bims-scepro 2024-04-21 papers

bims-scepro

Biomed News

on Stem cell proteostasis

Issue of 2024–04–21
twenty-two papers selected by
William Grey, University of York

iNOS regulates hematopoietic stem and progenitor cells via mitochondrial signaling and is critical for bone marrow regeneration.
Aging-induced MCPH1 translocation activates necroptosis and impairs hematopoietic stem cell function.
Ascorbate depletion increases quiescence and self-renewal potential in hematopoietic stem cells and multipotent progenitors.
EGFR-dependent endocytosis of Wnt9a and Fzd9b promotes β-catenin signaling during hematopoietic stem cell development in zebrafish.
Single-cell transcriptomics dissects the transcriptome alterations of hematopoietic stem cells in myelodysplastic neoplasms.
Bone marrow CD8+ Trm cells induced by IL-15 and CD16+ monocytes contribute to HSPC destruction in human severe aplastic anemia.
Monoallelic KRAS (G13C) mutation triggers dysregulated expansion in induced pluripotent stem cell-derived hematopoietic progenitor cells.
The potency of hematopoietic stem cell reprogramming for changing immune tone.
Caspase-resistant ROCK1 expression prolongs survival of Eµ-Myc B cell lymphoma mice.
Why an integrated view of gene expression studies on hematopoiesis in mouse aging is better than the sum of their parts.
Reciprocal antagonism of PIN1-APC/CCDH1 governs mitotic protein stability and cell cycle entry.
Mitochondrial tRNA pseudouridylation governs erythropoiesis.
Dynamics of DNA damage-induced nuclear inclusions are regulated by SUMOylation of Btn2.
Aging brain: exploring the interplay between bone marrow aging, immunosenescence, and neuroinflammation.
Heparan Sulfates and Heparan Sulfate Proteoglycans in Hematopoiesis.
Role of reactive oxygen species in myelodysplastic syndromes.
Lysosomal Degradation Targets Mutant Calreticulin and the Thrombopoietin Receptor in Myeloproliferative Neoplasms.
Cross-link assisted spatial proteomics to map sub-organelle proteomes and membrane protein topologies.
Tbl1 promotes Wnt/β-catenin signaling-induced degradation of the Tcf7l1 protein in mouse ESCs.
Hierarchical self-recognition and response in CSC and non-CSC micro-niches for cancer therapy.
Wnt signaling regulates chemokine production and cell migration of circulating human monocytes.
Luciferase- and HaloTag-based reporter assays to measure small-molecule-induced degradation pathway in living cells.

Free Radic Biol Med. 2024 Apr 16. pii: S0891-5849(24)00404-0. [Epub ahead of print]

iNOS regulates hematopoietic stem and progenitor cells via mitochondrial signaling and is critical for bone marrow regeneration.

Supriya Sinha, Priyanka Dhankani, Milind Nahiyera, Krishna Bhan Singh, Divya Singh, Madhav Nilakanth Mugale, Sharad Sharma, Jagavelu Kumaravelu, Madhu Dikshit, Sachin Kumar.

  Hematopoietic stem cells (HSCs) replenish blood cells under steady state and on demand, that exhibit therapeutic potential for Bone marrow failures and leukemia. Redox signaling plays key role in immune cells and hematopoiesis. However, the role of reactive nitrogen species in hematopoiesis remains unclear and requires further investigation. We investigated the significance of inducible nitric oxide synthase/ nitric oxide (iNOS/NO) signaling in hematopoietic stem and progenitor cells (HSPCs) and hematopoiesis under steady-state and stress conditions. HSCs contain low levels of NO and iNOS under normal conditions, but these increase upon bone marrow stress. iNOS-deficient mice showed subtle changes in peripheral blood cells but significant alterations in HSPCs, including increased HSCs and multipotent progenitors. Surprisingly, iNOS-deficient mice displayed heightened susceptibility and delayed recovery of blood progeny following 5-Fluorouracil (5-FU) induced hematopoietic stress. Loss of quiescence and increased mitochondrial stress, indicated by elevated MitoSOX and MMPhi HSCs, were observed in iNOS-deficient mice. Furthermore, pharmacological approaches to mitigate mitochondrial stress rescued 5-FU-induced HSC death. Conversely, iNOS-NO signaling was required for demand-driven mitochondrial activity and proliferation during hematopoietic recovery, as iNOS-deficient mice and NO signaling inhibitors exhibit reduced mitochondrial activity. In conclusion, our study challenges the conventional view of iNOS-derived NO as a cytotoxic molecule and highlights its intriguing role in HSPCs. Together, our findings provide insights into the crucial role of the iNOS-NO-mitochondrial axis in regulating HSPCs and hematopoiesis.

Keywords:  Bone marrow; Hematopoietic stem and progenitor cells (HSPCs); Inducible nitric oxide synthase (iNOS); Nitric oxide (NO); hematopoietic stress

DOI:  https://doi.org/10.1016/j.freeradbiomed.2024.04.225
Nat Aging. 2024 Apr;4(4): 510-526

Aging-induced MCPH1 translocation activates necroptosis and impairs hematopoietic stem cell function.

