Abstract
Mutations in the calreticulin gene (CALR) were recently identified in approximately 70-80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a nonhematopoietic cell line does not directly activate JAK/STAT signaling compared to wildtype CALR and JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 211-219 |
| Number of pages | 9 |
| Journal | American Journal of Hematology |
| Volume | 91 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2016 |
Fingerprint
ASJC Scopus subject areas
- Hematology
Cite this
Mutant calreticulin-expressing cells induce monocyte hyperreactivity through a paracrine mechanism. / Garbati, Michael R.; Welgan, Catherine A.; Landefeld, Sally H.; Newell, Laura; Agarwal, Anupriya; Dunlap, Jennifer; Chourasia, Tapan K.; Lee, Hyunjung; Elferich, Johannes; Traer, Elie; Rattray, Rogan; Cascio, Michael; Press, Richard; Bagby, Grover C.; Tyner, Jeffrey; Druker, Brian; Dao, Kim-Hien.
In: American Journal of Hematology, Vol. 91, No. 2, 01.02.2016, p. 211-219.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mutant calreticulin-expressing cells induce monocyte hyperreactivity through a paracrine mechanism
AU - Garbati, Michael R.
AU - Welgan, Catherine A.
AU - Landefeld, Sally H.
AU - Newell, Laura
AU - Agarwal, Anupriya
AU - Dunlap, Jennifer
AU - Chourasia, Tapan K.
AU - Lee, Hyunjung
AU - Elferich, Johannes
AU - Traer, Elie
AU - Rattray, Rogan
AU - Cascio, Michael
AU - Press, Richard
AU - Bagby, Grover C.
AU - Tyner, Jeffrey
AU - Druker, Brian
AU - Dao, Kim-Hien
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Mutations in the calreticulin gene (CALR) were recently identified in approximately 70-80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a nonhematopoietic cell line does not directly activate JAK/STAT signaling compared to wildtype CALR and JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.
AB - Mutations in the calreticulin gene (CALR) were recently identified in approximately 70-80% of patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis. All frameshift mutations generate a recurring novel C-terminus. Here we provide evidence that mutant calreticulin does not accumulate efficiently in cells and is abnormally enriched in the nucleus and extracellular space compared to wildtype calreticulin. The main determinant of these findings is the loss of the calcium-binding and KDEL domains. Expression of type I mutant CALR in Ba/F3 cells confers minimal IL-3-independent growth. Interestingly, expression of type I and type II mutant CALR in a nonhematopoietic cell line does not directly activate JAK/STAT signaling compared to wildtype CALR and JAK2-V617F expression. These results led us to investigate paracrine mechanisms of JAK/STAT activation. Here we show that conditioned media from cells expressing type I mutant CALR exaggerate cytokine production from normal monocytes with or without treatment with a toll-like receptor agonist. These effects are not dependent on the novel C-terminus. These studies offer novel insights into the mechanism of JAK/STAT activation in patients with JAK2-V617F-negative essential thrombocytosis and primary myelofibrosis.
UR - http://www.scopus.com/inward/record.url?scp=84961340359&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84961340359&partnerID=8YFLogxK
U2 - 10.1002/ajh.24245
DO - 10.1002/ajh.24245
M3 - Article
C2 - 26573090
AN - SCOPUS:84961340359
VL - 91
SP - 211
EP - 219
JO - American Journal of Hematology
JF - American Journal of Hematology
SN - 0361-8609
IS - 2
ER -