Pantetheinase activity of membrane‐bound Vanin‐1: lack of free cysteamine in tissues of Vanin‐1 deficient mice

Abstract

Pantetheinase (EC 3.5.1.‐) is an ubiquitous enzyme which in vitro has been shown to recycle pantothenic acid (vitamin B5) and to produce cysteamine, a potent anti‐oxidant. We show that the Vanin‐1 gene encodes pantetheinase widely expressed in mouse tissues: (1) a pantetheinase activity is specifically expressed by Vanin‐1 transfectants and is immunodepleted by specific antibodies; (2) Vanin‐1 is a GPI‐anchored pantetheinase, and consequently an ectoenzyme; (3) Vanin‐1 null mice are deficient in membrane‐bound pantetheinase activity in kidney and liver; (4) in these organs, a major metabolic consequence is the absence of detectable free cysteamine; this demonstrates that membrane‐bound pantetheinase is the main source of cysteamine in tissues under physiological conditions. Since the Vanin‐1 molecule was previously shown to be involved in the control of thymus reconstitution following sublethal irradiation in vivo, this raises the possibility that Vanin/pantetheinase might be involved in the regulation of some immune functions maybe in the context of the response to oxidative stress.