In:
American Journal of Physiology-Cell Physiology, American Physiological Society, Vol. 306, No. 4 ( 2014-02-15), p. C374-C384
Abstract:
Janus kinase 2 (JAK2) contributes to intracellular signaling of leptin and erythropoietin, hormones protecting cells during energy depletion. The present study explores whether JAK2 is activated by energy depletion and regulates Na + /K + -ATPase, the major energy-consuming pump. In Jurkat cells, JAK2 activity was determined by radioactive kinase assay, phosphorylated JAK2 detected by Western blotting, ATP levels measured by luciferase assay, as well as Na + /K + -ATPase α1-subunit transcript and protein abundance determined by real-time PCR and Western blotting, respectively. Ouabain-sensitive K + -induced currents ( I pump ) were measured by whole cell patch clamp. I pump was further determined by dual-electrode voltage clamp in Xenopus oocytes injected with cRNA-encoding JAK2, active V617F JAK2, or inactive K882E JAK2. As a result, in Jurkat T cells, JAK2 activity significantly increased following energy depletion by sodium azide (NaN 3 ) or 2,4- dinitro phenol (DNP). DNP- and NaN 3 -induced decrease of cellular ATP was significantly augmented by JAK2 inhibitor AG490 and blunted by Na + /K + -ATPase inhibitor ouabain. DNP decreased and AG490 enhanced I pump as well as Na + /K + -ATPase α1-subunit transcript and protein abundance. The α1-subunit transcript levels were also enhanced by signal transducer and activator of transcription-5 inhibitor CAS 285986-31-4. In Xenopus oocytes, I pump was significantly decreased by expression of JAK2 and V617F JAK2 but not of K882E JAK2, effects again reversed by AG490. In V617F JAK2-expressing Xenopus oocytes, neither DNP nor NaN 3 resulted in further decline of I pump . In Xenopus oocytes, the effect of V617F JAK2 on I pump was not prevented by inhibition of transcription with actinomycin. In conclusion, JAK2 is a novel energy-sensing kinase that curtails energy consumption by downregulating Na + /K + -ATPase expression and activity.
Type of Medium:
Online Resource
ISSN:
0363-6143
,
1522-1563
DOI:
10.1152/ajpcell.00320.2013
Language:
English
Publisher:
American Physiological Society
Publication Date:
2014
detail.hit.zdb_id:
1477334-X
SSG:
12
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