A NUCLEAR MATRIX PROTEIN STABILIZED BY LEAD-EXPOSURE - CURRENT KNOWLEDGE AND FUTURE-PROSPECTS

p32/6.3, a low-abundance, highly conserved nuclear protein, is a targe t for lead Very few low abundance nuclear proteins have been described and no others have been associated with lead Its wide distribution an d conservation indicate a fundamental nuclear role. Further, it increa ses many fold in grey matter of brain and spinal cord during the neona tal period; there are no other identified nuclear proteins which serve as markers for this period of nervous system development. There are s everal links between lead and p32/6.3. It is a major component of lead -induced intranuclear inclusion bodies from the kidney. Its accumulati on in kidney is a relatively early event in the process of lead intoxi cation. Exposure to lead increases p32/6.3 in mouse neuroblastoma 2a c ells within one day, blocking its degradation almost completely. These observations suggest that lead either structurally alters p32/6.3 or inhibits a protease for which p32/6.3 is a substrate. In these lead-tr eated cells nuclear envelope invaginations and small nuclear bodies in crease. The possible involvement of lead and p32/6.3 with the formatio n and movement of nuclear bodies is discussed. (C) 1993 Intox Press, I nc