The thrombopoietin/MPL axis is activated in the Gata1 low mouse model of myelofibrosis and is associated with a defective RPS14 signature
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PROVIDER: PRJNA352741 | ENA |
REPOSITORIES: ENA
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Project description:Myelofibrosis (MF) is caused by genetic abnormalities involving the thrombopoietin (TPO)/MPL/JAK2 axis. Furthermore MF patients have elevated serum TPO levels. MF is also associated with reduced GATA1 content in MK suggesting that this abnormality represents a phenotypic modifier. In 2014, Dr. Crispino suggested that in MF abnormal TPO signaling induces a ribosomal deficiency hampering GATA1 mRNA translation in MK. Support for MK GATA1 deficiency as “phenotypic modifier” in MF was provided by the observation that mice carrying the Gata1low mutation reducing Gata1 transcription in MK develop myelofibrosis. Since reduced RBC half-life subject these mice to continuous “erythroid stress”, we investigated the TPO/Mpl axis in this model. In Gata1low and wild-type mice, TPO mRNA was expressed by bone marrow (BM), spleen and liver. The greatest expression (by 300-fold) was detected in liver. Gata1low livers expressed TPO mRNA levels 6-fold greater than wild-type livers. TPO protein was detected in BM, spleen, liver and peritoneum washes and plasma. The greatest levels where detected in plasma. Gata1low plasma contained TPO levels 2-fold lower than wild-type plasma, but 2-times greater than plasma from bleed wild-type mice and Mplnull mice with similar thrombocytopenia, suggesting that TPO is overproduced in Gata1low mice. JAK2 and STAT5 were easily detected in Gata1low BM bur barely detectable in wild-type BM, suggesting that in the former MPL is prompt to signaling activation. Furthermore, Gata1low LSK expressed levels of Mpl mRNA 3-times greater than wild-type cells but expressed cell-surface levels of MPL 2-times lower than wild-type cells and similar to those on LSK from TPO-treated wild-type mice, suggesting that MPL is down-modulated in Gata1low LSK. The Crispino’s hypothesis that in MF activation of TPO/MPL/JAK2 induces a ribosomal deficiency hampering GATA1 mRNA translation and the realization that this axis is activated in Gata1low mice made us question the original hypothesis that reduced content of GATA1 in Gata1low MK results from deletion of lineage-specific enhancers. Microarray analyses indeed identified that Gata1low BM express a discordant ribosome signature including reduced expression of RPS24 and RPS36A, two genes mutated in Diamond Blackfan Anemia, a disease characterized by inefficient GATA1 mRNA translation. Electron microscopy identified that the cytoplasm of Gata1low MK contained poorly developed endoplasmic reticulum with rare polysomes. In conclusion, these results validate the Gata1low model as a MF model by indicating that these mice express an activated TPO/MPL axis and an abnormal ribosomal signature which may reduce efficiency of Gata1 mRNA translation.
2017-08-22 | GSE89628 | GEO
Project description:Myelofibrosis (MF) is caused by genetic abnormalities involving the thrombopoietin (TPO)/MPL/JAK2 axis. Furthermore MF patients have elevated serum TPO levels. MF is also associated with reduced GATA1 content in MK suggesting that this abnormality represents a phenotypic modifier. In 2014, Dr. Crispino suggested that in MF abnormal TPO signaling induces a ribosomal deficiency hampering GATA1 mRNA translation in MK. Support for MK GATA1 deficiency as “phenotypic modifier” in MF was provided by the observation that mice carrying the Gata1low mutation reducing Gata1 transcription in MK develop myelofibrosis. Since reduced RBC half-life subject these mice to continuous “erythroid stress”, we investigated the TPO/Mpl axis in this model. In Gata1low and wild-type mice, TPO mRNA was expressed by bone marrow (BM), spleen and liver. The greatest expression (by 300-fold) was detected in liver. Gata1low livers expressed TPO mRNA levels 6-fold greater than wild-type livers. TPO protein was detected in BM, spleen, liver and peritoneum washes and plasma. The greatest levels where detected in plasma. Gata1low plasma contained TPO levels 2-fold lower than wild-type plasma, but 2-times greater than plasma from bleed wild-type mice and Mplnull mice with similar thrombocytopenia, suggesting that TPO is overproduced in Gata1low mice. JAK2 and STAT5 were easily detected in Gata1low BM bur barely detectable in wild-type BM, suggesting that in the former MPL is prompt to signaling