PCMD-1: bridging the gap during cell division

Centrosomes are composed of an orthogonal pair of centrioles surrounded by a protein matrix termed the pericentriolar material (PCM). Although centrioles and the PCM are known to play an essential role during cell division, less is known about the proteins that link these structures together. Now, Tamara Mikeladze-Dvali and colleagues report that the coiled-coil protein pericentriolar matrix deficient-1 (PCMD-1) bridges centrioles and the PCM in C. elegans embryos. They first demonstrate that the outer centriolar protein SAS-7 recruits PCMD-1 to centrioles. Using a yeast-two hybrid assay, the authors further show that, although SAS-7 and PCMD-1 do not interact directly, PCMD-1 can interact with the centriolar protein SAS-4, the PCM protein SPD-5, the mitotic kinase PLK-1, and with itself. Moreover, they find that tethering PCMD-1 at an ectopic cellular location is sufficient to recruit SPD-5 and PKL-1 to this location. The authors also examine which parts of PCMD-1 are necessary for these interactions, revealing that the coiled-coil domain promotes PCMD-1 self-interaction and loading onto the centrosome, whereas regions within the C terminal promote binding to SAS-4 and to cilia. Together, these findings lead the authors to propose a model in which PCMD-1 anchors the PCM to centrioles and functionally bridges these two centrosomal components.