Deep coverage mouse red blood cell proteome: a first comparison with the human red blood cell

Mice have close genetic/physiological relationships to humans, breed rapidly, and can be genetically modified, making them the most used mammal in biomedical research. Because the red blood cell (RBC) is the sole gas transporter in vertebrates, diseases of the RBC are frequently severe; much research has therefore focused on RBC and cardiovascular disorders of mouse and humans. RBCs also host malaria parasites. Recently we presented an in-depth proteome for the human RBC. Here we present directly comparable data for the mouse RBC as membrane-only, soluble-only, and combined membrane-bound/soluble proteomes (comprising, respectively, 247, 232, and 165 proteins). All proteins were identified, validated, and categorized in terms of subcellular localization, protein family, and function, and in comparison with the human RBC, were classified as orthologs, family-related, or unique. Splice isoforms were identified, and polypeptides migrating with anomalous apparent molecular weights were grouped into putatively ubiquitinated or partially degraded complexes. Overall there was close concordance between mouse and human proteomes, confirming the unexpected RBC complexity. Several novel findings in the human proteome have been confirmed here. This comparison sheds light on several open issues in RBC biology and provides a departure point for more comprehensive understanding of RBC function.     

The Plasmodium falciparum-infected red blood cell

Plasmodium falciparum, the most virulent of the human malaria parasites, causes up to one million deaths per year. The parasite spends part of its lifecycle inside the red blood cells (RBCs) of its host. As it grows it ingests the RBC cytoplasm, digesting it in an acidic vacuole. Free haem released during haemoglobin digestion is detoxified by conversion to inert crystals of haemozoin. Malaria pathology is evident during the blood stage of the infection and is exacerbated by adhesion of infected RBCs to blood vessel walls, which prevents splenic clearance of the infected cells. Cytoadherence is mediated by surface-exposed virulence proteins that bind to endothelial cell receptors. These 'adhesins' are exported to the RBC surface via an exomembrane system that is established outside the parasite in the host cell cytoplasm. Antimalarial drugs that interfere with haem detoxification, or target other parasite-specific processes, have been effective in the treatment of malaria, but their use has been dogged by the development of resistance. Similarly, efforts to develop an effective blood vaccine are hindered by the variability of surface-exposed antigens.     

The reaction of red blood cell catalase with perchlorate

Sodium perchlorate forms a reversible and enzymatically inactive complex with human red blood cell catalase. The rates of binding and association constants increase inversely with pH. Analysis of the dependence of association constants on pH suggests participation of a carboxylate or imidazole group in the proton-assisted binding of perchlorate to catalase. Formation of the complex resulting from binding of perchlorate to the apoprotein involves a conformation change and is accompanied by alterations in the optical spectrum of catalase. In the presence of hydrogen peroxide the progressive inhibition of the enzyme by perchlorate is faster than at nonturnover conditions, indicating additional reaction of the ligand with catalase intermediate complexes.     

The human blood platelet: its derivation from the red blood cell. A morphologic study.

The blood platelet arises from the interior of the red blood cell when blood is either damaged or disturbed. The platelet body may be seen to form from an amorphous granular mass to a definite granular platelet body when blood is prevented from coagulating by the use of a retardant solution.     

Cadmium as a tool for studying calcium-dependent cation permeability of the human red blood cell membrane.

Three Ca(2+)-dependent procedures known to increase cation permeability of red blood cell membranes were tested with Cd2+ ions which equal Ca2+ ions both in their charge and the crystal radius, 1. Increase of non-selective permeability for monovalent cations by incubating the red cells in a Ca(2+)-free sucrose medium. Addition of Cd2+ to the suspension of leaky cells failed to restore the initial impermeability of the red cell membrane while a repairing effect of Ca2+ was evident both in the presence and absence of Cd2+. Thus, in low electrolyte medium, Cd2+ could neither mimic Ca2+, nor prevent the latter from interacting with membrane structures which control cation permeability. 2. Increase of the K(+)-selective permeability by propranolol plus Ca2+. Cd2+ added to a Ca(2+)-free Ringer type medium containing propranolol enhanced K+ permeability similar to that obtained with Ca2+. No changes of membrane permeability could be detected in the presence of 0.5 mmol/l Cd2+ in absence of propranolol. The Cd(2+)-stimulated K+ channels were different from those induced by Ca2+. They proved to be insensitive to quinine, exhibited a low K+/Na+ selectivity, and showed no tendency to self-inactivation. 3. Stimulation of K+ permeability by electron donors plus Ca2+. Substitution of Ca2+ by Cd2+ yielded results similar to those obtained with propranolol. The ability of Cd2+ to overtake the role of Ca2+ appears to depend on the system studied. It supplies information allowing to distinguish between the diverse Ca(2+)-dependent systems in cell membranes.     

The human red blood cell proteome and interactome

The red blood cell or erythrocyte is easily purified, readily available, and has a relatively simple structure. Therefore, it has become a very well studied cell in terms of protein composition and function. RBC proteomic studies performed over the last five years, by several laboratories, have identified 751 proteins within the human erythrocyte. As RBCs contain few internal structures, the proteome will contain far fewer proteins than nucleated cells. In this minireview, we summarize the current knowledge of the RBC proteome, discuss alterations in this partial proteome in varied human disease states, and demonstrate how in silico studies of the RBC interactome can lead to considerable insight into disease diagnosis, severity, and drug or gene therapy response. To make these latter points we focus on what is known concerning changes in the RBC proteome in Sickle Cell Disease.     

