Defective endomitosis during megakaryopoiesis leads to thrombocytopenia in Fanca−/− mice

Pawlikowska, Patrycja; Fouchet, Pierre; Vainchenker, William; Rosselli, Filippo; Naim, Valeria

doi:10.1182/blood-2014-01-551457

Cited by 26 publications

(18 citation statements)

References 32 publications

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“…Such patients suffer from progressive bone marrow failure, pancytopenia and predisposition to cancer. 50 Knockout mouse studies revealed that FANCA is needed for normal megakaryopoiesis and platelet production. Megakaryocytes in the deficient mice were found to be in a senescent state.…”

Section: Fanca Fanccmentioning

confidence: 99%

Clonal hematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding

et al. 2020

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Section: Fanca Fanccmentioning

confidence: 99%

Clonal hematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding

et al. 2020

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“…Importantly, persistent anaphase bridges have been observed in haematopoietic cells of FA mice, even in unperturbed conditions and are associated with cytokinesis failure and increased apoptotic cell death, 161 suggesting that endogenous replication stress or unresolved DNA damage that persists in mitosis may contribute to bone marrow failure and account for the exacerbated p53/p21 activation observed in FA 171 . Recently, the FA pathway has also been shown to counteract physiologic stress during megakaryopoiesis, preventing CFS instability and cell division abnormalities associated with defective megakaryocyte differentiation and thrombocytopenia of FA mice 282 . Finally, a variant form of xeroderma pigmentosum (XPV) is a cancer-prone disease that is caused by mutations in the gene coding for the TLS polymerase Polη, a protein shown to have a role in DNA synthesis at CFSs 6 …”

Section: The Role Of Mitotic Replication Stress In Human Diseasementioning

confidence: 99%

Rescue from replication stress during mitosis

Fragkos

Naim

2017

Cell Cycle

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Genomic instability is a hallmark of cancer and a common feature of human disorders, characterized by growth defects, neurodegeneration, cancer predisposition, and aging. Recent evidence has shown that DNA replication stress is a major driver of genomic instability and tumorigenesis. Cells can undergo mitosis with under-replicated DNA or unresolved DNA structures, and specific pathways are dedicated to resolving these structures during mitosis, suggesting that mitotic rescue from replication stress (MRRS) is a key process influencing genome stability and cellular homeostasis. Deregulation of MRRS following oncogene activation or loss-of-function of caretaker genes may be the cause of chromosomal aberrations that promote cancer initiation and progression. In this review, we discuss the causes and consequences of replication stress, focusing on its persistence in mitosis as well as the mechanisms and factors involved in its resolution, and the potential impact of incomplete replication or aberrant MRRS on tumorigenesis, aging and disease.

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“…It is generally accepted that FANC pathway-deficient mice present mild hematopoietic phenotypes (49). The Fanca -/model we used (50) is known to present reduced platelet counts, which mimics patient thrombocytopenia, and altered immunoglobulin formation in association with alterations in the DNA damage response and B cell differentiation (51)(52)(53), abnormalities already reported in FA patients (54). Nevertheless, Fanca -/and WT mice, independently of their ages (3-6 months old, i.e., young, or more than 1 year old, i.e., old) present similar levels of Lin -Sca + Kit + (LSK) cells and their 3 subpopulations, longterm HSCs (LT-HSCs, Flt3 -CD34 -), short-term HSCs (ST-HSCs, Flt3 -CD34 + ), and multipotent progenitors (MPPs, Flt3 + CD34 + ), on which the maintenance of hematopoiesis depends (Figure 4, A-C).…”

Section: Fanc Core Complex Loss Of Function Leads To Mitf Overexpressmentioning

confidence: 99%

Microphthalmia transcription factor expression contributes to bone marrow failure in Fanconi anemia

Oppezzo¹,

Bourseguin²,

Renaud³

et al. 2020

Journal of Clinical Investigation

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Fancd2-/and WT MEFs, but clearly lower in these cells than in Fanca-/or Fancc-/-MEFs (Figure 1F and data not shown). Together, our previous data robustly demonstrate that loss of function of key components of the FANC core complex is associated with high expression of MiTF at both the RNA and protein levels. SMAD and p38 signaling pathways are necessary but not sufficient to activate MiTF expression in FA MEFs. The increase in Mitf expression in FANC pathway-deficient MEFs with increasing time in the same culture medium (Figure 1, D and E) could be induced by cellto-cell contacts or in an autocrine manner by cell-secreted factor or factors. Consistent with the latter hypothesis, we observed that Mitf expression is robustly induced at both the protein and RNA levels by 24 hours after replating FANC pathway-deficient MEFs in a "conditioned" medium in which the same cells previously grew for 72 hours (Figure 2, A and B, and data not shown). Notably, WT-derived 72-hour-old conditioned medium was unable to significantly induce Mitf in Fanca-/or Fancc-/-MEFs. Similarly, Fanca-/-or Fancc-/-derived conditioned medium was unable to induce Mitf in WT MEFs (Figure 2, A and B, and data not shown). Thus, it is conceivable that Mitf is induced in response to the accumulation in the culture medium of factor or factors secreted by the Fanc-deficient cells themselves. FA cells appear able to secrete and respond to such factor(s), whereas WT cells are poor secretors and nonresponders. Next, we performed ELISA to determine the presence, if any, of known extracellular factors in the culture medium of MEFs. To better perform our analysis, 2 days after dilution, the complete culture medium was washed out, and the cells were fed 2 more days with medium without serum (a longer incubation affects cell morphology, indicating the presence of stress and survival). The serumfree medium was collected and filtered to eliminate detached cells and cellular debris to perform ELISA. We failed to detect TNF-α or IL-1β in FA-derived conditioned medium, but revealed 4 to 6 times higher concentrations of 2 TGF family members (43, 44), TGF-β and activin A (Figure 2, C and D). Finally, the conditioned medium was analyzed by mass spectrometry. Again, we identified high levels of both TGF-β and activin A in the culture medium isolated from FANC pathway-deficient MEFs, but did not distinguish other growth factors differentially expressed between WT and FA MEFs (data not shown). Thus, 2 alternative approaches validated that cultured FANC pathway-deficient MEFs secrete TGF-β and activin A. TGF-β and activin A determine cell fate and hematopoiesis by signaling mainly through the Smad and p38 pathways (8, 43-46), which were previously described as chronically activated in FA cells (24, 32). In Fanca-/or Fancc-/-MEFs maintained for 24 hours in 72-hour-old conditioned medium, we observed a modest but reproducible increase in Smad2/3 phosphorylation and extremely strong phosphorylation of p38 (Figure 2E). The culture of WT MEFs in conditioned medium (both from FA...

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Defective endomitosis during megakaryopoiesis leads to thrombocytopenia in Fanca−/− mice

Abstract: Key Points Fanca −/− megakaryocytes accumulate genomic instability through endomitotic cycles. Defective endomitosis induces senescence of Fanca−/− megakaryocytes.

Cited by 26 publications

References 32 publications

Clonal hematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding

Clonal hematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding

Rescue from replication stress during mitosis

Microphthalmia transcription factor expression contributes to bone marrow failure in Fanconi anemia

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