Receptor-mediated dimerization of JAK2 FERM domains is required for JAK2 activation

  1. Ryan D Ferrao
  2. Heidi Wallweber
  3. Patrick J Lupardus  Is a corresponding author
  1. Genentech Inc, United States

Abstract

Cytokines and interferons initiate intracellular signaling via receptor dimerization and activation of Janus kinases (JAKs). How JAKs structurally respond to changes in receptor conformation induced by ligand binding is not known. Here we present two crystal structures of the human JAK2 FERM and SH2 domains bound to Leptin receptor (LEPR) and Erythropoietin receptor (EPOR), which identify a novel dimeric conformation for JAK2. This 2:2 JAK2/receptor dimer, observed in both structures, identifies a previously uncharacterized receptor interaction essential to dimer formation that is mediated by a membrane-proximal peptide motif called the 'switch' region. Mutation of the receptor switch region disrupts STAT phosphorylation but does not affect JAK2 binding, indicating that receptor-mediated formation of the JAK2 FERM dimer is required for kinase activation. These data uncover the structural and molecular basis for how a cytokine-bound active receptor dimer brings together two JAK2 molecules to stimulate JAK2 kinase activity.

Data availability

Coordinates and structure factors have been deposited into the RCSB database as PDB ID 6E2Q (JAK2/EPOR) and PDB ID 6E2P (JAK2/LEPR).

The following data sets were generated

Article and author information

Author details

  1. Ryan D Ferrao

    Department of Structural Biology, Genentech Inc, South San Francisco, United States
    Competing interests
    Ryan D Ferrao, employee of Genentech, Inc. during the period when this work was performed. The author declares they have no competing interests..
  2. Heidi Wallweber

    Department of Structural Biology, Genentech Inc, South San Francisco, United States
    Competing interests
    Heidi Wallweber, employee of Genentech, Inc. during the period when this work was performed. The author declares they have no competing interests..
  3. Patrick J Lupardus

    Department of Structural Biology, Genentech Inc, South San Francisco, United States
    For correspondence
    lupardus.patrick@gene.com
    Competing interests
    Patrick J Lupardus, employee of Genentech, Inc. during the period when this work was performed. The author declares they have no competing interests..
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-8662-074X

Funding

No external funding was received for this work.

Reviewing Editor

  1. Yibing Shan, DE Shaw Research, United States

Publication history

  1. Received: May 4, 2018
  2. Accepted: July 24, 2018
  3. Accepted Manuscript published: July 25, 2018 (version 1)
  4. Version of Record published: August 6, 2018 (version 2)

Copyright

© 2018, Ferrao et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

Metrics

  • 3,081
    Page views
  • 577
    Downloads
  • 27
    Citations

Article citation count generated by polling the highest count across the following sources: Scopus, Crossref, PubMed Central.

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Open citations (links to open the citations from this article in various online reference manager services)

Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)

  1. Ryan D Ferrao
  2. Heidi Wallweber
  3. Patrick J Lupardus
(2018)
Receptor-mediated dimerization of JAK2 FERM domains is required for JAK2 activation
eLife 7:e38089.
https://doi.org/10.7554/eLife.38089

Further reading

    1. Biochemistry and Chemical Biology
    2. Computational and Systems Biology
    Laura M Doherty et al.
    Research Article

    Deubiquitinating enzymes (DUBs), ~100 of which are found in human cells, are proteases that remove ubiquitin conjugates from proteins, thereby regulating protein turnover. They are involved in a wide range of cellular activities and are emerging therapeutic targets for cancer and other diseases. Drugs targeting USP1 and USP30 are in clinical development for cancer and kidney disease respectively. However, the majority of substrates and pathways regulated by DUBs remain unknown, impeding efforts to prioritize specific enzymes for research and drug development. To assemble a knowledgebase of DUB activities, co-dependent genes, and substrates, we combined targeted experiments using CRISPR libraries and inhibitors with systematic mining of functional genomic databases. Analysis of the Dependency Map, Connectivity Map, Cancer Cell Line Encyclopedia, and multiple protein-protein interaction databases yielded specific hypotheses about DUB function, a subset of which were confirmed in follow-on experiments. The data in this paper are browsable online in a newly developed DUB Portal and promise to improve understanding of DUBs as a family as well as the activities of incompletely characterized DUBs (e.g. USPL1 and USP32) and those already targeted with investigational cancer therapeutics (e.g. USP14, UCHL5, and USP7).

    1. Biochemistry and Chemical Biology
    Erich J Goebel et al.
    Research Article

    Activin ligands are formed from two disulfide-linked inhibin β (Inhβ) subunit chains. They exist as homodimeric proteins, as in the case of activin A (ActA; InhβA/InhβA) or activin C (ActC; InhβC/InhβC), or as heterodimers, as with activin AC (ActAC; InhβA:InhβC). While the biological functions of ActA and activin B (ActB) have been well characterized, little is known about the biological functions of ActC or ActAC. One thought is that the InhβC chain functions to interfere with ActA production by forming less active ActAC heterodimers. Here, we assessed and characterized the signaling capacity of ligands containing the InhβC chain. ActC and ActAC activated SMAD2/3-dependent signaling via the type I receptor, activin receptor-like kinase 7 (ALK7). Relative to ActA and ActB, ActC exhibited lower affinity for the cognate activin type II receptors and was resistant to neutralization by the extracellular antagonist, follistatin. In mature murine adipocytes, which exhibit high ALK7 expression, ActC elicited a SMAD2/3 response similar to ActB, which can also signal via ALK7. Collectively, these results establish that ActC and ActAC are active ligands that exhibit a distinct signaling receptor and antagonist profile compared to other activins.