JK-1, a useful erythroleukemic cell line model to study a controlled erythroid differentiation from progenitors to terminal erythropoiesis.

New hematopoietic cell models have recently emerged through immortalization of CD34 cells to study and understand various molecular mechanisms of erythropoiesis. Here, we characterize the JK-1 CML-derived cell line, previously shown to spontaneously differentiate without cytokines. Using an epigenetic differentiation inhibitor that keeps JK-1 in an early differentiation phase, we characterized 2 progenitor stages: BFU-E JK-1 and CFU-E JK-1 with CD34+/CD36- and CD34-/CD36 + phenotypes respectively.

Duffy antigen is expressed during erythropoiesis in Duffy-negative individuals.

The erythrocyte silent Duffy blood group phenotype in Africans is thought to confer resistance to Plasmodium vivax blood-stage infection. However, recent studies report P. vivax infections across Africa in Fy-negative individuals.

Mice expressing RHAG and RHD human blood group genes.

Anti-RhD prophylaxis of haemolytic disease of the fetus and newborn (HDFN) is highly effective, but as the suppressive mechanism remains uncertain, a mouse model would be of interest. Here we have generated transgenic mice expressing human RhAG and RhD erythrocyte membrane proteins in the presence and, for human RhAG, in the absence, of mouse Rhag. Human RhAG associates with mouse Rh but not mouse Rhag on red blood cells.

AlphaII-spectrin is critical for cell adhesion and cell cycle.

Spectrins are ubiquitous scaffolding components of the membrane skeleton that organize and stabilize microdomains on both the plasma membrane and the intracellular organelles. By way of their numerous interactions with diverse protein families, they are implicated in various cellular functions. Using small interfering RNA strategy in the WM-266 cell line derived from human melanoma, we found that alphaII-spectrin deficiency is associated with a defect in cell proliferation, which is related to a cell cycle arrest at the G1 phase (first gap phase), as evaluated by DNA analysis and Rb phosphorylation.

Phosphorylation and ankyrin-G binding of the C-terminal domain regulate targeting and function of the ammonium transporter RhBG.

RhBG, a human member of the Amt/Mep/Rh/superfamily of ammonium transporters, has been shown to facilitate NH(3) transport and to be anchored to the basolateral plasma membrane of kidney epithelial cells, via ankyrin-G. We showed here that triple alanine substitution of the (419)FLD(421) sequence, which links the cytoplasmic C-terminal domain of RhBG to ankyrin-G, not only disrupted the interaction of RhBG with the spectrin-based skeleton but also delayed its cell surface expression, decreased its plasma membrane stability, and abolished its NH(3) transport function in epithelial cell lines. Similarly, we demonstrated that both anchoring to the membrane skeleton and ammonium transport activity are regulated by the phosphorylation status of the C-terminal tail of RhBG.

A mutant alphaII-spectrin designed to resist calpain and caspase cleavage questions the functional importance of this process in vivo.

alpha- and beta-spectrins are components of molecular scaffolds located under the lipid bilayer and named membrane skeletons. Disruption of these scaffolds through mutations in spectrins demonstrated that they are involved in the membrane localization or the maintenance of proteins associated with them. The ubiquitous alphaII-spectrin chain bears in its central region a unique domain that is sensitive to several proteases such as calpains or caspases.

The ammonium transporter RhBG: requirement of a tyrosine-based signal and ankyrin-G for basolateral targeting and membrane anchorage in polarized kidney epithelial cells.

RhBG is a nonerythroid member of the Rhesus (Rh) protein family, mainly expressed in the kidney and belonging to the Amt/Mep/Rh superfamily of ammonium transporters. The epithelial expression of renal RhBG is restricted to the basolateral membrane of the connecting tubule and collecting duct cells. We report here that sorting and anchoring of RhBG to the basolateral plasma membrane require a cis-tyrosine-based signal and an association with ankyrin-G, respectively.

Large-scale pre-diagnosis study of fetal RHD genotyping by PCR on plasma DNA from RhD-negative pregnant women.

Background: The routine prenatal determination of fetal RhD blood group would be very useful in the management of pregnancies in RhD-negative women, as up to 40% of these pregnancies bear a RhD-negative fetus. The fetal DNA present in maternal plasma offers an opportunity for risk-free prenatal diagnosis.

Aim: This study focused on the feasibility and accuracy of large-scale RhD fetal diagnosis in non-immunized and anti-D immunized RhD-negative women.