Uptake of Aggregating Transthyretin by Fat Body in a Drosophila Model for TTR-Associated Amyloidosis

Background: A functional link has been established between the severe neurodegenerative disorder Familial amyloidotic polyneuropathy and the enhanced propensity of the plasma protein transthyretin (TTR) to form aggregates in patients with single point mutations in the TTR gene. Previous work has led to the establishment of an experimental model based on transgenic expression of normal or mutant forms of human TTR in Drosophila flies. Remarkably, the severity of the phenotype was greater in flies that expressed a single copy than with two copies of the mutated gene. Methodology/Principal Findings: In this study, we analyze the distribution of normal and mutant TTR in transgenic flies, and the ultrastructure of TTR-positive tissues to clarify if aggregates and/or amyloid filaments are formed. We report the formation of intracellular aggregates of 20 nm spherules and amyloid filaments in thoracic adipose tissue and in brain glia, two tissues that do not express the transgene. The formation of aggregates of nanospherules increased with age and was more considerable in flies with two copies of mutated TTR. Treatment of human neuronal cells with protein extracts prepared from TTR flies of different age showed that the extracts from older flies were less toxic than those from younger flies. Conclusions/Significance: These findings suggest that the uptake of TTR from the circulation and its subsequent segregation into cytoplasmic quasi-crystalline arrays of nanospherules is part of a mechanism that neutralizes the toxic effect of TTR.Original Publication:Malgorzata Pokrzywa, Ingrid Dacklin, Monika Vestling, Dan Hultmark, Erik Lundgren and Rafael Cantera, Uptake of Aggregating Transthyretin by Fat Body in a Drosophila Model for TTR-Associated Amyloidosis, 2010, PLOS ONE, (5), 12.http://dx.doi.org/10.1371/journal.pone.0014343Licensee: Public Library of Science (PLoS)http://www.plos.org

Alzheimer's disease mutations and cellular signalling

Alzheimer's disease is the most frequent cause of dementia in elderly and is characterised neuropathologically by the extracellular deposition of amyloid plaques (containing the 39-43 amino acid Abeta peptide), as well as intracellular neurofibrillary tangles (NFTs) composed primarily of an abnormally hyperphosphorylated form of the microtubule-associated protein tau. A proportion (10- 15%) of Alzheimer's disease cases is familial, the remainder being sporadic. Familial Alzheimer's disease is genetically heterogeneous and can be caused by defects in at least three early- onset genes located on chromosomes 21 (amyloid precursor protein, APP), 14 (presenilin 1, PS 1) and 1 (presenilin 2, PS2). Increased production of Abeta is a common pathogenic phenotype in familial Alzheimer's disease due to APP and PS mutations. The major aim of this thesis was to determine whether the phenotypes of Alzheimer's disease causing APP and PSI mutations also include altered signalling. For this we used peripheral skin fibroblasts from sporadic as well as from familial Alzheimer's disease cases with the Swedish APP KM670/67 1 NI, mutation or different PSI mutations. Experiments were also performed on SH-SY5Y neuroblastoma cells transfected with wild-type and mutated forms of PSI. We studied signalling pathways known to be disrupted in sporadic Alzheimer's disease and thought to be implicated in either Abeta production, tau hyperphosphorylation, intracellular calcium homeostasis or apoptosis. The results obtained provide supportive evidence that an altered signalling occurs in Alzheimer's disease, but those groups with different disease origins (sporadic or familial) are affected in different ways. Mutations in different genes (APP vs PSI) differentially affect cellular signalling. The clearest finding was that the Swedish APP KM670/67INL mutation does not change any of the signal transduction parameters studied (beta-adrenoceptor-stimulated adenylyl cyclase, PKC activity, bradykinin-stimulated calcium release), the exception being a reduced bombesin-induced calcium release. The only abnormality previously reported in fibroblasts with this mutation is that of an increased secretion of Abeta. This effect appears to be relatively clean and is the most likely explanation for disease pathology in this family. The PSI mutations studied in primary skin fibroblasts gave alterations in a number of signalling parameters. These included an increased beta- adrenoceptor-stimulated adenylyl cyclase activity (as compared to a decrease seen in sporadic Alzheimer's disease fibroblasts), as well as a decreased PKC-mediated APPs secretion. We also conclude that the reported increased susceptibility of PSI mutation transfected SH-SY5Y neuroblastoma cells to undergo apoptosis after serum deprivation and high glucose stress, is unlikely due to a downregulation of Akt. Finally, the regulation of GSK-3 beta in response to the pro-apoptotic stimuli of either serum deprivation, P13 kinase inhibition or staurosporine treatment did not differ in PSI wild-type and mutation transfected SH-SY5Y cells

IV.13 - Iside

Objective: The aim of this study was to increase the understanding of stroke survivors' thoughts and experiences from returning to work after stroke. Methods: Semi-structured interviews were carried out with twelve persons, based on a thematic interview guide. A qualitative content analyse were performed. Results: The main theme; was Striving for optimal function at work creates mixed feelings of appreciation and frustration, contained three categories: 1) Multiple arrangements and strategies are necessary for returning to work, 2) Work as an activity holds multiple subjective meanings that are important for the motivation to return to work, and 3) The return-to-work process generates many and mixed feelings. Conclusions: The complexity of the process involving many different actors constitutes great challenges for the affected person in addition to general and medical problems. The stroke survivor should be encouraged to be an active participant during the return-to-work process. Our findings can be used for the development of a programme, including a personal mentor, to support the person striving for returning to work. For detailed planning of such a programme further research is needed

Quality of life after stroke: well-being, life satisfaction, and subjective aspects of work.

Stroke incidence in those of working age has been reported to be increasing significantly, implying strong incentives for research concerning working ability after stroke. This study focused on differences in subjective aspects of work and dimensions of quality of life after having experienced stroke. Sixty-five persons answered a postal questionnaire. The median age at the time of the stroke was 54 years, (Q3-Q1=8 years). “Financial aspects” and “intrinsic aspects” of work were rated as the most important by 37% and 36% of the respondents, respectively. Fewer respondents ranked “social aspects” as most important. In total, 23 persons had returned to work, but no difference in the ratings of the most important aspects of work between those who had returned to work and those who had not was found. Persons who rated “intrinsic aspects” of work as the most important were more satisfied with the subjective dimensions of quality of life “vocational situation” (p=0.020) and “work” (p=0.015) than the others. In conclusion, subjective aspects of work need to be explored and discussed thoroughly in rehabilitation of younger stroke patients