The potential role of Annexin 3 in diapause embryo restart of Artemia sinica and in response to stress of low temperature.

Annexins are highly conserved and ubiquitous in various somatic cell types. They are involved in membrane transport and a range of calcium-regulated activities on the cell membrane surface, including vesicular transport, membrane fusion in exocytosis, signal transduction, and formation of calcium channels. They also regulate inflammatory response, cell differentiation, and interaction between cytoskeletal proteins. In this study, for the first time, an ANX3 gene from Artemia sinica ( As-anx3) was cloned. The As-anx3 full-length complementary DNA comprises 1,024 bp and has a 948 bp open reading frame encoding a 315-amino-acid polypeptide with four ANX domains. The profiles of both As-ANX3 mRNA and protein expression exhibited peaks at the 0 hr stage and had the same significant downregulation trend throughout the post-diapause embryo development stage. The ERK1/2, the phosphorylation levels of ERK1/2, and cell cycle-related protein (CDK4) expressions were analyzed by western blot analysis. The results showed that CDK4 presented a significantly ascending trend from 0 and 40 hr, although the phosphorylation levels of ERK1/2 did not increase significantly. The transcriptional and protein expressions of As-ANX3 were highly upregulated when the temperature was lowered from 25 to 15°C, but the expressions showed a gradual downward trend when the temperature was further lowered to 5°C. These results indicated that As-ANX3 plays a crucial role in restarting diapause and low-temperature stress in A. sinica.