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Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging I

ABSTRACT: Maintaining proteostasis is key to resisting stress and to promoting healthy aging. Proteostasis is necessary to preserve stem cell function, but little is known about the mechanisms that regulate proteostasis during stress in stem cells, and whether disruptions in proteostasis contribute stem cell aging is largely unexplored. We determined that ex vivo cultured mouse and human hematopoietic stem cells (HSCs) rapidly increase protein synthesis. This challenge to HSC proteostasis was associated with nuclear accumulation of Hsf1, and deletion of Hsf1 impaired HSC maintenance ex vivo. Strikingly, supplementing cultures with small molecules that enhance Hsf1 activation partially suppressed protein synthesis, rebalanced proteostasis, and supported retention of HSC serial reconstituting activity. Although Hsf1 was dispensable for young adult HSCs in vivo, Hsf1 deficiency increased protein synthesis and impaired the reconstituting activity of middle-aged HSCs. Hsf1 thus promotes proteostasis and the regenerative activity of HSCs in response to culture stress and aging.

ORGANISM(S): Mus musculus

PROVIDER: GSE179412 | GEO | 2021/07/11

REPOSITORIES: GEO

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Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging II

Project description:Maintaining proteostasis is key to resisting stress and to promoting healthy aging. Proteostasis is necessary to preserve stem cell function, but little is known about the mechanisms that regulate proteostasis during stress in stem cells, and whether disruptions in proteostasis contribute stem cell aging is largely unexplored. We determined that ex vivo cultured mouse and human hematopoietic stem cells (HSCs) rapidly increase protein synthesis. This challenge to HSC proteostasis was associated with nuclear accumulation of Hsf1, and deletion of Hsf1 impaired HSC maintenance ex vivo. Strikingly, supplementing cultures with small molecules that enhance Hsf1 activation partially suppressed protein synthesis, rebalanced proteostasis, and supported retention of HSC serial reconstituting activity. Although Hsf1 was dispensable for young adult HSCs in vivo, Hsf1 deficiency increased protein synthesis and impaired the reconstituting activity of middle-aged HSCs. Hsf1 thus promotes proteostasis and the regenerative activity of HSCs in response to culture stress and aging.

2021-07-11 | GSE179413 | GEO

Hematopoietic Stem Cells Preferentially Traffic Misfolded Proteins to Aggresomes and Depend on Aggrephagy to Maintain Protein Homeostasis

Project description:Hematopoietic stem cells (HSCs) regenerate blood cells throughout life. To preserve their fitness, HSCs are particularly dependent on maintaining protein homeostasis (proteostasis). However, how HSCs purge misfolded proteins is unknown. Here we show that in contrast to most cells that primarily utilize the proteasome to degrade misfolded proteins, HSCs preferentially traffic misfolded proteins to aggresomes in a Bag3-dependent manner, and depend on aggrephagy, a selective form of autophagy, to maintain proteostasis in vivo. When autophagy is disabled, HSCs compensate by increasing proteasome activity, but proteostasis is ultimately disrupted as protein aggregates accumulate and HSC function is impaired. Bag3-deficiency blunts aggresome formation in HSCs, resulting in protein aggregate accumulation, myeloid-biased differentiation, and diminished self-renewal activity. Furthermore, HSC aging is associated with a severe loss of aggresomes and reduced autophagic flux. Protein degradation pathways are thus specifically configured in young adult HSCs to preserve proteostasis and fitness, but become dysregulated during aging.

2023-03-21 | GSE206051 | GEO

Molecular characterization of hematopoietic stem cells after in vitro amplification on biomimetic 3D PDMS cell culture scaffoldsMolecular characterization of hematopoietic stem cells after in vitro amplification on biomimetic 3D PDMS cell culture scaffolds

Project description:Hematopoietic stem cell transplantation (HSCT) is successfully applied since the late 1950s, however, its efficacy still needs to be improved. A promising strategy is to transplant high numbers of pluripotent hematopoietic stem cells (HSCs). Therefore, an advanced ex vivo culture system is needed that supports the proliferation and maintains the pluripotency of HSC to override possible limitations in cell numbers gained from donors. To model the natural HSC niche in vitro and thus, to amplify high numbers of undifferentiated HSCs, we used an optimized HSC cell culture medium in combination with artificial 3D bone marrow-like scaffolds made of polydimethylsiloxane (PDMS). After 14 days in vitro (DIV) cell culture, we performed transcriptome and proteome analysis of the whole cell populations. Ingenuity pathway analysis (IPA) indicated that our 3D PDMS cell culture scaffolds activated interleukin, SREBP, mTOR and FOXO signaling pathways as well as the HSC metabolism, which we confirmed by ELISA, Western blot and metabolic flux analysis. These molecular signaling pathways and HSC metabolism are well known to promote the expansion HSCs and are involved in their pluripotency maintenance. After selection and enrichment of immature CD34-positive/CD38-negative HSCs using FACS sorting, we could confirm our findings by another proteome analysis followed by IPA. Thus, we could show that our 3D bone marrow-like PDMS scaffolds activate key molecular signaling pathways to amplify the numbers of undifferentiated HSC efficiently ex vivo.

