Fig. 7

LSH, PKM2, and p53 promote cell lipid catabolism. a A549 cells transiently expressing the indicated constructs were seeded on glass coverslips overnight, and the cells were fixed and stained with red neutral lipid stain. Representative images from three independent experiments are presented (scale bars, 10 μm). Cells were treated with or without doxorubicin (DOX, 1 μM) and with or without 100 ng/ml EGF or untreated for 6 h. b ImageJ was used to analyse the intensity of LipidTox-Red staining. Statistical analysis was performed using Student’s t test. *P < 0.05; **P < 0.01 (n = 3). Error bars represent the SEM of triplicate experiments. c, d After the indicated constructs were overexpressed for 48 h, alterations in lipid metabolism genes were observed in HCT116 p53^−/− and HCT116 p53^+/+ cells. Cells were harvested, and the indicated mRNA levels were determined by real-time PCR. Statistical analysis was performed using Student’s t test. *P < 0.05; **P < 0.01. Error bars represent the SEM of triplicate experiments. e After the indicated constructs were overexpressed for 48 h, alterations in lipid metabolism genes were observed in A549 cells. Cells were harvested, and the indicated mRNA levels were determined by real-time PCR. Cells were treated with or without doxorubicin (DOX, 1 μM) and with or without 100 ng/ml EGF or untreated for 6 h. Statistical analysis was performed using Student’s t test. *P < 0.05; **P < 0.01. Error bars represent the SEM of triplicate experiments. f The working model of p53 regulation by LSH comprises three sequential activating steps: (1) LSH acts as a novel positive regulator of p53 stability by releasing MDM2 from p53 and inhibiting p53 ubiquitination and stabilization. (2) p53 is stress-induced to form a complex with PKM2 and LSH to promote its stabilization, which is mediated by phosphorylation (P). (3) p53 phosphorylation stabilizes p53 and DNA-bound p53 and then recruits transcriptional machinery to activate the transcription of p53 target lipid catabolism genes