Identification and functional analysis of YB-1 and YB-2 from Amur minnow (Phoxinus lagowskii)

Abstract

In vertebrates, Y-box proteins play a pivotal role in stress regulation. In this study, we cloned two Y-box genes (YB-1 and YB-2) from the cold-water fish, Amur minnow (Phoxinus lagowskii). Our findings showed that the full-length AmYB-1 and AmYB-2 genes encode proteins with a length of 324 and 297 amino acids, respectively, and are highly homologous to the YB-1 and YB-2 genes of other freshwater fish. AmYB-1 and AmYB-2 are expressed extensively throughout the body in P. lagowskii, AmYB-1 expression is the highest in the muscle and liver tissues, and AmYB-2 mRNA expression is the highest in the testis, ovary, and muscle tissues. The expression of AmYB-1 and AmYB-2 in the liver reached its peak at 24 h after cold stress, both at the mRNA and protein levels. In muscle tissues, the expression of AmYB-1 did not significantly differ between groups. However, the expression of AmYB-2 was significantly higher in the 3 h group than in the control, 6 h, and 24 h groups. We confirmed that AmYB-1 overexpression and knockdown could up-regulate and down-regulate, respectively, the mRNA levels of cell proliferation-related genes, including EGF (epidermal growth factor), MMP13 (matrix metalloproteinase-13), and β-catenin. This study is the first to focus on the functions of YB-1 and YB-2 in P. lagowskii during exposure to cold stress. Our findings provide key information that could guide other studies on cold tolerance in fish.

Keywords

• Phoxinus lagowskii
• Y-box proteins
• Cold stress
• Cloning
• Functional analysis