201. The Patatin-Like Phospholipase Domain Containing Protein 7 Facilitates VLDL Secretion by Modulating ApoE Stability.
- Author
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Wang X, Guo M, Wang Q, Wang Q, Zuo S, Zhang X, Tong H, Chen J, Wang H, Chen X, Guo J, Su X, Liang H, Zhou H, and Li JZ
- Subjects
- Animals, Apolipoproteins E genetics, Cell Line, Tumor, Endoplasmic Reticulum pathology, Fatty Liver blood, Fatty Liver diagnosis, Fatty Liver surgery, Female, Gene Knockdown Techniques, HEK293 Cells, Humans, Lipase genetics, Lipid Metabolism, Lipoproteins, VLDL blood, Lipoproteins, VLDL metabolism, Liver surgery, Lysophospholipase genetics, Male, Mice, Mice, Knockout, ApoE, Proteasome Endopeptidase Complex metabolism, Protein Stability, Proteolysis, Severity of Illness Index, Triglycerides blood, Triglycerides metabolism, Ubiquitination, Apolipoproteins E metabolism, Fatty Liver metabolism, Lipase metabolism, Liver pathology, Lysophospholipase metabolism
- Abstract
Background and Aims: The regulation of hepatic very-low-density lipoprotein (VLDL) secretion is vital for lipid metabolism whose pathogenetic status is involved in fatty liver disease and dyslipidemia seen in hepatic steatosis. Accumulated evidence suggest that apolipoprotein E (ApoE) is closely related to hepatic VLDL secretion. Here, we report that the expression of patatin-like phospholipase domain containing protein 7 (PNPLA7) is strongly induced by hepatic steatosis and positively correlates with plasma triacylglycerol (TAG) levels in the human subjects, whereas the role of PNPLA7 in hepatic VLDL secretion is unknown., Approach and Results: Herein, with genetic manipulation in the mice, the deficiency of hepatic PNPLA7 expression resulted in reduced VLDL secretion accompanied by enhanced hepatic lipid accumulation and decreased hepatic ApoE expression. Furthermore, knockdown of PNPLA7 in the livers of the db/db mice also resulted in significant reduction in plasma TAG level but aggravated hepatic steatosis. Importantly, we observed that PNPLA7 interacted with ApoE and presumably at the site of endoplasmic reticulum. Mechanistically, we have shown that PNPLA7 could modulate polyubiquitination and proteasomal-mediated degradation of ApoE. Overexpressed ApoE restored the impaired VLDL-TAG metabolism in PNPLA7-knockdown primary hepatocytes., Conclusion: PNPLA7 plays a critical role in regulating hepatic VLDL secretion by modulating ApoE stability through its interaction with ApoE., (© 2020 by the American Association for the Study of Liver Diseases.)
- Published
- 2020
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