Neuroglobin and cytoglobin

Abstract

The globin family has long been defined by myoglobin and hemoglobin, proteins with the functions of oxygen storage and transportation, respectively. Recently, two new members of this family were discovered: neuroglobin present in neurons and retinal cells and cytoglobin found in various types of tissue. The increased expression of these proteins in hypoxic conditions first suggested a role in oxygen supply. However structural and functional differences, such as the hexacoordinated heme, a high autoxidation rate and different concentrations between different cellular types, have dismissed this hypothesis. The protective role of these globins has already been established. In vitro and in vivo studies have demonstrated increased survival of neurons under stress in the presence of neuroglobin and increased resistance to neurodegenerative diseases. However the mechanism remains unknown. Functions, including detoxification of nitric oxide, free radical scavenging and as an antioxidant and signaling of apoptosis, have also been suggested for neuroglobin and an antifibrotic function for cytoglobin.

Involvement of hepatic stellate cell cytoglobin in acute hepatocyte damage through the regulation of CYP2E1-mediated xenobiotic metabolism

“…The aerobic metabolism of mammals relies on respiratory proteins that function in the transport and storage of O 2 .Four globin proteins are known to contribute to O 2 homeostasis in mammals. 6,7 Hemoglobin in erythrocytes has an important role in the transport of O 2 from the bloodstream to the viscera. In the viscera, myoglobin, neuroglobin, and cytoglobin (CYGB) act as local O 2 -binding molecules that facilitate the intracellular diffusion of O 2 .…”