MAPT Mutations V337M and N297K Alter Organelle Trafficking in Frontotemporal Dementia Patient-Specific Motor Neurons.

Frontotemporal dementia (FTD) is a neurodegenerative disease characterized by the progressive loss of neurons mainly in the frontal and temporal lobes of the brain. Mutations (e.g., V337M, N297K) in the microtubule-associated protein TAU (MAPT) are responsible 5-20% of familial FTD cases and have been associated with defects in organelle trafficking that plays a critical role in the proper function of cells, including transport of essential molecules and degradation of waste products. Due to the critical role of TAU mutations in microtubule stabilization and organelle transportation, it is of great interest to study these molecular mechanisms to develop effective therapeutic strategies. Therefore, herein, we analyzed mitochondrial and lysosomal trafficking in disease-specific spinal motor neurons by using live cell imaging in undirected (uncompartmentalized) and directed (compartmentalized) cell culture systems. While V337M neurons only expressed 3R TAU, the N297K mutant neurons expressed both 3R and 4R TAU. Axonal trafficking was affected differentially in V337M and N297 MAPT mutated neurons. These findings suggest that the MAPT mutations V337M and N297K impaired axon physiology differentially, which highlights the need for mutation- and/or 3R/4R TAU-specific therapeutic approaches.

Notch is Not Involved in Physioxia-Mediated Stem Cell Maintenance in Midbrain Neural Stem Cells.

Background and Objectives: The physiological oxygen tension in fetal brains (∼3%, physioxia) is beneficial for the maintenance of neural stem cells (NSCs). Sensitivity to oxygen varies between NSCs from different fetal brain regions, with midbrain NSCs showing selective susceptibility. Data on Hif-1α/Notch regulatory interactions as well as our observations that Hif-1α and oxygen affect midbrain NSCs survival and proliferation prompted our investigations on involvement of Notch signalling in physioxia-dependent midbrain NSCs performance. Methods and Results: Here we found that physioxia (3% O2) compared to normoxia (21% O2) increased proliferation, maintained stemness by suppression of spontaneous differentiation and supported cell cycle progression. Microarray and qRT-PCR analyses identified significant changes of Notch related genes in midbrain NSCs after long-term (13 days), but not after short-term physioxia (48 hours). Consistently, inhibition of Notch signalling with DAPT increased, but its stimulation with Dll4 decreased spontaneous differentiation into neurons solely under normoxic but not under physioxic conditions. Conclusions: Notch signalling does not influence the fate decision of midbrain NSCs cultured in vitro in physioxia, where other factors like Hif-1α might be involved. Our findings on how physioxia effects in midbrain NSCs are transduced by alternative signalling might, at least in part, explain their selective susceptibility to oxygen.

Systematic estimation of biological age of in vitro cell culture systems by an age-associated marker panel.

Aging is a process that affects almost all multicellular organisms and since our population ages with increasing prevalence of age-related diseases, it is important to study basic processes involved in aging. Many studies have been published so far using different and often single age markers to estimate the biological age of organisms or different cell culture systems. However, comparability of studies is often hampered by the lack of a uniform panel of age markers. Consequently, we here suggest an easy-to-use biomarker-based panel of classical age markers to estimate the biological age of cell culture systems that can be used in standard cell culture laboratories. This panel is shown to be sensitive in a variety of aging conditions. We used primary human skin fibroblasts of different donor ages and additionally induced either replicative senescence or artificial aging by progerin overexpression. Using this panel, highest biological age was found for artificial aging by progerin overexpression. Our data display that aging varies depending on cell line and aging model and even from individual to individual showing the need for comprehensive analyses.

A conserved long-distance telomeric silencing mechanism suppresses mTOR signaling in aging human fibroblasts.

Telomeres are repetitive nucleotide sequences at the ends of each chromosome. It has been hypothesized that telomere attrition evolved as a tumor suppressor mechanism in large long-lived species. Long telomeres can silence genes millions of bases away through a looping mechanism called telomere position effect over long distances (TPE-OLD). The function of this silencing mechanism is unknown. We determined a set of 2322 genes with high positional conservation across replicatively aging species that includes known and candidate TPE-OLD genes that may mitigate potentially harmful effects of replicative aging. Notably, we identified PPP2R2C as a tumor suppressor gene, whose up-regulation by TPE-OLD in aged human fibroblasts leads to dephosphorylation of p70S6 kinase and mammalian target of rapamycin suppression. A mechanistic link between telomeres and a tumor suppressor mechanism supports the hypothesis that replicative aging fulfills a tumor suppressor function and motivates previously unknown antitumor and antiaging strategies.

Ranking Biomarkers of Aging by Citation Profiling and Effort Scoring.

Aging affects most living organisms and includes the processes that reduce health and survival. The chronological and the biological age of individuals can differ remarkably, and there is a lack of reliable biomarkers to monitor the consequences of aging. In this review we give an overview of commonly mentioned and frequently used potential aging-related biomarkers. We were interested in biomarkers of aging in general and in biomarkers related to cellular senescence in particular. To answer the question whether a biological feature is relevant as a potential biomarker of aging or senescence in the scientific community we used the PICO strategy known from evidence-based medicine. We introduced two scoring systems, aimed at reflecting biomarker relevance and measurement effort, which can be used to support study designs in both clinical and research settings.

