Molecular pathophysiology of human MICU1 deficiency.

Funder: Ministerium für Innovation, Wissenschaft und Forschung des Landes Nordrhein‐Westfalen; Id: http://dx.doi.org/10.13039/501100009591Funder: Bundesministerium für Bildung und Forschung; Id: http://dx.doi.org/10.13039/501100002347AIMS: MICU1 encodes the gatekeeper of the mitochondrial Ca2+ uniporter, MICU1 and biallelic loss-of-function mutations cause a complex, neuromuscular disorder in children. Although the role of the protein is well understood, the precise molecular pathophysiology leading to this neuropaediatric phenotype has not been fully elucidated. Here we aimed to obtain novel insights into MICU1 pathophysiology. METHODS: Molecular genetic studies along with proteomic profiling, electron-, light- and Coherent anti-Stokes Raman scattering microscopy and immuno-based studies of protein abundances and Ca2+ transport studies were employed to examine the pathophysiology of MICU1 deficiency in humans. RESULTS: We describe two patients carrying MICU1 mutations, two nonsense (c.52C>T; p.(Arg18*) and c.553C>T; p.(Arg185*)) and an intragenic exon 2-deletion presenting with ataxia, developmental delay and early onset myopathy, clinodactyly, attention deficits, insomnia and impaired cognitive pain perception. Muscle biopsies revealed signs of dystrophy and neurogenic atrophy, severe mitochondrial perturbations, altered Golgi structure, vacuoles and altered lipid homeostasis. Comparative mitochondrial Ca2+ transport and proteomic studies on lymphoblastoid cells revealed that the [Ca2+ ] threshold and the cooperative activation of mitochondrial Ca2+ uptake were lost in MICU1-deficient cells and that 39 proteins were altered in abundance. Several of those proteins are linked to mitochondrial dysfunction and/or perturbed Ca2+ homeostasis, also impacting on regular cytoskeleton (affecting Spectrin) and Golgi architecture, as well as cellular survival mechanisms. CONCLUSIONS: Our findings (i) link dysregulation of mitochondrial Ca2+ uptake with muscle pathology (including perturbed lipid homeostasis and ER-Golgi morphology), (ii) support the concept of a functional interplay of ER-Golgi and mitochondria in lipid homeostasis and (iii) reveal the vulnerability of the cellular proteome as part of the MICU1-related pathophysiology

Phosphatidylserine-exposing extracellular vesicles in body fluids are an innate defence against apoptotic mimicry viral pathogens

Some viruses are rarely transmitted orally or sexually despite their presence in saliva, breast milk, or semen. We previously identified that extracellular vesicles (EVs) in semen and saliva inhibit Zika virus infection. However, the antiviral spectrum and underlying mechanism remained unclear. Here we applied lipidomics and flow cytometry to show that these EVs expose phosphatidylserine (PS). By blocking PS receptors, targeted by Zika virus in the process of apoptotic mimicry, they interfere with viral attachment and entry. Consequently, physiological concentrations of EVs applied in vitro efficiently inhibited infection by apoptotic mimicry dengue, West Nile, Chikungunya, Ebola and vesicular stomatitis viruses, but not severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus 1, hepatitis C virus and herpesviruses that use other entry receptors. Our results identify the role of PS-rich EVs in body fluids in innate defence against infection via viral apoptotic mimicries, explaining why these viruses are primarily transmitted via PS-EV-deficient blood or blood-ingesting arthropods rather than direct human-to-human contact

