1. Kinesin adapter JLP links PIKfyve to microtubule-based endosome-to-trans-Golgi network traffic of furin.
- Author
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Ikonomov OC, Fligger J, Sbrissa D, Dondapati R, Mlak K, Deeb R, and Shisheva A
- Subjects
- Adaptor Proteins, Signal Transducing genetics, Alternative Splicing physiology, Animals, Base Sequence, CHO Cells, Consensus Sequence physiology, Cricetinae, Cricetulus, Endosomes genetics, Furin genetics, Golgi Apparatus genetics, Humans, Kinesins genetics, Kinesins metabolism, Mice, Microtubules genetics, Molecular Sequence Data, Phosphatidylinositol 3-Kinases genetics, Protein Binding physiology, Protein Structure, Tertiary physiology, Protein Transport, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins metabolism, Two-Hybrid System Techniques, Adaptor Proteins, Signal Transducing metabolism, Endosomes metabolism, Furin metabolism, Golgi Apparatus metabolism, Microtubules metabolism, Phosphatidylinositol 3-Kinases metabolism
- Abstract
JIPs (c-Jun N-terminal kinase interacting proteins), which scaffold JNK/p38 MAP kinase signaling modules, also bind conventional kinesins and are implicated in microtubule-based membrane trafficking in neuronal cells. Here we have identified a novel splice variant of the Jip4 gene product JLP(L) (JNK-interacting leucine zipper protein) in yeast-two hybrid screens with the phosphoinositide kinase PIKfyve. The interaction was confirmed by pulldown and coimmunoprecipitation assays in native cells. It engages the PIKfyve cpn60_TCP1 consensus sequence and the last 75 residues of the JLP C terminus. Subpopulations of both proteins cofractionated and populated similar structures at the cell perinuclear region. Because PIKfyve is essential in endosome-to-trans-Golgi network (TGN) cargo transport, we tested whether JLP is a PIKfyve functional partner in this trafficking pathway. Short interfering RNA (siRNA)-mediated depletion of endogenous JLP or PIKfyve profoundly delayed the microtubule-based transport of chimeric furin (Tac-furin) from endosomes to the TGN in a CHO cell line, which was rescued upon ectopic expression of siRNA-resistant JLP or PIKfyve constructs. Peptides from the contact sites in PIKfyve and JLP, or a dominant-negative PIKfyve mutant introduced into cells by ectopic expression or microinjection, induced a similar defect. Because Tac-TGN38 delivery from endosomes to the TGN, unlike that of Tac-furin, does not require intact microtubules, we monitored the effect of JLP and PIKfyve depletion or the interacting peptides administration on Tac-TGN38 trafficking. Remarkably, neither maneuver altered the Tac-TGN38 delivery to the TGN. Our data indicate that JLP interacts with PIKfyve and that both proteins and their association are required in microtubule-based, but not in microtubule-independent, endosome-to-TGN cargo transport.
- Published
- 2009
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