Interkingdom Comparison of Threonine Metabolism for Stem Cell Maintenance in Plants and Animals

In multicellular organisms, tissue generation, maintenance, and homeostasis depend on stem cells. Cellular metabolic status is an essential component of different differentiated states, from stem to fully differentiated cells. Threonine (Thr) metabolism has emerged as a critical factor required to maintain pluripotent/multipotent stem cells in both plants and animals. Thus, both kingdoms conserved or converged upon this fundamental feature of stem cell function. Here, we examine similarities and differences in Thr metabolism-dependent mechanisms supporting stem cell maintenance in these two kingdoms. We then consider common features of Thr metabolism in stem cell maintenance and predict and speculate that some knowledge about Thr metabolism and its role in stem cell function in one kingdom may apply to the other. Finally, we outline future research directions to explore these hypotheses.

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The intrinsic chaperone network of Arabidopsis stem cells confers protection against proteotoxic stress

10.1101/2021.01.19.427268 ◽

2021 ◽

Author(s):

Ernesto Llamas ◽

Salvador Torres-Montilla ◽

Hyun Ju Lee ◽

María Victoria Barja ◽

Elena Schlimgen ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Protein Aggregation ◽

Cell Function ◽

Proteasome Inhibition ◽

Stem Cell Maintenance ◽

Proteotoxic Stress ◽

Differentiated Cells ◽

Plant Stem ◽

Chaperone Network

AbstractThe biological purpose of plant stem cells is to maintain themselves while providing new pools of differentiated cells that form organs and rejuvenate or replace damaged tissues1-3. Protein homeostasis, or proteostasis, is required for cell function and viability4-7. However, the link between proteostasis and plant stem cell identity remains unknown. In contrast to their differentiated counterparts, we find that root stem cells can prevent the accumulation of aggregated proteins even under proteotoxic stress conditions such as heat stress or proteasome inhibition. Notably, root stem cells exhibit enhanced expression of distinct chaperones that maintain proteome integrity. Particularly, intrinsic high levels of the TRiC/CCT chaperonin determine stem cell maintenance and their remarkable ability to suppress protein aggregation. Overexpression of CCT8, a key activator of TRiC/CCT assembly8, is sufficient to ameliorate protein aggregation in differentiated cells and confer resistance to proteotoxic stress in plants. Taken together, our results indicate that enhanced proteostasis mechanisms in stem cells could be an important requirement for plants to persist under extreme environmental conditions and reach extreme long ages. Thus, proteostasis of stem cells could provide insights to design and breed plants tolerant to environmental challenges caused by the climate change.

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Maintenance of high levels of pluripotent hematopoietic stem cells in vitro: effect of stromal cells and c-kit

Blood ◽

10.1182/blood.v81.2.365.bloodjournal812365 ◽

1993 ◽

Vol 81 (2) ◽

pp. 365-372 ◽

Cited By ~ 63

Author(s):

JP Wineman ◽

S Nishikawa ◽

CE Muller-Sieburg

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cell Line ◽

Stromal Cells ◽

Stromal Cell ◽

Hematopoietic Stem ◽

Stem Cell Maintenance ◽

Stromal Cell Line ◽

Cell Maintenance

We show here that mouse pluripotent hematopoietic stem cells can be maintained in vitro on stroma for at least 3 weeks at levels close to those found in bone marrow. The extent of stem cell maintenance is affected by the nature of the stromal cells. The stromal cell line S17 supported stem cells significantly better than heterogeneous, primary stromal layers or the stromal cell line Strofl-1. Stem cells cultured on S17 repopulated all hematopoietic lineages in marrow-ablated hosts for at least 10 months, indicating that this culture system maintained primitive stem cells with extensive proliferative capacity. Furthermore, we demonstrate that, while pluripotent stem cells express c-kit, this receptor appears to play only a minor role in stem cell maintenance in vitro. The addition of an antibody that blocks the interaction of c-kit with its ligand essentially abrogated myelopoiesis in cultures. However, the level of stem cells in antibody-treated cultures was similar to that found in untreated cultures. Thus, it seems likely that the maintenance of primitive stem cells in vitro depends on yet unidentified stromal cell-derived factor(s).

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me31B regulates stem cell homeostasis by preventing excess dedifferentiation in the Drosophila male germline

Journal of Cell Science ◽

10.1242/jcs.258757 ◽

2021 ◽

Author(s):

Lindy Jensen ◽

Zsolt G. Venkei ◽

George J. Watase ◽

Bitarka Bisai ◽

Scott Pletcher ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Critical Role ◽

Stem Cell Population ◽

Germline Stem Cells ◽

Cell Identity ◽

Stem Cell Maintenance ◽

Differentiated Cells ◽

Male Germline ◽

Elevated Frequency

Tissue-specific stem cells maintain tissue homeostasis by providing a continuous supply of differentiated cells throughout the life of organisms. Differentiated/differentiating cells can revert back to a stem cell identity via dedifferentiation to help maintain the stem cell pool beyond the lifetime of individual stem cells. Although dedifferentiation is important to maintain the stem cell population, it is speculated to underlie tumorigenesis. Therefore, this process must be tightly controlled. Here we show that a translational regulator me31B plays a critical role in preventing excess dedifferentiation in the Drosophila male germline: in the absence of me31B, spermatogonia (SGs) dedifferentiate into germline stem cells (GSCs) at a dramatically elevated frequency. Our results show that the excess dedifferentiation is likely due to misregulation of nos, a key regulator of germ cell identity and GSC maintenance. Taken together, our data reveal negative regulation of dedifferentiation to balance stem cell maintenance with differentiation.

