| YB‑1 (Y‑box binding protein 1) is a member of the evolutionarily conserved cold‑shock‑domain family of multifunctional DNA‑ and RNA‑binding proteins that regulate transcription, RNA processing, translation, and mRNA stability. It contains a conserved cold‑shock domain that mediates binding to single‑stranded DNA and RNA motifs, including classical Y‑box sequences (TAACC) in gene promoters, and a C‑terminal domain that contributes to nucleic‑acid binding, oligomerization, and subcellular localization. YB‑1 functions as a transcription factor that activates genes involved in proliferation and therapy resistance, such as EGFR, c‑ERBB2, and drug‑resistance‑related loci, while repressing genes associated with apoptosis and tumor suppression, including certain regulators of the p53 pathway and death‑receptor signaling. YB‑1 also participates in mRNP formation, stabilizes specific mRNAs such as interleukin‑2, and modulates translation of oncogenic transcripts in response to growth‑factor‑induced signaling. Nuclear translocation of YB‑1 is tightly regulated by cell‑cycle phase and extracellular cues, accumulating in the nucleus during late G2/M and in response to stresses such as hyperthermia, UV irradiation, and growth‑factor stimulation; this shuttling is controlled by phosphorylation at Ser102, dephosphorylation of key C‑terminal serines, and interaction with nuclear import machineries such as transportin‑1. Overexpression of YB‑1, particularly its nuclear form, is observed in multiple carcinomas including breast, lung, prostate, head‑and‑neck, nasopharyngeal, and gastrointestinal cancers, where it correlates with advanced stage, drug resistance, and poor survival. |
Lane 1: MEF, Lane 2: C2C12, Lane 3: H-4-II-E, Lane 4: COS-7
