Function
Corticosteroid 11-β-dehydrogenase isozyme 2 is an NAD+-dependent enzyme expressed in aldosterone-selective epithelial tissues such as the kidney, colon, salivary and sweat glands. HSD211B2 expression is also found in the brainstem in a small, aldosterone-sensitive subset of neurons located in the nucleus of the solitary tract.
In these tissues, HSD11B2 oxidizes the glucocorticoid cortisol to the inactive metabolite cortisone, thus preventing illicit activation of the mineralocorticoid receptor. This protective mechanism is necessary because cortisol circulates at 100-1000-fold higher concentrations than aldosterone, and binds with equal affinity to the mineralocorticoid receptor, thereby out-competing aldosterone in cells that do not produce HSD11B2.
This glucocorticoid-inactivating enzyme is also expressed in tissues that do not express the mineralocorticoid receptor, such as the placenta and testis, as well as parts of the developing brain, including the rhombencephalic progentitor cells that proliferate into cerebellar granule cells. In these tissues, HSD11B2 protects cells from the growth-inhibiting and/or pro-apoptotic effects of cortisol, particularly during embryonic development.
Read more about this topic: Corticosteroid 11-beta-dehydrogenase Isozyme 2
Famous quotes containing the word function:
“As a medium of exchange,... worrying regulates intimacy, and it is often an appropriate response to ordinary demands that begin to feel excessive. But from a modernized Freudian view, worrying—as a reflex response to demand—never puts the self or the objects of its interest into question, and that is precisely its function in psychic life. It domesticates self-doubt.”
—Adam Phillips, British child psychoanalyst. “Worrying and Its Discontents,” in On Kissing, Tickling, and Being Bored, p. 58, Harvard University Press (1993)
“For me being a poet is a job rather than an activity. I feel I have a function in society, neither more nor less meaningful than any other simple job. I feel it is part of my work to make poetry more accessible to people who have had their rights withdrawn from them.”
—Jeni Couzyn (b. 1942)
“The uses of travel are occasional, and short; but the best fruit it finds, when it finds it, is conversation; and this is a main function of life.”
—Ralph Waldo Emerson (1803–1882)