HNRNPD is an RNA-binding protein that functions as a critical post-transcriptional regulator with broad disease relevance. Primary Function: HNRNPD binds AU-rich elements (AREs) in 3'-UTRs of proto-oncogenes and cytokine mRNAs, regulating mRNA stability and translation 1. It also binds DNA sequences including telomeric repeats and functions in transcriptional regulation 2. Mechanism: HNRNPD modulates target mRNA stability through direct 3'-UTR binding. In cardiac ischemia/reperfusion, HNRNPD binds m6A-methylated TFEB pre-mRNA, reducing TFEB expression and suppressing autophagy 1. Similarly, HNRNPD stabilizes SERPINA3 mRNA when recruited by lncRNA SNHG1, promoting colorectal cancer metastasis 3. HNRNPD also binds dU-containing DNA and regulates its repair 2. Disease Relevance: HNRNPD promotes hepatocellular carcinoma metastasis by reducing LKB1 mRNA stability through circLARP1B competition 4. In osteoarthritis, HNRNPD upregulates FOXM1, promoting chondrocyte senescence and mitochondrial dysfunction 5. CircSTX6 sequesters HNRNPD away from ATF3 mRNA, accelerating HCC progression 6. Clinical Significance: HNRNPD dysregulation correlates with cancer progression, age-related diseases, and inflammatory pathology. Targeting the SNHG1/HNRNPD/SERPINA3 pathway represents a potential therapeutic strategy for preventing metastasis 3.