Both calmodulin and the unconventional myosin Myr4 regulate membrane trafficking along the recycling pathway of MDCK cells

被引:65
作者
Huber, LA
Fialka, I
Paiha, K
Hunziker, W
Sacks, DB
Bähler, M
Way, M
Gagescu, R
Gruenberg, J
机构
[1] Inst Mol Pathol, Res Inst Mol Pathol, A-1030 Vienna, Austria
[2] Inst Mol Cell Biol, Singapore 117609, Singapore
[3] Harvard Univ, Sch Med, Brigham & Womens Hosp, Boston, MA 02115 USA
[4] Univ Munster, Inst Allgemeine Zool & Genet, D-48149 Munster, Germany
[5] European Mol Biol Lab, D-69117 Heidelberg, Germany
[6] Univ Geneva, Dept Biochem, CH-1211 Geneva 4, Switzerland
关键词
actin; CaM; cell-free endosome fusion; endosome recognition and fusion; epithelial polarity; myr4;
D O I
10.1034/j.1600-0854.2000.010607.x
中图分类号
Q2 [细胞生物学];
学科分类号
071009 ; 090102 ;
摘要
In epithelial cells, endocytosed transferrin and its receptor, which cycle basolaterally, have been shown to transit through recycling endosomes which can also be accessed by markers internalized from the apical surface. In this work, we have used an in vitro assay to follow transfer of an endocytosed marker from apical or basolateral early endosomes to recycling endosomes labeled with transferrin. We show that calmodulin (CaM) function is necessary for transfer and identified myr4, a member of the unconventional myosin superfamily known to use CaM as a light chain, as a possible target protein for CaM. Since myr4 is believed to act as an actin-based mechanoenzyme, we tested the role of polymerized actin in the assay. Our data show that conditions which either prevent actin polymerization or induce the break-down of existing filaments strongly inhibit interactions between recycling endosomes and either set of early endosomes. Altogether, our data indicate that trafficking at early steps of the endocytic pathway in Madin-Darby Canine Kidney cells depends on the actin-based mechanoenzyme myr4, its light chain CaM, and polymerized actin.
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页码:494 / 503
页数:10
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