The Cdc42 Effector Kinase PAK4 Localizes to Cell-Cell Junctions and Contributes to Establishing Cell Polarity.

The serine/threonine kinase PAK4 is a Cdc42 effector whose role is not well understood; overexpression of PAK4 has been associated with some cancers, and there are reports that correlate kinase level with increased cell migration in vitro. Here we report that PAK4 is primarily associated with cell-cell junctions in all the cell lines we tested, and fails to accumulate at focal adhesions or at the leading edge of migrating cells. In U2OS osteosarcoma and MCF-7 breast cancer cell lines, PAK4 depletion did not affect collective cell migration, but affected cell polarization.

Group I and II mammalian PAKs have different modes of activation by Cdc42.

p21-activated kinases (PAKs) are Cdc42 effectors found in metazoans, fungi and protozoa. They are subdivided into PAK1-like (group I) or PAK4-like (group II) kinases. Human PAK4 is widely expressed and its regulatory mechanism is unknown.

TLS interaction with NMDA R1 splice variant in retinal ganglion cell line RGC-5.

Translocated in liposarcoma (TLS or FUS) is a multifunctional protein component of the heterogenous ribonuclear complex involved in the splicing of pre-mRNA and the export of fully processed mRNA from the nucleus to the cytoplasm. As we determined that TLS was substantially expressed in the adult retina, we investigated the functions of TLS in a rat retinal ganglion cell (RGC) line RGC-5. TLS was found to be associated with N-methyl-d-aspartate (NMDA) receptor 1 (NR1) and myosinVa (MyoVa) in a calcium-dependent manner.