Yang Jun, Li Tiansen
The Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
Exp Cell Res. 2005 Oct 1;309(2):379-89. doi: 10.1016/j.yexcr.2005.05.026.
The ciliary rootlet is a large striated fibrous network originating from basal bodies in ciliated cells. To explore its postulated role in intracellular transport, we investigated the interaction between kinesin light chains (KLCs) and rootletin, the structural component of ciliary rootlets. We show here that KLCs directly interact with rootletin and are located along ciliary rootlets. Their interactions are mediated by the heptad repeats of KLCs. Further studies found that these interactions tethered kinesin heavy chains along ciliary rootlets. However, the ciliary rootlet-bound kinesin-1 did not recruit microtubules or move along ciliary rootlets. Additionally, amyloid precursor protein (APP; a kinesin-1 vesicular cargo receptor) and presenilin 1 (a presumed cargo of APP/kinesin-1) were found to be enriched along the rootletin fibers, suggesting that the interaction between ciliary rootlets and kinesin-1 recruits APP and presenilin 1 along ciliary rootlets. These findings indicate that ciliary rootlets may provide a scaffold for kinesin-1 vesicular cargos and, thus, play a role in the intracellular transport in ciliated cells.
纤毛小根是一种起源于纤毛细胞基体的大型横纹纤维网络。为了探究其在细胞内运输中假定的作用，我们研究了驱动蛋白轻链（KLCs）与根蛋白（纤毛小根的结构成分）之间的相互作用。我们在此表明，KLCs直接与根蛋白相互作用，并沿纤毛小根定位。它们的相互作用由KLCs的七肽重复序列介导。进一步研究发现，这些相互作用将驱动蛋白重链束缚在纤毛小根上。然而，与纤毛小根结合的驱动蛋白-1并未募集微管，也未沿纤毛小根移动。此外，淀粉样前体蛋白（APP；一种驱动蛋白-1囊泡货物受体）和早老素1（一种推测的APP/驱动蛋白-1货物）被发现沿根蛋白纤维富集，这表明纤毛小根与驱动蛋白-1之间的相互作用沿纤毛小根募集了APP和早老素1。这些发现表明，纤毛小根可能为驱动蛋白-1囊泡货物提供一个支架，从而在纤毛细胞的细胞内运输中发挥作用。