activation. Furthermore, Gata1low LSK expressed levels of Mpl mRNA 3-times greater than wild-type cells but expressed cell-surface levels of MPL 2-times lower than wild-type cells and similar to those on LSK from TPO-treated wild-type mice, suggesting that MPL is down-modulated in Gata1low LSK. The Crispino’s hypothesis that in MF activation of TPO/MPL/JAK2 induces a ribosomal deficiency hampering GATA1 mRNA translation and the realization that this axis is activated in Gata1low mice made us question the original hypothesis that reduced content of GATA1 in Gata1low MK results from deletion of lineage-specific enhancers. Microarray analyses indeed identified that Gata1low BM express a discordant ribosome signature including reduced expression of RPS24 and RPS36A, two genes mutated in Diamond Blackfan Anemia, a disease characterized by inefficient GATA1 mRNA translation. Electron microscopy identified that the cytoplasm of Gata1low MK contained poorly developed endoplasmic reticulum with rare polysomes. In conclusion, these results validate the Gata1low model as a MF model by indicating that these mice express an activated TPO/MPL axis and an abnormal ribosomal signature which may reduce efficiency of Gata1 mRNA translation.
2017-08-22 | GSE89629 | GEO
Project description:Dnm2fl/fl Pf4-Cre (Dnm2Plt-/-) mice lacking the endocytic GTPase dynamin 2 (DNM2) in platelets and megakaryocytes (MKs) develop hallmarks of myelofibrosis. At the cellular level, the tyrosine kinase JAK2 is constitutively active but decreased in expression in Dnm2Plt-/- platelets. Additionally, Dnm2Plt-/- platelets cannot endocytose the thrombopoietin (TPO) receptor Mpl, leading to elevated circulating TPO levels. Here, we assessed whether the hyperproliferative phenotype of Dnm2Plt-/- mice was due to JAK2 constitutive activation or elevated circulating TPO levels. In unstimulated Dnm2Plt-/- platelets, STAT3 and to a lower extent STAT5 were phosphorylated, but their phosphorylation was slowed and diminished upon TPO stimulation. We further crossed Dnm2Plt-/- mice in the Mpl-/- background to generate Mpl-/- Dnm2Plt-/- mice lacking Mpl ubiquitously and DNM2 in platelets and MKs. Mpl-/- Dnm2Plt-/- platelets had severely reduced JAK2 and STAT3 but normal STAT5 expression. Mpl-/- Dnm2Plt-/- mice had severely reduced bone marrow MK and hematopoietic stem and progenitor cell numbers. Additionally, Mpl-/- Dnm2Plt-/- mice had severe erythroblast maturation defects, decreased expression of hemoglobin and heme homeostasis genes, increased expression of ribosome biogenesis and protein translation genes, and developed anemia with grossly elevated plasma erythropoietin levels, leading to early fatality by postnatal day 25. Mpl-/- Dnm2Plt+/+ mice had impaired EB development at three weeks of age, which normalized with adulthood. Together, the data shows that DNM2-dependent Mpl-mediated endocytosis in platelets and MKs is required for steady-state hematopoiesis and provides novel insights into a developmentally controlled role for Mpl in normal erythropoiesis, regulating hemoglobin and heme production.
2022-08-25 | GSE206343 | GEO
Project description:Myelofibrosis (MF) is characterized by hyperactivation of thrombopoietin (TPO) signaling, which induces a RPS14 deficiency that de-regulates GATA1 in megakaryocytes by hampering its mRNA translation. As mice carrying the hypomorphic Gata1low mutation, which reduces the levels of Gata1 mRNA in megakaryocytes, develop MF, we investigated whether the TPO axis is hyperactive in this model. Gata1low mice contained two times more Tpo mRNA in liver and TPO in plasma than wild-type littermates. Furthermore, Gata1low LSKs expressed levels of Mpl mRNA (five times greater than normal) and protein (two times lower than normal) similar to those expressed by LSKs from TPO-treated wild-type mice. Gata1low marrow and spleen contained more JAK2/STAT5 than wild-type tissues, an indication that these organs were reach of TPO-responsive cells. Moreover, treatment of Gata1low mice with the JAK inhibitor ruxolitinib reduced their splenomegaly. Also in Gata1low mice activation of the TPO/MPL axis was associated with a RSP14 deficiency and a discordant microarray ribosome signature (reduced RPS24, RPS26 and SBDS expression). Finally, electron microscopy revealed that Gata1low megakaryocytes contained poorly developed endoplasmic reticulum with rare polysomes. In summary, Gata1low mice are a bona fide model of MF, which recapitulates the hyperactivation of the TPO/MPL/JAK2 axis observed in megakaryocytes from myelofibrotic patients.
