Thermal shock induces host proteostasis disruption and endoplasmic reticulum stress in the model symbiotic cnidarian Aiptasia

ABSTRACT: Coral bleaching has devastating effects on coral survival and reef ecosystem function, but many of the fundamental cellular effects of thermal stress on cnidarian physiology are unclear. We used label-free liquid chromatography-tandem mass spectrometry to assess the effects of high temperatures on the proteome of the model symbiotic anemone Aiptasia sp. Anemones were acclimated to elevated temperatures (30 °C and 33.5 °C) for two weeks or exposed to short-term thermal shock (33.5 °C, 24 hours) without acclimation. We identified 2,137 protein clusters in Aiptasia, 136 of which were differentially abundant between treatments. There were minimal differences (nine proteins) in protein abundances between the control (25 °C) and acclimated high-temperature (30 °C and 33.5 °C) treatments, indicating that thermal acclimation in symbiotic cnidarians is not primarily regulated at the level of protein expression. Heat shock resulted in significant changes in the abundance of 104 proteins, including those involved in protein folding and synthesis, redox homeostasis, and central metabolism. Nineteen highly abundant cytoskeletal and structural proteins showed particularly reduced abundance (approximately 50%), demonstrating proteostasis disruption and inhibition of protein synthesis. Heat shock induced proteins involved in multiple mechanisms for stabilizing nascent proteins, preventing protein aggregation and degrading damaged proteins, indicative of endoplasmic reticulum stress. Antioxidant mechanisms and metabolic enzymes necessary for redox homeostasis were also upregulated. Disruption of host proteostasis occurred before either bleaching or symbiont photoinhibition was detected, strongly suggesting endogenous reactive oxygen species production as the proximate cause of thermal damage. The effects of thermal shock were most pronounced at the endoplasmic reticulum, and proteostasis maintenance and protein turnover mechanisms may be essential in the response to severe thermal stress in symbiotic cnidarians.

INSTRUMENT(S):

ORGANISM(S): Aiptasia

TISSUE(S): Whole Body

SUBMITTER: Clinton Oakley  

LAB HEAD: Simon Keith Davy

PROVIDER: PXD004257 | Pride | 2018-03-14

REPOSITORIES: Pride