Fish red blood cell carbon dioxide transport in vitro: A comparative study

Red blood cell (rbc) carbon dioxide transport was examined in vitro in three teleosts (Oncorhynchus mykiss, Anguilla anguilla, Scophthalmus maximus) and an elasmobranch (Scyliorhinus canicula) using a radioisotopic assay that measures the net conversion of plasma HCO₃⁻ to CO₂. The experiments were designed to compare the intrinsic rates of rbc CO₂ excretion and the impact of haemoglobin oxygenation/deoxygenation among the species.Under conditions simulating in vivo levels of plasma HCO₃⁻ and natural haematocrits, the rate of whole blood CO₂ excretion varied between 14.0 μmol ml⁻¹ h⁻¹ (S. canicula) and 17.6 μmol ml⁻¹ h⁻¹ (O. mykiss). The rate of CO₂ excretion in separated plasma was significantly greater in the dogfish, S. canicula. The contribution of the rbc to overall whole blood CO₂ excretion was low in the dogfish (46 ± 6%) compared to the teleosts (trout, 71 ± 4%; turbot, 64 ± 5%; eel, 55 ± 3%).To eliminate the naturally occurring differences in haematocrit and plasma [HCO₃⁻] as inter-specific variables, the rates of whole blood CO₂ excretion were determined in blood that had been resuspended to constant [HCO₃⁻] (5 mmol⁻¹) and haematocrit (20%) in appropriate teleost and elasmobranch Ringer solutions. Under such normalized conditions, the rate of whole blood CO₂ excretion was significantly higher in the turbot (22.4 ± 1.3 μmol ml⁻¹ h⁻¹) in comparison to the other species (16.4–18.4 μmol ml⁻¹ h⁻¹) and thus revealed a greater intrinsic rate of rbc CO₂ excretion in the turbot.To study the contribution of Bohr protons, the rates of whole blood CO₂ excretion were assessed in blood subjected to rapid oxygenation during the initial phase of the 3 min assay period. Rapid oxygenation significantly enhanced the rate of CO₂ excretion in the teleosts but not in the elasmobranch. The extent of the increase provided by the rapid oxygenation of haemoglobin was a linear function of the extent of the Haldane effect, as quantified in each species from in vitro CO₂ dissociation (combining) curves. Under steady-state conditions, deoxygenated blood exhibited greater rates of CO₂ excretion than oxygenated blood in the teleosts but not in the elasmobranch. As a consequence of the Haldane effect, rbc intracellular pH was increased in the teleosts by deoxygenation but was unaltered in the elasmobranch.The results, by extrapolation, suggest that the rates of CO₂ excretion in vivo are influenced by the magnitude of the Haldane effect and the extent of haemoglobin oxygenation during gill transit in addition to the intrinsic rate at which the rbc converts plasma HCO₃⁻ to CO₂.     

The human blood platelet: its derivation from the red blood cell. II. Instantaneous changes in form in the platelet and red cell. A morphologic study

The human blood platelet arises from the interior of the red cell instantaneously as blood is either damaged or disturbed. The platelet starts out as a fine granular structure that rather suddenly changes in form and function with the passage of a very small amount of time.     

Rabbit red blood cell hexokinase

Summary Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in reticulocytes as two distinct molecular forms, designated hexokinase Ia and Ib, but only one of these was consistently present in mature red cells. In vivo, hexokinase la and Ib show a decay rate of 3 and 8% a day, respectively, while in vitro they show a similar stability.The possibility that the proteolytic activities of the reticulocyte could be responsible for the fast decay of hexokinase was investigated. No differences were found in the decay rates of hexokinase la and Ib during in vitro reticulocyte maturation in presence or absence of proteolytic inhibitors. Contrariwise, many findings indicate the ATP-dependent proteolytic system of the reticulocyte as a possible mechanism. In fact, the decay of hexokinase and the degradation of 3H-globins are both stimulated by ATP and ubiquitin; they show similar kinetic properties and both disappear during reticulocyte maturation.The cellular localization of hexokinase la and Ib was shown to be responsible for the differences found between their decay rates.Abbreviations PMSF phenylmethylsulfonyl fluoride - TPCK 1-1-tosylamide-2-phenylethyl-chloromethyl ketone - TLCK N -p-tosyl-L-lysine chloromethyl ketone     

The embryo makes red blood cell progenitors in every tissue simultaneously with blood vessel morphogenesis

During embryonic life, hematopoiesis occurs first in the yolk sac, followed by the aorto-gonado-mesonephric region, the fetal liver, and the bone marrow. The possibility of hematopoiesis in other embryonic sites has been suspected for a long time. With the use of different methodologies (transgenic mice, electron microscopy, laser capture microdissection, organ culture, and cross-transplant experiments), we show that multiple regions within the embryo are capable of forming blood before and during organogenesis. This widespread phenomenon occurs by hemo-vasculogenesis, the formation of blood vessels accompanied by the simultaneous generation of red blood cells. Erythroblasts develop within aggregates of endothelial cell precursors. When the lumen forms, the erythroblasts "bud" from endothelial cells into the forming vessel. The extensive hematopoietic capacity found in the embryo helps explain why, under pathological circumstances such as severe anemia, extramedullary hematopoiesis can occur in any adult tissue. Understanding the intrinsic ability of tissues to manufacture their own blood cells and vessels has the potential to advance the fields of organogenesis, regeneration, and tissue engineering.