Post-transcriptional Regulation of De Novo Lipogenesis by mTORC1-S6K1-SRPK2 Signaling. Author Gina Lee, Yuxiang Zheng, Sungyun Cho, Cholsoon Jang, Christina England, Jamie Dempsey, Yonghao Yu, Xiaolei Liu, Long He, Paola Cavaliere, Andre Chavez, Erik Zhang, Meltem Isik, Anthony Couvillon, Noah Dephoure, T Keith Blackwell, Jane Yu, Joshua Rabinowitz, Lewis Cantley, John Blenis Publication Year 2017 Type Journal Article Abstract mTORC1 is a signal integrator and master regulator of cellular anabolic processes linked to cell growth and survival. Here, we demonstrate that mTORC1 promotes lipid biogenesis via SRPK2, a key regulator of RNA-binding SR proteins. mTORC1-activated S6K1 phosphorylates SRPK2 at Ser494, which primes Ser497 phosphorylation by CK1. These phosphorylation events promote SRPK2 nuclear translocation and phosphorylation of SR proteins. Genome-wide transcriptome analysis reveals that lipid biosynthetic enzymes are among the downstream targets of mTORC1-SRPK2 signaling. Mechanistically, SRPK2 promotes SR protein binding to U1-70K to induce splicing of lipogenic pre-mRNAs. Inhibition of this signaling pathway leads to intron retention of lipogenic genes, which triggers nonsense-mediated mRNA decay. Genetic or pharmacological inhibition of SRPK2 blunts de novo lipid synthesis, thereby suppressing cell growth. These results thus reveal a novel role of mTORC1-SRPK2 signaling in post-transcriptional regulation of lipid metabolism and demonstrate that SRPK2 is a potential therapeutic target for mTORC1-driven metabolic disorders. Keywords Animals, Mice, Humans, Signal Transduction, Gene Expression Regulation, Fatty Acids, RNA Processing, Post-Transcriptional, Female, Cell Nucleus, Heterografts, Mechanistic Target of Rapamycin Complex 1, Mice, Nude, Neoplasm Transplantation, Cholesterol, Lipogenesis, Ribosomal Protein S6 Kinases, 70-kDa, Protein Serine-Threonine Kinases Journal Cell Volume 171 Issue 7 Pages 1545-1558.e18 Date Published 2017 Dec 14 ISSN Number 1097-4172 DOI 10.1016/j.cell.2017.10.037 Alternate Journal Cell PMCID PMC5920692 PMID 29153836 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML