Cytoglobin at the Crossroads of Vascular Remodeling

Since its discovery ≈15 years ago, cytoglobin has been studied extensively. Because it is found outside the red cell, cytoglobin is categorized as a nonerythroid globin, along with (in humans) proteins, such as myoglobin, neuroglobin, androglobin, and hemoglobin α. The putative functions of these nonerythroid globins are linked to tissue protection from conditions such as hypoxia, ischemia, and oxidative stress.1 Cytoglobin not only fulfills these functions but also has been related to other roles, including tumor suppression and the regulation of fibrosis in cell and animal models.2–7 Like other heme globins, cytoglobin can reversibly bind oxygen and other small molecules. The ability of cytoglobin to store and sense oxygen, as well as its involvement in nitrite and nitric oxide (NO) metabolism, being able to both scavenge NO and produce NO from nitrite, is probably key to its function(s).8,9 However, in spite of significant progress in understanding the structure, localization, and functional characteristics of cytoglobin, the central physiological roles of this protein have yet to be fully elucidated.10–12 See accompanying article on page 1944 In this issue of Arteriosclerosis, Thrombosis, and Vascular Biology , Jourd’heuil et al13 examine the role of cytoglobin in controlling apoptosis and vascular remodeling after injury. Cytoglobin seems to be the predominant globin in vessel walls of humans, rats, and …