Anisotropic local physical properties of human dental enamel in comparison to properties of some common dental filling materials.

OBJECTIVE: A major aspect in evaluating the quality of dental materials is their physical properties. Their properties should be a best fit of the ones of dental hard tissues. Manufacturers give data sheets for each material. The properties listed are characterized by a specific value. This assumes (but does not prove) that there is no direction dependence of the properties. However, dental enamel has direction-dependent properties which additionally vary with location in the tooth. The aim of this paper is to show the local direction dependence of physical properties like the elastic modulus or the thermal expansion in dental hard tissues. With this knowledge the 'perfect filling/dental material' could be characterized. MATERIALS AND METHOD: Enamel sections of ∼400-500 µm thickness have been cut with a diamond saw from labial/buccal to palatal/lingual (canine, premolar and molar) and parallel to labial (incisor). Crystallite arrangements have been measured in over 400 data points on all types of teeth with x-ray scattering techniques, known from materials science. RESULTS: X-ray scattering measurements show impressively that dental enamel has a strong direction dependence of its physical properties which also varies with location within the tooth. Dental materials possess only little or no property direction dependence. Therefore, a mismatch was found between enamel and dental materials properties. CONCLUSION: Since dental materials should possess equal (direction depending) properties, worthwhile properties could be characterized by transferring the directional properties of enamel into a property 'wish list' which future dental materials should fulfil. Hereby the 'perfect dental material' can be characterized.

Interferon-beta therapy in multiple sclerosis: the short-term and long-term effects on the patients' individual gene expression in peripheral blood.

Therapy with interferon-beta (IFN-beta) is a mainstay in the management of relapsing-remitting multiple sclerosis (MS), with proven long-term effectiveness and safety. Much has been learned about the molecular mechanisms of action of IFN-beta in the past years. Previous studies described more than a hundred genes to be modulated in expression in blood cells in response to the therapy. However, for many of these genes, the precise temporal expression pattern and the therapeutic relevance are unclear. We used Affymetrix microarrays to investigate in more detail the gene expression changes in peripheral blood mononuclear cells from MS patients receiving subcutaneous IFN-beta-1a. The blood samples were obtained longitudinally at five different time points up to 2 years after the start of therapy, and the patients were clinically followed up for 5 years. We examined the functions of the genes that were upregulated or downregulated at the transcript level after short-term or long-term treatment. Moreover, we analyzed their mutual interactions and their regulation by transcription factors. Compared to pretreatment levels, 96 genes were identified as highly differentially expressed, many of them already after the first IFN-beta injection. The interactions between these genes form a large network with multiple feedback loops, indicating the complex crosstalk between innate and adaptive immune responses during therapy. We discuss the genes and biological processes that might be important to reduce disease activity by attenuating the proliferation of autoreactive immune cells and their migration into the central nervous system. In summary, we present novel insights that extend the current knowledge on the early and late pharmacodynamic effects of IFN-beta therapy and describe gene expression differences between the individual patients that reflect clinical heterogeneity.

Elevated type I interferon-like activity in a subset of multiple sclerosis patients: molecular basis and clinical relevance.

BACKGROUND: A subset of patients with multiple sclerosis (MS) shows an increased endogenous IFN-like activity before initiation of IFN-beta treatment. The molecular basis of this phenomenon and its relevance to predict individual therapy outcomes are not yet fully understood. We studied the expression patterns of these patients, the prognostic value of an elevated IFN-like activity, and the gene regulatory effects of exogenously administered IFN-beta. METHODS: Microarray gene expression profiling was performed for 61 MS patients using peripheral blood mononuclear cells obtained before and after 1 month of IFN-beta therapy. Expression levels of genes involved in pathways either inducing or being activated by IFN-beta were compared between patients with high (MX1(high) cohort) and low (MX1(low) cohort) endogenous IFN-like activity. Patients were followed for 5 years and relapses as well as progression on the expanded disability status scale (EDSS) were documented. RESULTS: Before the start of therapy, 11 patients presented elevated mRNA levels of IFN-stimulated genes indicative of a relatively high endogenous IFN-like activity (MX1(high)). In these patients, pathogen receptors (for example, TLR7, RIG-I and IFIH1) and transcription factors were also expressed more strongly, which could be attributed to an overactivity of IFN-stimulated gene factor 3 (ISGF3, a complex formed by STAT1, STAT2 and IFN regulatory factor 9). After 1 month of IFN-beta therapy, the expression of many pathway genes was significantly induced in MX1(low) patients, but remained unaltered in MX1(high) patients. During follow-up, relapse rate and changes in EDSS were comparable between both patient groups, with differences seen between different types of IFN-beta drug application. CONCLUSIONS: Therapeutic IFN-beta induces the transcription of several genes involved in IFN-related pathways. In a subgroup of MS patients, the expression of these genes is already increased before therapy initiation, possibly driven by an overexpression of ISGF3. Patients with high and low endogenous IFN-like activity showed similar clinical long-term courses of disease. Different results were obtained for different IFN-beta drug preparations, and this merits further investigation.