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DNA Repair in Stem Cell Maintenance and Conversion to Cancer Stem Cells

Cancer Stem Cells ◽

10.1007/2789_2007_053 ◽

2007 ◽

pp. 231-244 ◽

Cited By ~ 1

Author(s):

S. L. Gerson ◽

J. Reese ◽

J. Kenyon

Keyword(s):

Stem Cells ◽

Dna Repair ◽

Stem Cell ◽

Cancer Stem Cells ◽

Stem Cell Maintenance ◽

Cell Maintenance

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Abstract 2621: OLIG2 regulates stem cell maintenance and cell cycle in glioma stem cells

10.1158/1538-7445.sabcs18-2621 ◽

2019 ◽

Author(s):

Norihiko Saito ◽

Nozomi Hirai ◽

Kazuya Aoki ◽

Satoshi Fujita ◽

Haruo Nakayama ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Stem Cell ◽

Glioma Stem Cells ◽

Stem Cell Maintenance ◽

Cell Maintenance

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Loss of Mob1a/b impairs the differentiation of mouse embryonic stem cells into the three germ layer lineages

Experimental & Molecular Medicine ◽

10.1038/s12276-019-0342-z ◽

2019 ◽

Vol 51 (11) ◽

pp. 1-12 ◽

Cited By ~ 3

Author(s):

June Sung Bae ◽

Sun Mi Kim ◽

Yoon Jeon ◽

Juyeon Sim ◽

Ji Yun Jang ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Hippo Pathway ◽

Critical Role ◽

Embryonic Stem ◽

Mouse Escs ◽

Germ Layers ◽

Stem Cell Maintenance ◽

The Hippo Pathway ◽

Cell Maintenance

AbstractThe Hippo pathway plays a crucial role in cell proliferation and apoptosis and can regulate stem cell maintenance and embryonic development. MOB kinase activators 1A and 1B (Mob1a/b) are key components of the Hippo pathway, whose homozygous deletion in mice causes early embryonic lethality at the preimplantation stage. To investigate the role of Mob1a/b in stem cell maintenance and differentiation, an embryonic stem cell (ESC) clone in which Mob1a/b could be conditionally depleted was generated and characterized. Although Mob1a/b depletion did not affect the stemness or proliferation of mouse ESCs, this depletion caused defects in differentiation into the three germ layers. Yap knockdown rescued the in vitro and in vivo defects in differentiation caused by Mob1a/b depletion, suggesting that differentiation defects caused by Mob1a/b depletion were Yap-dependent. In teratoma experiments, Yap knockdown in Mob1a/b-depleted ESCs partially restored defects in differentiation, indicating that hyperactivation of Taz, another effector of the Hippo pathway, inhibited differentiation into the three germ layers. Taken together, these results suggest that Mob1a/b or Hippo signaling plays a critical role in the differentiation of mouse ESCs into the three germ layers, which is dependent on Yap. These close relationship of the Hippo pathway with the differentiation of stem cells supports its potential as a therapeutic target in regenerative medicine.

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Maintenance of Pluripotent Stem Cells is Influenced by Ser/Thr Metabolism

Blood ◽

10.1182/blood.v124.21.sci-43.sci-43 ◽

2014 ◽

Vol 124 (21) ◽

pp. SCI-43-SCI-43

Author(s):

Lewis C. Cantley

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Cell Fate ◽

Embryonic Stem ◽

Isocitrate Dehydrogenase 1 ◽

Advisory Committees ◽

Metabolic Intermediates ◽

Stem Cell Maintenance ◽

Differentiated Cells ◽

Methylation Of Dna

Abstract Recent studies have suggested not only that stem cells have different metabolic requirements than terminally differentiated cells, but also that metabolic intermediates may play a role in the maintenance of stem cells. It has long been clear that changes in acetylation and methylation of histones, as well as methylation of DNA play critical roles in deciding cell fate. The availability of critical intermediates in metabolism, especially S-adenosylmethionine (SAM), acetyl-CoA, nicotinamide adenine dinucleotide (NAD) and a-ketoglutarate play critical roles in modulating acetylation and methylation of histones and methylation of DNA. In the course of evaluating an unusual requirement of threonine (Thr) for the growth of murine embryonic stem cells, we found that metabolism of Thr to glycine (Gly) and the subsequent use of the methyl group of Gly for converting homocysteine to methionine is critical for maintaining high levels of SAM and low levels of S-adenosyl-homocysteine. Importantly, depletion of Thr from the media resulted in decreased tri-methylation of histone H3 lysine-4 (H3K4me3), leading to slowed growth and increased differentiation. Thus, abundance of SAM appears to influence H3K4me3, providing a possible mechanism by which modulation of a metabolic pathway might influence stem cell fate. Demethylation of histones and DNA can also be controlled by metabolic intermediates. Mutated forms of isocitrate dehydrogenase 1 (IDH1) and IDH2 that drive acute myeloid leukemia (AML) and other cancers, produce an oncometabolite (2-hydrogyglutarate) that can compete with the a-ketoglutarate requirement for enzymes involved in hydroxy-methylation and subsequent demethylation of DNA and histones. Recent studies indicate that 2-hydroxyglutarate plays a role in blocking differentiation of cancer cells. These and other observations linking intermediates in metabolism to stem cell maintenance will be discussed. Disclosures Cantley: Agios Pharmaceuticals: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

