Hrs regulates the endocytic sorting of the fibroblast growth factor receptor 2b.
The keratinocyte growth factor receptor or fibroblast growth factor receptor 2b (KGFR/FGFR2b) is activated by the specific interaction with the keratinocyte growth factor (KGF/FGF7), which targets the receptor to the degradative pathway, and the fibroblast growth factor 10 (FGF10/KGF2), which drives the receptor to the juxtanuclear recycling route. Hrs plays a key role in the regulation of the endocytic degradative transport of ubiquitinated receptor tyrosine kinases, but the direct involvement of this protein in the regulation of FGFR endocytosis has not been investigated yet. We investigated here the possible role of Hrs in the alternative endocytic pathways of KGFR. Quantitative immunofluorescence microscopy and biochemical analysis showed that both overexpression and siRNA interference of Hrs inhibit the KGF-triggered KGFR degradation, blocking receptor transport to lysosomes and causing its rapid reappearance at the plasma membrane. In contrast, the FGF10-induced KGFR targeting to the recycling compartment is not affected by Hrs overexpression or depletion. Coimmunoprecipitation approaches indicated that Hrs is recruited to KGFR only after KGF treatment, although it is not tyrosine phosphorylated by the ligand. In conclusion, Hrs regulates the KGFR degradative pathway, but not its juxtanuclear recycling transport. In addition, the results suggest that Hrs recruitment to the receptor, but not its ligand-induced phosphorylation, could be required for its function.
Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Medicina Sperimentale, Università di Roma La Sapienza, Rome, Italy. francesca.belleudi@uniroma1.it
Francesca
F
Belleudi
Laura
L
Leone
Maddalena
M
Maggio
Maria Rosaria
MR
Torrisi
D000818:Animals; D004705:Endocytosis / Q000502:physiology*; D056827:Endosomal Sorting Complexes Required for Transport; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D051526:Fibroblast Growth Factor 10 / Q000494:pharmacology; D051523:Fibroblast Growth Factor 7 / Q000494:pharmacology; D006367:HeLa Cells / Q000187:drug effects; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells / Q000187:drug effects; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D056827:Endosomal Sorting Complexes Required for Transport; D051526:Fibroblast Growth Factor 10; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate; D051523:Fibroblast Growth Factor 7; D066246:ErbB Receptors; D051497:Receptor, Fibroblast Growth Factor, Type 2