scholarly journals Lattice defects induce microtubule self-renewal

2018 ◽  
Author(s):  
Laura Schaedel ◽  
Denis Chrétien ◽  
Charlotte Aumeier ◽  
Jérémie Gaillard ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Mechanical Stress ◽  
Dynamic Instability ◽  
Structural Defects ◽  
Structural Rearrangements ◽  
Self Renewal ◽  
Tubulin Dimer ◽  
Fast Growing ◽  
Core Property ◽  
Apparent Stability

ABSTRACTThe dynamic instability of microtubules is powered by the addition and removal of tubulin dimers at the ends of the microtubule. Apart from the end, the microtubule shaft is not considered to be dynamic. However recent evidence suggests that free dimers can be incorporated into the shaft of a microtubule damaged by mechanical stress. Here we explored whether dimer exchange was a core property of the microtubule lattice independently of any external constraint. We found that dimers can be removed from and incorporated into the lattice at sites along the microtubule shaft. Furthermore, we showed by experiment and by modeling that rapid dimer renewal requires structural defects in the lattice, which occur in fast growing microtubules. Hence long-lived microtubules have the capacity to self-renew despite their apparent stability and thereby can potentially regulate signaling pathways and structural rearrangements associated with tubulin-dimer exchange at sites along their entire length.

scholarly journals Differential Coupling of Self-Renewal Signaling Pathways in Murine Induced Pluripotent Stem Cells

PLoS ONE ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. e30234 ◽  
Author(s):  
Luca Orlando ◽  
Yolanda Sanchez-Ripoll ◽  
James Foster ◽  
Heather Bone ◽  
Claudia Giachino ◽  
...  
Keyword(s):  
Stem Cells ◽  
Induced Pluripotent Stem Cells ◽  
Signaling Pathways ◽  
Pluripotent Stem Cells ◽  
Self Renewal ◽  
Induced Pluripotent ◽  
Differential Coupling

scholarly journals Maintenance of Hematopoietic Stem Cells Through Regulation of Wnt and mTOR Pathways.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2309-2309
Author(s):  
Jian Huang ◽  
Peter S. Klein
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Signaling Pathways ◽  
Glycogen Synthase ◽  
Dependent Manner ◽  
Mtor Inhibition ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 2309 Hematopoietic stem cells (HSCs) maintain the ability to self-renew and to differentiate into all lineages of the blood. The signaling pathways regulating hematopoietic stem cell (HSCs) self-renewal and differentiation are not well understood. We are very interested in understanding the roles of glycogen synthase kinase-3 (Gsk3) and the signaling pathways regulated by Gsk3 in HSCs. In our previous study (Journal of Clinical Investigation, December 2009) using loss of function approaches (inhibitors, RNAi, and knockout) in mice, we found that Gsk3 plays a pivotal role in controlling the decision between self-renewal and differentiation of HSCs. Disruption of Gsk3 in bone marrow transiently expands HSCs in a b-catenin dependent manner, consistent with a role for Wnt signaling. However, in long-term repopulation assays, disruption of Gsk3 progressively depletes HSCs through activation of mTOR. This long-term HSC depletion is prevented by mTOR inhibition and exacerbated by b-catenin knockout. Thus GSK3 regulates both Wnt and mTOR signaling in HSCs, with opposing effects on HSC self-renewal such that inhibition of Gsk3 in the presence of rapamycin expands the HSC pool in vivo. In the current study, we found that suppression of the mammalian target of rapamycin (mTOR) pathway, an established nutrient sensor, combined with activation of canonical Wnt/ß-catenin signaling, allows the ex vivo maintenance of human and mouse long-term HSCs under cytokine-free conditions. We also show that combining two clinically approved medications that activate Wnt/ß-catenin signaling and inhibit mTOR increases the number of long-term HSCs in vivo. Disclosures: No relevant conflicts of interest to declare.

