Emerging roles of POLR2L of RNA polymerase II dynamics and disease mechanisms (Review).

RNA polymerase II (Pol II) is an essential eukaryotic enzyme that transcribes protein‑coding genes and various non‑coding RNAs. RNA polymerase II, I and III subunit L (POLR2L) is a highly conserved component shared by RNA polymerase subunits I, II, and III, which contributes to transcriptional regulation, enzymatic structural integrity, key cellular processes such as proliferation, differentiation, and stress responses. Recent research has shown that POLR2L is not merely a Pol II structural subunit but also plays key roles in disease progression, particularly cancer, where POLR2L dysregulation contributes to tumor growth, metastasis, and resistance to chemotherapy. Additionally, POLR2L is closely linked to major signaling pathways including the PI3K‑Akt, Wnt/β‑catenin, and TGF‑β pathways, highlighting the diverse roles played by POLR2L in cellular signaling. This review summarizes current knowledge on the structural and functional properties of POLR2L, its involvement in various diseases, and its potential as a therapeutic target. By outlining the diagnostic and therapeutic relevance of POLR2L, this review aims to provide a framework for understanding how POLR2L related research may inform transcriptional regulation and its impact on human health and disease.