FGF21 trafficking in intact human cells revealed by cryo-electron tomography with gold nanoparticles

Abstract

The fibroblast growth factor FGF21 was labeled with molecularly defined gold nanoparticles (AuNPs), applied to human adipocytes, and imaged by cryo-electron tomography (cryo-ET). Most AuNPs were in pairs about 80 Å apart, on the outer cell surface. Pairs of AuNPs were also abundant inside the cells in clathrin-coated vesicles and endosomes. AuNPs were present but no longer paired in multivesicular bodies. FGF21 could thus be tracked along the endocytotic pathway. The methods developed here to visualize signaling coupled to endocytosis can be applied to a wide variety of cargo and may be extended to studies of other intracellular transactions.

Additional Information

© 2019 Azubel et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited. Received: 26 October 2018; Accepted: 07 January 2019; Published: 28 January 2019. Data availability: All data is provided in the manuscript and supporting files. This research was supported by NIH grants AI 21144 to RDK and R35 122588 to GJJ. We thank Amgen Department of Protein Sciences for providing some of the reagents used in this study. We thank Dr. E P Geiduschek for discussion and comments on the manuscript. The funders had role in study design, and the decision to submit the work for publication. Competing interests: Jennifer Weiszmann, Jun Zhang, Yang Li: Employee of Amgen at the time the study was conducted. There are no other competing financial interests to declare. The other authors declare that no competing interests exist. Author contributions: Maia Azubel, Conceptualization, Data curation, Formal analysis, Supervision, Validation, Investigation, Visualization, Methodology, Writing—original draft, Project administration, Writing—review and editing; Stephen D Carter, Investigation, Methodology, Writing—review and editing; Jennifer Weiszmann, Resources, Investigation, Visualization, Methodology, Writing—review and editing; Jun Zhang, Resources, Writing—review and editing; Grant J Jensen, Conceptualization, Resources, Funding acquisition, Writing—review and editing; Yang Li, Conceptualization, Resources, Supervision, Funding acquisition, Methodology, Writing—review and editing; Roger D Kornberg, Conceptualization, Resources, Supervision, Writing—original draft, Writing—review and editing.

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Published - elife-43146-v1.pdf

Supplemental Material - elife-43146-transrepform-v1.docx

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