| TAB2 (TAK1-binding protein 2/MAP3K7IP2) is a ubiquitin-binding adaptor of the TAK1–TAB scaffold family that links Lys63‑linked polyubiquitin signals generated downstream of receptors to activation of MAP3K7/TAK1 and divergent NF‑κB, JNK, and noncanonical Wnt pathways, while also exerting context‑specific roles in survival signaling and cardiac homeostasis. The protein contains an N‑terminal CUE/GLUE-like region and coiled-coil segments that mediate association with TAK1 and other partners, and a C‑terminal RanBP2-type zinc finger (NZF) domain that binds Lys63‑linked and mixed Lys63/Lys48‑linked polyubiquitin chains, unanchored or attached to substrates such as RIPK1 and RIPK2, creating a scaffold that positions TAK1 in proximity to ubiquitin-decorated receptor complexes and promotes TAK1 autophosphorylation. Upon stimulation by IL‑1 or TNF family ligands, TAB2 translocates from membranes to the cytosol and bridges TRAF6- or RIPK-containing ubiquitin platforms with TAK1–TAB1, enabling TAK1 activation and subsequent phosphorylation of the IKK core complex and MKKs that drive NF‑κB and JNK signaling, thereby coupling receptor-proximal ubiquitination to transcriptional responses that control inflammation, apoptosis, and proliferation. TAB2 also scaffolds TAK1 with Nemo-like kinase (NLK) in the Wnt cascade; in this setting TAB2-associated TAK1–NLK phosphorylates LEF1/TCF transcription factors and represses β‑catenin–dependent transcription, indicating that TAB2 can support noncanonical Wnt outputs that counterbalance canonical signaling during development and tissue homeostasis. Genetic and biochemical analyses show that TAB2 is not strictly required for all TAK1-dependent NF‑κB and MAPK activation, but performs additional functions in TNF signaling at the level of cytotoxic complex II, where its NZF-mediated binding to ubiquitinated components limits the abundance of apoptosis- and necroptosis-inducing complexes and maintains a pro‑survival checkpoint independently of TAK1 recruitment. In the myocardium, TAB2 has a critical role in preserving myocardial structure and function: TAB2 deficiency in mouse hearts promotes RIPK1-dependent apoptosis and necroptosis, amplifies inflammatory signaling, and leads to progressive dilated cardiomyopathy, showing that TAB2-dependent control of RIPK1-containing complexes is essential for myocardial homeostasis and remodeling under stress. Heterozygous TAB2 variants in families with syndromic congenital heart defects, adult-onset cardiomyopathy, and connective-tissue features, consistent with a dosage-sensitive requirement for TAB2-based signaling scaffolds during cardiac development and long-term ventricular integrity. TAB2 also interacts with nuclear receptor coregulators such as NCOR1 and estrogen receptor α in breast cancer cells, where defined central domains of TAB2 mediate dismissal of NCOR1 from antagonist-bound ERα on chromatin and contribute to tamoxifen resistance; disruption of this TAB2–ERα interface by competitive peptides restores antiproliferative responses to tamoxifen. |
