Molecular mechanisms of nuclear translocation of TRAIL-R2

• Applicant: Professorin Dr. Anna Trauzold
• Subject Area: Hematology, Oncology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 405349881

Plasma membrane expressed TRAIL-R1 and TRAIL-R2 can induce cell death and diverse non-apoptotic signaling pathways as a response to the binding of their ligand TRAIL. In tumors, these receptors are present mainly intracellularly, in the cytoplasm and in the nucleus. Interestingly, high intracellular expression of particularly TRAIL-R2 frequently correlates with bad patient’s prognosis. We found that in tumor cells TRAIL-R2 is located predominantly in the nucleus where it interacts with the core microprocessor complex and its accessory proteins. Via these interactions, nuclear TRAIL-R2 (nTRAIL-R2) inhibits the maturation of the miRNA let-7 thereby increasing tumor cell malignancy. In addition, our unpublished data show that nuclear TRAIL-R2 interacts with the p53 tumor suppressor protein and negatively influences its functions. Furthermore, our observation that TRAIL-R2 associates with the chromatin fraction indicates a possible role of nTRAIL-R2 in the regulation of the gene expression. The involvement of TRAIL-R2 in the regulation of let-7 maturation as well as the functions of wt p53 is of utmost importance for the understanding of the role of these receptors in the malignant transformation and opens new perspectives for therapeutic strategies. However, for the development of such strategies, it is mandatory to understand the mechanisms of the nuclear translocation of TRAIL-R2. In this project, we will clarify: i) the impact of TRAIL and ii) other TRAIL receptors on the nuclear translocation of TRAIL-R2. iii) We will uncover the mechanisms of nuclear import/export of TRAIL-R2. In particular, we will determine the importance of Clathrin-dependent and -independent endocytosis, Sec61-translocons as well as Importin β and CRM-1/Exportin 1. iv) In addition, we will identify the protein domains of TRAIL-R2 responsible for its nuclear translocation. v) Using chromatin immunoprecipitation techniques coupled to mass spectrometry and ChIP-Seq, we will identify TRAIL-R2-interacting chromatin-associated proteins and DNA-sequences, respectively. We are convinced that the results of our project will allow uncovering further functions of nTRAIL-R2 and thereby novel aspects of TRAIL-Receptor biology. Understanding the mechanisms of intracellular trafficking of TRAIL-R2, in particular its nuclear translocation will allow designing drugs for manipulating its intracellular distribution which subsequently will lead to the development of novel therapeutic strategies.

• DFG Programme: Research Grants