Histone demethylase PHF2 drives olanzapine-induced dyslipidemia via epigenomic rewiring of hepatic lipogenic genes.

Olanzapine, an atypical antipsychotic agent, is widely used in treating psychotic disorders, yet its metabolic side effects remain a clinical concern. Emerging evidence suggests that dynamic alterations in histone methylation are implicated in olanzapine-induced hepatic lipid metabolic disorders. PHF2, a JmjC family histone demethylase mediating H3K9me2 demethylation, functions as a transcriptional repressor by regulating downstream targets. To elucidate PHF2's role in this process, we utilized an olanzapine-induced dyslipidemia rat model. ChIP-qPCR analysis demonstrated a significant reduction in dimethylated histone H3 lysine 9 (H3K9me2) on the promoters of lipogenic genes (Fasn, Acc1, Scd1) in the liver, accompanied by elevated nuclear expression of PHF2 in olanzapine-treated rats. Co-immunoprecipitation (Co-IP) assays revealed a physical interaction between PHF2 and ChREBP, a glucose-responsive lipogenic transcription factor. Olanzapine was found to enhance the formation of this complex. Overexpression of PHF2 led to upregulated protein levels of FASN/ACC1 and intracellular lipid accumulation, whereas knockdown of PHF2 using siRNA attenuated these effects. Notably, the upregulation of FASN/ACC1 expression induced by olanzapine was markedly diminished in PHF2-deficient AML12 cells via ChREBP-PHF2-mediated H3K9me2 demethylation. Additionally, olanzapine inhibited the nuclear translocation of FOXA2, a PHF2 transcriptional regulator, thereby augmenting PHF2 expression. These findings uncover a novel epigenetic mechanism underlying olanzapine-induced dyslipidemia, positioning the FOXA2-PHF2-ChREBP axis as a potential therapeutic target through modulation of hepatic histone methylation.