Inhibitor of DNA binding protein family (ID family) (ID family)

The Inhibitor of DNA binding (Id) protein family, consisting of Id1, Id2, Id3, and Id4, are helix-loop-helix (HLH) transcription regulators that lack a DNA-binding domain [1, 2]. They act as dominant-negative inhibitors by heterodimerizing with basic helix-loop-helix (bHLH) transcription factors, such as E-proteins, thereby preventing them from binding to E-box DNA sequences and activating genes required for cell differentiation [2, 4]. While essential for maintaining stem cell populations during embryonic development, Id proteins are typically downregulated in adult tissues [2, 9]. However, their reactivation and overexpression are frequently observed in various malignancies and neovascular diseases, where they drive cell proliferation, survival, angiogenesis, and metastasis [3, 5, 6]. Therapeutic strategies targeting the pan-Id family aim to disrupt these protein-protein interactions, often leading to the ubiquitin-mediated degradation of Id proteins and the restoration of bHLH-mediated differentiation or growth arrest [6, 8]. Small-molecule antagonists like AGX51 have shown promise in preclinical models by inhibiting tumor growth and pathologic ocular neovascularization [6, 14].

Other names

Inhibitor of differentiation proteinsID proteinsClass V helix-loop-helix proteinsInhibitor of DNA binding proteinsId1-4Pan-Id family

Antagonism of Id-E protein interactions leading to ubiquitin-mediated degradation of Id proteins and restoration of bHLH transcriptional activity.