Phosphorylation destabilizes Per3 to promote gallbladder carcinoma

Irregular circadian rhythm drives tumor malignant progression by governing a range of cellular processes, but its roles in gallbladder carcinoma (GBC) remain unclear. As a potential tumor suppressor gene, Per3 was down-regulated in GBC with a poor prognosis. Overexpression of Per3 inhibited GBC growth and metastasis in vitro and in vivo. Mechanistically, Per3 combined with P4HA1 to promote degradation of HIF-1α protein, consequently, HIF-1α-targeted genes were transcriptionally down-regulated to inhibit glycolytic capacity. Meanwhile, the key inducers of epithelial-mesenchymal transition (EMT), TGFB1 and TGFBI were transcriptionally repressed by Per3 combining at the promoters, subsequently reducing the mRNA levels of EMT-related genes and blocking EMT progression. The decrease of Per3 was determined at protein post-translational modification (PTM), not at transcription. Mass spectrometry identified that CKII, not CKI or other kinases, phosphorylated Per3 at S1048, which promoted ubiquitination-dependent degradation of Per3, leading to loss of its tumor-suppressive function. Collectively, these results reveal the mechanisms of Per3 S1048 phosphorylation-driven degradation and the roles of Per3 in regulating HIF-1α/glycolysis and TGF-β/EMT in gallbladder carcinoma.