overt clinical symptoms. Moreover, the absence of C/EBPD did not affect the extent of the disease-related gliosis. However, C/EBPD-deficient APP/PS1 double transgenic mice displayed significantly increased amyloid beta (Abeta) plaque burdens while amyloid precursor protein (APP) expression and expression of genes involved in beta amyloid transport and turnover remained unchanged. Gene expression analysis in mixed glia cultures demonstrated a strong dependency of complement component C3 on the presence of C/EBPD. Accordingly, C3 mRNA levels were significantly lower in brain tissue of C/EBPD-deficient mice. Vice versa, C3 expression in U-373 MG cells increased upon transfection with a C/EBPD expression vector. Taken together, our data indicate that a C/EBPD-deficiency leads to increased Abeta plaque burden in AD model mice. Furthermore, as shown in vivo and in vitro, C/EBPD is an important driver of the expression of acute phase response genes like C3 in the amyloid-affected CNS.
Subject(s)
Alzheimer Disease/metabolism , CCAAT-Enhancer-Binding Protein-delta/metabolism , Plaque, Amyloid/metabolism , Alzheimer Disease/pathology , Animals , Disease Models, Animal , Mice , Mice, TransgenicABSTRACT
Tumorigenesis is a multi-step process involving several consecutive genetic alterations resulting in loss of genomic stability and deregulated signal transduction pathways. To study these deregulated processes in vitro, typically established cancer cell lines derived from primary tumors, ascites, or from metastases are used. However, these cancer cell lines reflect only late stages of the tumorigenic process. To better understand the consequences of the sequential genetic alterations in an in vitro model system, we applied consecutive immortalization and transformation of primary human mammary epithelial cells (HMECs) combining shRNA-mediated knockdown of tumor suppressor genes and overexpression of oncogenes. Thereby, we developed a panel of isogenic HMEC-derived cell lines reflecting the multi-step process of tumorigenesis. The immortalized cell lines have a normal epithelial morphology and proliferate indefinitely and anchorage-dependently. In contrast, the transformed cells exhibit mesenchymal-like morphological changes and strong colony-forming activity in soft agar. SNP array analysis showed that none of the cell lines displayed gross chromosomal aberrations in 80 % of the chromosomes. However, massive changes were observed in some chromosomes of the transformed cells indicating that the transformed phenotype is characterized by chromosomal alterations. The isogenic immortalized and transformed cells described here provide a powerful tool for the in vitro validation of target genes for cancer therapy.
