Use of genetically altered animal models in understanding the role of metallothionein in cadmium toxicity*

Acute Cd exposure produces liver injury, whereas chronic Cd exposure damages the kidney but not the liver. Previous experiments suggest that the low-molecular-weight, metal-binding protein metallothionein (MT) in liver protects against liver injury, but is responsible for the kidney injury observed after chronic Cd exposure. Thus, prior to the development of MT-transgenic and MT-knockout mice models, MT’s role was always assumed to be a toxicological paradox, hepatoprotection but nephrotoxicity. The development of MTtransgenic and MT-knockout mice models has reconfirmed MT’s protective role against Cdinduced hepatotoxicity, but it has challenged MT’s suggested role in Cd-induced nephrotoxicity. In this communication, recent data using these genetically altered mice models indicate that MT protects against not only the Cd-induced hepatotoxicity, but also nephrotoxicity, hematotoxicity, immunotoxicity, and bone damage.