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  • 1
    Publikationsdatum: 2014-10-23
    Beschreibung: Morphogenesis is the process whereby cell collectives are shaped into differentiated tissues and organs. The self-organizing nature of morphogenesis has been recently demonstrated by studies showing that stem cells in three-dimensional culture can generate complex organoids, such as mini-guts, optic-cups and even mini-brains. To achieve this, cell collectives must regulate the activity of secreted signalling molecules that control cell differentiation, presumably through the self-assembly of microenvironments or niches. However, mechanisms that allow changes in tissue architecture to feedback directly on the activity of extracellular signals have not been described. Here we investigate how the process of tissue assembly controls signalling activity during organogenesis in vivo, using the migrating zebrafish lateral line primordium. We show that fibroblast growth factor (FGF) activity within the tissue controls the frequency at which it deposits rosette-like mechanosensory organs. Live imaging reveals that FGF becomes specifically concentrated in microluminal structures that assemble at the centre of these organs and spatially constrain its signalling activity. Genetic inhibition of microlumen assembly and laser micropuncture experiments demonstrate that microlumina increase signalling responses in participating cells, thus allowing FGF to coordinate the migratory behaviour of cell groups at the tissue rear. As the formation of a central lumen is a self-organizing property of many cell types, such as epithelia and embryonic stem cells, luminal signalling provides a potentially general mechanism to locally restrict, coordinate and enhance cell communication within tissues.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Durdu, Sevi -- Iskar, Murat -- Revenu, Celine -- Schieber, Nicole -- Kunze, Andreas -- Bork, Peer -- Schwab, Yannick -- Gilmour, Darren -- England -- Nature. 2014 Nov 6;515(7525):120-4. doi: 10.1038/nature13852. Epub 2014 Oct 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Molecular Biology Laboratory Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25337877" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Cell Communication ; Cell Differentiation ; Cell Movement ; Dose-Response Relationship, Drug ; Extracellular Space/metabolism ; Fibroblast Growth Factors/metabolism/secretion ; *Organogenesis ; *Signal Transduction ; Time Factors ; Zebrafish/*embryology/metabolism
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2015-02-24
    Beschreibung: Pancreatic beta cells lower insulin release in response to nutrient depletion. The question of whether starved beta cells induce macroautophagy, a predominant mechanism maintaining energy homeostasis, remains poorly explored. We found that, in contrast to many mammalian cells, macroautophagy in pancreatic beta cells was suppressed upon starvation. Instead, starved beta cells induced lysosomal degradation of nascent secretory insulin granules, which was controlled by protein kinase D (PKD), a key player in secretory granule biogenesis. Starvation-induced nascent granule degradation triggered lysosomal recruitment and activation of mechanistic target of rapamycin that suppressed macroautophagy. Switching from macroautophagy to insulin granule degradation was important to keep insulin secretion low upon fasting. Thus, beta cells use a PKD-dependent mechanism to adapt to nutrient availability and couple autophagy flux to secretory function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Goginashvili, Alexander -- Zhang, Zhirong -- Erbs, Eric -- Spiegelhalter, Coralie -- Kessler, Pascal -- Mihlan, Michael -- Pasquier, Adrien -- Krupina, Ksenia -- Schieber, Nicole -- Cinque, Laura -- Morvan, Joelle -- Sumara, Izabela -- Schwab, Yannick -- Settembre, Carmine -- Ricci, Romeo -- New York, N.Y. -- Science. 2015 Feb 20;347(6224):878-82. doi: 10.1126/science.aaa2628.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM, CNRS, Universite de Strasbourg, 67404 Illkirch, France. ; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany. ; Dulbecco Telethon Institute and Telethon Institute of Genetics and Medicine (TIGEM), 80131 Naples, Italy. ; Dulbecco Telethon Institute and Telethon Institute of Genetics and Medicine (TIGEM), 80131 Naples, Italy. Medical Genetics, Department of Medical and Translational Science Unit, Federico II University, Via Pansini 5, 80131 Naples, Italy. ; Institut de Genetique et de Biologie Moleculaire et Cellulaire (IGBMC), INSERM, CNRS, Universite de Strasbourg, 67404 Illkirch, France. Nouvel Hopital Civil, Laboratoire de Biochimie et de Biologie Moleculaire, Universite de Strasbourg, 67091 Strasbourg, France. romeo.ricci@igbmc.fr.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25700520" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Autophagy ; Cells, Cultured ; Fasting ; Humans ; Insulin/*secretion ; Insulin-Secreting Cells/*physiology/secretion/ultrastructure ; Mice ; Mice, Mutant Strains ; Mice, Transgenic ; Mitogen-Activated Protein Kinase 13/genetics ; Protein Kinase C/physiology ; Secretory Vesicles/*physiology/secretion
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2015-09-22
    Print ISSN: 0022-1007
    Digitale ISSN: 1540-9538
    Thema: Medizin
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2015-09-03
    Beschreibung: Dysfunction of caveolae is involved in human muscle disease, although the underlying molecular mechanisms remain unclear. In this paper, we have functionally characterized mouse and zebrafish models of caveolae-associated muscle disease. Using electron tomography, we quantitatively defined the unique three-dimensional membrane architecture of the mature muscle surface. Caveolae occupied around 50% of the sarcolemmal area predominantly assembled into multilobed rosettes. These rosettes were preferentially disassembled in response to increased membrane tension. Caveola-deficient cavin-1 –/– muscle fibers showed a striking loss of sarcolemmal organization, aberrant T-tubule structures, and increased sensitivity to membrane tension, which was rescued by muscle-specific Cavin-1 reexpression. In vivo imaging of live zebrafish embryos revealed that loss of muscle-specific Cavin-1 or expression of a dystrophy-associated Caveolin-3 mutant both led to sarcolemmal damage but only in response to vigorous muscle activity. Our findings define a conserved and critical role in mechanoprotection for the unique membrane architecture generated by the caveolin–cavin system.
