%0 Generic
%A Lujan Miralles, Pablo
%D 2017
%F heidok:23478
%R 10.11588/heidok.00023478
%T New roles for the phosphatase PRL-3 in epithelial architecture maintenance and endocytosis
%U https://archiv.ub.uni-heidelberg.de/volltextserver/23478/
%X Phosphorylation and dephosphorylation of proteins and lipids are the major post-translational modifications involved in virtually all molecular signaling pathways in the cell and are catalyzed by kinases and phosphatases respectively. Abnormal variation in kinase and phosphatase activity leads to the development of several human diseases. Phosphatase of regenerating liver (PRL)-3 is a dual specificity  phosphatase that has been related to cell proliferation, migration, invasion, and epithelial to mesenchymal transition. Interestingly, while PRL-3 is aberrantly  overexpressed in primary and metastatic tumors, it is barely expressed at all in healthy human tissue. Therefore, PRL-3 represents a promising therapeutic target in cancer  treatment and an emerging prognostic marker for tumor progression. However, finding robust PRL-3 substrate candidates remains a challenge in the field. The aim of  the present work is to gain insight in both the cellular and molecular pathways where PRL-3 is involved.  The first part of this project is focused on the characterization of the role of PRL-3 in epithelial cell polarity using organotypic 3D-culture systems. We show that  overexpression of PRL-3 disrupts epithelial architecture by promoting the development of cysts with ectopic lumens that arise from mispositioned midbodies.  Furthermore, we propose a novel cellular mechanism where midbodies are retained in the lateral membrane due to acceleration of cytokinesis driven by PRL-3 overexpression.  The second part of the work deals with investigating PRL-3 PI(4,5)P2 phosphatase activity in cells, which was previously established in vitro. Here, we demonstrate this activity in vivo with a novel technique developed for this purpose.  Moreover, we prove that the low phosphoinositide phosphatase activity of PRL-3 and its specific interaction with PI(4,5)P2 are essential for enhancing clathrin-mediated  internalization.  In conclusion, we show that PRL-3 overexpression disrupts epithelial cell polarization probably by accelerating cytokinesis, and we demonstrate that it is a phosphoinositide phosphatase, increasing clathrin-dependent endocytosis.