Diagnostic significance of metallothionein members in recognizing cadmium exposure in various organs under low-dose exposure

Metallothioneins (MTs) are known to protect cells against oxidative stress, especially providing protection against cadmium (Cd) toxicity. To date, besides liver and kidney, the expression profiles of MT members have not been thoroughly determined in a full-spectrum of organs, especially under low-dose exposure settings. Furthermore, their diagnostic value has not been evaluated in reflecting the Cd exposure in diverse organs. In the present study, we unearthed the expression profiles of five MT members in diverse organs from mice upon low-dose Cd exposure. Compared to most organs, the deposition of Cd in cartilage has been overlooked in the past, implying the potential Cd toxicity to the joint. In contrast to MT1 and MT2 (MT1/2), the expression levels of MT3, MTL5 and MT4 were minimal with or without Cd treatment. Distinct from Cd mass, the levels of MT1/2 were similar in heart and lung to that of kidney. Our study signified the rationale of MT1/2 induction in recognizing Cd exposure extent in diverse organs including liver, kidney, heart and lung. Importantly, MT1/2 expression was induced in liver and lung cells even upon low-dose Cd exposure. Thus, our combined data unraveled the expression of MT members across various organs in Cd-exposed mice, and pinpointed their diagnostic value in characterizing Cd poisoning.