Transcription initiation factor IA (TIF-IA)

Transcription initiation factor IA (TIF‐IA) is an essential transcription factor that regulates the synthesis of ribosomal RNA (rRNA) by facilitating the recruitment of RNA polymerase I to ribosomal DNA promoters. It acts as a key mediator between cellular growth signals—particularly those from the PI3K/Akt/mTOR pathway—and rRNA production. Phosphorylation events modulate its activity; for example, Akt activation enhances TIF‐IA stability and nucleolar localization via casein kinase 2–mediated phosphorylation, thereby promoting rRNA transcription and supporting cell proliferation. Conversely, downregulation or inhibition of TIF‐IA leads to reduced rRNA synthesis, impaired ribosome biogenesis, developmental arrest in model organisms like Drosophila, and decreased cell viability. Due to its central role in controlling protein biosynthesis capacity through ribosome production—and thus influencing cancer cell growth—TIF‐IA is considered a potential therapeutic target in oncology research.

Other names

Rrn3 (yeast homolog)TIF-IATranscription initiation factor IRNA polymerase I transcription factor TIF-IA

Inhibition of upstream signaling pathways (PI3K/Akt/mTOR) reduces TIF‐IA activity and rRNA synthesis