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  • 1
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    Distinct stem cells contribute to mammary gland development and maintenance (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-10-11
    Description: The mammary epithelium is composed of several cell lineages including luminal, alveolar and myoepithelial cells. Transplantation studies have suggested that the mammary epithelium is maintained by the presence of multipotent mammary stem cells. To define the cellular hierarchy of the mammary gland during physiological conditions, we performed genetic lineage-tracing experiments and clonal analysis of the mouse mammary gland during development, adulthood and pregnancy. We found that in postnatal unperturbed mammary gland, both luminal and myoepithelial lineages contain long-lived unipotent stem cells that display extensive renewing capacities, as demonstrated by their ability to clonally expand during morphogenesis and adult life as well as undergo massive expansion during several cycles of pregnancy. The demonstration that the mammary gland contains different types of long-lived stem cells has profound implications for our understanding of mammary gland physiology and will be instrumental in unravelling the cells at the origin of breast cancers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Van Keymeulen, Alexandra -- Rocha, Ana Sofia -- Ousset, Marielle -- Beck, Benjamin -- Bouvencourt, Gaelle -- Rock, Jason -- Sharma, Neha -- Dekoninck, Sophie -- Blanpain, Cedric -- England -- Nature. 2011 Oct 9;479(7372):189-93. doi: 10.1038/nature10573.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Universite Libre de Bruxelles, IRIBHM, Brussels B-1070, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21983963" target="_blank"〉PubMed〈/a〉
    Keywords: Aging ; Animals ; Cell Differentiation ; *Cell Lineage ; Cell Transplantation ; Epithelium ; Female ; Homeostasis ; Lactation/physiology ; Mammary Glands, Animal/*cytology/*growth & development/physiology/transplantation ; Mice ; Multipotent Stem Cells/cytology ; Pregnancy ; Stem Cells/*cytology/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    A vascular niche and a VEGF-Nrp1 loop regulate the initiation and stemness of skin tumours (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-10-21
    Description: Angiogenesis is critical during tumour initiation and malignant progression. Different strategies aimed at blocking vascular endothelial growth factor (VEGF) and its receptors have been developed to inhibit angiogenesis in cancer patients. It has become increasingly clear that in addition to its effect on angiogenesis, other mechanisms including a direct effect of VEGF on tumour cells may account for the efficiency of VEGF-blockade therapies. Cancer stem cells (CSCs) have been described in various cancers including squamous tumours of the skin. Here we use a mouse model of skin tumours to investigate the impact of the vascular niche and VEGF signalling on controlling the stemness (the ability to self renew and differentiate) of squamous skin tumours during the early stages of tumour progression. We show that CSCs of skin papillomas are localized in a perivascular niche, in the immediate vicinity of endothelial cells. Furthermore, blocking VEGFR2 caused tumour regression not only by decreasing the microvascular density, but also by reducing CSC pool size and impairing CSC renewal properties. Conditional deletion of Vegfa in tumour epithelial cells caused tumours to regress, whereas VEGF overexpression by tumour epithelial cells accelerated tumour growth. In addition to its well-known effect on angiogenesis, VEGF affected skin tumour growth by promoting cancer stemness and symmetric CSC division, leading to CSC expansion. Moreover, deletion of neuropilin-1 (Nrp1), a VEGF co-receptor expressed in cutaneous CSCs, blocked VEGF's ability to promote cancer stemness and renewal. Our results identify a dual role for tumour-cell-derived VEGF in promoting cancer stemness: by stimulating angiogenesis in a paracrine manner, VEGF creates a perivascular niche for CSCs, and by directly affecting CSCs through Nrp1 in an autocrine loop, VEGF stimulates cancer stemness and renewal. Finally, deletion of Nrp1 in normal epidermis prevents skin tumour initiation. These results may have important implications for the prevention and treatment of skin cancers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beck, Benjamin -- Driessens, Gregory -- Goossens, Steven -- Youssef, Khalil Kass -- Kuchnio, Anna -- Caauwe, Amelie -- Sotiropoulou, Panagiota A -- Loges, Sonja -- Lapouge, Gaelle -- Candi, Aurelie -- Mascre, Guilhem -- Drogat, Benjamin -- Dekoninck, Sophie -- Haigh, Jody J -- Carmeliet, Peter -- Blanpain, Cedric -- England -- Nature. 2011 Oct 19;478(7369):399-403. doi: 10.1038/nature10525.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉IRIBHM, Universite Libre de Bruxelles, 808 route de Lennik, 1070 Brussels, Belgium.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22012397" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carcinoma, Squamous Cell/*blood supply/*pathology ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Disease Models, Animal ; Epithelial Cells/cytology ; Gene Deletion ; Gene Expression Regulation, Neoplastic ; Mice ; Neoplastic Stem Cells ; Neuropilin-1/genetics/*metabolism ; *Signal Transduction ; Skin Neoplasms/*blood supply/*pathology ; Vascular Endothelial Growth Factor A/genetics/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Earliest evidence of mammalian social behaviour in the basal Tertiary of Bolivia (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-05-10
