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result(s) for
"Grimm, Christian"
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In a glass Grimmly
Frog joins cousins Jack and Jill in leaving their own stories to seek a magic mirror, encountering such creatures as giants, mermaids, and goblins along the way. Based in part on fairy tales from the Brothers Grimm and Hans Christian Andersen.
Book
Two-pore channels control Ebola virus host cell entry and are drug targets for disease treatment
Ebola virus causes sporadic outbreaks of lethal hemorrhagic fever in humans, but there is no currently approved therapy. Cells take up Ebola virus by macropinocytosis, followed by trafficking through endosomal vesicles. However, few factors controlling endosomal virus movement are known. Here we find that Ebola virus entry into host cells requires the endosomal calcium channels called two-pore channels (TPCs). Disrupting TPC function by gene knockout, small interfering RNAs, or small-molecule inhibitors halted virus trafficking and prevented infection. Tetrandrine, the most potent small molecule that we tested, inhibited infection of human macrophages, the primary target of Ebola virus in vivo, and also showed therapeutic efficacy in mice. Therefore, TPC proteins play a key role in Ebola virus infection and may be effective targets for antiviral therapy.
Journal Article
أروع القصص الخيالية
يعد هذا الكتاب وهي قصص مخصصة للأطفال يتحدث عن القصص الخيالية تستهدف الطفولة المبكرة وتعمل على استثمار الطفل في بناء المهارات المختلفة المرتبطة بالخيال والابتكار وقوة الشخصية والبحث عن حلول إبداعية ويستمد الطفل من خلالها الكثير من العلم والمعرفة والمعلومات ويعد من المنهج السلوكي التربوي رائع يعلم الطفل كيف يستخلص من مشكلاته.
Book
CLN3 is required for the clearance of glycerophosphodiesters from lysosomes
Lysosomes have many roles, including degrading macromolecules and signalling to the nucleus
1
. Lysosomal dysfunction occurs in various human conditions, such as common neurodegenerative diseases and monogenic lysosomal storage disorders (LSDs)
2
–
4
. For most LSDs, the causal genes have been identified but, in some, the function of the implicated gene is unknown, in part because lysosomes occupy a small fraction of the cellular volume so that changes in lysosomal contents are difficult to detect. Here we develop the LysoTag mouse for the tissue-specific isolation of intact lysosomes that are compatible with the multimodal profiling of their contents. We used the LysoTag mouse to study CLN3, a lysosomal transmembrane protein with an unknown function. In children, the loss of
CLN3
causes juvenile neuronal ceroid lipofuscinosis (Batten disease), a lethal neurodegenerative LSD. Untargeted metabolite profiling of lysosomes from the brains of mice lacking CLN3 revealed a massive accumulation of glycerophosphodiesters (GPDs)—the end products of glycerophospholipid catabolism. GPDs also accumulate in the lysosomes of CLN3-deficient cultured cells and we show that CLN3 is required for their lysosomal egress. Loss of CLN3 also disrupts glycerophospholipid catabolism in the lysosome. Finally, we found elevated levels of glycerophosphoinositol in the cerebrospinal fluid of patients with Batten disease, suggesting the potential use of glycerophosphoinositol as a disease biomarker. Our results show that CLN3 is required for the lysosomal clearance of GPDs and reveal Batten disease as a neurodegenerative LSD with a defect in glycerophospholipid metabolism.
The lysosomal transmembrane protein CLN3 is required for the lysosomal clearance of glycerophosphodiesters in mice and in human cells, suggesting that the loss of CLN3 causes Batten disease in children due to defects in glycerophospholipid metabolism.
Journal Article
Endolysosomal Cation Channels and MITF in Melanocytes and Melanoma
Microphthalmia-associated transcription factor (MITF) is the principal transcription factor regulating pivotal processes in melanoma cell development, growth, survival, proliferation, differentiation and invasion. In recent years, convincing evidence has been provided attesting key roles of endolysosomal cation channels, specifically TPCs and TRPMLs, in cancer, including breast cancer, glioblastoma, bladder cancer, hepatocellular carcinoma and melanoma. In this review, we provide a gene expression profile of these channels in different types of cancers and decipher their roles, in particular the roles of two-pore channel 2 (TPC2) and TRPML1 in melanocytes and melanoma. We specifically discuss the signaling cascades regulating MITF and the relationship between endolysosomal cation channels, MAPK, canonical Wnt/GSK3 pathways and MITF.
Journal Article
mRNA trans-splicing dual AAV vectors for (epi)genome editing and gene therapy
Large genes including several CRISPR-Cas modules like gene activators (CRISPRa) require dual adeno-associated viral (AAV) vectors for an efficient in vivo delivery and expression. Current dual AAV vector approaches have important limitations, e.g., low reconstitution efficiency, production of alien proteins, or low flexibility in split site selection. Here, we present a dual AAV vector technology based on
re
constitution
v
ia m
R
NA
t
rans-splicing (REVeRT). REVeRT is flexible in split site selection and can efficiently reconstitute different split genes in numerous in vitro models, in human organoids, and in vivo. Furthermore, REVeRT can functionally reconstitute a CRISPRa module targeting genes in various mouse tissues and organs in single or multiplexed approaches upon different routes of administration. Finally, REVeRT enabled the reconstitution of full-length ABCA4 after intravitreal injection in a mouse model of Stargardt disease. Due to its flexibility and efficiency REVeRT harbors great potential for basic research and clinical applications.
