Stimulation of the amino acid transporter SLC6A19 by JAK2

• Published in: Biochemical and biophysical research communications 2011-10, Vol.414 (3), p.456-461
• Main Authors: Bhavsar, Shefalee K., Hosseinzadeh, Zohreh, Merches, Katja, Gu, Shuchen, Bröer, Stefan, Lang, Florian
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Amino Acid Transport Systems, Neutral - metabolism; Amino acid uptake; Amino Acids - metabolism; Animals; Brefeldin A - pharmacology; Cell Line, Tumor; CELL MEMBRANES; CELL PROLIFERATION; CHEMILUMINESCENCE; DISEASES; ERYTHROPOIETIN; Humans; INHIBITION; JAK2V617F; Janus Kinase 2 - metabolism; LEPTIN; LEUCINE; MUTANTS; MUTATIONS; OOCYTES; SODIUM IONS; STIMULATION; TUMOR CELLS; UPTAKE; VANADIUM 61; Xenopus
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2011.09.074

► The amino acid transporter SLC6A19 is upregulated by Janus kinase-2 JAK2. ► The V617FJAK2 mutant, causing myeloproliferative disease, is more effective. ► JAK2 inhibitor AG490 reverses stimulation of SLC6A19 by V617FJAK2. ► JAK2 enhances SLC6A19 protein insertion into the cell membrane. ► SLC6A19 may contribute to amino acid uptake into V617FJAK2 expressing tumor cells. 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 (Ile), 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 Ile. According to chemiluminescence JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of Ile 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.