Resource conservation in Antarctica

Die Arbeit untersucht die Problematik des Ressourcenschutzes in der Antarktis, ein Gebiet welches keine klar definierten Besitzrechte aufweist. Die Resourcen des Kontinents und der umliegenden Meere sind vielfältig, unter anderem zählen Fisch, Krill, Mineralien, Trinkwasser aber auch die besondere und unberührte Natur dazu. Obwohl die Antarktis auf Grund der ungeklärten Besitzverhältnisse und einer sensiblen Umwelt ein typisches Allmendenproblem zu sein scheint, werden die natürlichen Ressourcen der Region seit in Kraft treten der Antarktisverträge (Antarctic Treaty System) nicht übernutzt oder ausgebeutet. In dieser Masterarbeit wird argumentiert dass das Antarctic Treaty System die Antarktis von einer Allmende (Commons) in eine Anti-Allmende (Anticommons) umwandelt. Dies geschieht dadurch, dass jedes Mitglied der Verträge weitreichende Veto-Rechte bekommt, mit denen die Nutzung jeglicher Ressourcen untersagt werden kann. Dies steht im Gegensatz zur Allmendenproblematik, bei der jedes Mitglied Nutzrechte besitzt, jedoch nicht die Möglichkeit hat andere von der Nutzung der Allmende abzuhalten. Die Möglichkeit eines jeden Vertragsmitgliedes die Nutzung einer Ressource zu unterbinden erhöht die Kosten eine Übereinstimmung bezüglich der Verwendung eines jeden Rohstoffs zu erreichen signifikant. Dies entspricht der Anti-Allmendenproblematik: auf Grund eines Preises oberhalb des effizienten Preislevels wird ein Gut nur ineffizient genutzt. Genau dieser Mechanismus und die daraus resultierende, ineffiziente Nutzung von Gütern, schützt die antarktischen Ressourcen vor Ausbeutung. Zusätzlich kann dieses Konzept auch ohne klar definierte Besitzrechte angewendet werden, was insbsonder für die Antarktis wichtig ist, da es keine absehbare Einigung bezüglich potentieller Ansprüche oder Besitzverhältnisse gibt.The thesis examines the issue of resource conservation in Antarctica, an area without clearly defined property-rights. The continent and its surrounding seas offer a wide variety of resources, e.g. fish, krill, minerals, potable water or pristine wilderness. Although, Antarctica appears to be a typical Tragedy of the Commons, without clearly defined ownership but with an environment sensitive to exploitation, there is no resource overuse since the Antarctic Treaty System entered into force. In the thesis, it is argued that the ATS turns Antarctic natural resources, usually prone to overuse, from Commons into Anticommons by giving any member of the ATS exclusion instead of use rights. Any potential resource use can be vetoed by any Treaty party, thus, increasing the transaction costs of reaching an agreement and the costs of exploitation significantly. This results in the Tragedy of the Anticommons, an inefficient underuse of a good or resource due to prices above the efficient price level. The Tragedy of the Anticommons protects Antarctic resources from exploitation and circumnavigates the delicate question of ownership

The Effect of the Thickness of the Sensitive Layer on the Performance of the Accumulating NOx Sensor

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Utilization of Aminoguanidine Prevents Cytotoxic Effects of Semen

Studies of human semen in cell or tissue culture are hampered by the high cytotoxic activity of this body fluid. The components responsible for the cell damaging activity of semen are amine oxidases, which convert abundant polyamines, such as spermine or spermidine in seminal plasma into toxic intermediates. Amine oxidases are naturally present at low concentrations in seminal plasma and at high concentrations in fetal calf serum, a commonly used cell culture supplement. Here, we show that, in the presence of fetal calf serum, seminal plasma, as well as the polyamines spermine and spermidine, are highly cytotoxic to immortalized cells, primary blood mononuclear cells, and vaginal tissue. Thus, experiments investigating the effect of polyamines and seminal plasma on cellular functions should be performed with great caution, considering the confounding cytotoxic effects. The addition of the amine oxidase inhibitor aminoguanidine to fetal calf serum and/or the utilization of serum-free medium greatly reduced this serum-induced cytotoxicity of polyamines and seminal plasma in cell lines, primary cells, and tissues and, thus, should be implemented in all future studies analyzing the role of polyamines and semen on cellular functions

Excited-State Dynamics of Protochlorophyllide Revealed by Subpicosecond Infrared Spectroscopy

To gain a better understanding of the light-induced reduction of protochlorophyllide (PChlide) to chlorophyllide as a key regulatory step in chlorophyll synthesis, we performed transient infrared absorption measurements on PChlide in d4-methanol. Excitation in the Q-band at 630 nm initiates dynamics characterized by three time constants: τ1 = 3.6 ± 0.2, τ2 = 38 ± 2, and τ3 = 215 ± 8 ps. As indicated by the C13′=O carbonyl stretching mode in the electronic ground state at 1686 cm−1, showing partial ground-state recovery, and in the excited electronic state at 1625 cm−1, showing excited-state decay, τ2 describes the formation of a state with a strong change in electronic structure, and τ3 represents the partial recovery of the PChlide electronic ground state. Furthermore, τ1 corresponds with vibrational energy relaxation. The observed kinetics strongly suggest a branched reaction scheme with a branching ratio of 0.5 for the path leading to the PChlide ground state on the 200 ps timescale and the path leading to a long-lived state (>>700 ps). The results clearly support a branched reaction scheme, as proposed previously, featuring the formation of an intramolecular charge transfer state with ∼25 ps, its decay into the PChlide ground state with 200 ps, and a parallel reaction path to the long-lived PChlide triplet state