2021-11-10 | PXD025849 | Pride

Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging

Project description:Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging

| PRJNA743654 | ENA

High levels of canonical Wnt signaling lead to loss of stemness and increased differentiation in hematopoietic stem cells

Project description:Canonical Wnt signalling regulates the self-renewal of most if not all stem cell systems. In the blood system, the role of Wnt signalling has been subject of much debate, with positive and negative roles of Wnt signalling proposed for hematopoietic stem cells (HSC). As we have shown previously, this controversy can be largely explained by the effects of different dosages of Wnt signalling. What remained unclear however, was why high Wnt signals would lead to loss of reconstituting capacity. To better understand this phenomenon, we have taken advantage of a series of hypomorphic mutant Apc alleles resulting in a broad range of Wnt dosages in HSCs, purified those HSCs and performed whole genome gene expression analyses. Gene expression profiling and functional studies show that HSCs with APC mutations lead to high Wnt levels , enhanced differentiation and diminished proliferation, but have no effect on apoptosis, collectively leading to loss of stemness. Thus, we provide mechanistic insight into the role of APC mutations and Wnt signalling in HSC biology. As Wnt signals are explored in various in vivo and ex vivo expansion protocols for HSCs, our findings also have clinical ramifications. To investigate the effects of Wnt signals in hematopoietic cells, mice carrying floxed Apc or hypomorphic Apc mutants were crossed, LSK cells were isolated and treated with Cre IRES GFP gamma-retrovirus ex vivo, GFP+ cells were sorted and RNA expression was determined.

2016-03-23 | E-GEOD-79495 | biostudies-arrayexpress

Effect of bioengineered niches on perivascular stem cell phenotype.

Project description:Long-term reconstituting haematopoietic stem cells (LT-HSCs) are used to treat blood disorders via allogeneic stem cell transplantation (alloSCT), to engraft and repopulate the blood system. The very low abundance of LT-HSCs and their rapid differentiation during in vitro culture hinders their clinical utility. Previous developments using stromal feeder layers, defined media cocktails, and bioengineering have enabled HSC expansion in culture, but of mostly short-term HSCs (ST-HSC) and progenitor populations at the expense of naïve LT-HSCs. Here, we report the creation of a bioengineered LT-HSC maintenance niche that recreates physiological extracellular matrix organisation, using soft collagen type-I hydrogels to drive nestin expression in perivascular stromal cells (PerSCs or pericytes). We demonstrate that nestin, which is expressed by HSC-supportive bone marrow stromal cells, is cytoprotective and, via regulation of metabolism, is important for HIF-1 expression in PerSCs. When CD34+ve HSCs were added to the bioengineered niches comprising nestin/HIF-1 expressing PerSCs, LT-HSC numbers were maintained with normal clonal and in vivo reconstitution potential, without media supplementation. We provide proof-of-concept that our bioengineered niches can support the survival of CRISPR edited HSCs. Successful editing of LT-HSCs ex vivo can have potential impact on the treatment of blood disorders.

2024-04-25 | GSE265789 | GEO

Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging I

Project description:Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging I

| PRJNA743652 | ENA

Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging II

Project description:Hsf1 promotes hematopoietic stem cell fitness and proteostasis in response to ex vivo culture stress and aging II

| PRJNA743655 | ENA

Oncogenic Nras has a bimodal effect on hematopoietic stem cells promoting proliferation and self-renewal

Project description:Pre-leukemic mutations are thought to promote clonal expansion of hematopoietic stem cells (HSCs) by increasing self-renewal and competitiveness. However, mutations that increase HSC proliferation tend to reduce competitiveness and self-renewal potential, raising the question of how a mutant HSC can sustainably outcompete wild-type HSCs. Activating mutations in NRAS are prevalent in human myeloproliferative disease and leukemia. Here we show that a single allele of oncogenic NrasG12D increases HSC proliferation but also increases reconstituting and self-renewal potential upon serial transplantation in irradiated mice, all without immortalizing HSCs or causing leukemia in our experiments. NrasG12D also confers long-term self-renewal potential upon multipotent progenitors. To explore the mechanism by which NrasG12D promotes HSC proliferation and self-renewal we assessed HSC cell cycle kinetics using H2B-GFP label retention. We found that NrasG12D had a bimodal effect on HSCs, increasing the proliferation of some HSCs while increasing the quiescence and competitiveness of other HSCs. One signal can therefore increase HSC proliferation, competitiveness, and self-renewal through a bimodal effect that promotes proliferation in some HSCs and quiescence in others. 12 RNA samples from mouse bone marrows were analyzed. There are three biological replicates for each subtype.

2014-03-14 | E-GEOD-45194 | biostudies-arrayexpress

ID2 and HIF-1α Collaborate to Protect Quiescent Hematopoietic Stem Cells from Activation, Differentiation and Exhaustion [RNA-seq]

Project description:Defining mechanism(s) that maintain tissue stem quiescence is important for improving tissue regeneration, cell therapies, aging, and cancer. We report here that genetic ablation of Id2 in adult hematopoietic stem cells (HSCs) promotes increased HSC activation and differentiation, which results in HSC exhaustion and bone marrow failure over time. Id2Δ/Δ HSCs show increased HSC cycling, reactive oxygen species (ROS) production, mitochondrial activation, and DNA damage supporting the conclusion that Id2Δ/Δ HSCs are less quiescent. Mechanistically, HIF-1α expression is decreased in Id2Δ/Δ HSCs, and stabilization of HIF-1α in Id2Δ/Δ HSCs restores HSC quiescence and rescues HSC exhaustion. ID2 promotes HIF-1α expression by binding to the Von Hippel-Lindau (VHL) protein and interfering with proteasomal degradation of HIF-1α. HIF-1α promotes Id2 expression and enforces a positive feedback loop between ID2 and HIF-1α to maintain HSC quiescence. Thus, sustained ID2 expression could protect HSCs during stress, and improve HSC expansion for gene editing and cell therapies.

2022-05-31 | GSE203076 | GEO

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