Spectrin Interactome under normal and HbE-disease conditions

Abstract

Spectrin, the major component of the erythrocyte membrane skeleton is a key player in red cell biology. It has a significant role in signalling pathways and as such knowledge of spectrin interactors becomes crucial. Here we report the cytosolic interactome of human erythroid spectrin (ProteomeXchange id: PXD021525). This is to the best of our knowledge the first report of the interactome of human erythroid spectrin. We have further investigated the spectrin interactome under HbE disease conditions. Our findings indicate that there is no difference in the identity of the proteins interacting with spectrin between normal and disease conditions. However relative abundance of the interacting partners is seen to change. Very interestingly the interacting chaperone proteins, heme-containing proteins and redox active proteins are seen to be up-regulated in HbE disease state. This is consistent with our previous observation that presence of oxidation prone hemoglobin variants leads to an increase of redox regulators and chaperones in the red cell proteome. Spectrin can also interact with horse radish peroxidase and oxidatively crosslink hemoglobin, which has possible implications in oxidative stress management. Since a large fraction of spectrin interacting proteins are chaperones and redox active proteins, it is possible that spectrin may have a broader role in redox regulation, especially in cases where there are unstable hemoglobin variants present.

Erythroid spectrin binding modulates peroxidase and catalase activity of heme proteins

“…Spectrin is also able to act as a chaperone for other heme‐containing proteins like HRP, and in that case it is seen that there is a modulation of enzyme activity of HRP as well 10 . A recent proteomic study from our lab has identified several redox regulators and heme‐containing proteins like cytochrome, catalase, peroxiredoxin etc., as a major part of the interactome of spectrin 3 . Thus, from all these lines of evidence, we believe spectrin may have a role in the redox biology of hemoglobin and other heme‐containing proteins 7 …”

“…Spectrin is the major component of the membrane skeleton in mature human erythrocytes (RBCs) 1 . It has been shown that spectrin interacts with hemoglobin, as evidenced by fluorescence and light scattering‐based studies, as well as proteomic investigations 2–5 . So far, the only known consequence of the spectrin–hemoglobin interaction is via the ability of spectrin to act as a chaperone for hemoglobin 2,6,7 …”

“…10 A recent proteomic study from our lab has identified several redox regulators and heme-containing proteins like cytochrome, catalase, peroxiredoxin etc., as a major part of the interactome of spectrin. 3 Thus, from all these lines of evidence, we believe spectrin may have a role in the redox biology of hemoglobin and other heme-containing proteins. 7 Moreover, it is known that spectrin can accept liberated heme, that is, lost from hemoglobin due to stress conditions, and this spectrin-heme conjugate may then show modulated the redox activity.…”

“…studies, as well as proteomic investigations. [2][3][4][5] So far, the only known consequence of the spectrin-hemoglobin interaction is via the ability of spectrin to act as a chaperone for hemoglobin. 2,6,7 Spectrin has been shown to act as a chaperone for hemoglobin, and display a preference for more structurally unstable isoforms of hemoglobin, like hemoglobin E (HbE), and such hemoglobin interactions are known to be redox active, as seen in the oxidative cross-linking of HbE and spectrin.…”

Erythroid spectrin binding modulates peroxidase and catalase activity of heme proteins

“…Spectrin is the major component of the membrane skeleton in mature human erythrocytes (RBCs) [1]. It has been shown that spectrin interacts with hemoglobin, as evidenced by fluorescence and light scattering based studies, as well as proteomic investigations [2][3][4][5]. So far, the only known consequence of the spectrin-hemoglobin interaction is via the ability of spectrin to act as a chaperone for hemoglobin [2,6,7].…”