Homeodomain-interacting protein kinase 2–Mothers against decapentaplegic homolog 3 interface (HIPK2–Smad3 interface)

The Homeodomain-interacting protein kinase 2 (HIPK2)–Smad3 interface is a critical regulatory node in the transforming growth factor-beta (TGF-beta) signaling pathway, primarily responsible for driving pathological fibrosis. HIPK2 is a serine/threonine kinase that physically interacts with and phosphorylates Smad3, a key transcription factor, thereby enhancing its transcriptional activity and promoting the expression of profibrotic genes (UniProt: Q9H2X6, P84022). This interaction is significantly upregulated in conditions such as chronic kidney disease and liver fibrosis, where it facilitates the transition of epithelial cells to myofibroblasts (PMID: 25607108). Targeting this specific protein-protein interaction or the kinase activity of HIPK2 has shown promise in preclinical models for attenuating tissue scarring and preserving organ function (PMID: 28031211). Experimental small molecules like BT173 have been developed to disrupt this axis, demonstrating the potential for therapeutic intervention in fibrotic diseases. However, because HIPK2 also functions as a tumor suppressor by activating p53-mediated apoptosis, therapeutic strategies must carefully navigate the risk of unintended oncogenic effects. The interface represents a high-value target for precision medicine aimed at decoupling the profibrotic effects of TGF-beta from its other essential biological roles.

Other names

HIPK2-Smad3 complexHIPK2-Smad3 interactionHomeodomain-interacting protein kinase 2–Smad3 interface

Inhibition of the physical interaction between HIPK2 and Smad3 or inhibition of HIPK2-mediated phosphorylation of Smad3 to prevent the activation of profibrotic gene transcription.