Characterization of DNA-binding-dependent and -independent functions of SCL/TAL1 during human erythropoiesis

Blood ◽  
2004 ◽  
Vol 103 (9) ◽  
pp. 3326-3335 ◽  
Author(s):  
Emmanuel Ravet ◽  
Damien Reynaud ◽  
Monique Titeux ◽  
Brigitte Izac ◽  
Serge Fichelson ◽  
...  

Abstract The transcription factor TAL1 has major functions during embryonic hematopoiesis and in adult erythropoiesis and megakaryocytopoiesis. These functions rely on different TAL1 structural domains that are responsible for dimerization, transactivation, and DNA binding. Previous work, most often done in mice, has shown that some TAL1 functions do not require DNA binding. To study the role of TAL1 and the relevance of the TAL1 DNA-binding domain in human erythropoiesis, we developed an approach that allows an efficient enforced wild-type or mutant TAL1 protein expression in human hematopoietic CD34+ cells using a lentiviral vector. Differentiation capacities of the transduced cells were studied in a culture system that distinguishes early and late erythroid development. Results indicate that enforced TAL1 expression enhances long-term culture initiating cell (LTC-IC) potential and erythroid differentiation of human CD34+ cells as shown by increased βglobin and porphobilinogen deaminase (PBGD) gene expressions and erythroid colony-forming units (CFU-Es), erythroid burst-forming units (BFU-Es), and glycophorin A-positive (GPA+) cell productions. Enforced expression of a TAL1 protein deleted of its DNA-binding domain (named ΔbTAL1) mimicked most TAL1 effects except for the LTC-IC enhancement, the down-regulation of the CD34 surface marker, and the GPA+ cell production. These results provide the first functional indications of DNA-binding-dependent and -independent roles of TAL1 in human erythropoiesis. (Blood. 2004;103:3326-3335)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1249-1249
Author(s):  
Shuiling Jin ◽  
Ngoc-Tung Tran ◽  
Hairui Su ◽  
Suming Huang ◽  
Xinyang Zhao ◽  
...  

Abstract The isoforms of key transcription factors in hematopoiesis such as TAL1, GATA1 and RUNX1 are generated through alternative RNA splicing regulated by the PRMT1-RBM15 axis (Zhang et al. 2015). The functions of short isoforms of GATA1 (GATA1s) and RUNX1 (RUNX1a) are well characterized, yet it is unknown how the short isoform of TAL1 (TAL1s) regulates hematopoiesis. In this presentation, we report that the short isoform of TAL1, i.e. TAL1s, is generated via alternative RNA splicing as detected by isoform specific real-time PCR reactions using RNA isolated from leukemia cell lines and primary human cord blood cells. RBM15, an RNA binding protein, which is involved in chromosome translocation to produce RBM15-MKL1 fusion protein in acute megakaryocytic leukemia, regulates the alternative RNA splicing of TAL1. RBM15 promotes the production of full-length TAL1 mRNA, while reduction of RBM15 protein level via PRMT1-mediated degradation pathway favors the production of TAL1s. RBM15 directly binds to intronic regions on TAL1 pre-mRNA. Binding of RBM15 is responsible for recruiting SF3B1-associated RNA splicing complex. Given that PRMT1 senses the hypoxia status of hematopoietic cells, the changing of TAL1s/TAL1fl ratio by PRMT1 activity may be an adaptive response of hematopoietic cells to hypoxia status. The short form TAL1s still contains the helix-loop-helix DNA binding domain but not the N terminal regions upstream of the DNA binding domain. Thus, the TAL1s may act as a dominant negative mutant of the full-length TAL1fl to block TAL1fl-regulated transcription. We demonstrated that overexpression of TAL1s not the full-length TAL1promotes the erythroid differentiation of K562 cells. Although TAL1 gene is required for both erythroid and megakaryocyte differentiation at early stage of hematopoiesis, TAL1s does not promote megakaryocyte differentiation. Therefore, fine-tuning the TAL1 isoforms by the PRMT1-RBM15 axis determine the cell fate of a MEP progenitor cell. Using immunoprecipitation assays and mass spectrometry analysis, we identified proteins specifically associated with the N terminal region of TAL1. How unique TAL1s-associated transcriptional regulatory complex plays in erythroid differentiation will be discussed in the presentation in comparison with the Tal1fl-asociated protein complex. In summary, our findings stratify another new layer of regulation by PRMT1, which relays extracellular signals (such as hypoxia signal) to transcriptional regulatory program. Given that PRMT1 is often constitutively highly expressed in leukemia cells, how overproduction of short form TAL1 interferes with normal hematopoiesis may help to explain the molecular mechanisms of many hematological malignancies associated with dysregulation of TAL1 expression. Disclosures No relevant conflicts of interest to declare.


1999 ◽  
Vol 96 (9/10) ◽  
pp. 1580-1584 ◽  
Author(s):  
I. Ségalas ◽  
S. Desjardins ◽  
H. Oulyadi ◽  
Y. Prigent ◽  
S. Tribouillard ◽  
...  

1985 ◽  
Vol 260 (4) ◽  
pp. 2301-2306
Author(s):  
H Pande ◽  
J Calaycay ◽  
D Hawke ◽  
C M Ben-Avram ◽  
J E Shively

2021 ◽  
Vol 296 ◽  
pp. 100612
Author(s):  
Chuandong Fan ◽  
Hongjoo An ◽  
Mohamed Sharif ◽  
Dongkyeong Kim ◽  
Yungki Park

1982 ◽  
Vol 257 (11) ◽  
pp. 6102-6105
Author(s):  
M Nishikimi ◽  
K Ogasawara ◽  
I Kameshita ◽  
T Taniguchi ◽  
Y Shizuta

2021 ◽  
Vol 548 ◽  
pp. 39-46
Author(s):  
Chang Woo Han ◽  
Han Na Lee ◽  
Mi Suk Jeong ◽  
So Young Park ◽  
Se Bok Jang

Genetics ◽  
1998 ◽  
Vol 148 (4) ◽  
pp. 1441-1451
Author(s):  
Johan G de Boer ◽  
Barry W Glickman

Abstract The lacI gene has been used extensively for the recovery and analysis of mutations in bacteria with various DNA repair backgrounds and after exposure to a wide variety of mutagens. This has resulted in a large database of information on mutational mechanisms and specificity of many mutagens, as well as the effect of DNA repair background on mutagenicity. Most importantly, knowledge about the mutational sensitivity of the lacI gene is now available, yielding information about mutable nucleotides. This popularity and available knowledge resulted in the use of the lacI gene in transgenic rodents for the study of mutagenesis in mammals, where it resides in ~40 repeated copies. As the number of sequenced mutations recovered from these animals increases, we are able to analyze the sites at which mutations have been recovered in great detail and to compare the recovered sites between bacteria and transgenic animals. The nucleotides that code for the DNA-binding domain are nearly saturated with base substitutions. Even after determining the sequences of ~10,000 mutations recovered from the animals, however, new sites and new changes are still being recovered. In addition, we compare the nature of deletion mutations between bacteria and animals. Based on the nature of deletions in the animals, we conclude that each deletion occurs in a single copy of the gene.


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