Characterization Of PHB1in Artemia And Its Role In Mitochondrial Function And Yolk Platelet Degradation

Artemia is widely distributed Crustacea. It is highly resistant to high salty water, and to cope with extreme environment, such as periodic low temperature, desiccation, hypoxia etc, Artemia release diapaused cysts, which are capable to withstand extreme conditions. The encysted embryo diapaused at the gastro phase, which maintains low metabolic rate and ceased mRNA and protein synthesis, especially under the condition of hypoxia and extremely desiccation, the respiration rate can be low to detection limit of devices. The encysted embryo can survive harsh conditions for long period of time until the appropriate conditions are met. Then the encysted embryos resume development, metabolic activities and other cellular processes. But how the encysted embryos maintain a low metabolic rate and resume metabolic activities when the environment allows is hardly known.Our work here was to explore the role of ArPHB1in controlling the metabolic remodeling. Our work revealed that ArPHB1is important in maintaining the normal function of mitochondria and the homeostasis of metabolism. PHB1is a widely existed membrane protein in eukaryotics. It is involved in cell differentiation, cell growth and aging. The most well known function of PHB1is for maintaining the normal function of mitochondria. Our research found ArPHB1did play important roles in metabolic remodeling, but this role was not limited in mitochondria.In this research, we characterized ArPHB1during the post-diapause development, and found that the mRNA level of ArPHB1was low in the diapaused cysts, then gradually increased after the resumption of development. But the protein level of ArPHB1was not increased after the resumption of development. We thought that it may be due the higher turnover rate of the protein after the resumption of development. Then we performed analysis on the phosphorylation status of ArPHB1and the nuclear location of ArPHB1. We found that the phosphorylation of Tyr-114and Ser-121was detected in the diapaused cysts, and ArPHB1was detected in the nuclear. Then after24h of hatching, the phosphorylation of Tyr-114and Ser-121disappeared, and the ArPHB1in nuclear disappeared too.So we performed RNA interference to investigate the role of ArPHB1in the embryonic development. After successfully knockdown ArPHB1, the released naupliaus show compromised swimming activity and reduced ability to resist cold. Further analysis found that ArPHB1knockdown lead to the increased activity of AMPK and aberrant mitochondrial function. In the mean time we found that the yolk platelet degradation is blocked in the ArPHB1knockdown nauplius. Then we found that ArPHB1existed in the yolk platelets, and then we found ArPHB1was degraded through ubiquitination.