Hanqing He, Yuqian Wang, Baixue Tang, Qiongye Dong, Chou Wu, Wanling Sun, Jianwei Wang.

DNA damage contributes to the aging of hematopoietic stem cells (HSCs), yet the underlying molecular mechanisms are not fully understood. In this study, we identified a heterogeneous functional role of microcephalin (MCPH1) in the nucleus and cytoplasm of mouse HSCs. In the nucleus, MCPH1 maintains genomic stability, whereas in the cytoplasm, it prevents necroptosis by binding with p-RIPK3. Aging triggers MCPH1 translocation from cytosol to nucleus, reducing its cytoplasmic retention and leading to the activation of necroptosis and deterioration of HSC function. Mechanistically, we found that KAT7-mediated lysine acetylation within the NLS motif of MCPH1 in response to DNA damage facilitates its nuclear translocation. Targeted mutation of these lysines inhibits MCPH1 translocation and, consequently, compromises necroptosis. The dysfunction of necroptosis signaling, in turn, improves the function of aged HSCs. In summary, our findings demonstrate that DNA damage-induced redistribution of MCPH1 promotes HSC aging and could have broader implications for aging and aging-related diseases.

DOI: https://doi.org/10.1038/s43587-024-00609-z
bioRxiv. 2024 Apr 02. pii: 2024.04.01.587574. [Epub ahead of print]

Ascorbate depletion increases quiescence and self-renewal potential in hematopoietic stem cells and multipotent progenitors.

Stefano Comazzetto, Daniel L Cassidy, Andrew W DeVilbiss, Elise C Jeffery, Bethany R Ottesen, Amanda R Reyes, Sarah Muh, Thomas P Mathews, Brandon Chen, Zhiyu Zhao, Sean J Morrison.

  Ascorbate (vitamin C) limits hematopoietic stem cell (HSC) function and suppresses leukemia development by promoting the function of the Tet2 tumor suppressor. In humans, ascorbate is obtained from the diet while in mice it is synthesized in the liver. In this study, we show that deletion of the Slc23a2 ascorbate transporter severely depleted ascorbate from hematopoietic cells. Slc23a2 deficiency increased HSC reconstituting potential and self-renewal potential upon transplantation into irradiated mice. Slc23a2 deficiency also increased the reconstituting and self-renewal potential of multipotent hematopoietic progenitors (MPPs), conferring the ability to long-term reconstitute irradiated mice. Slc23a2-deficient HSCs and MPPs divided much less frequently than control HSCs and MPPs. Increased self-renewal and reconstituting potential were observed particularly in quiescent Slc23a2-deficient HSCs and MPPs. The effect of Slc23a2 deficiency on MPP self-renewal was not mediated by reduced Tet2 function. Ascorbate thus regulates quiescence and restricts self-renewal potential in HSCs and MPPs such that ascorbate depletion confers MPPs with long-term self-renewal potential.

Keywords:  bone marrow transplantation; metabolism; quiescence; vitamin C

DOI:  https://doi.org/10.1101/2024.04.01.587574
Sci Signal. 2024 Apr 16. 17(832): eadf4299

EGFR-dependent endocytosis of Wnt9a and Fzd9b promotes β-catenin signaling during hematopoietic stem cell development in zebrafish.

Nicole Nguyen, Kelsey A Carpenter, Jessica Ensing, Carla Gilliland, Emma J Rudisel, Emily M Mu, Kate E Thurlow, Timothy J Triche, Stephanie Grainger.

Cell-to-cell communication through secreted Wnt ligands that bind to members of the Frizzled (Fzd) family of transmembrane receptors is critical for development and homeostasis. Wnt9a signals through Fzd9b, the co-receptor LRP5 or LRP6 (LRP5/6), and the epidermal growth factor receptor (EGFR) to promote early proliferation of zebrafish and human hematopoietic stem cells during development. Here, we developed fluorescently labeled, biologically active Wnt9a and Fzd9b fusion proteins to demonstrate that EGFR-dependent endocytosis of the ligand-receptor complex was required for signaling. In human cells, the Wnt9a-Fzd9b complex was rapidly endocytosed and trafficked through early and late endosomes, lysosomes, and the endoplasmic reticulum. Using small-molecule inhibitors and genetic and knockdown approaches, we found that Wnt9a-Fzd9b endocytosis required EGFR-mediated phosphorylation of the Fzd9b tail, caveolin, and the scaffolding protein EGFR protein substrate 15 (EPS15). LRP5/6 and the downstream signaling component AXIN were required for Wnt9a-Fzd9b signaling but not for endocytosis. Knockdown or loss of EPS15 impaired hematopoietic stem cell development in zebrafish. Other Wnt ligands do not require endocytosis for signaling activity, implying that specific modes of endocytosis and trafficking may represent a method by which Wnt-Fzd specificity is established.

DOI: https://doi.org/10.1126/scisignal.adf4299
J Transl Med. 2024 Apr 17. 22(1): 359

Single-cell transcriptomics dissects the transcriptome alterations of hematopoietic stem cells in myelodysplastic neoplasms.

