| 1. |
- Kuchenbauer, Florian, et al.
(author)
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Comprehensive analysis of mammalian miRNA* species and their role in myeloid cells.
- 2011
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In: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 118:12, s. 3350-8
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Journal article (peer-reviewed)abstract
- Processing of pre-miRNA through Dicer1 generates an miRNA duplex that consists of an miRNA and miRNA* strand. Despite the general view that miRNA*s have no functional role, we further investigated miRNA* species in 10 deep-sequencing libraries from mouse and human tissue. Comparisons of miRNA/miRNA* ratios across the miRNA sequence libraries revealed that 50% of the investigated miRNA duplexes exhibited a highly dominant strand. Conversely, 10% of miRNA duplexes showed a comparable expression of both strands, whereas the remaining 40% exhibited variable ratios across the examined libraries, as exemplified by miR-223/miR-223* in murine and human cell lines. Functional analyses revealed a regulatory role for miR-223* in myeloid progenitor cells, which implies an active role for both arms of the miR-223 duplex. This was further underscored by the demonstration that miR-223 and miR-223* targeted the insulin-like growth factor 1 receptor/phosphatidylinositol 3-kinase axis and that high miR-223* levels were associated with increased overall survival in patients with acute myeloid leukemia. Thus, we found a supporting role for miR-223* in differentiating myeloid cells in normal and leukemic cell states. The fact that the miR-223 duplex acts through both arms extends the complexity of miRNA-directed gene regulation of this myeloid key miRNA.
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| 2. |
- Landry, Josette-Renée, et al.
(author)
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The opitz syndrome gene mid1 is transcribed from a human endogenous retroviral promoter.
- 2002
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In: Molecular biology and evolution. - 0737-4038. ; 19:11, s. 1934-1942
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Journal article (peer-reviewed)abstract
- Human endogenous retroviruses (HERVs) and other long terminal repeat (LTR)–containing elements comprise a significant portion (8%) of the human genome and are likely vestiges of retroviral infections during primate evolution. Many of the HERVs present in human DNA have retained functional promoter, enhancer, and polyadenylation signals, and these regulatory sequences have the potential to modify the expression of nearby genes. To identify retroviral elements that contribute to the transcription of human genes, we screened sequence databases for chimeric (viral-cellular) transcripts. These searches revealed a fusion transcript containing the LTR of an HERV-E element linked to the Opitz syndrome gene Mid1. We confirmed the authenticity of the chimeric transcript by 5' rapid amplification of cDNA ends (RACE) and established that the Mid1 mRNA isoform was transcribed from a retroviral LTR. The identification of a retroviral first exon suggested the existence of alternative promoters for Mid1 because nonretroviral (native) 5' untranslated regions (UTRs) had been reported previously for this gene. Although Mid1 transcripts could be detected in all tissues tested, quantitative real-time reverse transcription–polymerase chain reaction indicated that the retroviral promoter contributes significantly to the level of Mid1 transcripts in placenta and embryonic kidney, where chimeric mRNAs were found to represent 25% and 22% of overall Mid1 mRNAs, respectively. Transient transfection studies supported a role for the LTR as a strong tissue-specific promoter in placental and embryonic kidney cell lines and suggested a function for the LTR as an enhancer. These findings provide further evidence that some endogenous retroviruses have evolved a biological function by contributing transcriptional regulatory elements to cellular genes.
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| 3. |
- Martins, Leila R., et al.
(author)
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Stk33 is required for spermatid differentiation and male fertility in mice
- 2018
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In: Developmental Biology. - : Academic Press. - 0012-1606 .- 1095-564X. ; 433:1, s. 84-93
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Journal article (peer-reviewed)abstract
- Spermiogenesis is the final phase during sperm cell development in which round spermatids undergo dramatic morphological changes to generate spermatozoa. Here we report that the serine/threonine kinase Stk33 is essential for the differentiation of round spermatids into functional sperm cells and male fertility. Constitutive Stk33 deletion in mice results in severely malformed and immotile spermatozoa that are particularly characterized by disordered structural tail elements. Stk33 expression first appears in primary spermatocytes, and targeted deletion of Stk33 in these cells recapitulates the defects observed in constitutive knockout mice, confirming a germ cell-intrinsic function. Stk33 protein resides in the cytoplasm and partially co-localizes with the caudal end of the manchette, a transient structure that guides tail elongation, in elongating spermatids, and loss of Stk33 leads to the appearance of a tight, straight and elongated manchette. Together, these results identify Stk33 as an essential regulator of spermatid differentiation and male fertility.
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| 4. |
- Mohr, Sebastian, et al.
(author)
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Hoxa9 and Meis1 Cooperatively Induce Addiction to Syk Signaling by Suppressing miR-146a in Acute Myeloid Leukemia.
