TRIB3

TRIB3 Full Name

tribbles pseudokinase 3

TRIB3 Introduction

TRIB3 encodes the third mammalian tribbles pseudokinase, a catalytically impaired kinase-like scaffold that has become a focal point for understanding how cells integrate metabolic and stress signals. The tribbles family comprises three mammalian paralogs, TRIB1, TRIB2, and TRIB3, all sharing the same pseudokinase architecture and a propensity to operate as adaptors rather than enzymes. Like its tribbles relatives, TRIB3 does not phosphorylate substrates efficiently; instead it binds and modulates the activity of key signaling proteins. It interacts with the serine/threonine kinase AKT to restrain its phosphorylation, and it partners with transcription factors of the integrated stress response, including ATF4, CHOP (DDIT3), and NF-kappaB, thereby coupling nutrient and endoplasmic-reticulum stress to changes in gene expression. TRIB3 expression is itself strongly induced by stresses such as endoplasmic-reticulum overload, fasting, and inflammatory cytokines, making it a sensor that rises precisely when cellular homeostasis is threatened.

Figure 1. TRB3 at the crossroads of ER stress and mTORC function. (Source: Cunard R. 2013)

The physiological impact of TRIB3 is most vividly seen in energy metabolism and disease. Genetic deletion of Trb3 in mice revealed that hepatic insulin signaling and glucose homeostasis remain largely intact, yet tribbles proteins continue to be implicated in adipocyte biology, where TRIB3 controls lipid handling, proliferation, and the balance between differentiation and lipid storage through MAPK/ERK, PKA, and beta-catenin pathways. In human disease, TRIB3 has generated considerable debate as both a contributor to type 2 diabetes-related insulin resistance and a context-dependent tumor promoter or suppressor. Its prolific network of protein-protein interactions, rather than any single enzymatic output, explains why TRIB3 sits at a junction of pathways that govern cell survival, inflammation, and metabolic adaptation, and why it remains a compelling albeit challenging therapeutic target. Elevated TRIB3 has also been linked to diabetic complications such as retinopathy and nephropathy, and to cancer cell survival under metabolic stress, underscoring its role as a stress-responsive node whose output depends heavily on cellular context.

Alternate Names for TRIB3

TRIB3; tribbles pseudokinase 3; NIPK; SINK; TRB3; SKIP3; C20orf97; tribbles homolog 3; TRB-3; p65-interacting inhibitor of NF-kappaB; p65-interacting inhibitor of NF-kappa-B; neuronal cell death inducible putative kinase; neuronal cell death-inducible putative kinase;

• 1. Cunard R. Mammalian tribbles homologs at the crossroads of endoplasmic reticulum stress and Mammalian target of rapamycin pathways. Scientifica (Cairo). 2013;2013:750871.
  2. Okamoto H, et al. Genetic deletion of Trb3, the mammalian Drosophila tribbles homolog, displays normal hepatic insulin signaling and glucose homeostasis. Diabetes. 2007 May;56(5):1350-6.