Xiangzong Zeng, Yichen Wang, Min Dai, Wei Li, Qingtian Huang, Lingsha Qin, Yuquan Li, Yanwen Yan, Xiangjun Xue, Fang Yi, Wenhao Li, Langyu He, Qifa Liu, Ling Qi.

   BACKGROUND: Myelodysplastic neoplasms (MDS) are myeloid neoplasms characterized by disordered differentiation of hematopoietic stem cells and a predisposition to acute myeloid leukemia (AML). The underline pathogenesis remains unclear.
METHODS: In this study, the trajectory of differentiation and mechanisms of leukemic transformation were explored through bioinformatics analysis of single-cell RNA-Seq data from hematopoietic stem and progenitor cells (HSPCs) in MDS patients.
RESULTS: Among the HSPC clusters, the proportion of common myeloid progenitor (CMP) was the main cell cluster in the patients with excess blasts (EB)/ secondary AML. Cell cycle analysis indicated the CMP of MDS patients were in an active proliferative state. The genes involved in the cell proliferation, such as MAML3 and PLCB1, were up-regulated in MDS CMP. Further validation analysis indicated that the expression levels of MAML3 and PLCB1 in patients with MDS-EB were significantly higher than those without EB. Patients with high expression of PLCB1 had a higher risk of transformation to AML. PLCB1 inhibitor can suppress proliferation, induce cell cycle arrest, and activate apoptosis of leukemic cells in vitro.
CONCLUSION: This study revealed the transcriptomic change of HSPCs in MDS patients along the pseudotime and indicated that PLCB1 plays a key role in the transformation of MDS into leukemia.

Keywords:  Hematopoietic stem cells; Leukemic transformation; Myelodysplastic neoplasms; Transcriptome alterations

DOI:  https://doi.org/10.1186/s12967-024-05165-z
Clin Immunol. 2024 Apr 16. pii: S1521-6616(24)00114-1. [Epub ahead of print] 110223

Bone marrow CD8+ Trm cells induced by IL-15 and CD16+ monocytes contribute to HSPC destruction in human severe aplastic anemia.

Jie Long, Xing You, Qiong Yang, Song-Rong Wang, Ming Zhou, Wei Zhou, Caixia Wang, Huafeng Xie, Yuping Zhang, Shunqing Wang, Zhe-Xiong Lian, Liang Li.

  Idiopathic severe aplastic anemia (SAA) is a disease of bone marrow failure caused by T-cell-induced destruction of hematopoietic stem and progenitor cells (HSPCs), however the mechanism remains unclear. We performed single-cell RNA sequencing of PBMCs and BMMCs from SAA patients and healthy donors and identified a CD8+ T cell subset with a tissue residency phenotype (Trm) in bone marrow that exhibit high IFN-γ and FasL expression and have a higher ability to induce apoptosis in HSPCs in vitro through FasL expression. CD8+ Trm cells were induced by IL-15 presented by IL-15Rα on monocytes, especially CD16+ monocytes, which were increased in SAA patients. CD16+ monocytes contributed to IL-15-induced CD38+CXCR6+ pre-Trm differentiation into CD8+ Trm cells, which can be inhibited by the CD38 inhibitor 78c. Our results demonstrate that IL-15-induced CD8+ Trm cells are pathogenic cells that mediate HSPC destruction in SAA patients and are therapeutic targets for future treatments.

Keywords:  Aplastic anemia; Bone marrow; Monocytes; Single cell RNA sequencing; Tissue resident memory CD8(+)T cell

DOI:  https://doi.org/10.1016/j.clim.2024.110223
Stem Cell Res Ther. 2024 Apr 16. 15(1): 106

Monoallelic KRAS (G13C) mutation triggers dysregulated expansion in induced pluripotent stem cell-derived hematopoietic progenitor cells.

Huan-Ting Lin, Masatoshi Takagi, Kenji Kubara, Kazuto Yamazaki, Fumiko Michikawa, Takashi Okumura, Takuya Naruto, Tomohiro Morio, Koji Miyazaki, Hideki Taniguchi, Makoto Otsu.

   BACKGROUND: Although oncogenic RAS mutants are thought to exert mutagenic effects upon blood cells, it remains uncertain how a single oncogenic RAS impacts non-transformed multipotent hematopoietic stem or progenitor cells (HPCs). Such potential pre-malignant status may characterize HPCs in patients with RAS-associated autoimmune lymphoproliferative syndrome-like disease (RALD). This study sought to elucidate the biological and molecular alterations in human HPCs carrying monoallelic mutant KRAS (G13C) with no other oncogene mutations.
METHODS: We utilized induced pluripotent stem cells (iPSCs) derived from two unrelated RALD patients. Isogenic HPC pairs harboring either wild-type KRAS or monoallelic KRAS (G13C) alone obtained following differentiation enabled reliable comparative analyses. The compound screening was conducted with an established platform using KRAS (G13C) iPSCs and differentiated HPCs.
RESULTS: Cell culture assays revealed that monoallelic KRAS (G13C) impacted both myeloid differentiation and expansion characteristics of iPSC-derived HPCs. Comprehensive RNA-sequencing analysis depicted close clustering of HPC samples within the isogenic group, warranting that comparative studies should be performed within the same genetic background. When compared with no stimulation, iPSC-derived KRAS (G13C)-HPCs showed marked similarity with the wild-type isogenic control in transcriptomic profiles. After stimulation with cytokines, however, KRAS (G13C)-HPCs exhibited obvious aberrant cell-cycle and apoptosis responses, compatible with "dysregulated expansion," demonstrated by molecular and biological assessment. Increased BCL-xL expression was identified amongst other molecular changes unique to mutant HPCs. With screening platforms established for therapeutic intervention, we observed selective activity against KRAS (G13C)-HPC expansion in several candidate compounds, most notably in a MEK- and a BCL-2/BCL-xL-inhibitor. These two compounds demonstrated selective inhibitory effects on KRAS (G13C)-HPCs even with primary patient samples when combined.
CONCLUSIONS: Our findings indicate that a monoallelic oncogenic KRAS can confer dysregulated expansion characteristics to non-transformed HPCs, which may constitute a pathological condition in RALD hematopoiesis. The use of iPSC-based screening platforms will lead to discovering treatments that enable selective inhibition of RAS-mutated HPC clones.

