Protein chibby homolog 1 (CBY1)

Protein chibby homolog 1 (CBY1) is a small, evolutionarily conserved protein that acts as a key "antagonist of β-catenin" and a negative regulator of canonical Wnt/β-catenin signaling[1][3][4][5][6]. CBY1 exerts its function by binding directly to the C-terminal region of β-catenin, inhibiting its interaction with Tcf/Lef transcription factors, and thereby repressing β-catenin-mediated transcriptional activity[1][2][4][5]. CBY1 also forms a complex with β-catenin and 14-3-3 proteins, promoting β-catenin's nuclear export and further decreasing its transcriptional activation. In addition to its role in Wnt signaling, CBY1 is important for cellular differentiation—especially in adipogenesis and cardiomyocyte development—and is essential for ciliogenesis through its localization and function at centrioles and basal bodies[1][7]. Loss or downregulation of CBY1, through genetic mutation or promoter hypermethylation, leads to enhanced Wnt/β-catenin signaling and has been implicated in the pathogenesis of various cancers (including chronic myeloid leukemia, colorectal, gastric, and laryngeal carcinomas) as well as in ciliopathy syndromes such as Joubert syndrome[1][2][4]. Currently, CBY1 itself is not a direct therapeutic target for approved drugs, but its expression/status serves as a mechanistic marker for aberrant Wnt/β-catenin signaling in disease contexts[2][4][7].

Other names

Chibby1ChibbyARB1C22orf2CBYPGEA1HRIHFB2025PIGEA14PIGEA-14ARPP-binding proteinCytosolic leucine-rich proteinPKD2 interactorGolgi and endoplasmic reticulum-associated 1chibby CTNNB1-mediated transcription inhibitorchibby family member 1coiled-coil protein PIGEA-14polycystin-2 interactorGolgi- and endoplasmic reticulum-associated protein14 kDa

Negative regulation of β-catenin-mediated transcription by direct binding to β-catenin's C-terminal region, preventing interaction with Tcf/Lef transcription factors; Formation of a tripartite complex with β-catenin and 14-3-3 proteins, facilitating β-catenin nuclear export and reducing nuclear activity