Cystine Starvation Induces Reversible Large-Body Formation from Nuclear Bodies in T24 Cells

Abstract

Nuclear bodies (PML nuclear bodies; also referred to as PODs or ND10) are small intranuclear structures which contain PML as an essential constituent and from several to 20 or more of them are present per nucleus. When starved of amino acids, nuclear bodies reversibly form one or more doughnut-shaped large bodies in T24 cells. Here, I present evidence that cystine is essential for the maintenance of normal-sized nuclear bodies: Cystine deficiency induces the formation of large bodies, and the addition of cystine or cysteine induces the reappearance of many normal-sized nuclear bodies. Both PML and Sp100 exhibit the same behavior as that of the nuclear body antigen(s) of AP435 MAb with regard to these changes. l-buthionine-[ S,R]-sulfoximine, an inhibitor of glutathione synthesis, also induced the formation of large bodies that could be reversed to nuclear bodies by both β-mercaptoethanol and dithiothreitol as well as cystine. Large bodies have the characteristic electron-dense, spherical, and concentric or reticulated features of nuclear bodies as observed by electron microscopy. The results indicate that environmental cystine controls reversible change between nuclear bodies and large bodies, which are not mere aggregates of nuclear bodies, but rather reconstituted nuclear bodies.