Keywords:  Apoptosis regulatory proteins; Biological models; Cell cycle; Hematopoietic system; Human-induced pluripotent stem cells; Inhibitors; KRAS protein; Lymphoproliferative disorders; Oncogene; Stem cells

DOI:  https://doi.org/10.1186/s13287-024-03723-2
Immunol Rev. 2024 Apr 17.

The potency of hematopoietic stem cell reprogramming for changing immune tone.

Andrew W Daman, Jin Gyu Cheong, Laura Berneking, Steven Z Josefowicz.

  Innate immune memory endows innate immune cells with antigen independent heightened responsiveness to subsequent challenges. The durability of this response can be mediated by inflammation induced epigenetic and metabolic reprogramming in hematopoietic stem and progenitor cells (HSPCs) that are maintained through differentiation to mature immune progeny. Understanding the mechanisms and extent of trained immunity induction by pathogens and vaccines, such as BCG, in HSPC remains a critical area of exploration with important implications for health and disease. Here we review these concepts and present new analysis to highlight how inflammatory reprogramming of HSPC can potently alter immune tone, including to enhance specific anti-tumor responses. New findings in the field pave the way for novel HSPC targeting therapeutic strategies in cancer and other contexts of immune modulation. Future studies are expected to unravel diverse and extensive effects of infections, vaccines, microbiota, and sterile inflammation on hematopoietic progenitor cells and begin to illuminate the broad spectrum of immunologic tuning that can be established through altering HSPC phenotypes. The purpose of this review is to draw attention to emerging and speculative topics in this field where we posit that focused study of HSPC in the framework of trained immunity holds significant promise.

Keywords:  PIE‐seq; epigenetics; hematopoietic stem and progenitor cells; inflammatory hematopoiesis; innate immune memory; myelopoiesis; snRNA/ATAC‐seq; trained immunity

DOI:  https://doi.org/10.1111/imr.13335
Dis Model Mech. 2024 Apr 15. pii: dmm.050631. [Epub ahead of print]

Caspase-resistant ROCK1 expression prolongs survival of Eµ-Myc B cell lymphoma mice.

Katerina Mardilovich, Gregory Naylor, Linda Julian, Narisa Phinichkusolchit, Karen Keeshan, Karen Blyth, Michael F Olson.

  Apoptosis is characterized by membrane blebbing and apoptotic body formation. Caspase cleavage of ROCK1 generates an active fragment that promotes actin-myosin mediated contraction and membrane blebbing during apoptosis. Expression of caspase-resistant non-cleavable ROCK1 (Rock1 NC) prolonged survival of mice that rapidly develop B cell lymphomas due to Eµ-Myc transgene expression. Eµ-Myc; Rock1 NC mice had significantly fewer bone marrow cells relative to Eµ-Myc mice expressing wild-type ROCK1 (Rock1 WT), which was associated with altered cell cycle profiles. Circulating macrophage numbers were lower in Eµ-Myc; Rock1 NC mice, but there were higher levels of bone marrow macrophages, consistent with spontaneous cell death in Eµ-Myc; Rock1 NC mice bone marrows being more inflammatory. Rock1 WT recipient mice transplanted with pre-neoplastic Eµ-Myc; Rock1 NC bone marrow cells survived longer than mice transplanted with Eµ-Myc; Rock1 WT cells, indicating that the survival benefit was intrinsic to the Eµ-Myc; Rock1 NC bone marrow cells. The results suggest that the apoptotic death of Eµ-Myc; Rock1 NC cells generates a proliferation-suppressive microenvironment in bone marrows that reduces cell numbers and prolongs B cell lymphoma mouse survival.

Keywords:  Apoptosis; Cytoskeleton; Kinase; Lymphoma; ROCK1; Rho GTPase

DOI:  https://doi.org/10.1242/dmm.050631
FEBS Lett. 2024 Apr 16.

Why an integrated view of gene expression studies on hematopoiesis in mouse aging is better than the sum of their parts.

Leonid V Bystrykh.

