TY - JOUR
T1 - Stimulation of the amino acid transporter SLC6A19 by JAK2
AU - Bhavsar, Shefalee K.
AU - Hosseinzadeh, Zohreh
AU - Merches, Katja
AU - Gu, Shuchen
AU - Bröer, Stefan
AU - Lang, Florian
PY - 2011/10/28
Y1 - 2011/10/28
N2 - JAK2 (Janus kinase-2) is expressed in a wide variety of cells including tumor cells and contributes to the proliferation and survival of those cells. The gain of function mutation V617FJAK2 mutant is found in the majority of myeloproliferative diseases. Cell proliferation depends on the availability of amino acids. Concentrative cellular amino acid uptake is in part accomplished by Na + coupled amino acid transport through SLC6A19 (B(0)AT). The present study thus explored whether JAK2 activates SLC6A19. To this end, SLC6A19 was expressed in Xenopus oocytes with or without wild type JAK2, V617FJAK2 or inactive K882EJAK2 and electrogenic amino acid transport determined by dual electrode voltage clamp. In SLC6A19-expressing oocytes but not in oocytes injected with water or JAK2 alone, the addition of leucine (2mM) to the bath generated a current (I le), which was significantly increased following coexpression of JAK2 or V617FJAK2, but not by coexpression of K882EJAK2. Coexpression of JAK2 enhanced the maximal transport rate without significantly modifying the affinity of the carrier. Exposure of the oocytes to the JAK2 inhibitor AG490 (40μM) resulted in a gradual decline of I le. According to chemiluminescence JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of I le following inhibition of carrier insertion by brefeldin A (5μM) was similar in the absence and presence of JAK2 indicating that JAK2 stimulates carrier insertion into rather than inhibiting carrier retrival from the cell membrane. In conclusion, JAK2 up-regulates SLC6A19 activity which may foster amino acid uptake into JAK2 expressing cells.
AB - JAK2 (Janus kinase-2) is expressed in a wide variety of cells including tumor cells and contributes to the proliferation and survival of those cells. The gain of function mutation V617FJAK2 mutant is found in the majority of myeloproliferative diseases. Cell proliferation depends on the availability of amino acids. Concentrative cellular amino acid uptake is in part accomplished by Na + coupled amino acid transport through SLC6A19 (B(0)AT). The present study thus explored whether JAK2 activates SLC6A19. To this end, SLC6A19 was expressed in Xenopus oocytes with or without wild type JAK2, V617FJAK2 or inactive K882EJAK2 and electrogenic amino acid transport determined by dual electrode voltage clamp. In SLC6A19-expressing oocytes but not in oocytes injected with water or JAK2 alone, the addition of leucine (2mM) to the bath generated a current (I le), which was significantly increased following coexpression of JAK2 or V617FJAK2, but not by coexpression of K882EJAK2. Coexpression of JAK2 enhanced the maximal transport rate without significantly modifying the affinity of the carrier. Exposure of the oocytes to the JAK2 inhibitor AG490 (40μM) resulted in a gradual decline of I le. According to chemiluminescence JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of I le following inhibition of carrier insertion by brefeldin A (5μM) was similar in the absence and presence of JAK2 indicating that JAK2 stimulates carrier insertion into rather than inhibiting carrier retrival from the cell membrane. In conclusion, JAK2 up-regulates SLC6A19 activity which may foster amino acid uptake into JAK2 expressing cells.
KW - Amino acid uptake
KW - Erythropoietin
KW - JAK2V617F
KW - Leptin
KW - Tumor cells
UR - http://www.scopus.com/inward/record.url?scp=80054905552&partnerID=8YFLogxK
U2 - 10.1016/j.bbrc.2011.09.074
DO - 10.1016/j.bbrc.2011.09.074
M3 - Article
SN - 0006-291X
VL - 414
SP - 456
EP - 461
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 3
ER -