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Selective targeting of the BRG/PB1 bromodomains impairs embryonic and trophoblast stem cell maintenance

Science Advances ◽

10.1126/sciadv.1500723 ◽

2015 ◽

Vol 1 (10) ◽

pp. e1500723 ◽

Cited By ~ 65

Author(s):

Oleg Fedorov ◽

Josefina Castex ◽

Cynthia Tallant ◽

Dafydd R. Owen ◽

Sarah Martin ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Protein Interaction ◽

Embryonic Stem ◽

High Specificity ◽

Stem Cell Differentiation ◽

Head Group ◽

Stem Cell Maintenance ◽

Trophoblast Stem ◽

Cell Maintenance

Mammalian SWI/SNF [also called Brg/Brahma-associated factors (BAFs)] are evolutionarily conserved chromatin-remodeling complexes regulating gene transcription programs during development and stem cell differentiation. BAF complexes contain an ATP (adenosine 5′-triphosphate)–driven remodeling enzyme (either BRG1 or BRM) and multiple protein interaction domains including bromodomains, an evolutionary conserved acetyl lysine–dependent protein interaction motif that recruits transcriptional regulators to acetylated chromatin. We report a potent and cell active protein interaction inhibitor, PFI-3, that selectively binds to essential BAF bromodomains. The high specificity of PFI-3 was achieved on the basis of a novel binding mode of a salicylic acid head group that led to the replacement of water molecules typically maintained in other bromodomain inhibitor complexes. We show that exposure of embryonic stem cells to PFI-3 led to deprivation of stemness and deregulated lineage specification. Furthermore, differentiation of trophoblast stem cells in the presence of PFI-3 was markedly enhanced. The data present a key function of BAF bromodomains in stem cell maintenance and differentiation, introducing a novel versatile chemical probe for studies on acetylation-dependent cellular processes controlled by BAF remodeling complexes.

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STEM-14. THE WRAD COMPLEX REPRESENTS A THERAPEUTIC TARGET FOR CANCER STEM CELLS IN GLIOBLASTOMA

Neuro-Oncology ◽

10.1093/neuonc/noab196.088 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi23-vi24

Author(s):

Kelly Mitchell ◽

Joseph Alvarado ◽

Christopher Goins ◽

Steven Martinez ◽

Jonathan Macdonald ◽

...

Keyword(s):

Stem Cells ◽

Stem Cell ◽

Transcription Factors ◽

Cancer Stem Cells ◽

Molecular Mechanisms ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Self Renewal ◽

Stem Cell Maintenance ◽

Cell Maintenance

Abstract Glioblastoma (GBM) progression and resistance to conventional therapies is driven in part by cells within the tumor with stem cell properties including quiescence, self-renewal and drug efflux potential. It is thought that eliminating these cancer stem cells (CSCs) is a key component to successful clinical management of GBM. However, currently, few known molecular mechanisms driving CSCs can be exploited for therapeutic development. Core transcription factors such as SOX2, OLIG2, OCT4 and NANOG maintain the CSC state in GBM. Our laboratory recently uncovered a self-renewal signaling axis involving RBBP5 that is necessary and sufficient for CSC maintenance through driving expression of these core stem cell maintenance transcription factors. RBBP5 is a component of the WRAD complex, which promotes Lys4 methylation of histone H3 to positively regulate transcription. We hypothesized that targeting RBBP5 could be a means to disrupt epigenetic programs that maintain CSCs in stemness transcriptional states. We found that genetic and pharmacologic inhibition of the WRAD complex reduced CSC growth, self-renewal and tumor initiation potential. WRAD inhibitors partially dissembled the WRAD complex and reduced H3K4 trimethylation both globally and at the promoters of key stem cell maintenance transcription factors. Using a CSC reporter system, we demonstrated that WRAD complex inhibition decreased growth of SOX2/OCT4 expressing CSCs in a concentration-dependent manner as quantified by live imaging. Overall, our studies assess the function of the WRAD complex and the effect of WRAD complex inhibitors in preclinical models and specifically on the stem cell state for the first time in GBM. Studying the functions of the WRAD complex in CSCs may improve understanding of GBM pathogenesis and elucidate how CSCs survive despite aggressive chemotherapy and radiation. Our ongoing studies aim to develop brain penetrant inhibitors targeting the WRAD complex as an anti-CSC strategy that could potentially synergize with standard of care treatments.

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