  Globally, the human population is aging, with an increased proportion of people in "old age" (over 60 years). This trend leads to a growing demand in aging research, stimulating studies in animal models such as mice, fish, and invertebrates. Recently, we published a research summary on the aging of hematopoietic stem cells (HSCs) in C57BL/6 mice based on 12 gene expression datasets. Here, I discuss in greater detail the added value of taking an integrated view, rather than considering each publication separately, to determine genes involved in aging. Considerable variation exists between lists of differentially expressed (DE) genes in HSCs, comparing young and old mice. This variation can result from factors such as inconsistent definitions of "young" and "old", technical variations and variations between laboratory mouse strains. We previously demonstrated that the variation between gene lists could be circumvented by forming a unified list of DE genes-the "aging list"-with citation indexes attached. The most frequently detected DE genes [approximately 200 most cited, which we named the "aging signature" (AS)] were highly consistent across publications. Gene Ontology classification of the AS list identified additional sources of variation between studies: one comes from the specifics of how the data are collected and analyzed; another comes from inconsistencies between how we define the gene categories. As discussed, overcoming these variations is the next challenge toward an integral approach to our systematic knowledge of the aging process.

Keywords:  data analysis; gene expression; gene regulation; hematopoietic aging; murine hematopoiesis; transcriptome

DOI:  https://doi.org/10.1002/1873-3468.14869
Nat Commun. 2024 Apr 15. 15(1): 3220

Reciprocal antagonism of PIN1-APC/CCDH1 governs mitotic protein stability and cell cycle entry.

Shizhong Ke, Fabin Dang, Lin Wang, Jia-Yun Chen, Mandar T Naik, Wenxue Li, Abhishek Thavamani, Nami Kim, Nandita M Naik, Huaxiu Sui, Wei Tang, Chenxi Qiu, Kazuhiro Koikawa, Felipe Batalini, Emily Stern Gatof, Daniela Arango Isaza, Jaymin M Patel, Xiaodong Wang, John G Clohessy, Yujing J Heng, Galit Lahav, Yansheng Liu, Nathanael S Gray, Xiao Zhen Zhou, Wenyi Wei, Gerburg M Wulf, Kun Ping Lu.

Induced oncoproteins degradation provides an attractive anti-cancer modality. Activation of anaphase-promoting complex (APC/CCDH1) prevents cell-cycle entry by targeting crucial mitotic proteins for degradation. Phosphorylation of its co-activator CDH1 modulates the E3 ligase activity, but little is known about its regulation after phosphorylation and how to effectively harness APC/CCDH1 activity to treat cancer. Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1)-catalyzed phosphorylation-dependent cis-trans prolyl isomerization drives tumor malignancy. However, the mechanisms controlling its protein turnover remain elusive. Through proteomic screens and structural characterizations, we identify a reciprocal antagonism of PIN1-APC/CCDH1 mediated by domain-oriented phosphorylation-dependent dual interactions as a fundamental mechanism governing mitotic protein stability and cell-cycle entry. Remarkably, combined PIN1 and cyclin-dependent protein kinases (CDKs) inhibition creates a positive feedback loop of PIN1 inhibition and APC/CCDH1 activation to irreversibly degrade PIN1 and other crucial mitotic proteins, which force permanent cell-cycle exit and trigger anti-tumor immunity, translating into synergistic efficacy against triple-negative breast cancer.

DOI: https://doi.org/10.1038/s41467-024-47427-w
Blood. 2024 Apr 18. pii: blood.2023022004. [Epub ahead of print]

Mitochondrial tRNA pseudouridylation governs erythropoiesis.

Bichen Wang, Deyang Shi, Shuang Yang, Yu Lian, Haoyuan Li, Mutian Cao, Yifei He, Lele Zhang, Chen Qiu, Tong Liu, Wei Wen, Yuanwu Ma, Lei Shi, Tao Cheng, Lihong Shi, Weiping Yuan, Yajing Chu, Jun Shi.

Pseudouridine is the most prevalent RNA modification, and its aberrant function is implicated in various human diseases. However, the specific impact of pseudouridylation on hematopoiesis remains poorly understood. In this study, we investigated the role of tRNA pseudouridylation in erythropoiesis and its association with mitochondrial myopathy, lactic acidosis, and sideroblastic anemia syndrome (MLASA) pathogenesis. By utilizing patient-specific induced pluripotent stem cells (iPSCs) carrying a genetic PUS1 mutation and a corresponding mutant mouse model, we demonstrated impaired erythropoiesis in MLASA iPSCs and anemia in the MLASA mouse model. Both MLASA iPSCs and mouse erythroblasts exhibited compromised mitochondrial function and impaired protein synthesis. Mechanistically, we revealed that PUS1 deficiency resulted in reduced mitochondrial tRNA levels due to pseudouridylation loss, leading to aberrant mitochondrial translation. Screening of mitochondrial supplements aimed at enhancing respiration or heme synthesis showed limited effect in promoting erythroid differentiation. Interestingly, the mTOR inhibitor rapamycin facilitated erythroid differentiation in MLASA-iPSCs by suppressing mTOR signaling and protein synthesis, and consistent results were observed in the MLASA mouse model. Importantly, rapamycin treatment effectively ameliorated anemia phenotypes in the MLASA patient. Our findings provide novel insights into the crucial role of mitochondrial tRNA pseudouridylation in governing erythropoiesis and present potential therapeutic strategies for anemia patients facing challenges related to protein translation.