Stable isotopes (d(13)C, d(15)N) and biomarkers as indicators of the hydrological regime of fens in a European east-west transect

Peatland degradation is tightly connected to hydrological changes and microbial metabolism. To better understand these metabolism processes, more information is needed on how microbial communities and substrate cycling are affected by changing hydrological regimes. These activities should be imprinted in stable isotope bulk values (delta N-15, delta C-13) due to specific isotopic fractionation by different microbial communities, their metabolic pathways and nutrient sources. We hypothesize that stable isotope values and microbial abundance are correlated and act as indicators of dif-ferent hydrological regimes. We sampled an East-West transect across European fens in 14 areas and conducted a stable isotope (delta C-13, delta N-15) and membrane fatty acid (mFA) analysis. Within each area an undrained, drained and rewetted site was selected. Rewetted sites were separated based on when rewetting occurred. We found differences in the upper layers of all sites in microbial-derived mFAs and stable isotope values corresponding to hydrological re-gimes. The highest and lowest quantities of microbial-derived mFAs were measured in undrained and drained sites, respectively. Fungal-derived mFAs were especially lower in drained sites. Simultaneously, delta N-15 stable isotope values were highest in drained sites. In addition, stable isotope values and microbial-derived mFAs showed distinct depth trends. In undrained sites stable isotopes values slightly increased with depth. In drained sites, delta N-15 values decreased downwards, whereas delta C-13 values increased. Overall microbial-derived mFAs decreased with depth. These patterns presumably result from anoxic conditions and high peat recalcitrance in the deeper layers. In sites with short time of rewetting, the microbial-derived mFAs and stable isotope values were similar to values of drained sites, while with increasing rewetting time values shifted to those of undrained sites. We conclude that biomarkers indicate that stable isotope values reflect specific microbial metabolic processes, which differ with hydrological regimes, and thus could indicate both drainage and rewetting in fens

Griscelli Syndrome Type 2 Sine Albinism: Unraveling Differential RAB27A Effector Engagement.

Griscelli syndrome type 2 (GS-2) is an inborn error of immunity characterized by partial albinism and episodes of hemophagocytic lymphohistiocytosis (HLH). It is caused by RAB27A mutations that encode RAB27A, a member of the Rab GTPase family. RAB27A is expressed in many tissues and regulates vesicular transport and organelle dynamics. Occasionally, GS-2 patients with RAB27A mutation display normal pigmentation. The study of such variants provides the opportunity to map distinct binding sites for tissue-specific effectors on RAB27A. Here we present a new case of GS-2 without albinism (GS-2 sine albinism) caused by a novel missense mutation (Val143Ala) in the RAB27A and characterize its functional cellular consequences. Using pertinent animal cell lines, the Val143Ala mutation impairs both the RAB27A-SLP2-A interaction and RAB27A-MUNC13-4 interaction, but it does not affect the RAB27A-melanophilin (MLPH)/SLAC2-A interaction that is crucial for skin and hair pigmentation. We conclude that disruption of the RAB27A-MUNC13-4 interaction in cytotoxic lymphocytes leads to the HLH predisposition of the GS-2 patient with the Val143Ala mutation. Finally, we include a review of GS-2 sine albinism cases reported in the literature, summarizing their genetic and clinical characteristics

Germline biallelic PIK3CG mutations in a multifaceted immunodeficiency with immune dysregulation

International audienceThe PI3K-AKT-mTOR signaling axis is a critical molecular pathway in humans, regulating multiple cellular processes. Phosphatidylinositol-3-kinases (PI3K) represent key signaling hubs for signal propagation, driving cell activation, cell polarization and morphological adaptations. Studies on PI3K in human disease have highlighted PI3K-gamma (PI3Kγ) as an appealing drug target for treatment of human disorders.2 Murine PI3Kγ studies showed its importance in regulating innate immune functions and development and activation of T cells, revealing its role in controlling inflammation. However, its role in the human immune system and diseases remains to be investigated