| S-EPMC5520398 | biostudies-literature
Project description:Thrombopoietin (TPO) and its receptor MPL play crucial roles in hematopoietic stem cell (HSC) function and platelet production. However, the precise effects of TPO/MPL signaling on HSC regulation in different hematopoietic niches remain unclear. Here, we investigated the effects of TPO/MPL ablation on marrow and splenic hematopoiesis in TPO-/- and MPL-/- mice during aging. Despite severe thrombocytopenia, TPO-/- and MPL-/- mice did not develop marrow failure during a 2-year follow-up. Marrow and splenic HSCs exhibited different responses to TPO/MPL ablation and exogenous TPO treatment. Splenic niche cells compensated for marrow HSC loss in TPO-/- and MPL-/- mice by upregulating CXCL12 levels. These findings provide new insights into the complex regulation of HSCs by TPO/MPL and reveal a previously unknown link between TPO and CXCL12, two key growth factors for HSC maintenance. Understanding the distinct regulatory mechanisms between marrow and spleen hematopoiesis will help develop novel therapeutic approaches for hematopoietic disorders.
2023-12-16 | GSE249912 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2017-08-22 | GSE89630 | GEO
Project description:5q- syndrome is a somatic ribosomopathy linked to the monoallelic deletion of the RPS14 gene and characterized by a proeminent erythroid phenotype. The mechanism of anemia involves an impaired differentiation and increased apoptosis of erythroblasts. We have analyzed total cell extracts from UT7 cells with or without a decrease of RPS14 proteins induced by shRNAs. Our data show that GATA1 protein expression is low in line with a defect in the representation of its mRNA at the ribosome. A global analysis of transcripts on polysomes indicates that translation is selective with a decreased representation of the transcripts with a short coding sequence and UTRs and a highly structured 3’UTR, a subset of transcripts that includes GATA1. Our whole proteome analysis confirms that post-transcriptionally downregulated proteins were encoded by transcripts with a short length and structured 3’UTR. We identified a subset of post-translationally downregulated proteins including ribosomal proteins and translation elongation factors encoded by 5’TOP mRNAs that were enriched on the ribosome. Our results indicate that the thermodynamic characteristics of 3’UTR and in a lesser extend 5’UTR and the transcript length are the determinants of translation selectivity under RPS14 haploinsufficiency conditions and that a post-translational regulation of ribosomal proteins accounts for their decreased content in the cell.
2021-04-28 | PXD008650 | Pride
Project description:In the previous studies, we reported that Mpl alternative splicing form Mpl-del overexpressed in acute megakaryoblasttic leukemia (AMKL) patients and mediated thrombopoietin signaling to promote AMKL cells malignant proliferation and chemotherapy resisitance. To investigate the detailed mechanism of Mpl-del mediated AMKL cells proliferation and survival, the AMKL cell Dami stably expressing GFP or Mpl-del-GFP were established by transduction with GFP or Mpl-del-GFP lentiviruses and treated with 20ng/ml TPO for RNA-SEQ analysis to examine the expression of proliferation and survival-related genes. Our results indicated that the levels of the "leading edge" genes that account for survival and prolieration were significantly higher in Mpl--del overexpressed AMKL cells.
2019-04-04 | GSE127762 | GEO
Project description:The thrombopoietin/MPL axis is activated in the Gata1 low mouse model of myelofibrosis and is associated with a defective RPS14 signature [BM]
| PRJNA352763 | ENA
Project description:The thrombopoietin/MPL axis is activated in the Gata1 low mouse model of myelofibrosis and is associated with a defective RPS14 signature [spleen]
| PRJNA352764 | ENA