DOI: https://doi.org/10.1182/blood.2023022004
Nat Commun. 2024 Apr 13. 15(1): 3215

Dynamics of DNA damage-induced nuclear inclusions are regulated by SUMOylation of Btn2.

Arun Kumar, Veena Mathew, Peter C Stirling.

Spatial compartmentalization is a key facet of protein quality control that serves to store disassembled or non-native proteins until triage to the refolding or degradation machinery can occur in a regulated manner. Yeast cells sequester nuclear proteins at intranuclear quality control bodies (INQ) in response to various stresses, although the regulation of this process remains poorly understood. Here we reveal the SUMO modification of the small heat shock protein Btn2 under DNA damage and place Btn2 SUMOylation in a pathway promoting protein clearance from INQ structures. Along with other chaperones, and degradation machinery, Btn2-SUMO promotes INQ clearance from cells recovering from genotoxic stress. These data link small heat shock protein post-translational modification to the regulation of protein sequestration in the yeast nucleus.

DOI: https://doi.org/10.1038/s41467-024-47615-8
Front Immunol. 2024 ;15 1393324

Aging brain: exploring the interplay between bone marrow aging, immunosenescence, and neuroinflammation.

Ludmila Müller, Svetlana Di Benedetto.

  Aging is a complex process characterized by a myriad of physiological changes, including alterations in the immune system termed immunosenescence. It exerts profound effects on both the bone marrow and the central nervous system, with significant implications for immunosenescence in neurological contexts. Our mini-review explores the complex relationship between bone marrow aging and its impact on immunosenescence, specifically within the context of neurological diseases. The bone marrow serves as a crucial hub for hematopoiesis and immune cell production, yet with age, it undergoes significant alterations, including alterations in hematopoietic stem cell function, niche composition, and inflammatory signaling. These age-related shifts in the bone marrow microenvironment contribute to dysregulation of immune cell homeostasis and function, impacting neuroinflammatory processes and neuronal health. In our review, we aim to explore the complex cellular and molecular mechanisms that link bone marrow aging to immunosenescence, inflammaging, and neuroinflammation, with a specific focus on their relevance to the pathophysiology of age-related neurological disorders. By exploring this interplay, we strive to provide a comprehensive understanding of how bone marrow aging impacts immune function and contributes to the progression of neurological diseases in aging individuals. Ultimately, this knowledge can hold substantial promise for the development of innovative therapeutic interventions aimed at preserving immune function and mitigating the progression of neurological disorders in the elderly population.

Keywords:  aging; bone marrow; brain; immunosenescence; inflammaging; neuroinflammation; neurological disorders

DOI:  https://doi.org/10.3389/fimmu.2024.1393324
Blood. 2024 Mar 22. pii: blood.2023022736. [Epub ahead of print]

Heparan Sulfates and Heparan Sulfate Proteoglycans in Hematopoiesis.

Richard T Piszczatowski, Hannes Buelow, Ulrich Steidl.

From signaling mediators in stem cells, to markers of differentiation and lineage commitment, to facilitators for the entry of viruses like HIV-1, cell surface heparan sulfate (HS) glycans with their distinct modification patterns play important roles in hematopoietic biology. In this review, we provide an overview of the importance of HS and the proteoglycans (HSPGs) to which they are attached, within the major cellular subtypes of the hematopoietic system. We summarize the roles of HSPGs, HS, and HS modifications within each main hematopoietic cell lineage of both myeloid and lymphoid arms. Lastly, we discuss the biological advances of the detection of HS modifications, and their potential to further discriminate cell types within hematopoietic tissue.

DOI: https://doi.org/10.1182/blood.2023022736
Cell Mol Biol Lett. 2024 Apr 14. 29(1): 53

Role of reactive oxygen species in myelodysplastic syndromes.

Qiangan Jing, Chaoting Zhou, Junyu Zhang, Ping Zhang, Yunyi Wu, Junyu Zhou, Xiangmin Tong, Yanchun Li, Jing Du, Ying Wang.

  Reactive oxygen species (ROS) serve as typical metabolic byproducts of aerobic life and play a pivotal role in redox reactions and signal transduction pathways. Contingent upon their concentration, ROS production not only initiates or stimulates tumorigenesis but also causes oxidative stress (OS) and triggers cellular apoptosis. Mounting literature supports the view that ROS are closely interwoven with the pathogenesis of a cluster of diseases, particularly those involving cell proliferation and differentiation, such as myelodysplastic syndromes (MDS) and chronic/acute myeloid leukemia (CML/AML). OS caused by excessive ROS at physiological levels is likely to affect the functions of hematopoietic stem cells, such as cell growth and self-renewal, which may contribute to defective hematopoiesis. We review herein the eminent role of ROS in the hematological niche and their profound influence on the progress of MDS. We also highlight that targeting ROS is a practical and reliable tactic for MDS therapy.