    Digitale ISSN: 1540-8140
    Thema: Biologie
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2013-12-25
    Beschreibung: Control of lipid droplet (LD) nucleation and copy number are critical, yet poorly understood, processes. We use model peptides that shift from the endoplasmic reticulum (ER) to LDs in response to fatty acids to characterize the initial steps of LD formation occurring in lipid-starved cells. Initially, arriving lipids are rapidly packed in LDs that are resistant to starvation (pre-LDs). Pre-LDs are restricted ER microdomains with a stable core of neutral lipids. Subsequently, a first round of "emerging" LDs is nucleated, providing additional lipid storage capacity. Finally, in proportion to lipid concentration, new rounds of LDs progressively assemble. Confocal microscopy and electron tomography suggest that emerging LDs are nucleated in a limited number of ER microdomains after a synchronized stepwise process of protein gathering, lipid packaging, and recognition by Plin3 and Plin2. A comparative analysis demonstrates that the acyl-CoA synthetase 3 is recruited early to the assembly sites, where it is required for efficient LD nucleation and lipid storage.
    Digitale ISSN: 1540-8140
    Thema: Biologie
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2015-02-04
    Beschreibung: Sphingomyelin (SM) is a major sphingolipid in mammalian cells and is reported to form specific lipid domains together with cholesterol. However, methods to examine the membrane distribution of SM are limited. We demonstrated in model membranes that fluorescent protein conjugates of 2 specific SM-binding toxins, lysenin (Lys) and equinatoxin II (EqtII), recognize different membrane distributions of SM; Lys exclusively binds clustered SM, whereas EqtII preferentially binds dispersed SM. Freeze-fracture immunoelectron microscopy showed that clustered but not dispersed SM formed lipid domains on the cell surface. Glycolipids and the membrane concentration of SM affect the SM distribution pattern on the plasma membrane. Using derivatives of Lys and EqtII as SM distribution-sensitive probes, we revealed the exclusive accumulation of SM clusters in the midbody at the time of cytokinesis. Interestingly, apical membranes of differentiated epithelial cells exhibited dispersed SM distribution, whereas SM was clustered in basolateral membranes. Clustered but not dispersed SM was absent from the cell surface of acid sphingomyelinase-deficient Niemann-Pick type A cells. These data suggest that both the SM content and membrane distribution are crucial for pathophysiological events bringing therapeutic perspective in the role of SM membrane distribution.—Makino, A., Abe, M., Murate, M., Inaba, T., Yilmaz, N., Hullin-Matsuda, F., Kishimoto, T., Schieber, N. L., Taguchi, T., Arai, H., Anderluh, G., Parton, R. G., Kobayashi, T. Visualization of the heterogeneous membrane distribution of sphingomyelin associated with cytokinesis, cell polarity, and sphingolipidosis.
    Print ISSN: 0892-6638
    Digitale ISSN: 1530-6860
    Thema: Biologie
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Publikationsdatum: 2017-03-31
    Beschreibung: We identified a novel, nontoxic mushroom protein that specifically binds to a complex of sphingomyelin (SM), a major sphingolipid in mammalian cells, and cholesterol (Chol). The purified protein, termed nakanori, labeled cell surface domains in an SM- and Chol-dependent manner and decorated specific lipid domains that colocalized with inner leaflet small GTPase H-Ras, but not K-Ras. The use of nakanori as a lipid-domain–specific probe revealed altered distribution and dynamics of SM/Chol on the cell surface of Niemann-Pick type C fibroblasts, possibly explaining some of the disease phenotype. In addition, that nakanori treatment of epithelial cells after influenza virus infection potently inhibited virus release demonstrates the therapeutic value of targeting specific lipid domains for anti-viral treatment.—Makino, A., Abe, M., Ishitsuka, R., Murate, M., Kishimoto, T., Sakai, S., Hullin-Matsuda, F., Shimada, Y., Inaba, T., Miyatake, H., Tanaka, H., Kurahashi, A., Pack, C.-G., Kasai, R. S., Kubo, S., Schieber, N. L., Dohmae, N., Tochio, N., Hagiwara, K., Sasaki, Y., Aida, Y., Fujimori, F., Kigawa, T., Nishibori, K., Parton, R. G., Kusumi, A., Sako, Y., Anderluh, G., Yamashita, M., Kobayashi, T., Greimel, P., Kobayashi, T. A novel sphingomyelin/cholesterol domain-specific probe reveals the dynamics of the membrane domains during virus release and in Niemann-Pick type C.
    Print ISSN: 0892-6638
    Digitale ISSN: 1530-6860
    Thema: Biologie
    Standort Signatur Einschränkungen Verfügbarkeit
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