Large genes require dual adeno-associated viral (AAV) vectors for in vivo delivery/expression, but current methods have limitations. Here the authors develop and functionally evaluate REVeRT, an efficient and flexible dual AAV vector technology based on reconstitution via mRNA trans-splicing.
Journal Article
Targeting Hif1a rescues cone degeneration and prevents subretinal neovascularization in a model of chronic hypoxia
Background
Degeneration of cone photoreceptors leads to loss of vision in patients suffering from age-related macular degeneration (AMD) and other cone dystrophies. Evidence, such as choroidal ischemia and decreased choroidal blood flow, implicates reduced tissue oxygenation in AMD pathology and suggests a role of the cellular response to hypoxia in disease onset and progression. Such a chronic hypoxic situation may promote several cellular responses including stabilization of hypoxia-inducible factors (HIFs).
Methods
To investigate the consequence of a chronic activation of the molecular response to hypoxia in cones, von Hippel Lindau protein (VHL) was specifically ablated in cones of the all-cone
R91W;Nrl
-/-
mouse. Retinal function and morphology was evaluated by ERG and light microscopy, while differential gene expression was tested by real-time PCR. Retinal vasculature was analyzed by immunostainings and fluorescein angiography. Two-way ANOVA with Šídák’s multiple comparison test was performed for statistical analysis.
Results
Cone-specific ablation of
Vhl
resulted in stabilization and activation of hypoxia-inducible factor 1A (HIF1A) which led to increased expression of genes associated with hypoxia and retinal stress. Our data demonstrate severe cone degeneration and pathologic vessel growth, features that are central to AMD pathology. Subretinal neovascularization was accompanied by vascular leakage and infiltration of microglia cells. Interestingly, we observed increased expression of tissue inhibitor of metalloproteinase 3 (
Timp3
) during the aging process, a gene associated with AMD and Bruch’s membrane integrity. Additional deletion of
Hif1a
protected cone cells, prevented pathological vessel growth and preserved vision.
Conclusions
Our data provide evidence for a HIF1A-mediated mechanism leading to pathological vessel growth and cone degeneration in response to a chronic hypoxia-like situation. Consequently, our results identify HIF1A as a potential therapeutic target to rescue hypoxia-related vision loss in patients.
Journal Article
Agonist-mediated switching of ion selectivity in TPC2 differentially promotes lysosomal function
Ion selectivity is a defining feature of a given ion channel and is considered immutable. Here we show that ion selectivity of the lysosomal ion channel TPC2, which is hotly debated (Calcraft et al., 2009; Guo et al., 2017; Jha et al., 2014; Ruas et al., 2015; Wang et al., 2012), depends on the activating ligand. A high-throughput screen identified two structurally distinct TPC2 agonists. One of these evoked robust Ca2+-signals and non-selective cation currents, the other weaker Ca2+-signals and Na+-selective currents. These properties were mirrored by the Ca2+-mobilizing messenger, NAADP and the phosphoinositide, PI(3,5)P2, respectively. Agonist action was differentially inhibited by mutation of a single TPC2 residue and coupled to opposing changes in lysosomal pH and exocytosis. Our findings resolve conflicting reports on the permeability and gating properties of TPC2 and they establish a new paradigm whereby a single ion channel mediates distinct, functionally-relevant ionic signatures on demand.
Journal Article
TRPML2 in distinct states reveals the activation and modulation principles of the TRPML family
TRPML2 activity is critical for endolysosomal integrity and chemokine secretion, and can be modulated by various ligands. Interestingly, two ML-SI3 isomers regulate TRPML2 oppositely. The molecular mechanism underlying this unique isomeric preference as well as the TRPML2 agonistic mechanism remains unknown. Here, we present six cryo-EM structures of human TRPML2 in distinct states revealing that the π-bulge of the S6 undergoes a π-α transition upon agonist binding, highlighting the remarkable role of the π-bulge in ion channel regulation. Moreover, we identify that PI(3,5)P
2
allosterically affects the pose of ML2-SA1, a TRPML2 specific activator, resulting in an open channel without the π-α transition. Functional and structural studies show that mutating the S5 of TRPML1 to that of TRPML2 enables the mutated TRPML1 to be activated by (+)ML-SI3 and ML2-SA1. Thus, our work elucidates the activation mechanism of TRPML channels and paves the way for the development of selective TRPML modulators.
TRPML2, a lysosomal TRP channel, regulates endolysosomal integrity and chemokine secretion. This work reports the cryo-EM structures of TRPML2 in multiple states bound to modulators revealing its diverse regulatory mechanisms among ion channels.
Journal Article