Keywords:  Hematological niche; Myelodysplastic syndromes; Oxidative stress; Reactive oxygen species

DOI:  https://doi.org/10.1186/s11658-024-00570-0
Blood Adv. 2024 Apr 19. pii: bloodadvances.2023011432. [Epub ahead of print]

Lysosomal Degradation Targets Mutant Calreticulin and the Thrombopoietin Receptor in Myeloproliferative Neoplasms.

Amanpreet Kaur, Arunkumar Venkatesan, Malathi Kandarpa, Moshe Talpaz, Malini Raghavan.

Somatic mutants of calreticulin (CRT) drive myeloproliferative neoplasms (MPNs) via binding to the thrombopoietin receptor (MPL) and aberrant activation of the JAK/STAT pathway. Compared with healthy donors, platelets from MPN patients with CRT mutations display low cell surface MPL. Additionally, co-expression of MPL with an MPN-linked CRT mutant (CRTDel52) reduces cell surface MPL, suggesting that CRTDel52 may induce MPL degradation. We show that lysosomal degradation is relevant to the turnover of CRTDel52 and MPL. Furthermore, CRTDel52 increases the lysosomal localization and degradation of MPL. Mammalian target of rapamycin (mTOR) inhibitors reduce cellular CRTDel52, MPL and secreted CRTDel52 levels, and impair CRTDel52-mediated cell proliferation. mTOR inhibition also reduces colony formation and differentiation of CD34+ cells from MPN patients but not healthy donors. Together, these findings indicate low surface MPL as a biomarker of mutant CRT-mediated MPN and induced degradation of CRTDel52 and MPL as an avenue for therapeutic intervention.

DOI: https://doi.org/10.1182/bloodadvances.2023011432
Nat Commun. 2024 Apr 17. 15(1): 3290

Cross-link assisted spatial proteomics to map sub-organelle proteomes and membrane protein topologies.

Ying Zhu, Kerem Can Akkaya, Julia Ruta, Nanako Yokoyama, Cong Wang, Max Ruwolt, Diogo Borges Lima, Martin Lehmann, Fan Liu.

The functions of cellular organelles and sub-compartments depend on their protein content, which can be characterized by spatial proteomics approaches. However, many spatial proteomics methods are limited in their ability to resolve organellar sub-compartments, profile multiple sub-compartments in parallel, and/or characterize membrane-associated proteomes. Here, we develop a cross-link assisted spatial proteomics (CLASP) strategy that addresses these shortcomings. Using human mitochondria as a model system, we show that CLASP can elucidate spatial proteomes of all mitochondrial sub-compartments and provide topological insight into the mitochondrial membrane proteome. Biochemical and imaging-based follow-up studies confirm that CLASP allows discovering mitochondria-associated proteins and revising previous protein sub-compartment localization and membrane topology data. We also validate the CLASP concept in synaptic vesicles, demonstrating its applicability to different sub-cellular compartments. This study extends the scope of cross-linking mass spectrometry beyond protein structure and interaction analysis towards spatial proteomics, and establishes a method for concomitant profiling of sub-organelle and membrane proteomes.

DOI: https://doi.org/10.1038/s41467-024-47569-x
J Cell Sci. 2024 Apr 19. pii: jcs.261241. [Epub ahead of print]

Tbl1 promotes Wnt/β-catenin signaling-induced degradation of the Tcf7l1 protein in mouse ESCs.

Yang Yu, Liwei Liu, Jianjian Cao, Ru Huang, Quanchao Duan, Shou-Dong Ye.

  Activation of the Wnt/β-catenin signaling pathway by CHIR99021, a specific inhibitor of GSK3β, induces Tcf7l1 protein degradation, which facilitates the maintenance of an undifferentiated state in mouse embryonic stem cells (mESCs). However, the precise mechanism is still inconclusive. Here, we showed that the overexpression of transducin-β-like protein 1 (Tbl1) or its family member Tblr1 can decrease Tcf7l1 protein levels, while the knockdown of each increases Tcf7l1 levels without affecting Tcf7l1 transcription. Interestingly, only Tbl1, not Tblr1, interacts with Tcf7l1. Mechanistically, Tbl1 translocates from the cytoplasm into the nucleus in association with β-catenin after the addition of CHIR99021 and functions as an adaptor to promote the ubiquitination of the Tcf7l1 protein. Functional assays further revealed that enforced expression of Tbl1 is capable of delaying mESC differentiation. In contrast, the knockdown of Tbl1 attenuated the effect of CHIR99021 on Tcf7l1 protein stability and mESC self-renewal. Our results provide insight into the regulatory network of the Wnt/β-catenin signaling pathway in promoting the maintenance of naïve pluripotency.

Keywords:  CHIR99021; Embryonic stem cells; Self-renewal; Tbl1; Tcf7l1

DOI:  https://doi.org/10.1242/jcs.261241
Biomaterials. 2024 Apr 15. pii: S0142-9612(24)00115-7. [Epub ahead of print]308 122581

Hierarchical self-recognition and response in CSC and non-CSC micro-niches for cancer therapy.

Yiliang Yang, Yiwei Peng, Yitian Du, Meng Lin, Jiajia Li, Datong Gao, Zhenzhen Yang, Wei Wang, Yanxia Zhou, Xinru Li, Taiqiang Yan, Xianrong Qi.

  Cancer stem cells (CSCs) characterized by self-renewal, invasiveness, tumorigenicity and resistance to treatment are regarded as the thorniest issues in refractory tumors. We develop a targeted and hierarchical controlled release nano-therapeutic platform (SEED-NPs) that self-identifies and responds to CSC and non-CSC micro-niches of tumors. In non-CSC micro-niche, reactive oxygen species (ROS) trigger the burst release of the chemotherapeutic drug and photosensitizer to kill tumor cells and reduce tumor volume by combining chemotherapy and photodynamic therapy (PDT). In CSC micro-niche, the preferentially released differentiation drug induces CSC differentiation and transforms CSCs into chemotherapy-sensitive cells. SEED-NPs exhibit an extraordinary capacity for downregulating the stemness of CD44+/CD24- SP (side population) cell population both in vitro and in vivo, and reveal a 4-fold increase of tumor-targeted accumulation. Also, PDT-generated ROS promote the formation of tunneling nanotubes and facilitate the divergent network transport of drugs in deep tumors. Moreover, ROS in turn promotes CSC differentiation and drug release. This positive-feedback-loop strategy enhances the elimination of refractory CSCs. As a result, SEED-NPs achieve excellent therapeutic effects in both 4T1 SP tumor-bearing mice and regular 4T1 tumor-bearing mice without obvious toxicities and eradicate half of mice tumors. SEED-NPs integrate differentiation, chemotherapy and PDT, which proved feasible and valuable, indicating that active targeting and hierarchical release are necessary to enhance antitumor efficacy. These findings provide promising prospects for overcoming barriers in the treatment of CSCs.

Keywords:  Cancer stem cells (CSCs); Cell hierarchical delivery system; Differentiation; Positive feedback loop; Self-recognition and response

DOI:  https://doi.org/10.1016/j.biomaterials.2024.122581
Cell Commun Signal. 2024 Apr 16. 22(1): 229

Wnt signaling regulates chemokine production and cell migration of circulating human monocytes.

Natalie Zelikson, Shaina Ben, Michal Caspi, Raneen Tarabe, Yonatan Shaleve, Yael Pri-Paz Basson, Oshrat Tayer-Shifman, Elad Goldberg, Shaye Kivity, Rina Rosin-Arbesfeld.

The β-catenin dependent canonical Wnt signaling pathway plays a crucial role in maintaining normal homeostasis. However, when dysregulated, Wnt signaling is closely associated with various pathological conditions, including inflammation and different types of cancer.Here, we show a new connection between the leukocyte inflammatory response and the Wnt signaling pathway. Specifically, we demonstrate that circulating human primary monocytes express distinct Wnt signaling components and are susceptible to stimulation by the classical Wnt ligand-Wnt-3a. Although this stimulation increased the levels of β-catenin protein, the expression of the classical Wnt-target genes was not affected. Intriguingly, treating circulating human monocytes with Wnt-3a induces the secretion of cytokines and chemokines, enhancing monocyte migration. Mechanistically, the enhanced monocyte migration in response to Wnt stimuli is mediated through CCL2, a strong monocyte-chemoattractant.To further explore the physiological relevance of these findings, we conducted ex-vivo experiments using blood samples of patients with rheumatic joint diseases (RJD) - conditions where monocytes are known to be dysfunctional. Wnt-3a generated a unique cytokine expression profile, which was significantly distinct from that observed in monocytes obtained from healthy donors.Thus, our results provide the first evidence that Wnt-3a may serve as a potent stimulator of monocyte-driven immune processes. These findings contribute to our understanding of inflammatory diseases and, more importantly, shed light on the role of a core signaling pathway in the circulation.

DOI: https://doi.org/10.1186/s12964-024-01608-8
Nat Protoc. 2024 Apr 18.

Luciferase- and HaloTag-based reporter assays to measure small-molecule-induced degradation pathway in living cells.

Martin P Schwalm, Krishna Saxena, Susanne Müller, Stefan Knapp.

The rational development of small-molecule degraders (e.g., proteolysis targeting chimeras) remains a challenge as the rate-limiting steps that determine degrader efficiency are largely unknown. Standard methods in the field of targeted protein degradation mostly rely on classical, low-throughput endpoint assays such as western blots or quantitative proteomics. Here we applied NanoLuciferase- and HaloTag-based screening technologies to determine the kinetics and stability of small-molecule-induced ternary complex formation between a protein of interest and a selected E3 ligase. A collection of live-cell assays were designed to probe the most critical steps of the degradation process while minimizing the number of required expression constructs, making the proposed assay pipeline flexible and adaptable to the requirements of the users. This approach evaluates the underlying mechanism of selective target degraders and reveals the exact characteristics of the developed degrader molecules in living cells. The protocol allows scientists trained in basic cell culture and molecular biology to carry out small-molecule proximity-inducer screening via tracking of the ternary complex formation within 2 weeks of establishment, while degrader screening using the HiBiT system requires a CRISPR-Cas9 engineered cell line whose generation can take up to 3 months. After cell-line generation, degrader screening and validation can be carried out in high-throughput manner within days.

DOI: https://doi.org/10.1038/s41596-024-00979-z