PUM1 (Pumilio RNA binding family member 1) is a sequence-specific RNA-binding protein that functions as a post-transcriptional repressor by binding to the 3'-UTR of target mRNAs through the Pumilio Response Element (PRE) consensus sequence 5'-UGUANAUA-3' 1. PUM1 regulates gene expression through multiple mechanisms, including direct recruitment of deadenylase complexes for mRNA degradation and facilitating miRNA accessibility to target sites 1. The protein plays critical roles in cellular processes including cell cycle regulation, aging, and immune responses. PUM1 suppresses cellular senescence by downregulating TLR4 mRNA translation, thereby inhibiting NF-κB signaling pathways 2. In cancer contexts, PUM1 promotes tumor progression through multiple pathways: it stabilizes DEPTOR mRNA to activate glycolysis in gastric cancer 3, suppresses p21 expression to promote colorectal cancer growth 4, and facilitates immune escape by regulating the NPM3/NPM1/PD-L1 axis 5. Clinically, PUM1 mutations cause neurodevelopmental disorders, with haploinsufficiency leading to developmental delay and seizures (PADDAS syndrome), while milder mutations result in adult-onset cerebellar ataxia 1. The protein's dysfunction is also implicated in recurrent miscarriage and intervertebral disc degeneration 67.