- 2017
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In: Cancer cell. - : Elsevier BV. - 1878-3686 .- 1535-6108. ; 31:4
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Journal article (peer-reviewed)abstract
- The transcription factor Meis1 drives myeloid leukemogenesis in the context of Hox gene overexpression butis currently considered undruggable. We therefore investigated whether myeloid progenitor cells transformed by Hoxa9 and Meis1 become addicted to targetable signaling pathways. A comprehensive (phospho)proteomic analysis revealed that Meis1 increased Syk protein expression and activity. Syk upregulation occurs through a Meis1-dependent feedback loop. By dissecting this loop, we show that Syk is a direct target of miR-146a, whose expression is indirectly regulated by Meis1 through the transcription factor PU.1. In the context of Hoxa9 overexpression, Syk signaling induces Meis1, recapitulating several leukemogenic features of Hoxa9/Meis1-driven leukemia. Finally, Syk inhibition disrupts the identified regulatory loop, prolonging survival of mice with Hoxa9/Meis1-driven leukemia.
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| 5. |
- Schneider, Edith, et al.
(author)
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MicroRNA-155 is a direct target of Meis1, but not a driver in acute myeloid leukemia.
- 2018
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In: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 103, s. 246-255
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Journal article (peer-reviewed)abstract
- MicroRNA-155 (miR-155) is one of the first described oncogenic miRNAs. Although multiple direct targets of miR-155 have been identified, it is not clear how it contributes to the pathogenesis of acute myeloid leukemia. We found miR-155 to be a direct target of Meis1 in murine Hoxa9/Meis1 induced acute myeloid leukemia. The additional overexpression of miR 155 accelerated the formation of acute myeloid leukemia in Hoxa9 as well as in Hoxa9/Meis1 cells in vivo. However, in the absence or after the removal of miR-155, leukemia onset and progression were unaffected. Although, miR-155 accelerated growth and homing as well as impaired differentiation, our data underscore the pathophysiological relevance of miR 155 as an accelerator rather than a driver of leukemogenesis. This further highlights the complexity of the oncogenic program of Meis1 to compensate for the loss of a potent oncogene such as miR-155. These findings are highly relevant to current and developing approaches for targeting miR-155 in acute myeloid leukemia.
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| 6. |
- Schneider, Edith, et al.
(author)
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MicroRNA-155 is upregulated in MLL-rearranged AML but its absence does not affect leukemia development.
- 2016
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In: Experimental hematology. - : Elsevier BV. - 1873-2399 .- 0301-472X. ; 44:12, s. 1166-71
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Journal article (peer-reviewed)abstract
- MicroRNA-155 (miR-155) is an oncogenic miRNA upregulated in various tumor types and leukemias and has been suggested as a potential drug target. Based on our previous work detecting high miR-155 levels in response to Meis1 overexpression in a murine Hox leukemia model, we show here the relationship among HOXA9, MEIS1, and miR-155 levels in MLL-translocated acute myeloid leukemia (AML) patients. Using mouse bone marrow cells transformed by MLL-fusion genes expressing graduated levels of Meis1, we show a positive correlation between miR-155 and Meis1. However, using a miR-155-knockout mouse model, we show that the absence and the depletion of miR-155 have no effect on leukemia formation or progression. We also show for the first time that miR-155 levels are correlated with MLL translocations, but that miR-155 expression is dispensable for the formation of AML and has no effect on leukemia progression.
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| 7. |
- Schneider, Edith, et al.
(author)
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MicroRNA-708 is a novel regulator of the Hoxa9 program in myeloid cells.
- 2020
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In: Leukemia. - : Springer Science and Business Media LLC. - 1476-5551 .- 0887-6924. ; 34, s. 1253-1265
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Journal article (peer-reviewed)abstract
- MicroRNAs (miRNAs) are commonly deregulated in acute myeloid leukemia (AML), affecting critical genes not only through direct targeting, but also through modulation of downstream effectors. Homeobox (Hox) genes balance self-renewal, proliferation, cell death, and differentiation in many tissues and aberrant Hox gene expression can create a predisposition to leukemogenesis in hematopoietic cells. However, possible linkages between the regulatory pathways of Hox genes and miRNAs are not yet fully resolved. We identified miR-708 to be upregulated in Hoxa9/Meis1 AML inducing cell lines as well as in AML patients. We further showed Meis1 directly targeting miR-708 and modulating its expression through epigenetic transcriptional regulation. CRISPR/Cas9 mediated knockout of miR-708 in Hoxa9/Meis1 cells delayed disease onset in vivo, demonstrating for the first time a pro-leukemic contribution of miR-708 in this context. Overexpression of miR-708 however strongly impeded Hoxa9 mediated transformation and homing capacity in vivo through modulation of adhesion factors and induction of myeloid differentiation. Taken together, we reveal miR-708, a putative tumor suppressor miRNA and direct target of Meis1, as a potent antagonist of the Hoxa9 phenotype but an effector of transformation in Hoxa9/Meis1. This unexpected finding highlights the yet unexplored role of miRNAs as indirect regulators of the Hox program during normal and aberrant hematopoiesis.
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