Regulation of Neuronal APL-1 Expression by Cholesterol Starvation

Background: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the deposition of b-amyloid plaques composed primarily of the amyloid-b peptide, a cleavage product of amyloid precursor protein (APP). While mutations in APP lead to the development of Familial Alzheimer’s Disease (FAD), sporadic AD has only one clear genetic modifier: the e4 allele of the apolipoprotein E (ApoE) gene. Cholesterol starvation in Caenorhabditis elegans leads to molting and arrest phenotypes similar to loss-of-function mutants of the APP ortholog, apl-1 (amyloid precursor-like protein 1), and lrp-1 (lipoprotein receptor-related protein 1), suggesting a potential interaction between apl-1 and cholesterol metabolism. Methodology/Principal Findings: Previously, we found that RNAi knock-down of apl-1 leads to aldicarb hypersensitivity, indicating a defect in synaptic function. Here we find the same defect is recapitulated during lrp-1 knock-down and by cholesterol starvation. A cholesterol-free diet or loss of lrp-1 directly affects APL-1 levels as both lead to loss of APL-1::GFP fluorescence in neurons. However, loss of cholesterol does not affect global transcription or protein levels as seen by qPCR and Western blot. Conclusions: Our results show that cholesterol and lrp-1 are involved in the regulation of synaptic transmission, similar to apl-1. Both are able to modulate APL-1 protein levels in neurons, however cholesterol changes do not affect global apl-1 transcription or APL-1 protein indicating the changes are specific to neurons. Thus, regulation of synaptic transmission an

Knockdown of Amyloid Precursor Protein in Zebrafish Causes Defects in Motor Axon Outgrowth

Amyloid precursor protein (APP) plays a pivotal role in Alzheimer’s disease (AD) pathogenesis, but its normal physiological functions are less clear. Combined deletion of the APP and APP-like protein 2 (APLP2) genes in mice results in post-natal lethality, suggesting that APP performs an essential, if redundant, function during embryogenesis. We previously showed that injection of antisense morpholino to reduce APP levels in zebrafish embryos caused convergent-extension defects. Here we report that a reduction in APP levels causes defective axonal outgrowth of facial branchiomotor and spinal motor neurons, which involves disorganized axonal cytoskeletal elements. The defective outgrowth is caused in a cell-autonomous manner and both extracellular and intracellular domains of human APP are required to rescue the defective phenotype. Interestingly, wild-type human APP rescues the defective phenotype but APPswe mutation, which causes familial AD, does not. Our results show that the zebrafish model provides a powerful system to delineate APP functions in vivo and to study the biological effects of APP mutations

The amyloid precursor protein controls PIKfyve function

While the Amyloid Precursor Protein (APP) plays a central role in Alzheimer's disease, its cellular function still remains largely unclear. It was our goal to establish APP function which will provide insights into APP's implication in Alzheimer's disease. Using our recently developed proteo-liposome assay we established the interactome of APP's intracellular domain (known as AICD), thereby identifying novel APP interactors that provide mechanistic insights into APP function. By combining biochemical, cell biological and genetic approaches we validated the functional significance of one of these novel interactors. Here we show that APP binds the PIKfyve complex, an essential kinase for the synthesis of the endosomal phosphoinositide phosphatidylinositol-3,5-bisphosphate. This signalling lipid plays a crucial role in endosomal homeostasis and receptor sorting. Loss of PIKfyve function by mutation causes profound neurodegeneration in mammals. Using C. elegans genetics we demonstrate that APP functionally cooperates with PIKfyve in vivo. This regulation is required for maintaining endosomal and neuronal function. Our findings establish an unexpected role for APP in the regulation of endosomal phosphoinositide metabolism with dramatic consequences for endosomal biology and important implications for our understanding of Alzheimer's disease

Patient-provider interaction from the perspectives of type 2 diabetes patients in Muscat, Oman: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Patients' expectations and perceptions of the medical encounter and interactions are important tools in diabetes management. Some problems regarding the interaction during encounters may be related to a lack of communication skills on the part of either the physician or the patient.</p> <p>This study aimed at exploring the perceptions of type 2 diabetes patients regarding the medical encounters and quality of interactions with their primary health-care providers.</p> <p>Methods</p> <p>Four focus group discussions (two women and two men groups) were conducted among 27 purposively selected patients (13 men and 14 women) from six primary health-care centres in Muscat, Oman. Qualitative content analysis was applied.</p> <p>Results</p> <p>The patients identified some weaknesses regarding the patient-provider communication like: unfriendly welcoming; interrupted consultation privacy; poor attention and eye contact; lack of encouraging the patients to ask questions on the providers' side; and inability to participate in medical dialogue or express concerns on the patients' side. Other barriers and difficulties related to issues of patient-centeredness, organization of diabetes clinics, health education and professional competency regarding diabetes care were also identified.</p> <p>Conclusion</p> <p>The diabetes patients' experiences with the primary health-care providers showed dissatisfaction with the services. We suggest appropriate training for health-care providers with regard to diabetes care and developing of communication skills with emphasis on a patient-centred approach. An efficient use of available resources in diabetes clinics and distributing responsibilities between team members in close collaboration with patients and their families seems necessary. Further exploration of the providers' work situation and barriers to good interaction is needed. Our findings can help the policy makers in Oman, and countries with similar health systems, to improve the quality and organizational efficiency of diabetes care services.</p

Quality of interaction between primary health-care providers and patients with type 2 diabetes in Muscat, Oman: an observational study

