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RGF1 controls root meristem size through ROS signalling 期刊论文
NATURE, 2020, 577 (7788) : 85-+
作者:  Yamada, Masashi;  Han, Xinwei;  Benfey, Philip N.
收藏  |  浏览/下载:27/0  |  提交时间:2020/07/03

The stem cell niche and the size of the root meristem in plants are maintained by intercellular interactions and signalling networks involving a peptide hormone, root meristem growth factor 1 (RGF1)(1). Understanding how RGF1 regulates the development of the root meristem is essential for understanding stem cell function. Although five receptors for RGF1 have been identified(2-4), the downstream signalling mechanism remains unknown. Here we report a series of signalling events that follow RGF1 activity. We find that the RGF1-receptor pathway controls the distribution of reactive oxygen species (ROS) along the developmental zones of the Arabidopsis root. We identify a previously uncharacterized transcription factor, RGF1-INDUCIBLE TRANSCRIPTION FACTOR 1 (RITF1), that has a central role in mediating RGF1 signalling. Manipulating RITF1 expression leads to the redistribution of ROS along the root developmental zones. Changes in ROS distribution in turn enhance the stability of the PLETHORA2 protein, a master regulator of root stem cells. Our results thus clearly depict a signalling cascade that is initiated by RGF1, linking this peptide to mechanisms that regulate ROS.


  
Hair-bearing human skin generated entirely from pluripotent stem cells 期刊论文
NATURE, 2020
作者:  von Appen, Alexander;  LaJoie, Dollie;  Johnson, Isabel E.;  Trnka, Michael J.;  Pick, Sarah M.;  Burlingame, Alma L.;  Ullman, Katharine S.;  Frost, Adam
收藏  |  浏览/下载:77/0  |  提交时间:2020/07/03

Skin organoids generated in vitro from human pluripotent stem cells form complex, multilayered skin tissue with hair follicles, sebaceous glands and neural circuitry, and integrate with endogenous skin when grafted onto immunocompromised mice.


The skin is a multilayered organ, equipped with appendages (that is, follicles and glands), that is critical for regulating body temperature and the retention of bodily fluids, guarding against external stresses and mediating the sensation of touch and pain(1,2). Reconstructing appendage-bearing skin in cultures and in bioengineered grafts is a biomedical challenge that has yet to be met(3-9). Here we report an organoid culture system that generates complex skin from human pluripotent stem cells. We use stepwise modulation of the transforming growth factor beta (TGF beta) and fibroblast growth factor (FGF) signalling pathways to co-induce cranial epithelial cells and neural crest cells within a spherical cell aggregate. During an incubation period of 4-5 months, we observe the emergence of a cyst-like skin organoid composed of stratified epidermis, fat-rich dermis and pigmented hair follicles that are equipped with sebaceous glands. A network of sensory neurons and Schwann cells form nerve-like bundles that target Merkel cells in organoid hair follicles, mimicking the neural circuitry associated with human touch. Single-cell RNA sequencing and direct comparison to fetal specimens suggest that the skin organoids are equivalent to the facial skin of human fetuses in the second trimester of development. Moreover, we show that skin organoids form planar hair-bearing skin when grafted onto nude mice. Together, our results demonstrate that nearly complete skin can self-assemble in vitro and be used to reconstitute skin in vivo. We anticipate that our skin organoids will provide a foundation for future studies of human skin development, disease modelling and reconstructive surgery.


  
Extra help for neuron grafts 期刊论文
NATURE, 2020, 582 (7810) : 39-40
作者:  Raz, Mical
收藏  |  浏览/下载:15/0  |  提交时间:2020/07/03

Grafts of stem-cell-derived precursors of dopamine neurons could be used to treat Parkinson'  s disease, but this approach has limitations. Injecting a growth factor three weeks after transplantation can overcome some of these limits.


Steps to improve function and survival of dopamine-neuron transplants.


  
AQP5 enriches for stem cells and cancer origins in the distal stomach 期刊论文
NATURE, 2020, 578 (7795) : 437-+
作者:  Athukoralage, Januka S.;  McMahon, Stephen A.;  Zhang, Changyi;  Grueschow, Sabine;  Graham, Shirley;  Krupovic, Mart;  Whitaker, Rachel J.;  Gloster, Tracey M.;  White, Malcolm F.
收藏  |  浏览/下载:42/0  |  提交时间:2020/07/03