Signaling pathways influencing stem cell self-renewal and differentiation—Special emphasis on cardiomyocytes

2021 ◽  
pp. 157-168
Author(s):  
Selvaraj Jayaraman ◽  
Ponnulakshmi Rajagopal ◽  
Vijayalakshmi Periyasamy ◽  
Kanagaraj Palaniyandi ◽  
R. Ileng Kumaran ◽  
...  
Keyword(s):  
Stem Cell ◽  
Signaling Pathways ◽  
Self Renewal

scholarly journals Protein Kinases and Their Inhibitors in Pluripotent Stem Cell Fate Regulation

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Jungwoon Lee ◽  
Young-Jun Park ◽  
Haiyoung Jung
Keyword(s):  
Stem Cells ◽  
Signaling Pathways ◽  
Protein Kinases ◽  
Cell Fate ◽  
Pluripotent Stem Cells ◽  
Intracellular Signaling ◽  
Regulatory Networks ◽  
Kinase Signaling ◽  
Self Renewal ◽  
Lineage Differentiation

Protein kinases modulate the reversible postmodifications of substrate proteins to their phosphorylated forms as an essential process in regulating intracellular signaling transduction cascades. Moreover, phosphorylation has recently been shown to tightly control the regulatory network of kinases responsible for the induction and maintenance of pluripotency, defined as the particular ability to differentiate pluripotent stem cells (PSCs) into every cell type in the adult body. In particular, emerging evidence indicates that the balance between the self-renewal and differentiation of PSCs is regulated by the small molecules that modulate kinase signaling pathways. Furthermore, new reprogramming technologies have been developed using kinase modulators, which have provided novel insight of the mechanisms underlying the kinase regulatory networks involved in the generation of induced pluripotent stem cells (iPSCs). In this review, we highlight the recent progress made in defining the roles of protein kinase signaling pathways and their small molecule modulators in regulating the pluripotent states, self-renewal, reprogramming process, and lineage differentiation of PSCs.

Ca2+ -depended signaling pathways regulate self-renewal and pluripotency of stem cells

2018 ◽  
Vol 42 (9) ◽  
pp. 1086-1096 ◽  
Author(s):  
Alexander Ermakov ◽  
Alexandra Daks ◽  
Olga Fedorova ◽  
Oleg Shuvalov ◽  
Nickolai A. Barlev
Keyword(s):  
Stem Cells ◽  
Signaling Pathways ◽  
Self Renewal

Lnk Constrains Oncogenic JAK2-Induced Myeloproliferative Disease in Mice.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1437-1437
Author(s):  
Alexey Bersenev ◽  
Chao Wu ◽  
Joanna Balcerek ◽  
Wei Tong
Keyword(s):  
Signaling Pathways ◽  
Conflicts Of Interest ◽  
Adaptor Protein ◽  
Janus Kinase ◽  
Negative Regulator ◽  
Myelogenous Leukemia ◽  
Cell Surface Receptor ◽  
Cytokine Signaling ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 1437 Poster Board I-460 Hematopoietic stem cell (HSC) homeostasis and self-renewal are regulated by intrinsic cytokine signaling pathways. One important signaling axis for HSC is the cell surface receptor, Mpl, and its ligand, thrombopoietin (Tpo). Upon Tpo stimulation, Mpl activates Janus Kinase (JAK2), which in turn triggers a cascade of downstream signal transduction pathways that regulate key aspects of cell development. Mice that lack the inhibitory adaptor protein Lnk harbor a vastly expanded HSC pool with enhanced self-renewal. We previously demonstrated that Lnk controls HSC self-renewal predominantly through the Mpl/JAK2 pathway. Lnk binds directly to phosphorylated tyrosine 813 in JAK2 upon Tpo stimulation. Moreover, Lnk-deficient HSCs display potentiated JAK2 activation. Dysregulation of cytokine receptor signaling pathways frequently lead to hematological malignancies. Abnormal activation of JAK2 by a chromosomal translocation between the transcription factor Tel and JAK2 (Tel/JAK2) was shown to cause atypical Chronic Myelogenous Leukemia (aCML) in human patients. Moreover, the JAK2 V617F mutation has been observed at high frequency in several myeloproliferative diseases (MPDs). The JAK2V617F retains Lnk binding, suggesting that alterations in Lnk could influence MPD development. Indeed, we found that loss of Lnk accelerates and exacerbates oncogenic JAK2-induced MPD in mouse transplant models. Specifically, Lnk deficiency enhanced cytokine signaling, thereby augmenting the ability of oncogenic JAK2 to expand myeloid progenitors. To test whether the interaction between Lnk and JAK2V617F directly constrains MPD development in mice, we transplanted wild-type bone marrow cells expressing the JAK2V617F/Y813F double mutant that does not interact with Lnk (WT;JAK2VF/YF). WT;JAK2VF/YF engrafted mice exhibited increased myeloid expansion when compared to WT;JAK2VF mice, and conferred accelerated polycythemia vera development in secondary transplants. In summary, we identified Lnk as a physiological negative regulator of JAK2 in stem cells that may constrain leukemic transformation conferred by oncogenic JAK2. Disclosures No relevant conflicts of interest to declare.

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