White adipose tissue (WAT) is not only the main tissue for energy storage but also an endocrine organ that secretes adipokines. Obesity is the most common metabolic disorder and is related to alterations in WAT characteristics, such as chronic inflammation and increasing oxidative stress. WW domain containing E3 ubiquitin protein ligase 1 (WWP1) is a HECT-type ubiquitin E3 ligase that has been implicated in various pathologies. In the present study, we found that WWP1 was upregulated in obese WAT in a p53-dependent manner. To investigate the functions of WWP1 in adipocytes, a proteome analysis of WWP1 overexpression (OE) and knockdown (KD) 3T3-L1 cells was performed. This analysis showed a positive correlation between WWP1 expression and the abundance of several antioxidative proteins. Thus, we measured reactive oxygen species (ROS) in WWP1 OE and KD cells. Consistent with the proteome results, WWP1 OE reduced ROS levels, whereas KD increased them. These findings indicate that WWP1 is an obesity-inducible E3 ubiquitin ligase that can protect against obesity-associated oxidative stress in WAT. (C) 2018 The Authors. Published by Elsevier Inc.