Díaz Moreno, IreneCorrales Guerrero, Laura2025-06-202025-06-202025-03-21Baños Jaime, B. (2025). Regulation of the RNA-binding protein Human antigen R by tyrosine 5 Phosphorylation. (Tesis Doctoral Inédita). Universidad de Sevilla, Sevilla.https://hdl.handle.net/11441/174537Human antigen R (HuR) is an RNA binding protein mainly involved in maintaining the stability and controlling the translation of mRNAs, critical for immune response, cell survival, proliferation and apoptosis. Although HuR is a nuclear protein, its mRNA translational-related function occurs at the cytoplasm, where the oligomeric form of HuR is more abundant. However, the regulation of nucleo-cytoplasmic transport of HuR and its connection with protein oligomerization remain unclear. In this work, we describe the phosphorylation of tyrosine 5 as a new hallmark for HuR activation. Our biophysical, structural and computational assays using phosphorylated and phosphomimetic HuR proteins demonstrate that phosphorylation of tyrosine 5 at the disordered N-end stretch induces global changes on HuR dynamics and conformation, modifying the solvent accessible surface of the HuR nucleo-cytoplasmic shuttling (HNS) sequence and releasing regions implicated in HuR dimerization. These findings explain the preferential cytoplasmic accumulation of phosphorylated HuR in HeLa cells and its later dimerization. Moreover, tyrosine 5 phosphorylation weakens HuR interaction with ANP32B, one of its preferential nuclear exporters under stress conditions. This fact discards ANP32B transport route as the responsible for the cytoplasmic localization of tyrosine 5-phosphorylated HuR. This work aids to comprehend the mechanisms underlying HuR nucleus-cytoplasm shuttling and oligomerization, both of which are relevant in HuR-related pathogenesis.application/pdf180 p.engAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccess