Loss of heterogeneous nuclear ribonucleoprotein L (HNRNP L) leads to mitochondrial dysfunction, DNA damage response and caspase-dependent cell death in hematopoietic stem cells

2016 ◽  
Vol 44 (9) ◽  
pp. S78-S79 ◽  
Author(s):  
Anne Helness ◽  
Marie-Claude Gaudreau ◽  
Damien Grapton ◽  
Charles Vadnais ◽  
Jennifer Fraszczak ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Cell Death ◽  
Mitochondrial Dysfunction ◽  
Dna Damage Response ◽  
Hematopoietic Stem ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Damage Response ◽  
Dependent Cell ◽  
Nuclear Ribonucleoprotein

Distinct Roles of CHK2 and Cell Death in Suppressing Oncogenic Potential of Tandem DNA Breaks in Human Hematopoietic Stem Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2659-2659
Author(s):  
Shahar Biechonski ◽  
Muhammad Yassin ◽  
Nasma Aqaqe ◽  
Leonid Olender ◽  
Melanie Rall ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Cell Death ◽  
Hematopoietic Stem Cells ◽  
Dna Damage Response ◽  
Parp Cleavage ◽  
Hematopoietic Stem ◽  
Damage Response ◽  
Induced Apoptosis ◽  
Dna Ends

Abstract DNA double strand breaks (DSBs) are the most dangerous genomic lesions that can be induced by endogenous and exogenous sources. DNA damage response determines cellular fate decisions following DSBs and can lead to cell death or cell survival. Incorrect DSB repair via canonical Non-Homologous End Joining (cNHEJ) or Alternative NHEJ (Alt-NHEJ) is the main source of oncogenic aberrations, including leukemogenic translocations, DNA sequence deletions and insertions. The long life span of Hematopoietic Stem Cells (HSC) and their practically unlimited potential for self-renewal requires efficient strategies to cope with DNA damage to eliminate erroneous genetic information inheritance to daughter cells. Although the critical importance of maintaining genome integrity for normal hematopoiesis and prevention of leukemogenesis has been established, definitive analysis of DNA damage response and its mutagenic outcomes in human HSC and Progenitors in response to DSBs is missing. Here we repot that human cord blood purified HSC (defined as CD34+CD38-CD45RA-) are exquisitely sensitive to irradiation (IR)-induced apoptosis in contrast to committed progenitors (defined as CD34+CD38+) as validated by PARP cleavage induction. Interestingly, pan-caspase inhibitor Z-VAD-FMK prevented, whereas CHK2 inhibitor (PV1019) failed in altering apoptosis onset of irradiated HSC. Strikingly, CHK2 inhibitor blocked IR-induced apoptosis in cycling HSC, suggesting differential wiring of DNA damage induced apoptosis in quiescent versus mitogenically stimulated HSC. To characterize cNHEJ repair pathway and its mutagenic potential in live primitive hematopoietic cells we analyzed I-SceI endonuclease induced tandem DSBs joining capacity using DNA repair reporter assay. We found that HSC exhibit inferior cNHEJ capacity as compared with committed progenitors. By decreasing DSBs persistence we revealed that progenitors utilize to the higher degree than HSC the mutagenic component of cNHEJ pathway that results in DNA deletions. We identified HSC-specific contribution of CHK2 kinase activity in limiting incorrect DNA ends joining. Blockade of apoptosis induction also led to the selective increase in mutagenic NHEJ in HSC. On the other hand, inhibition of DNA-PK led to increased oncogenic repair in progenitors only. Importantly, we revealed that HSC utilized mutagenic Alt-NHEJ pathway that depends on microhomologies search and extensive DNA ends processing less efficiently than Progenitors. Thus, our results indicate that oncogenic consequences of DSBs repair in HSC are distinctly minimized by the non-redundant cell death and CHK2 dependent mechanisms. More broadly, these findings will help to elucidate additional repair modifiers and the mechanism by which HSC contend with genotoxic stress. Disclosures No relevant conflicts of interest to declare.

