Nuclear Functions of the Tyrosine Kinase Src

Abstract

Src is the representative member of the Src-family kinases (SFKs), a group of tyrosine kinases involved in several cellular processes. Its main function has been for long confined to the plasma membrane/cytoplasm compartment, being a myristoylated protein anchored to the cell membrane and functioning downstream to receptors, most of them lacking intrinsic kinase activity. In the last decades, new roles for some SFKs have been described in the nuclear compartment, suggesting that these proteins can also be involved in directly regulating gene transcription or nucleoskeleton architecture. In this review, we focused on those nuclear functions specifically attributable to Src, by considering its function as both tyrosine kinase and adapting molecule. In particular, we addressed the Src involvement in physiological as well as in pathological conditions, especially in tumors.

Keywords: Src-family kinases; Tyrosine phosphorylation; nucleus; oncogenes; subcellular localization.

Figure 1

Domain structure of Src family kinases.

Figure 2

In the upper panels: representative confocal microscope images of immunofluorescent staining for Src (left panel), nuclear dye DRAQ-5 (middle panel) and the overlay fluorescence (right panel - pseudo-colored in purple) of detailed nuclei of human osteosarcoma cell line SaOS2. Scale bar: 20 μm. In the lower panels: confocal microscope average XYZ projection of a stack of images of Src (left panel) and DRAQ-5 (right panel) fluorescences. The yellow cross-section pinpoints the location for the YZ and XZ axes projections.