General transcription factor IIIA (GTF3A)

General transcription factor IIIA (GTF3A) is a zinc finger transcription factor with nine Cys[2]-His[2] domains that functions in the nucleus to induce transcription of 5S ribosomal RNA (rRNA) genes by RNA polymerase III. GTF3A is a member of the general transcription factor family and part of the zinc finger protein group. It specifically recognizes a 50 base pair internal control region (ICR) within 5S rRNA genes, nucleating the formation of a pre-initiation complex that recruits other transcription factors (TFIIIC, TFIIIB) and RNA polymerase III. It is crucial for RNA polymerase III-mediated transcription, especially for 5S rRNA, and binds the internal promoter of these genes. Beyond its core role in ribosomal RNA biogenesis, GTF3A and its altered expression have been implicated in cancer, with overexpression associated with tumor progression in colorectal cancer and adverse clinical prognosis. Upregulation is linked to oncogenic pathways (cell cycle, WNT/β-catenin signaling) and poor cancer prognosis. GTF3A also has physiological significance in sexual development: its transcription in fish oocytes is required for 5S rRNA accumulation and serves as a marker for feminization and intersex condition due to endocrine disruption. In vertebrates, including humans, only a single canonical GTF3A gene is present; in teleost fish, subfunctional paralogs exist for oocyte- and general-cell isoforms. Disease associations documented include colorectal cancer, intellectual disabilities, and glaucoma. While there is no evidence it is a direct therapeutic target of drugs, it can be important as a prognostic biomarker in oncology. No direct drug interactions or therapeutic targeting are reported in the current biomedical literature. Its use as a biomarker is best established in research/experimental pathology, particularly in colorectal cancer and in environmental toxicity studies with fish.

Other names

Transcription factor IIIATFIIIATF3AAP2