The Splicing Factor Heterogeneous Nuclear Ribonucleoprotein L (hnRNPL) Restricts p53 Dependent and p53 Independent Cell Death Pathways In Hematopoietic Stem Cells

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2445-2445
Author(s):  
Marie-Claude Gaudreau ◽  
Damien Grapton ◽  
Florian Heyd ◽  
Charles Vadnais ◽  
Brian T Wilhelm ◽  
...  
Keyword(s):  
Stem Cells ◽  
Alternative Splicing ◽  
Hematopoietic Stem Cells ◽  
Fetal Liver ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Heterogeneous Nuclear Ribonucleoprotein ◽  
Effector Genes ◽  
Damage Response ◽  
Nuclear Ribonucleoprotein

Abstract Hematopoiesis is sustained by a pool of multipotent hematopoietic stem cells (HSCs) that have the capacity to differentiate into cells of all blood cell lineages. The pool of long-lived HSCs is maintained throughout life by the self-renewal ability of HSCs. New evidence suggests the process of alternative splicing is an important regulator of the maturation and activation of blood and immune effector cells. It is presently estimated that almost all multi-exon genes in human genome undergo alternative pre-mRNA splicing, and aberrant splicing has been linked to a variety of human pathologies. However, the role that pre-mRNA splicing may have for HSCs behaviour remains largely unexplored. Heterogeneous nuclear ribonucleoprotein L (hnRNPL) is an RNA-binding protein that regulates alternative splicing by binding exonic splicing silencers elements (ESS) resulting in exon exclusion from the mature mRNA. RT-PCR analyses showed that hnRNPL is expressed in early stages of hematopoiesis including HSCs and lineage restricted hematopoietic progenitors. To test the role of hnRNPL in hematopoietic differentiation, we have generated conditional deficient mice, since a constitutive deletion of hnRNPL results in early embryonic lethality. Animals carrying two hnRNPL-floxed alleles (hnRNPLfl/fl) can be deleted at adult stage by the pIpC inducible MxCre transgene or by the VavCre transgene, which is expressed in all hematopoietic cells starting at embryonic stage E14. VavCre+hnRNPLfl/fl mice were not viable and did not progress further in their development than embryonic stage E17.5 and ablation of hnRNPL by pIpC injection caused a high rate of mortality in adult MxCre+hnRNPLfl/fl mice compared to control animals. Both the fetal liver (FL) of VavCre+hnRNPLfl/fl mice and the bone marrow (BM) of adult MxCre+hnRNPLfl/fl mice had a significantly reduced cellularity. Furthermore, flow cytometric analysis revealed in both FL and BM a significant reduction in frequency and absolute numbers of all mature blood cells, the lymphoid and myeloid precursors, CLPS, CMPs and GMPs and to a lesser extent the erythroid/megakaryocytic precursors (MEPs). Methylcellulose and both competitive and non-competitive transplantation assays demonstrated that HSCs lacking hnRNPL cannot generate lineage-committed progenitors and have lost their self-renewal capacity and reconstitution potential. A genome-wide analysis of mRNA expression and splicing through next-generation RNA sequencing of wild-type (WT) or VavCre+hnRNPLfl/fl E14.5 Lin- c-kit+ fetal liver cells (FLCs) revealed that hnRNPL deficiency affects not only alternative splicing but also gene expression levels in hematopoietic progenitors. In the absence of hnRNPL, genes implicated in regulating apoptosis, DNA damage response and cell division where found up-regulated in Lin- c-kit+ FLCs. Among those genes, many were p53 effector genes such as Cdkn1a, Ccng1, Trp53inp1, TrailR2, Bax and Zmat3. In addition genes that are known to be required for normal hematopoiesis and HSCs functions such as Gfi1, CD34, Csfr1, Egr1 and Runx1 were found down-regulated in those cells. Further analyses by qPCR and Western blots confirmed those findings and also showed that the level of p53 protein expression was upregulated in VavCre+hnRNPLfl/fl FLCs although the mRNA level is the same as in the WT cells suggesting that hnRNPL affects p53 mRNA translation efficiency. Similarly, several genes found differentially spliced are implicated in cell cycle progression or required for normal hematopoiesis in FL such as Bcl11a, Cdk4, Ccnd2 and TRP53bp1. These results together with an increased level of Reactive Oxygen Species (ROS) and elevated levels of phosphorylated histone H2AX (γ-H2AX, a sensor for double strand DNA breaks) suggest that hnRNPL regulates the activation of a p53 dependent DNA damage response pathway in hematopoietic stem cells. As a consequence loss of hnRNPL results in a loss of hematopoietic stem and progenitor cells. Our data also suggest that hnRNPL does not only regulate alternative splicing but also expression levels of a set of specific effector genes involved in HSC survival, proliferation, ultimately affecting self-renewal. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Tight regulation of ubiquitin-mediated DNA damage response by USP3 preserves the functional integrity of hematopoietic stem cells

