Modulation of activation-loop phosphorylation by JAK inhibitors is binding mode dependent.
Janus kinase (JAK) inhibitors are being developed for the treatment of rheumatoid arthritis, psoriasis, myeloproliferative neoplasms, and leukemias. Most of these drugs target the ATP-binding pocket and stabilize the active conformation of the JAK kinases. This type I binding mode can lead to an increase in JAK activation loop phosphorylation, despite blockade of kinase function. Here we report that stabilizing the inactive state via type II inhibition acts in the opposite manner, leading to a loss of activation loop phosphorylation. We used X-ray crystallography to corroborate the binding mode and report for the first time the crystal structure of the JAK2 kinase domain in an inactive conformation. Importantly, JAK inhibitor-induced activation loop phosphorylation requires receptor interaction, as well as intact kinase and pseudokinase domains. Hence, depending on the respective conformation stabilized by a JAK inhibitor, hyperphosphorylation of the activation loop may or may not be elicited.
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Rita
R
Andraos
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Zhiyan
Z
Qian
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Débora
D
Bonenfant
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Joëlle
J
Rubert
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Eric
E
Vangrevelinghe
Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Clemens
C
Scheufler
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Fanny
F
Marque
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Catherine H
CH
Régnier
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Alain
A
De Pover
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Hugues
H
Ryckelynck
Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center.|Gerstner Sloan Kettering Graduate School of Biomedical Sciences.
Neha
N
Bhagwat
Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center.
Priya
P
Koppikar
Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center.
Aviva
A
Goel
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Lorenza
L
Wyder
Center for Proteomic Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Gisele
G
Tavares
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Fabienne
F
Baffert
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Carole
C
Pissot-Soldermann
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Paul W
PW
Manley
Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Christoph
C
Gaul
Developmental and Molecular Pathways, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Hans
H
Voshol
Human Oncology and Pathogenesis Program and Leukemia Service, Department of Medicine, Memorial Sloan Kettering Cancer Center.
Ross L
RL
Levine
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
William R
WR
Sellers
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Francesco
F
Hofmann
Disease Area Oncology, Novartis Institutes for BioMedical Research, Basel, Switzerland.
Thomas
T
Radimerski
D000818:Animals; D001665:Binding Sites; D045744:Cell Line, Tumor; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000737:chemistry; D053612:Janus Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D050799:STAT5 Transcription Factor / Q000378:metabolism
D047428:Protein Kinase Inhibitors; D050799:STAT5 Transcription Factor; D053614:Janus Kinase 2; D053612:Janus Kinases