K-CL co-transport plays an important role in normal and   thalassemic erythropoiesis

Abstract

Background and ObjectivesCell volume changes are hallmarks of both cell maturation and apoptosis, and are paralleled by modulation of membrane ion transport pathways. We evaluated the possible role of K-Cl co-transport (KCC) in both normal and β-thalassemic erythropoiesis in vitro. Design and MethodsWe studied the effects of the KCC inhibitor, DIOA, on cell proliferation and differentiation, on expression of KCC mRNA and polypeptides, and on expression of cell cycle and apoptosis genes in in vitro liquid-cultures of CD34 + cells from normal and β-thalassemic subjects. Resultsβ-thalassemic erythroid precursors showed increased abundance of KCC1-3 mRNA and of KCC polypeptides in late erythropoiesis. DIOA markedly modified the composition of normal erythroid precursors, promoting differentiation and arrest at the polychromatic erythroblast stage and resulting in a precursor distribution profile similar to that of untreated β-thalassemic cells. DIOA up-regulated cyclin-D mRNA levels in late erythropoiesis in both cell models, paralleling changes in the percentage of S-phasecells. Caspase-3 activity in late erythropoiesis declined to similar degrees in both cell models. DIOA did not modify caspase-3 or -8 mRNA levels. Interpretation and ConclusionsIneffective erythropoiesis of in vitro cultured β-thalassemic cells is likely related to impaired cell maturation. KCC activity appears to contribute to erythroid cell growth during late erythropoiesis. ABSTRACT© F e r r a t a S t o r t i F o u n d a t i o n E rythropoiesis is a complex multistage process characterized by differentiation of pluripotent hematopoietic progenitors to reticulocytes and then to mature red cells. Although understanding of the mechanisms involved in the maturation of normal erythroid precursors has progressed in the last decade, much remains unknown about erythroid maturation in inherited erythroid diseases. β thalassemia is a congenital red cell disorder characterized by the absence or reduced synthesis of hemoglobin β globin chains. Despite extensive knowledge of the molecular defects causing β thalassemia, less is known about the major factors contributing to β thalassemic anemia: the reduction of β thalassemic red cell life-span and ineffective erythropoiesis. 1-4Ineffective erythropoiesis has been shown in β thalassemia in vivo by ferrokinetic assays, suggesting a block in erythroid precursors and a precocious cell death in bone marrow.2-5 Recently, Mathias et al. showed that ineffective erythropoiesis in the bone marrow precursors of patients with β thalassemia major is associated with progressively increased apoptosis of polychromatophilic normoblasts of late erythropoiesis and seems to be related to hemoglobin chain synthesis.6 However, the mechanisms underlying apoptosis of β thalassemic erythroid precursors and the developmental kinetics of β thalassemic ineffective erythropoiesis need further investigation.Since cell volume change is one of the hallmarks of cell progression towards apoptosis or proliferation, the modulation of ion tran...

Cryohydrocytosis: increased activity of cation carriers in red cells from a patient with a band 3 mutation

“…35 Uncontrolled activation of the KCC has been reported in patients with sickle cell anemia and beta-thalassemia in whom pathological RBC dehydration is abundant. 36,37 Our observations show that this is also the case in the CHC patient's RBC. As for most ion transport systems, the activity of the KCC in normal RBC is down-regulated in response to cooling.…”

The genetics of blood disorders: the hereditary hemoglobinopathies

“…Embora com menor conteúdo intracelular de Hb, hemácias talassêmicas podem apresentar valores de densidade tanto menores quanto maiores que hemácias normais 6,94 .…”

TO MONITOR TREATMENT OF A LARGE COHORT OF PATIENTS WITH β-THALASSAEMIA MAJOR, INTERMEDIA & SICKLE CELL ANAEMIA IN ORDER TO ESTABLISH THE RESPONSE TO TRANS-RESVERATROL AND THE ASSOCIATED ELEMENTS.

“…Despite extensive knowledge of the molecular defects causing β-thalassemia, less is known about the mechanisms responsible for the associated ineffective erythropoiesis and reduced red cell survival (1)(2)(3)(4)(5)(6)(7). Increased levels of reactive oxygen species (ROS) have been reported to contribute to the anemia of β-thalassemia, although the effects of ROS have not been fully defined (1,(2)(3)(4)(5)(6)(7)(8). Exogenous anti-oxidant molecules might represent complementary therapeutic strategies to counteract the toxic effects of ROS in β-thalassemia.…”

“…5(7), 1190-1194 1191 have been shown to beneficially affect in vivo β-thalassaemic red cell features and/or thalassaemic ineffective erythropoiesis in vivo. (3)(4)(5)(6)(7)(8) Recent studies have shown that Resveratrol is a ribo-nucleotide reductase inhibitor, much more effective than hydroxyurea (HU), a molecule that has been used clinically as therapeutic agent for the treatment of Sickle cell anaemia, a haemoglobinopathy characterized by the polymerization of a mutated form of adult haemoglobin (HbS) leading to erythrocyte sickling which plays an important part in the disease morbidity. Hydroxyurea has proven its clinical benefit as it can increase fetal haemoglobin (HbF) levels in the red cells of sickle cell patients inhibiting HbS polymer formation.…”