    Description: The vast majority of Mesozoic and early Cenozoic metatherian mammals (extinct relatives of modern marsupials) are known only from partial jaws or isolated teeth, which give insight into their probable diets and phylogenetic relationships but little else. The few skulls known are generally crushed, incomplete or both, and associated postcranial material is extremely rare. Here we report the discovery of an exceptionally large number of almost undistorted, nearly complete skulls and skeletons of a stem-metatherian, Pucadelphys andinus, in the early Palaeocene epoch of Tiupampa in Bolivia. These give an unprecedented glimpse into early metatherian morphology, evolutionary relationships and, especially, ecology. The remains of 35 individuals have been collected, with 22 of these represented by nearly complete skulls and associated postcrania. These individuals were probably buried in a single catastrophic event, and so almost certainly belong to the same population. The preservation of multiple adult, sub-adult and juvenile individuals in close proximity (〈1 m(2)) is indicative of gregarious social behaviour or at least a high degree of social tolerance and frequent interaction. Such behaviour is unknown in living didelphids, which are highly solitary and have been regarded, perhaps wrongly, as the most generalized living marsupials. The Tiupampan P. andinus population also exhibits strong sexual dimorphism, which, in combination with gregariousness, suggests strong male-male competition and polygyny. Our study shows that social interactions occurred in metatherians as early as the basal Palaeocene and that solitary behaviour may not be plesiomorphic for Metatheria as a whole.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ladeveze, Sandrine -- de Muizon, Christian -- Beck, Robin M D -- Germain, Damien -- Cespedes-Paz, Ricardo -- England -- Nature. 2011 Jun 2;474(7349):83-6. doi: 10.1038/nature09987. Epub 2011 May 8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Paleontology, Royal Belgian Institute of Natural Sciences, 29 rue Vautier, B-1000 Brussels, Belgium. sandrine.ladeveze@naturalsciences.be〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21552278" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bolivia ; Female ; *Fossils ; Male ; Marsupialia/anatomy & histology/*classification ; Sex Characteristics ; *Social Behavior
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-04-02
    Description: Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies. Here we report observations of gravity-mode period spacings in red giants that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly approximately 50 seconds) and those that are also burning helium (period spacing approximately 100 to 300 seconds).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bedding, Timothy R -- Mosser, Benoit -- Huber, Daniel -- Montalban, Josefina -- Beck, Paul -- Christensen-Dalsgaard, Jorgen -- Elsworth, Yvonne P -- Garcia, Rafael A -- Miglio, Andrea -- Stello, Dennis -- White, Timothy R -- De Ridder, Joris -- Hekker, Saskia -- Aerts, Conny -- Barban, Caroline -- Belkacem, Kevin -- Broomhall, Anne-Marie -- Brown, Timothy M -- Buzasi, Derek L -- Carrier, Fabien -- Chaplin, William J -- Di Mauro, Maria Pia -- Dupret, Marc-Antoine -- Frandsen, Soren -- Gilliland, Ronald L -- Goupil, Marie-Jo -- Jenkins, Jon M -- Kallinger, Thomas -- Kawaler, Steven -- Kjeldsen, Hans -- Mathur, Savita -- Noels, Arlette -- Aguirre, Victor Silva -- Ventura, Paolo -- England -- Nature. 2011 Mar 31;471(7340):608-11. doi: 10.1038/nature09935.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sydney Institute for Astronomy, School of Physics, University of Sydney, New South Wales 2006, Australia. t.bedding@physics.usyd.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21455175" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
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    Fast core rotation in red-giant stars as revealed by gravity-dominated mixed modes (2011)
    Nature Publishing Group (NPG)
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    Publication Date: 2011-12-14
    Description: When the core hydrogen is exhausted during stellar evolution, the central region of a star contracts and the outer envelope expands and cools, giving rise to a red giant. Convection takes place over much of the star's radius. Conservation of angular momentum requires that the cores of these stars rotate faster than their envelopes; indirect evidence supports this. Information about the angular-momentum distribution is inaccessible to direct observations, but it can be extracted from the effect of rotation on oscillation modes that probe the stellar interior. Here we report an increasing rotation rate from the surface of the star to the stellar core in the interiors of red giants, obtained using the rotational frequency splitting of recently detected 'mixed modes'. By comparison with theoretical stellar models, we conclude that the core must rotate at least ten times faster than the surface. This observational result confirms the theoretical prediction of a steep gradient in the rotation profile towards the deep stellar interior.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beck, Paul G -- Montalban, Josefina -- Kallinger, Thomas -- De Ridder, Joris -- Aerts, Conny -- Garcia, Rafael A -- Hekker, Saskia -- Dupret, Marc-Antoine -- Mosser, Benoit -- Eggenberger, Patrick -- Stello, Dennis -- Elsworth, Yvonne -- Frandsen, Soren -- Carrier, Fabien -- Hillen, Michel -- Gruberbauer, Michael -- Christensen-Dalsgaard, Jorgen -- Miglio, Andrea -- Valentini, Marica -- Bedding, Timothy R -- Kjeldsen, Hans -- Girouard, Forrest R -- Hall, Jennifer R -- Ibrahim, Khadeejah A -- England -- Nature. 2011 Dec 7;481(7379):55-7. doi: 10.1038/nature10612.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Leuven, Belgium. paul.beck@ster.kuleuven.be〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22158105" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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