Nonalcoholic fatty liver disease (
NAFLD) is characterized by a massive accumulation of lipid droplets (LDs). The aim of this study was to determine the function of 17β-hydroxysteroid dehydrogenase-13 (17β-HSD13), one of our newly identified LD-associated
proteins in human subjects with normal liver histology and simple steatosis, in
NAFLD development. LDs were isolated from 21 human liver biopsies, including 9 cases with normal liver histology (group 1) and 12 cases with simple steatosis (group 2). A complete set of LD-associated
proteins from three liver samples of group 1 or group 2 were determined by 2D LC-MS/MS. By comparing the LD-associated
protein profiles between subjects with or without
NAFLD, 54 up-regulated and 35 down-regulated LD-associated
proteins were found in
NAFLD patients. Among them, 17β-HSD13 represents a previously unidentified LD-associated
protein with a significant up-regulation in
NAFLD. Because the 17β-HSD family plays an important role in lipid metabolism, 17β-HSD13 was selected for validating the proteomic findings and exploring its role in the pathogenesis of
NAFLD. Increased hepatic 17β-HSD13 and its LD surface location were confirmed in db/db (diabetic) and high-fat diet-fed mice. Adenovirus-mediated hepatic overexpression of human 17β-HSD13 induced a
fatty liver phenotype in C57BL/6 mice, with a significant increase in mature
sterol regulatory element-binding protein 1 and
fatty acid synthase levels. The present study reports an extensive set of human liver LD
proteins and an array of
proteins differentially expressed in human
NAFLD. We also identified 17β-HSD13 as a pathogenic
protein in the development of
NAFLD.