p53 Ubiquitination Comediated by HUWE1 and TRAF6 Contributes to White Spot Syndrome Virus Infection in Crustacean

Abstract

p53, the guardian of the genome, is a short-lived protein that is tightly controlled at low levels by constant ubiquitination and proteasomal degradation in higher organisms. p53 stabilization and activation are early crucial events to cope with external stimuli in cells. However, the role of p53 ubiquitination and its relevant molecular mechanisms have not been addressed in invertebrates. In this study, our findings revealed that both HUWE1 (HECT, UBA, and WWE domain-containing E3 ubiquitin-protein ligase 1) and TRAF6 (TNF receptor associated factor 6) could serve as E3 ubiquitin ligases for p53 in mud crab ( Scylla paramamosain ). Moreover, the expressions of HUWE1 and TRAF6 were significantly down-regulated during WSSV (White spot syndrome virus) infection, and therefore the ubiquitination of p53 was interrupted, leading to the activation of apoptosis and ROS (Reactive oxygen species) signals through p53 accumulation, which eventually suppressed viral invasion in mud crab. To the best of our knowledge, this is the first study to reveal the p53 ubiquitination simultaneously induced by two E3 ligases in arthropods, which provides a novel molecular mechanism of invertebrates in resistance to viral infection. Importance p53, which is a well-known tumor suppressor that has been widely studied in higher animals, has been reported to be tightly controlled at low levels by Ubiquitin-dependent proteasomal degradation. However, the recent p53 ubiquitination-relevant research is mainly involved in an individual E3 ubiquitin ligase, whether there exist other mechanisms that need to be explored. The results of this study showed that HUWE1 and TRAF6 could serve as p53 E3 ubiquitin ligases, and synchronously mediate p53 ubiquitination in mud crab, which confirmed the diversity of the p53 ubiquitination regulatory pathway. In addition, the effects of p53 ubiquitination are mainly focused on tumorigenesis, but few on the host immune defense in invertebrates. Our findings revealed that p53 ubiquitination could affect ROS and apoptosis signals to cope with WSSV infection in mud crab, which firstly clarified the immunologic functions and mechanisms of p53 ubiquitination in invertebrates.