Mass spectrometry-based proteomic analysis reveals the interacting partners of lipin1.

As a lipin family founding member, lipin1 exerts dual functions as a phosphatidate phosphatase enzyme and/or a co-transcriptional regulator in lipid metabolism. In fact, it is also involved in many other cell processes. In this study, we utilized pull down assay coupled with mass spectrometry (MS) to unravel protein-protein interaction networks of lipin1 in 293T human embryonic kidney cells. Pull-down assay on the Ni2+-chelating column was used to isolate lipin1 complexes from 293T cells transfected with 6-His tagged lipin1. The lipin1 complexes were analyzed on Q Exactive mass spectrometer. A total of 30 proteins were identified from label free quantitation of the MS data by Proteome Discoverer platform. The physical interaction between lipin1 and eEF1A1 was further affirmed in 293T cells transfected with 6-His tagged lipin1 and hepatocyte SMMC7721 cells by protein immunoprecipitation and immunofluorescence microscopy. Lipin1 also interacted with HIST1H2BK, which was confirmed in SMMC7721 cells by protein immunoprecipitation. Our proteomic analysis implicated lipin1 in novel roles in various cellular processes. (C) 2018