JIP3 knockout protects mice against high fat diet-induced liver injury

Abstract

Multiple pathways contribute to nonalcoholic fatty liver disease (NAFLD) in response to high fat diets (HFD). A homolog of mammalian JNK-interacting protein 3 (JIP3), also known as JSAP-1, activates different components in various signaling pathways to modulate cellular processes. The purpose of this study was to examine the role of JIP3 in obesity-related pathologies pathway. Wild-type (WT) C57BL/6 and JIP3-knockout (JIP3^-/-) mice were randomized to chow or HFD. HFD-fed WT mice increased hepatic JIP3 expression. Mice lacking JIP3 exhibited reduced weight gain, hepatic steatosis, insulin resistance, lipid accumulation, oxidative stress and inflammatory response in mice fed a HFD, which were, importantly, dependent on various signaling pathways. Lipogenesis-linked pathway was inhibited in JIP3^-/- mice after HFD, while PPARα/γ were increased. Additionally, JIP3^-/- inhibited hepatic oxidative stress, evidenced by down-regulation of total reactive oxygen species (ROS), H₂O₂, O₂^.-, malondialdehyde (MDA), xanthine oxidase (XO), inducible nitric oxide synthase (iNOS), and up-regulation of superoxide dismutase (SOD) and total antioxidant capacity (TAC) in mice after HFD feeding, which might be related to nuclear respiratory factor 2 (Nrf-2) pathway activation. Further, inflammatory response was blocked in JIP3^-/- mice fed with HFD. The process might be attributed to the suppression of toll-like receptors (TLRs), p-nuclear factor kappa B (NF-κB) and p-c-Jun-N-terminal kinase (JNK). Thus, JIP3 absence is associated with decreased lipogenesis, oxidative stress and inflammation, supplying a new target for NAFLD treatment.

Keywords: Inflammation; JIP3; Lipogenesis; NAFLD; Oxidative stress.