PCBP2 post-transcriptionally regulates sortilin expression by binding to a C-rich element in its 3' UTR

Post-transcriptional regulation of cytokine production is crucial to ensure appropriate immune responses. We previously demonstrated that poly-rC-binding protein-1 (PCBP1) can act as a trans-acting factor to stabilize transcripts encoding sortilin, which mediates cytokine trafficking. Here, we report that PCBP2, which strongly resembles PCBP1, can stabilize sortilin transcripts in macrophages using the same mechanism employed by PCBP1. PCBP2 recognized the C-rich element in the 3' UTR of sortilin mRNA, and PCBP2 knockdown decreased sortilin transcripts, indicating that PCBP2 stabilizes sortilin mRNA by binding to its 3' UTR. Zn(2+) reversibly inhibited the nucleotide binding ability of PCBP2 in vitro. These findings suggest that both PCBP2 and PCBP1 may control the stability of sortilin transcripts by sensing intracellular Zn(2+) levels in immune cells.