Analyses of expression of cytoglobin by immunohistochemical studies in human tissues.

Cytoglobin (Cygb) is a recently discovered member of the vertebrate globin family, which includes probably most extensively studied proteins, hemoglobin (Hb), myoglobin (Mb) and neuroglobin (Ngb). It has been reported that Cygb is expressed ubiquitously at the mRNA or protein level. However, details of the distribution of Cygb in the various tissues have hitherto been unclear. In this experiment, we clarified the distribution of Cygb in various human tissues by immunohistochemical staining. First, we prepared a rabbit anti human Cygb polyclonal antibody. Using the antibody, we stained a tissue array slide containing 60 normal tissues from 40 human organs. We confirmed the staining patterns of the antibodies in these various tissues using autopsy samples from our university. In general, Cygb is positive in the epithelial cells, hepatocytes, pancreatic acinar cells, cardiomyocytes and skeletal muscle but rarely so in cells in the interstitial tissues. Cytoglobin is usually positive in the cytoplasm, but is also positive in the nucleus in some hepatocytes. In contrast, Cygb is negative in the smooth muscle. The distribution of Cygb could suggest its roles.