Reversible binding of hemoglobin to band 3 constitutes the molecular switch that mediates O2 regulation of erythrocyte properties

Abstract

Functional studies have shown that the oxygenation state of the erythrocyte regulates many important pathways, including glucose metabolism, membrane mechanical stability, and cellular adenosine triphosphate (ATP) release. Deoxyhemoglobin (deoxyHb), but not oxyhemoglobin, binds avidly and reversibly to band 3, the major erythrocyte membrane protein. Because band 3 associates with multiple metabolic, solute transport, signal transduction, and structural proteins, the hypothesis naturally arises that the O-dependent regulation of erythrocyte properties might be mediated by the reversible association of deoxyHb with band 3. To explore whether the band 3-deoxyHb interaction constitutes a "molecular switch" for regulating erythrocyte biology, we have generated transgenic mice with mutations in the deoxyHb-binding domain of band 3. One strain of mouse contains a "humanized" band 3 in which the N-terminal 45 residues of mouse band 3 are replaced by the homologous sequence from human band 3, including the normal human band 3 deoxyHb-binding site. The second mouse contains the same substitution as the first, except the deoxyHb site on band 3 (residues 12-23) has been deleted. Comparison of these animals with wild-type mice demonstrates that the following erythrocyte properties are controlled by the O-dependent association of hemoglobin with band 3: (1) assembly of a glycolytic enzyme complex on the erythrocyte membrane which is associated with a shift in glucose metabolism between the pentose phosphate pathway and glycolysis, (2) interaction of ankyrin with band 3 and the concomitant regulation of erythrocyte membrane stability, and (3) release of ATP from the red cell which has been linked to vasodilation.

Biocompatible coupling of therapeutic fusion proteins to human erythrocytes

“…RBCs can respond to their environment in diverse ways including dynamic changes in linkage of membrane protein complexes, 56 phosphorylation of membrane and cytoskeletal components, [57][58][59][60] calcium influx, 61,62 PS exposure, 29,63 and oxidative stress responses. 30 In targeting RBCs for delivery of therapeutics, the present findings suggest that dose-and target-dependent changes in membrane physiology, and ultimately, circulatory behavior should be carefully considered.…”

Lipid metabolism in terminal erythropoiesis

“…Among these, the subtle control of glucose metabolism, cytoskeletal integrity, and membrane permeability by oxygen tension has recently been elucidated. 2 During maturation, the developing red cell must both proliferate and undergo considerable modifications to acquire the necessary properties to survive in the circulatory system, where it lacks the ability to synthesize proteins de novo while experiencing profound challenges such as repeated episodes of shear and oxidative stress. Many important changes occur during later erythrogenesis, including loss of the nucleus, shedding of surface markers, establishment of the final surface area/volume ratio, and establishment of a robust but malleable cytoskeleton.…”

“…One could inquire about studying gut microbiota when an assessment of the upper respiratory microbiota might have been more germane to study because of its proximity to the portal of entry and the site of infection; other studies suggest loss of diversity of upper respiratory microbiota diversity is associated with lower tract infection. 2 One could ask why the microbiota pattern at engraftment would have long-lasting effects affecting the risk for events months later. Moreover, does restoration of butyrate-producing populations at a later time after engraftment occur in some patients and, if so, does restoration abrogate the risk?…”

Mechanism of O2-sensitive red cell properties

“…1 CML-BC progenitors, 1 suggesting that targeting IL-1 signaling in CML-BC might simultaneously lead to apoptosis of both CML LSCs and CML progenitors with or without leukemia-initiating capacity. 10 In conclusion, the data presented in this issue of Blood demonstrate that eradication of LSCs can be achieved by using IL-1RAP to direct ADCC 1 or by blocking IL-1 signaling, In this issue of Blood, Chu et al show that oxygen, by changing the conformation of hemoglobin (Hb), modulates many red cell properties by altering its interaction with band 3, the major red cell membrane protein.…”

“…2 In addition to providing evidence that IL-1RA may potentially be used in the clinic for inducing the killing of LSCs, the data presented in this issue of Blood offer an additional therapeutic strategy. In fact, the use of IL-1RAP antibodies resulted in ADCCdependent increased survival of mice engrafted with primary human CML and BV173 (lymphoid blast crisis [BC]) cells, 1 suggesting that blocking IL-1 signaling may benefit CML-BC patients, too. In fact, increased IL-1R type 1 (IL-1R1) and IL-1RAP expression and IL-1-dependent NF-kB induction were also observed in CD34…”