BACKGROUND: A good patient-physician interaction is particularly important in chronic diseases like diabetes. There are so far no published data regarding the interaction between the primary health-care providers and patients with type 2 diabetes in Oman, where diabetes is a major and growing health problem. This study aimed at exploring how health-care providers interact with patients with type 2 diabetes at primary health-care level in Muscat, Oman, focusing on the consultation environment, and some aspects of care and information. METHODS: Direct observations of 90 consultations between 23 doctors and 13 diabetes nurses concerned with diabetes management during their consultations with type 2 diabetes patients in six primary health-care centres in the Muscat region, using checklists developed from the National Diabetes Guidelines. Consultations were assessed as optimal if more than 75% of observed aspects were fulfilled and sub-optimal if less than 50% were fulfilled. RESULTS: Overall 52% of the doctors' consultations were not optimal. Some important aspects for a positive consultation environment were fulfilled in only about half of the doctors' consultations: ensuring privacy of consultation (49%), eye contact (49%), good attention (52%), encouraging asking questions (47%), and emphasizing on the patients' understanding of the provided information (52%). The doctors enquired about adverse effects of anti-diabetes drugs in less than 10% of consultations. The quality of the nurses' consultations was sub-optimal in about 75% of 85 consultations regarding aspects of consultation environment, care and information. CONCLUSION: The performance of the primary health-care doctors and diabetes nurses needs to be improved. The role of the diabetes nurses and the teamwork should be enhanced. We suggest a multidisciplinary team approach, training and education to the providers to upgrade their skills regarding communication and care. Barriers to compliance with the guidelines need to be further explored. Improving the work situation mainly for the diabetes nurses and further improvement in the organizational efficiency of diabetes services such as lowering the number of patients in diabetes clinic, are suggested

Intracellular Trafficking and Synaptic Function of APL-1 in Caenorhabditis elegans

Background: Alzheimer’s disease (AD) is a neurodegenerative disorder primarily characterized by the deposition of b-amyloid plaques in the brain. Plaques are composed of the amyloid-b peptide derived from cleavage of the amyloid precursor protein (APP). Mutations in APP lead to the development of Familial Alzheimer’s Disease (FAD), however, the normal function of this protein has proven elusive. The organism Caenorhabditis elegans is an attractive model as the amyloid precursor-like protein (APL-1) is the single ortholog of APP, and loss of apl-1 leads to a severe molting defect and early larval lethality. Methodology/Principal Findings: We report here that lethality and molting can be rescued by full length APL-1, C-terminal mutations as well as a C-terminal truncation, suggesting that the extracellular region of the protein is essential for viability. RNAi knock-down of apl-1 followed by drug testing on the acetylcholinesterase inhibitor aldicarb showed that loss of apl-1 leads to aldicarb hypersensitivity, indicating a defect in synaptic function. The aldicarb hypersensitivity can be rescued by full length APL-1 in a dose dependent fashion. At the cellular level, kinesins UNC-104/KIF-1A and UNC-116/kinesin-1 are positive regulators of APL-1 expression in the neurons. Knock-down of the small GTPase rab-5 also leads to a dramatic decrease in the amount of apl-1 expression in neurons, suggesting that trafficking from the plasma membrane to the early endosome is important for apl-1 function. Loss of function of a different small GTPase, UNC-108, on the contrary, leads t

Using C. elegans to discover therapeutic compounds for ageing-associated neurodegenerative diseases

Age-associated neurodegenerative disorders such as Alzheimer’s disease are a major public health challenge, due to the demographic increase in the proportion of older individuals in society. However, the relatively few currently approved drugs for these conditions provide only symptomatic relief. A major goal of neurodegeneration research is therefore to identify potential new therapeutic compounds that can slow or even reverse disease progression, either by impacting directly on the neurodegenerative process or by activating endogenous physiological neuroprotective mechanisms that decline with ageing. This requires model systems that can recapitulate key features of human neurodegenerative diseases that are also amenable to compound screening approaches. Mammalian models are very powerful, but are prohibitively expensive for high-throughput drug screens. Given the highly conserved neurological pathways between mammals and invertebrates, Caenorhabditis elegans has emerged as a powerful tool for neuroprotective compound screening. Here we describe how C. elegans has been used to model various human ageing-associated neurodegenerative diseases and provide an extensive list of compounds that have therapeutic activity in these worm models and so may have translational potential

Comparative Genome Analysis of Filamentous Fungi Reveals Gene Family Expansions Associated with Fungal Pathogenesis

Fungi and oomycetes are the causal agents of many of the most serious diseases of plants. Here we report a detailed comparative analysis of the genome sequences of thirty-six species of fungi and oomycetes, including seven plant pathogenic species, that aims to explore the common genetic features associated with plant disease-causing species. The predicted translational products of each genome have been clustered into groups of potential orthologues using Markov Chain Clustering and the data integrated into the e-Fungi object-oriented data warehouse (http://www.e-fungi.org.uk/). Analysis of the species distribution of members of these clusters has identified proteins that are specific to filamentous fungal species and a group of proteins found only in plant pathogens. By comparing the gene inventories of filamentous, ascomycetous phytopathogenic and free-living species of fungi, we have identified a set of gene families that appear to have expanded during the evolution of phytopathogens and may therefore serve important roles in plant disease. We have also characterised the predicted set of secreted proteins encoded by each genome and identified a set of protein families which are significantly over-represented in the secretomes of plant pathogenic fungi, including putative effector proteins that might perturb host cell biology during plant infection. The results demonstrate the potential of comparative genome analysis for exploring the evolution of eukaryotic microbial pathogenesis