[High activity of deoxyribonuclease I identified in human pituitary gland--structure and function]

Human deoxyribonuclease I (DNase I) showing genetic polymorphism has been evaluated to be well suited for practical purposes such as criminal individualization or paternity testing. DNase I has so far been recognized to be functionally active only during the digestion of exogenous DNA, because this enzyme is secreted into the alimentary tract from exocrine glands such as the pancreas. However, it was discovered that the human pituitary gland, non-digestive tissue, exhibited higher DNase I enzyme activity and expression of its gene, being comparable to those of the pancreas. These findings strongly support the hypothesis that DNase I plays (a) biological role(s) other than a digestive one. Furthermore, we observed that all hypothalamic hormones examined induced a significant elevation or decline of pituitary, serum and urine DNase I activity in a rapid and transient manner similar to the corresponding anterior pituitary hormones. Therefore, DNase I was demonstrated to be coupled with the secretion of anterior pituitary hormones in a hypothalamic pituitary system. Thus, recent progress of our studies on human DNase I for purpose of practical uses in forensic sciences has permitted us to succeed in the clarification of a novel biological function inherent in the enzyme.