Differences in signaling through the B-cell leukemia oncoprotein CRLF2 in response to TSLP and through mutant JAK2.
Approximately 10% of B-cell acute lymphoblastic leukemias (B-ALLs) overexpress the cytokine receptor subunit CRLF2, which may confer a poor prognosis. CRLF2 binds its ligand thymic stromal lymphopoietin (TSLP) as a heterodimer with IL7R. Subsets of CRLF2-overexpressing B-ALLs also have a gain-of-function CRLF2 F232C mutation or activating mutations in JAK2. Whether these mutant alleles confer differences in signaling has not been addressed. Through a domain mutation analysis, we demonstrate a distinct dependence on the CRLF2 intracellular tyrosine Y368 in signaling by CRLF2 F232C, but not signaling induced by TSLP or through CRLF2/mutant JAK2. In contrast, CRLF2 signaling in each context is strictly dependent on both the CRLF2 box1 domain and the intracellular tryptophan W286. Using a global quantitative analysis of tyrosine phosphorylation induced by TSLP, we previously identified TSLP-induced phosphorylation of multiple kinases implicated in B-cell receptor signaling, including Lyn, Btk, Hck, Syk, MAPK8, MAPK9, and MAPK10. We now demonstrate that cells dependent on CRLF2/mutant JAK2 have reduced phosphorylation at these targets, suggesting that the kinases promote TSLP-mediated proliferation but serve as negative regulators of CRLF2/mutant JAK2 signaling. Thus, targetable nodes downstream of CRLF2 differ based on the presence or absence of additional mutations in CRLF2 signaling components.
Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
Diederik
D
van Bodegom
Jun
J
Zhong
Nadja
N
Kopp
Chaitali
C
Dutta
Min-Sik
MS
Kim
Liat
L
Bird
Oliver
O
Weigert
Jeffrey
J
Tyner
Akhilesh
A
Pandey
Akinori
A
Yoda
David M
DM
Weinstock
D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D006801:Humans; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010766:Phosphorylation; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000378:metabolism* / Q000473:pathology; D054448:Precursor Cells, B-Lymphoid / Q000166:cytology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D018121:Receptors, Cytokine / Q000235:genetics / Q000378:metabolism*; D020395:Receptors, Interleukin-7 / Q000378:metabolism; D000094632:Thymic Stromal Lymphopoietin
C498762:CRLF2 protein, human; D016207:Cytokines; D034741:RNA, Small Interfering; D018121:Receptors, Cytokine; D020395:Receptors, Interleukin-7; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D000094632:Thymic Stromal Lymphopoietin