A high concentration of triiodothyronine attenuates the stimulatory effect on hemin-induced erythroid differentiation of human erythroleukemia K562 cells

Abstract

Thyroid hormone stimulates erythropoiesis and clinical hypothyroidism is often complicated by reductions in red cell mass and total blood volume, and by normocytic normochromic anemia [1][2][3][4]. Clinically, bone marrow has been observed to show erythroid hyperplasia in patients with hyperthyroidism [5]. However, anemia is sometimes observed in patients with hyperthyroidism such as Graves' disease (GD). Some reports indicate that anemia associated with hyperthyroidism occurs in 10-22% of cases of non-treated hyperthyroidism, and that these cases recover well with treatment of A high concentration of triiodothyronine attenuates the stimulatory effect on hemin-induced erythroid differentiation of human erythroleukemia K562 cells Abstract. Although thyroid hormone is a known stimulator of erythropoietic differentiation, severe anemia is sometimes observed in patients with hyperthyroidism and this mechanism is not fully understood. The aim of this study was to investigate the effect of triiodothyronine (T3) on hemin-induced erythropoiesis. Human erythroleukemia K562 cells were used as an erythroid differentiation model. Cell differentiation was induced by hemin and the effect of pre-incubation with T3 (0.1 to 100 nM) was analyzed by measuring the benzidine-positive rate, hemoglobin content, CD71 expression (transferrin receptor), and mRNA expression for transcription factors related to erythropoiesis and thyroid hormone receptors (TRs). Hemin, a promoter of erythroid differentiation, increased the levels of mRNAs for TRα, TRβ, and retinoid X receptor α (RXRα), as well as those for nuclear factor-erythroid 2 (NFE2), GATA-binding protein 1 (GATA1) and GATA-binding protein 2 (GATA2). Lower concentrations of T3 had a stimulatory effect on hemin-induced hemoglobin production (1 and 10 nM), CD71 expression (0.1 nM), and α-globin mRNA expression (1 nM), while a higher concentration of T3 (100 nM) abrogated the stimulatory effect on these parameters. T3 at 100 nM did not affect cell viability and proliferation, suggesting that the abrogation of erythropoiesis enhancement was not due to toxicity. T3 at 100 nM also significantly inhibited expression of GATA2 and RXRα mRNA, compared to 1 nM T3. We conclude that a high concentration of T3 attenuates the classical stimulatory effect on erythropoiesis exerted by a low concentration of T3 in hemin-induced K562 cells.

MiR-27a Promotes Hemin-Induced Erythroid Differentiation of K562 Cells by Targeting CDC25B

“…Our findings revealed a novel mechanism of CDC25B mRNA turnover, wherein CDC25B is inactivated by miR-27a in K562 cells. Similarly, this type of miRNA-mediated proteolysis has also been demonstrated in several previous studies, i.e., CDC25A inactivation requires miR-21 and miR-16 [16, 23]. In addition, our study further demonstrated that CDC25B was significantly decreased during erythroid differentiation in hemin-induced K562 cells, and CDC25B siRNA up-regulated the expression of γ-globin in hemin-induced K562 cells.…”

“…CDC25B, which mainly activates CDK1-cyclin B at the G2-M transition phase, has also been demonstrated to be recruited to the mother centrosome and to be involved in the centrosome duplication cycle and microtubule nucleation [14]. The overexpression of CDC25B correlates with malignant disease and poor prognosis in certain malignancies and leads to genetic instability in mice [13, 15, 16]. In addition, CDC25B is a key regulator of the cell cycle in red blood cell (RBC) precursors and is downregulated in the bone marrow, owing to the inhibition of erythropoiesis after myelosuppression treatment [17].…”

PKR activation and eIF2α phosphorylation mediate human globin mRNA splicing at spliceosome assembly

“…Differentiating human erythroleukemia cells do not express β-globin; very low levels of β-globin mRNA were detected, relative to α-globin mRNA, in conditions inhibiting cell proliferation [37]. Even before induction of differentiation, K562 cells expressed fully spliced α-globin mRNA, whereas pre-mRNA was not detectable (LSN, data not shown).…”

miR-150 inhibits terminal erythroid proliferation and differentiation

“…To test this hypothesis, human K562 erythroleukemia cells, which have been proven to be a very useful tool for erythroid-lineage development research, were induced into erythroid differentiation with 50 μM hemin [ 28 , 34 – 35 , 66 – 67 ]. As expected, forced expression of miR-150 suppressed hemin-dependent erythropoiesis in K562 cells; commitment to hemoglobinization and GPA marking were reduced compared to the controls at each time point.…”