Cell Biology

More Ciliary Signaling

Science's STKE  01 Nov 2005:
Vol. 2005, Issue 308, pp. tw384
DOI: 10.1126/stke.3082005tw384

Hot on the heels of the demonstration that Smoothened (the receptor for the morphogen Hedgehog) needs to be localized to cilia to function (see http://stke.sciencemag.org/cgi/content/abstract/sigtrans;2005/306/tw369) comes a report of essential localization of the platelet-derived growth factor receptor α (PDGFRα) to the primary cilium of NIH3T3 fibroblasts. The PDGFRα was localized to the primary cilium, which formed when cells withdrew from the cell cycle after being deprived of serum. PDGFRβ, on the other hand, was distributed in clusters throughout the cell surface. PDGFAA, a form of PDGF that activates only homodimers of PDGFRα (and not heterodimers containing PDGFRβ or homodimers of PDGFRβ), stimulated signaling through the mitogen-activated kinases ERK1 and ERK2 and reentry into the cell cycle (monitored by phosphorylation of the cell cycle regulators Rb and Cdc2). These effects of PDGFAA were lost in mouse embryo fibroblasts from animals lacking the intraflagellar transport protein IFT88 (also called polaris), which failed to form cilia. The authors note that better understanding of the reasons for localization of the PDGFRα at cilia could help in preventing its abnormal function, which is known to contribute to human malignancies.

L. Schneider, C. A. Clement, S. C. Teilmann, G. J. Pazour, E. K. Hoffmann, P. Satir, S. T. Christensen, PDGFRαα signaling is regulated through the primary cilium in fibroblasts. Curr. Biol. 15, 1861-1866 (2005). [PubMed]