2014 ◽  
Vol 206 (4) ◽  
pp. 2064OIA143
Author(s):  
Cesare Lancini ◽  
Paul C.M. van den Berk ◽  
Joseph H.A. Vissers ◽  
Gaetano Gargiulo ◽  
Ji-Ying Song ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Hematopoietic Stem Cells ◽  
Dna Damage Response ◽  
Hematopoietic Stem ◽  
Functional Integrity ◽  
Damage Response

scholarly journals The Intersection of DNA Damage Response and Ferroptosis—A Rationale for Combination Therapeutics

Biology ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 187
Author(s):  
Po-Han Chen ◽  
Watson Hua-Sheng Tseng ◽  
Jen-Tsan Chi
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Ionizing Radiation ◽  
Dna Damage Response ◽  
Synergistic Effects ◽  
Genetic Disorders ◽  
Evolutionarily Conserved ◽  
Damage Response ◽  
Dependent Cell ◽  
Disease Relevance

Ferroptosis is a novel form of iron-dependent cell death characterized by lipid peroxidation. While the importance and disease relevance of ferroptosis are gaining recognition, much remains unknown about its interaction with other biological processes and pathways. Recently, several studies have identified intricate and complicated interplay between ferroptosis, ionizing radiation (IR), ATM (ataxia–telangiectasia mutated)/ATR (ATM and Rad3-related), and tumor suppressor p53, which signifies the participation of the DNA damage response (DDR) in iron-related cell death. DDR is an evolutionarily conserved response triggered by various DNA insults to attenuate proliferation, enable DNA repairs, and dispose of cells with damaged DNA to maintain genome integrity. Deficiency in proper DDR in many genetic disorders or tumors also highlights the importance of this pathway. In this review, we will focus on the biological crosstalk between DDR and ferroptosis, which is mediated mostly via noncanonical mechanisms. For clinical applications, we also discuss the potential of combining ionizing radiation and ferroptosis-inducers for synergistic effects. At last, various ATM/ATR inhibitors under clinical development may protect ferroptosis and treat many ferroptosis-related diseases to prevent cell death, delay disease progression, and improve clinical outcomes.

scholarly journals DNA-damage response gene GADD45A induces differentiation in hematopoietic stem cells without inhibiting cell cycle or survival

Stem Cells ◽  
2016 ◽  
Vol 34 (3) ◽  
pp. 699-710 ◽  
Author(s):  
Susanne Wingert ◽  
Frederic B. Thalheimer ◽  
Nadine Haetscher ◽  
Maike Rehage ◽  
Timm Schroeder ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Dna Damage ◽  
Hematopoietic Stem Cells ◽  
Dna Damage Response ◽  
Response Gene ◽  
Hematopoietic Stem ◽  
Damage Response

scholarly journals A Distinctive DNA Damage Response in Human Hematopoietic Stem Cells Reveals an Apoptosis-Independent Role for p53 in Self-Renewal

2010 ◽  
Vol 7 (2) ◽  
pp. 186-197 ◽  
Author(s):  
Michael Milyavsky ◽  
Olga I. Gan ◽  
Magan Trottier ◽  
Martin Komosa ◽  
Ofer Tabach ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Hematopoietic Stem Cells ◽  
Dna Damage Response ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Damage Response
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