Regulation of Biomineralization and Autophagy by the Stress-Sensing Transcription Factor CgRunx1 in Crassostrea gigas Under Daylight Ultraviolet B Radiation

As human activities increase and environmental changes persist, increased ultraviolet B (UVB) radiation in aquatic ecosystems poses significant threats to aquatic life. This study, through transcriptomic analysis of the mantle tissue of Crassostrea gigas following UVB radiation exposure, identified and validated two key transcription factors, CgRunx1 and CgCBFβ. The highest expression levels of CgRunx1 and CgCBFβ in the mantle suggest their pivotal roles in this tissue. Co-immunoprecipitation experiments revealed that CgRunx1 and CgCBFβ could form heterodimers and interact with each other. Furthermore, this study assessed the impact of UVB radiation on the levels of reactive oxygen species of the C. gigas, speculating that CgRunx1, as a potential redox-sensitive transcription factor, might be regulated by intracellular ROS. Through screening and binding site prediction analysis of target genes, coupled with dual-luciferase reporter assays, we verified that CgRunx1 might participate in regulating the biomineralization and autophagy processes in C. gigas by activating the transcriptional expression of target genes Transport and Golgi organization 1 and V-type proton ATPase catalytic subunit A. These findings provide new insights into the molecular response mechanisms of the C. gigas to UVB radiation and lay an important foundation for studying the adaptive evolution of bivalves to environmental stress.