Expression and Functional Analysis of the Metallothionein and Metal-Responsive Transcription Factor 1 in under Zn Stress.

Metallothioneins (MTs) are non-enzymatic metal-binding proteins widely found in animals, plants, and microorganisms and are regulated by metal-responsive transcription factor 1 (MTF1). MT and MTF1 play crucial roles in detoxification, antioxidation, and anti-apoptosis. Therefore, they are key factors allowing organisms to endure the toxicity of heavy metal pollution. is a marine invertebrate that inhabits intertidal zones and has a high tolerance to heavy metal stress. In this study, we cloned and identified and genes from (designated as and ). and were widely expressed in all tissues and highly expressed in the intestine. When exposed to 16.8, 33.6, and 84 mg/L of zinc ions, the expression levels of and in the intestine increased first and then decreased, peaking at 12 and 6 h, respectively, indicating that both and rapidly responded to Zn stress. The recombinant pGEX-6p-1-MT protein enhanced the Zn tolerance of and showed a dose-dependent ABTS free radical scavenging ability. After RNA interference (RNAi) with and 24 h of Zn stress, the oxidative stress indices (MDA content, SOD activity, and GSH content) and the apoptosis indices (Caspase 3, Caspase 8, and Caspase 9 activities) were significantly increased, implying that MT plays an important role in Zn detoxification, antioxidation, and anti-apoptosis. Moreover, the expression level of in the intestine was significantly decreased after RNAi with and 24 h of Zn stress, which preliminarily proved that MTF1 has a regulatory effect on MT. Our data suggest that MT and MTF1 play important roles in the resistance of to Zn stress and are the key factors allowing to endure the toxicity of Zn.