Cullin-3 regulates late endosome maturation.

Jatta Huotari, Nathalie Meyer-Schaller, Michaela Hubner, Sarah Stauffer, Nadja Katheder, Peter Horvath, Roberta Mancini, Ari Helenius, Matthias Peter

Institute of Biochemistry, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.

Proceedings of the National Academy of Sciences of the United States of America 2012 Jan 17

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Cullin-3 (Cul3) functions as a scaffolding protein in the Bric-a-brac, Tramtrack, Broad-complex (BTB)-Cul3-Rbx1 ubiquitin E3 ligase complex. Here, we report a previously undescribed role for Cul3 complexes in late endosome (LE) maturation. RNAi-mediated depletion of Cul3 results in a trafficking defect of two cargoes of the endolysosomal pathway, influenza A virus (IAV) and epidermal growth factor receptor (EGFR). IAV is able to reach an acidic endosomal compartment, coinciding with LE/lysosome (LY) markers. However, it remains trapped or the capsid is unable to uncoat after penetration into the cytosol. Similarly, activation and subsequent ubiquitination of EGFR appear normal, whereas downstream EGFR degradation is delayed and its ligand EGF accumulates in LE/LYs. Indeed, Cul3-depleted cells display severe morphological defects in LEs that could account for these trafficking defects; they accumulate acidic LE/LYs, and some cells become highly vacuolated, with enlarged Rab7-positive endosomes. Together, these results suggest a crucial role of Cul3 in regulating late steps in the endolysosomal trafficking pathway.

Citation

Jatta Huotari, Nathalie Meyer-Schaller, Michaela Hubner, Sarah Stauffer, Nadja Katheder, Peter Horvath, Roberta Mancini, Ari Helenius, Matthias Peter. Cullin-3 regulates late endosome maturation. Proceedings of the National Academy of Sciences of the United States of America. 2012 Jan 17;109(3):823-8