CHTOP (chr1 target of PRMT1) is a versatile nuclear protein that serves dual roles in transcriptional regulation and mRNA processing. As a component of the TREX complex, CHTOP is essential for mRNA nuclear export by coupling transcription, splicing, and export processes 1. The protein functions through arginine methylation by PRMT1, which regulates post-transcriptional intron retention and splicing kinetics 2. CHTOP activates transcription of specific gene groups, including estrogen-inducible genes in breast cancer and genes involved in glioblastomagenesis, while also repressing fetal γ-globin expression 3. Its expression is strictly autoregulated through intron retention and nonsense-mediated mRNA decay mechanisms 3. Clinically, CHTOP shows significant disease relevance across multiple cancer types. High CHTOP expression correlates with poor disease-free survival in ovarian cancer patients and promotes malignant behaviors including invasion, chemoresistance, and stemness 4. The protein contributes to cisplatin resistance in ovarian cancer through the circHIPK2/miR-338-3p/CHTOP pathway 5. Additionally, CHTOP has emerged as a potential biomarker for islet cell death, with circulating unmethylated CHTOP DNA fragments showing promise for detecting β-cell damage in diabetes 6.