Karyopherin subunit α2 interactome in human pluripotent stem cells

Abstract

Karyopherin subunit α2 (KPNA2) functions as a nuclear importer that transfers macromolecules from the cytoplasm to the nucleus. Based on literature and our preliminary data, KPNA2 seems to be upregulated in human pluripotent stem cells (hPSCs) and thus could play a role in their biology. KPNA2 could be a possible regulator of key pluripotency transcription factors and other proteins associated with pluripotency regarding their entry to the nucleus. By understanding the mechanisms behind pluripotency, these cells could be utilized more efficiently in biomedical and clinical applications, highlighting the significance of this research. This thesis aims to study the expression of KPNA2 in hPSCs and identify the interacting proteins to find out if it has a connection with pluripotency-associated proteins.

The expression of KPNA2 in hPSCs was studied with Western blot and immunofluorescence. The expression of KPNA2 was compared between hPSCs and fibroblasts, and after differentiation with BMP4. Co-immunoprecipitation combined with mass spectrometry was performed to acquire proteins interacting with KPNA2. A protein network visualising the interacting proteins was created in STRING database from the selected proteins of interest in the acquired mass spectrometry data.

Our experiments revealed that KPNA2 is upregulated in hPSCs and downregulated upon differentiation, indicating that it might have a specific function in these cells. KPNA2 co-precipitates with pluripotency-associated proteins and shows both direct and indirect interactions with them. In light of these promising results, it is indicated that KPNA2 could possibly be contributing to the regulation of stemness. This study provides a strong background and highlights the need for future experiments concerning KPNA2 alongside the entire nuclear traffic network of hPSCs.