1. Inhibiting clathrin-mediated endocytosis of the leucine-rich G protein-coupled receptor-5 diminishes cell fitness
- Author
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Alan S. Waggoner, Lauren K. Rochelle, Larry S. Barak, Veronica Lubkov, Marc G. Caron, Caroline A. Ray, Cheryl B. Bock, Thomas F. Pack, Joshua C. Snyder, and H. Kim Lyerly
- Subjects
0301 basic medicine ,media_common.quotation_subject ,education ,Biology ,Cell fate determination ,Endocytosis ,Biochemistry ,Clathrin ,Epithelium ,Lignans ,Receptors, G-Protein-Coupled ,Mice ,03 medical and health sciences ,0302 clinical medicine ,Leucine ,Cell Line, Tumor ,Animals ,Homeostasis ,Humans ,Protein Isoforms ,Cell Lineage ,Internalization ,Wnt Signaling Pathway ,Molecular Biology ,Cell Proliferation ,media_common ,G protein-coupled receptor ,Adenosine Triphosphatases ,Stochastic Processes ,Cell growth ,Stem Cells ,Wnt signaling pathway ,Dioxolanes ,Cell Biology ,Receptor-mediated endocytosis ,Rats ,Cell biology ,Mice, Inbred C57BL ,030104 developmental biology ,biology.protein ,Female ,030217 neurology & neurosurgery - Abstract
The leucine-rich G protein-coupled receptor-5 (LGR5) is expressed in adult tissue stem cells of many epithelia, and its overexpression is negatively correlated with cancer prognosis. LGR5 potentiates WNT/β-catenin signaling through its unique constitutive internalization property that clears negative regulators of the WNT-receptor complex from the membrane. However, both the mechanism and physiological relevance of LGR5 internalization are unclear. Therefore, a natural product library was screened to discover LGR5 internalization inhibitors and gain mechanistic insight into LGR5 internalization. The plant lignan justicidin B blocked the constitutive internalization of LGR5. Justicidin B is structurally similar to more potent vacuolar-type H+-ATPase inhibitors, which all inhibited LGR5 internalization by blocking clathrin-mediated endocytosis. We then tested the physiological relevance of LGR5 internalization blockade in vivo. A LGR5-rainbow (LBOW) mouse line was engineered to express three different LGR5 isoforms along with unique fluorescent protein lineage reporters in the same mouse. In this manner, the effects of each isoform on cell fate can be simultaneously assessed through simple fluorescent imaging for each lineage reporter. LBOW mice express three different forms of LGR5, a wild-type form that constitutively internalizes and two mutant forms whose internalization properties have been compromised by genetic perturbations within the carboxyl-terminal tail. LBOW was activated in the intestinal epithelium, and a year-long lineage-tracing course revealed that genetic blockade of LGR5 internalization diminished cell fitness. Together these data provide proof-of-concept genetic evidence that blocking the clathrin-mediated endocytosis of LGR5 could be used to pharmacologically control cell behavior.
- Published
- 2017