Abstract
ABSTRACTThe nuclear transport of paxillin appears to be crucial for paxillin function but the mechanism of transport remains unclear. Here, we show that the nuclear transport of paxillin is regulated by focal adhesion turnover and the presence of FAT domains. Focal adhesion turnover was controlled using triangular or circular fibronectin islands. Circular islands caused higher focal adhesion turnover and increased the nuclear transport of paxillin relative to triangular islands. Mutating several residues of paxillin had no effect on its nuclear transport, suggesting that the process is controlled by multiple domains. Knocking out FAK (also known as PTK2) and vinculin caused an increase in nuclear paxillin. This could be reversed by rescue with wild-type FAK but not by FAK with a mutated FAT domain, which inhibits paxillin binding. Expressing just the FAT domain of FAK not only brought down nuclear levels of paxillin but also caused a large immobile fraction of paxillin to be present at focal adhesions, as demonstrated by fluorescence recovery after photobleaching (FRAP) studies. Taken together, focal adhesion turnover and FAT domains regulate the nuclear localization of paxillin, suggesting a possible role for transcriptional control, through paxillin, by focal adhesions.
Highlights
Members of the LIM domain family of proteins, such as zyxin, Trip6, Hic-5 and paxillin, play a role in the mechanosensitive control of transcription (Kadrmas and Beckerle, 2004; Mammoto et al, 2012; Wang and Gilmore, 2003)
We show that paxillin transport to the nucleus depends on the cellular geometry, which affects focal adhesion dynamics
In order to compare nuclear paxillin in cells with varying expression levels, we used the nuclear to total intensity ratio (NTIR) as a standard measure
Summary
Members of the LIM domain family of proteins, such as zyxin, Trip6, Hic-5 and paxillin, play a role in the mechanosensitive control of transcription (Kadrmas and Beckerle, 2004; Mammoto et al, 2012; Wang and Gilmore, 2003). We show that paxillin transport to the nucleus depends on the cellular geometry, which affects focal adhesion dynamics. We show that nuclear transport of paxillin is increased by knocking out FAK or vinculin, whereas the overexpression of focal-adhesion-targeting (FAT) domains reduces nuclear transport.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