LGR5 marks resident adult epithelial stem cells at the gland base in the mouse pyloric stomach(1), but the identity of the equivalent human stem cell population remains unknown owing to a lack of surface markers that facilitate its prospective isolation and validation. In mouse models of intestinal cancer, LGR5(+) intestinal stem cells are major sources of cancer following hyperactivation of the WNT pathway(2). However, the contribution of pyloric LGR5(+) stem cells to gastric cancer following dysregulation of the WNT pathway-a frequent event in gastric cancer in humans(3)-is unknown. Here we use comparative profiling of LGR5(+) stem cell populations along the mouse gastrointestinal tract to identify, and then functionally validate, the membrane protein AQP5 as a marker that enriches for mouse and human adult pyloric stem cells. We show that stem cells within the AQP5(+) compartment are a source of WNT-driven, invasive gastric cancer in vivo, using newly generated Aqp5-creERT2 mouse models. Additionally, tumour-resident AQP5(+) cells can selectively initiate organoid growth in vitro, which indicates that this population contains potential cancer stem cells. In humans, AQP5 is frequently expressed in primary intestinal and diffuse subtypes of gastric cancer (and in metastases of these subtypes), and often displays altered cellular localization compared with healthy tissue. These newly identified markers and mouse models will be an invaluable resource for deciphering the early formation of gastric cancer, and for isolating and characterizing human-stomach stem cells as a prerequisite for harnessing the regenerative-medicine potential of these cells in the clinic.


AQP5 is identified as a marker for pyloric stem cells in humans and mice, and stem cells in the AQP5(+) compartment are shown to be a source of invasive gastric cancer in mouse models.


  
Hydraulic limitations in dominant trees as a contributing mechanism to the age-related growth decline of boreal forest stands 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2018, 427: 135-142
作者:  Baret, Matthieu;  Pepin, Steeve;  Pothier, David
收藏  |  浏览/下载:16/0  |  提交时间:2019/04/09
Growth dominance  Stem sapflow  Leaf isotopic composition  Stand development  Old-growth stands  
Field evidences for the positive effects of aerosols on tree growth 期刊论文
GLOBAL CHANGE BIOLOGY, 2018, 24 (10) : 4983-4992
作者:  Wang, Xin;  Wu, Jin;  Chen, Min;  Xu, Xiangtao;  Wang, Zhenhua;  Wang, Bin;  Wang, Chengzhang;  Piao, Shilong;  Lin, Weili;  Miao, Guofang;  Deng, Meifeng;  Qiao, Chunlian;  Wang, Jing;  Xu, Shan;  Liu, Lingli
收藏  |  浏览/下载:27/0  |  提交时间:2019/04/09
aerosol loading  aerosol-meteorology interactions  canopy photosynthesis  diffuse radiation  mechanistic photosynthesis model  sun  shade leaf  tree stem growth  vapor pressure deficit  
Nitrogen deposition outweighs climatic variability in driving annual growth rate of canopy beech trees: Evidence from long-term growth reconstruction across a geographic gradient 期刊论文
GLOBAL CHANGE BIOLOGY, 2018, 24 (7) : 2898-2912
作者:  Gentilesca, Tiziana;  Rita, Angelo;  Brunetti, Michele;  Giammarchi, Francesco;  Leonardi, Stefano;  Magnani, Federico;  van Noije, Twan;  Tonon, Giustino;  Borghetti, Marco
收藏  |  浏览/下载:13/0  |  提交时间:2019/04/09
age  climate change  Fagus sylvatica L  forest  height growth  nitrogen deposition  stem analysis  volume growth  
Competition for water in a xeric forest ecosystem - Effects of understory removal on soil micro-climate, growth and physiology of dominant Scots pine trees 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2018, 409: 241-249
作者:  Giuggiola, Arnaud;  Zweifel, Roman;  Feichtinger, Linda M.;  Vollenweider, Pierre;  Bugmann, Harald;  Haeni, Matthias;  Rigling, Andreas
收藏  |  浏览/下载:19/0  |  提交时间:2019/04/09
Competition  Drought stress  Forest management  Land-use change  Predawn water potential  Sap flow  Stem growth  Tree physiology  
Growth and water use performance of four co-occurring riparian tree species in a Mediterranean riparian forest 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2017, 396
作者:  Nadal-Sala, Daniel;  Sabate, Santiago;  Sanchez-Costa, Elisenda;  Poblador, Silvia;  Sabater, Francesc;  Gracia, Carlos
收藏  |  浏览/下载:18/0  |  提交时间:2019/04/09
Mediterranean riparian forests  Black locust  Invasive tree species  Forest transpiration  Stem growth  Water use efficiency  
Evergreen and ever growing - Stem and canopy growth dynamics of a temperate eucalypt forest 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2017, 389
作者:  Griebel, Anne;  Bennett, Lauren T.;  Arndt, Stefan K.
收藏  |  浏览/下载:14/0  |  提交时间:2019/04/09
Canopy dynamics  Carbon allocation  Eddy covariance  Eucalypt forest  Stem growth  Terrestrial lidar